/src/git/apply.c

Source
/*
 * apply.c
 *
 * Copyright (C) Linus Torvalds, 2005
 *
 * This applies patches on top of some (arbitrary) version of the SCM.
 *
 */

#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "abspath.h"
#include "base85.h"
#include "config.h"
#include "odb.h"
#include "delta.h"
#include "diff.h"
#include "dir.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "xdiff-interface.h"
#include "merge-ll.h"
#include "lockfile.h"
#include "name-hash.h"
#include "object-name.h"
#include "object-file.h"
#include "parse-options.h"
#include "path.h"
#include "quote.h"
#include "read-cache.h"
#include "repository.h"
#include "rerere.h"
#include "apply.h"
#include "entry.h"
#include "setup.h"
#include "symlinks.h"
#include "wildmatch.h"
#include "ws.h"

struct gitdiff_data {
  struct strbuf *root;
  const char *patch_input_file;
  int linenr;
  int p_value;
};

static void git_apply_config(void)
{
  repo_config_get_string(the_repository, "apply.whitespace", &apply_default_whitespace);
  repo_config_get_string(the_repository, "apply.ignorewhitespace", &apply_default_ignorewhitespace);
  repo_config(the_repository, git_xmerge_config, NULL);
}

static int parse_whitespace_option(struct apply_state *state, const char *option)
{
  if (!option) {
    state->ws_error_action = warn_on_ws_error;
    return 0;
  }
  if (!strcmp(option, "warn")) {
    state->ws_error_action = warn_on_ws_error;
    return 0;
  }
  if (!strcmp(option, "nowarn")) {
    state->ws_error_action = nowarn_ws_error;
    return 0;
  }
  if (!strcmp(option, "error")) {
    state->ws_error_action = die_on_ws_error;
    return 0;
  }
  if (!strcmp(option, "error-all")) {
    state->ws_error_action = die_on_ws_error;
    state->squelch_whitespace_errors = 0;
    return 0;
  }
  if (!strcmp(option, "strip") || !strcmp(option, "fix")) {
    state->ws_error_action = correct_ws_error;
    return 0;
  }
  /*
   * Please update $__git_whitespacelist in git-completion.bash,
   * Documentation/git-apply.adoc, and Documentation/git-am.adoc
   * when you add new options.
   */
  return error(_("unrecognized whitespace option '%s'"), option);
}

static int parse_ignorewhitespace_option(struct apply_state *state,
             const char *option)
{
  if (!option || !strcmp(option, "no") ||
      !strcmp(option, "false") || !strcmp(option, "never") ||
      !strcmp(option, "none")) {
    state->ws_ignore_action = ignore_ws_none;
    return 0;
  }
  if (!strcmp(option, "change")) {
    state->ws_ignore_action = ignore_ws_change;
    return 0;
  }
  return error(_("unrecognized whitespace ignore option '%s'"), option);
}

int init_apply_state(struct apply_state *state,
         struct repository *repo,
         const char *prefix)
{
  memset(state, 0, sizeof(*state));
  state->prefix = prefix;
  state->repo = repo;
  state->apply = 1;
  state->line_termination = '\n';
  state->p_value = 1;
  state->p_context = UINT_MAX;
  state->squelch_whitespace_errors = 5;
  state->ws_error_action = warn_on_ws_error;
  state->ws_ignore_action = ignore_ws_none;
  state->linenr = 1;
  string_list_init_nodup(&state->fn_table);
  string_list_init_nodup(&state->limit_by_name);
  strset_init(&state->removed_symlinks);
  strset_init(&state->kept_symlinks);
  strbuf_init(&state->root, 0);

  git_apply_config();
  if (apply_default_whitespace && parse_whitespace_option(state, apply_default_whitespace))
    return -1;
  if (apply_default_ignorewhitespace && parse_ignorewhitespace_option(state, apply_default_ignorewhitespace))
    return -1;
  return 0;
}

void clear_apply_state(struct apply_state *state)
{
  string_list_clear(&state->limit_by_name, 0);
  strset_clear(&state->removed_symlinks);
  strset_clear(&state->kept_symlinks);
  strbuf_release(&state->root);
  FREE_AND_NULL(state->fake_ancestor);

  /* &state->fn_table is cleared at the end of apply_patch() */
}

static void mute_routine(const char *msg UNUSED, va_list params UNUSED)
{
  /* do nothing */
}

int check_apply_state(struct apply_state *state, int force_apply)
{
  int is_not_gitdir = !startup_info->have_repository;

  if (state->apply_with_reject && state->threeway)
    return error(_("options '%s' and '%s' cannot be used together"), "--reject", "--3way");
  if (state->threeway) {
    if (is_not_gitdir)
      return error(_("'%s' outside a repository"), "--3way");
    state->check_index = 1;
  }
  if (state->apply_with_reject) {
    state->apply = 1;
    if (state->apply_verbosity == verbosity_normal)
      state->apply_verbosity = verbosity_verbose;
  }
  if (!force_apply && (state->diffstat || state->numstat || state->summary || state->check || state->fake_ancestor))
    state->apply = 0;
  if (state->check_index && is_not_gitdir)
    return error(_("'%s' outside a repository"), "--index");
  if (state->cached) {
    if (is_not_gitdir)
      return error(_("'%s' outside a repository"), "--cached");
    state->check_index = 1;
  }
  if (state->ita_only && (state->check_index || is_not_gitdir))
    state->ita_only = 0;
  if (state->check_index)
    state->unsafe_paths = 0;

  if (state->apply_verbosity <= verbosity_silent) {
    state->saved_error_routine = get_error_routine();
    state->saved_warn_routine = get_warn_routine();
    set_error_routine(mute_routine);
    set_warn_routine(mute_routine);
  }

  return 0;
}

static void set_default_whitespace_mode(struct apply_state *state)
{
  if (!state->whitespace_option && !apply_default_whitespace)
    state->ws_error_action = (state->apply ? warn_on_ws_error : nowarn_ws_error);
}

/*
 * This represents one "hunk" from a patch, starting with
 * "@@ -oldpos,oldlines +newpos,newlines @@" marker.  The
 * patch text is pointed at by patch, and its byte length
 * is stored in size.  leading and trailing are the number
 * of context lines.
 */
struct fragment {
  unsigned long leading, trailing;
  unsigned long oldpos, oldlines;
  unsigned long newpos, newlines;
  /*
   * 'patch' is usually borrowed from buf in apply_patch(),
   * but some codepaths store an allocated buffer.
   */
  const char *patch;
  unsigned free_patch:1,
    rejected:1;
  int size;
  int linenr;
  struct fragment *next;
};

/*
 * When dealing with a binary patch, we reuse "leading" field
 * to store the type of the binary hunk, either deflated "delta"
 * or deflated "literal".
 */
#define binary_patch_method leading
#define BINARY_DELTA_DEFLATED 1
#define BINARY_LITERAL_DEFLATED 2

static void free_fragment_list(struct fragment *list)
{
  while (list) {
    struct fragment *next = list->next;
    if (list->free_patch)
      free((char *)list->patch);
    free(list);
    list = next;
  }
}

void release_patch(struct patch *patch)
{
  free_fragment_list(patch->fragments);
  free(patch->def_name);
  free(patch->old_name);
  free(patch->new_name);
  free(patch->result);
}

static void free_patch(struct patch *patch)
{
  release_patch(patch);
  free(patch);
}

static void free_patch_list(struct patch *list)
{
  while (list) {
    struct patch *next = list->next;
    free_patch(list);
    list = next;
  }
}

/*
 * A line in a file, len-bytes long (includes the terminating LF,
 * except for an incomplete line at the end if the file ends with
 * one), and its contents hashes to 'hash'.
 */
struct line {
  size_t len;
  unsigned hash : 24;
  unsigned flag : 8;
#define LINE_COMMON     1
#define LINE_PATCHED  2
};

/*
 * This represents a "file", which is an array of "lines".
 */
struct image {
  struct strbuf buf;
  struct line *line;
  size_t line_nr, line_alloc;
};
#define IMAGE_INIT { \
  .buf = STRBUF_INIT, \
}

static void image_init(struct image *image)
{
  struct image empty = IMAGE_INIT;
  memcpy(image, &empty, sizeof(*image));
}

static void image_clear(struct image *image)
{
  strbuf_release(&image->buf);
  free(image->line);
  image_init(image);
}

static uint32_t hash_line(const char *cp, size_t len)
{
  size_t i;
  uint32_t h;
  for (i = 0, h = 0; i < len; i++) {
    if (!isspace(cp[i])) {
      h = h * 3 + (cp[i] & 0xff);
    }
  }
  return h;
}

static void image_add_line(struct image *img, const char *bol, size_t len, unsigned flag)
{
  ALLOC_GROW(img->line, img->line_nr + 1, img->line_alloc);
  img->line[img->line_nr].len = len;
  img->line[img->line_nr].hash = hash_line(bol, len);
  img->line[img->line_nr].flag = flag;
  img->line_nr++;
}

/*
 * "buf" has the file contents to be patched (read from various sources).
 * attach it to "image" and add line-based index to it.
 * "image" now owns the "buf".
 */
static void image_prepare(struct image *image, char *buf, size_t len,
        int prepare_linetable)
{
  const char *cp, *ep;

  image_clear(image);
  strbuf_attach(&image->buf, buf, len, len + 1);

  if (!prepare_linetable)
    return;

  ep = image->buf.buf + image->buf.len;
  cp = image->buf.buf;
  while (cp < ep) {
    const char *next;
    for (next = cp; next < ep && *next != '\n'; next++)
      ;
    if (next < ep)
      next++;
    image_add_line(image, cp, next - cp, 0);
    cp = next;
  }
}

static void image_remove_first_line(struct image *img)
{
  strbuf_remove(&img->buf, 0, img->line[0].len);
  img->line_nr--;
  if (img->line_nr)
    MOVE_ARRAY(img->line, img->line + 1, img->line_nr);
}

static void image_remove_last_line(struct image *img)
{
  size_t last_line_len = img->line[img->line_nr - 1].len;
  strbuf_setlen(&img->buf, img->buf.len - last_line_len);
  img->line_nr--;
}

/* fmt must contain _one_ %s and no other substitution */
static void say_patch_name(FILE *output, const char *fmt, struct patch *patch)
{
  struct strbuf sb = STRBUF_INIT;

  if (patch->old_name && patch->new_name &&
      strcmp(patch->old_name, patch->new_name)) {
    quote_c_style(patch->old_name, &sb, NULL, 0);
    strbuf_addstr(&sb, " => ");
    quote_c_style(patch->new_name, &sb, NULL, 0);
  } else {
    const char *n = patch->new_name;
    if (!n)
      n = patch->old_name;
    quote_c_style(n, &sb, NULL, 0);
  }
  fprintf(output, fmt, sb.buf);
  fputc('\n', output);
  strbuf_release(&sb);
}

#define SLOP (16)

/*
 * apply.c isn't equipped to handle arbitrarily large patches, because
 * it intermingles `unsigned long` with `int` for the type used to store
 * buffer lengths.
 *
 * Only process patches that are just shy of 1 GiB large in order to
 * avoid any truncation or overflow issues.
 */
#define MAX_APPLY_SIZE (1024UL * 1024 * 1023)

static int read_patch_file(struct strbuf *sb, int fd)
{
  if (strbuf_read(sb, fd, 0) < 0)
    return error_errno(_("failed to read patch"));
  else if (sb->len >= MAX_APPLY_SIZE)
    return error(_("patch too large"));
  /*
   * Make sure that we have some slop in the buffer
   * so that we can do speculative "memcmp" etc, and
   * see to it that it is NUL-filled.
   */
  strbuf_grow(sb, SLOP);
  memset(sb->buf + sb->len, 0, SLOP);
  return 0;
}

static unsigned long linelen(const char *buffer, unsigned long size)
{
  unsigned long len = 0;
  while (size--) {
    len++;
    if (*buffer++ == '\n')
      break;
  }
  return len;
}

static int is_dev_null(const char *str)
{
  return skip_prefix(str, "/dev/null", &str) && isspace(*str);
}

#define TERM_SPACE  1
#define TERM_TAB  2

static int name_terminate(int c, int terminate)
{
  if (c == ' ' && !(terminate & TERM_SPACE))
    return 0;
  if (c == '\t' && !(terminate & TERM_TAB))
    return 0;

  return 1;
}

/* remove double slashes to make --index work with such filenames */
static char *squash_slash(char *name)
{
  int i = 0, j = 0;

  if (!name)
    return NULL;

  while (name[i]) {
    if ((name[j++] = name[i++]) == '/')
      while (name[i] == '/')
        i++;
  }
  name[j] = '\0';
  return name;
}

static char *find_name_gnu(struct strbuf *root,
         const char *line,
         int p_value)
{
  struct strbuf name = STRBUF_INIT;
  char *cp;

  /*
   * Proposed "new-style" GNU patch/diff format; see
   * https://lore.kernel.org/git/7vll0wvb2a.fsf@assigned-by-dhcp.cox.net/
   */
  if (unquote_c_style(&name, line, NULL)) {
    strbuf_release(&name);
    return NULL;
  }

  for (cp = name.buf; p_value; p_value--) {
    cp = strchr(cp, '/');
    if (!cp) {
      strbuf_release(&name);
      return NULL;
    }
    cp++;
  }

  strbuf_remove(&name, 0, cp - name.buf);
  if (root->len)
    strbuf_insert(&name, 0, root->buf, root->len);
  return squash_slash(strbuf_detach(&name, NULL));
}

static size_t sane_tz_len(const char *line, size_t len)
{
  const char *tz, *p;

  if (len < strlen(" +0500") || line[len-strlen(" +0500")] != ' ')
    return 0;
  tz = line + len - strlen(" +0500");

  if (tz[1] != '+' && tz[1] != '-')
    return 0;

  for (p = tz + 2; p != line + len; p++)
    if (!isdigit(*p))
      return 0;

  return line + len - tz;
}

static size_t tz_with_colon_len(const char *line, size_t len)
{
  const char *tz, *p;

  if (len < strlen(" +08:00") || line[len - strlen(":00")] != ':')
    return 0;
  tz = line + len - strlen(" +08:00");

  if (tz[0] != ' ' || (tz[1] != '+' && tz[1] != '-'))
    return 0;
  p = tz + 2;
  if (!isdigit(*p++) || !isdigit(*p++) || *p++ != ':' ||
      !isdigit(*p++) || !isdigit(*p++))
    return 0;

  return line + len - tz;
}

static size_t date_len(const char *line, size_t len)
{
  const char *date, *p;

  if (len < strlen("72-02-05") || line[len-strlen("-05")] != '-')
    return 0;
  p = date = line + len - strlen("72-02-05");

  if (!isdigit(*p++) || !isdigit(*p++) || *p++ != '-' ||
      !isdigit(*p++) || !isdigit(*p++) || *p++ != '-' ||
      !isdigit(*p++) || !isdigit(*p++)) /* Not a date. */
    return 0;

  if (date - line >= strlen("19") &&
      isdigit(date[-1]) && isdigit(date[-2])) /* 4-digit year */
    date -= strlen("19");

  return line + len - date;
}

static size_t short_time_len(const char *line, size_t len)
{
  const char *time, *p;

  if (len < strlen(" 07:01:32") || line[len-strlen(":32")] != ':')
    return 0;
  p = time = line + len - strlen(" 07:01:32");

  /* Permit 1-digit hours? */
  if (*p++ != ' ' ||
      !isdigit(*p++) || !isdigit(*p++) || *p++ != ':' ||
      !isdigit(*p++) || !isdigit(*p++) || *p++ != ':' ||
      !isdigit(*p++) || !isdigit(*p++)) /* Not a time. */
    return 0;

  return line + len - time;
}

static size_t fractional_time_len(const char *line, size_t len)
{
  const char *p;
  size_t n;

  /* Expected format: 19:41:17.620000023 */
  if (!len || !isdigit(line[len - 1]))
    return 0;
  p = line + len - 1;

  /* Fractional seconds. */
  while (p > line && isdigit(*p))
    p--;
  if (*p != '.')
    return 0;

  /* Hours, minutes, and whole seconds. */
  n = short_time_len(line, p - line);
  if (!n)
    return 0;

  return line + len - p + n;
}

static size_t trailing_spaces_len(const char *line, size_t len)
{
  const char *p;

  /* Expected format: ' ' x (1 or more)  */
  if (!len || line[len - 1] != ' ')
    return 0;

  p = line + len;
  while (p != line) {
    p--;
    if (*p != ' ')
      return line + len - (p + 1);
  }

  /* All spaces! */
  return len;
}

static size_t diff_timestamp_len(const char *line, size_t len)
{
  const char *end = line + len;
  size_t n;

  /*
   * Posix: 2010-07-05 19:41:17
   * GNU: 2010-07-05 19:41:17.620000023 -0500
   */

  if (!isdigit(end[-1]))
    return 0;

  n = sane_tz_len(line, end - line);
  if (!n)
    n = tz_with_colon_len(line, end - line);
  end -= n;

  n = short_time_len(line, end - line);
  if (!n)
    n = fractional_time_len(line, end - line);
  end -= n;

  n = date_len(line, end - line);
  if (!n) /* No date.  Too bad. */
    return 0;
  end -= n;

  if (end == line) /* No space before date. */
    return 0;
  if (end[-1] == '\t') { /* Success! */
    end--;
    return line + len - end;
  }
  if (end[-1] != ' ') /* No space before date. */
    return 0;

  /* Whitespace damage. */
  end -= trailing_spaces_len(line, end - line);
  return line + len - end;
}

static char *find_name_common(struct strbuf *root,
            const char *line,
            const char *def,
            int p_value,
            const char *end,
            int terminate)
{
  int len;
  const char *start = NULL;

  if (p_value == 0)
    start = line;
  while (line != end) {
    char c = *line;

    if (!end && isspace(c)) {
      if (c == '\n')
        break;
      if (name_terminate(c, terminate))
        break;
    }
    line++;
    if (c == '/' && !--p_value)
      start = line;
  }
  if (!start)
    return squash_slash(xstrdup_or_null(def));
  len = line - start;
  if (!len)
    return squash_slash(xstrdup_or_null(def));

  /*
   * Generally we prefer the shorter name, especially
   * if the other one is just a variation of that with
   * something else tacked on to the end (ie "file.orig"
   * or "file~").
   */
  if (def) {
    int deflen = strlen(def);
    if (deflen < len && !strncmp(start, def, deflen))
      return squash_slash(xstrdup(def));
  }

  if (root->len) {
    char *ret = xstrfmt("%s%.*s", root->buf, len, start);
    return squash_slash(ret);
  }

  return squash_slash(xmemdupz(start, len));
}

static char *find_name(struct strbuf *root,
           const char *line,
           char *def,
           int p_value,
           int terminate)
{
  if (*line == '"') {
    char *name = find_name_gnu(root, line, p_value);
    if (name)
      return name;
  }

  return find_name_common(root, line, def, p_value, NULL, terminate);
}

static char *find_name_traditional(struct strbuf *root,
           const char *line,
           char *def,
           int p_value)
{
  size_t len;
  size_t date_len;

  if (*line == '"') {
    char *name = find_name_gnu(root, line, p_value);
    if (name)
      return name;
  }

  len = strchrnul(line, '\n') - line;
  date_len = diff_timestamp_len(line, len);
  if (!date_len)
    return find_name_common(root, line, def, p_value, NULL, TERM_TAB);
  len -= date_len;

  return find_name_common(root, line, def, p_value, line + len, 0);
}

/*
 * Given the string after "--- " or "+++ ", guess the appropriate
 * p_value for the given patch.
 */
static int guess_p_value(struct apply_state *state, const char *nameline)
{
  char *name, *cp;
  int val = -1;

  if (is_dev_null(nameline))
    return -1;
  name = find_name_traditional(&state->root, nameline, NULL, 0);
  if (!name)
    return -1;
  cp = strchr(name, '/');
  if (!cp)
    val = 0;
  else if (state->prefix) {
    /*
     * Does it begin with "a/$our-prefix" and such?  Then this is
     * very likely to apply to our directory.
     */
    if (starts_with(name, state->prefix))
      val = count_slashes(state->prefix);
    else {
      cp++;
      if (starts_with(cp, state->prefix))
        val = count_slashes(state->prefix) + 1;
    }
  }
  free(name);
  return val;
}

/*
 * Does the ---/+++ line have the POSIX timestamp after the last HT?
 * GNU diff puts epoch there to signal a creation/deletion event.  Is
 * this such a timestamp?
 */
static int has_epoch_timestamp(const char *nameline)
{
  /*
   * We are only interested in epoch timestamp; any non-zero
   * fraction cannot be one, hence "(\.0+)?" in the regexp below.
   * For the same reason, the date must be either 1969-12-31 or
   * 1970-01-01, and the seconds part must be "00".
   */
  const char stamp_regexp[] =
    "^[0-2][0-9]:([0-5][0-9]):00(\\.0+)?"
    " "
    "([-+][0-2][0-9]:?[0-5][0-9])\n";
  const char *timestamp = NULL, *cp, *colon;
  static regex_t *stamp;
  regmatch_t m[10];
  int zoneoffset, epoch_hour, hour, minute;
  int status;

  for (cp = nameline; *cp != '\n'; cp++) {
    if (*cp == '\t')
      timestamp = cp + 1;
  }
  if (!timestamp)
    return 0;

  /*
   * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
   * (west of GMT) or 1970-01-01 (east of GMT)
   */
  if (skip_prefix(timestamp, "1969-12-31 ", &timestamp))
    epoch_hour = 24;
  else if (skip_prefix(timestamp, "1970-01-01 ", &timestamp))
    epoch_hour = 0;
  else
    return 0;

  if (!stamp) {
    stamp = xmalloc(sizeof(*stamp));
    if (regcomp(stamp, stamp_regexp, REG_EXTENDED)) {
      warning(_("Cannot prepare timestamp regexp %s"),
        stamp_regexp);
      return 0;
    }
  }

  status = regexec(stamp, timestamp, ARRAY_SIZE(m), m, 0);
  if (status) {
    if (status != REG_NOMATCH)
      warning(_("regexec returned %d for input: %s"),
        status, timestamp);
    return 0;
  }

  hour = strtol(timestamp, NULL, 10);
  minute = strtol(timestamp + m[1].rm_so, NULL, 10);

  zoneoffset = strtol(timestamp + m[3].rm_so + 1, (char **) &colon, 10);
  if (*colon == ':')
    zoneoffset = zoneoffset * 60 + strtol(colon + 1, NULL, 10);
  else
    zoneoffset = (zoneoffset / 100) * 60 + (zoneoffset % 100);
  if (timestamp[m[3].rm_so] == '-')
    zoneoffset = -zoneoffset;

  return hour * 60 + minute - zoneoffset == epoch_hour * 60;
}

/*
 * Get the name etc info from the ---/+++ lines of a traditional patch header
 *
 * FIXME! The end-of-filename heuristics are kind of screwy. For existing
 * files, we can happily check the index for a match, but for creating a
 * new file we should try to match whatever "patch" does. I have no idea.
 */
static int parse_traditional_patch(struct apply_state *state,
           const char *first,
           const char *second,
           struct patch *patch)
{
  char *name;

  first += 4; /* skip "--- " */
  second += 4;  /* skip "+++ " */
  if (!state->p_value_known) {
    int p, q;
    p = guess_p_value(state, first);
    q = guess_p_value(state, second);
    if (p < 0) p = q;
    if (0 <= p && p == q) {
      state->p_value = p;
      state->p_value_known = 1;
    }
  }
  if (is_dev_null(first)) {
    patch->is_new = 1;
    patch->is_delete = 0;
    name = find_name_traditional(&state->root, second, NULL, state->p_value);
    patch->new_name = name;
  } else if (is_dev_null(second)) {
    patch->is_new = 0;
    patch->is_delete = 1;
    name = find_name_traditional(&state->root, first, NULL, state->p_value);
    patch->old_name = name;
  } else {
    char *first_name;
    first_name = find_name_traditional(&state->root, first, NULL, state->p_value);
    name = find_name_traditional(&state->root, second, first_name, state->p_value);
    free(first_name);
    if (has_epoch_timestamp(first)) {
      patch->is_new = 1;
      patch->is_delete = 0;
      patch->new_name = name;
    } else if (has_epoch_timestamp(second)) {
      patch->is_new = 0;
      patch->is_delete = 1;
      patch->old_name = name;
    } else {
      patch->old_name = name;
      patch->new_name = xstrdup_or_null(name);
    }
  }
  if (!name)
    return error(_("unable to find filename in patch at %s:%d"),
           state->patch_input_file, state->linenr);

  return 0;
}

static int gitdiff_hdrend(struct gitdiff_data *state UNUSED,
        const char *line UNUSED,
        struct patch *patch UNUSED)
{
  return 1;
}

/*
 * We're anal about diff header consistency, to make
 * sure that we don't end up having strange ambiguous
 * patches floating around.
 *
 * As a result, gitdiff_{old|new}name() will check
 * their names against any previous information, just
 * to make sure..
 */
#define DIFF_OLD_NAME 0
#define DIFF_NEW_NAME 1

static int gitdiff_verify_name(struct gitdiff_data *state,
             const char *line,
             int isnull,
             char **name,
             int side)
{
  if (!*name && !isnull) {
    *name = find_name(state->root, line, NULL, state->p_value, TERM_TAB);
    return 0;
  }

  if (*name) {
    char *another;
    if (isnull) {
      if (state->patch_input_file)
        return error(_("git apply: bad git-diff - expected /dev/null, got %s at %s:%d"),
               *name, state->patch_input_file, state->linenr);
      return error(_("git apply: bad git-diff - expected /dev/null, got %s on line %d"),
             *name, state->linenr);
    }
    another = find_name(state->root, line, NULL, state->p_value, TERM_TAB);
    if (!another || strcmp(another, *name)) {
      free(another);
      if (state->patch_input_file)
        return error((side == DIFF_NEW_NAME) ?
               _("git apply: bad git-diff - inconsistent new filename at %s:%d") :
               _("git apply: bad git-diff - inconsistent old filename at %s:%d"),
               state->patch_input_file, state->linenr);
      return error((side == DIFF_NEW_NAME) ?
             _("git apply: bad git-diff - inconsistent new filename on line %d") :
             _("git apply: bad git-diff - inconsistent old filename on line %d"),
             state->linenr);
    }
    free(another);
  } else {
    if (!is_dev_null(line)) {
      if (state->patch_input_file)
        return error(_("git apply: bad git-diff - expected /dev/null at %s:%d"),
               state->patch_input_file, state->linenr);
      return error(_("git apply: bad git-diff - expected /dev/null on line %d"),
             state->linenr);
    }
  }

  return 0;
}

static int gitdiff_oldname(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  return gitdiff_verify_name(state, line,
           patch->is_new, &patch->old_name,
           DIFF_OLD_NAME);
}

static int gitdiff_newname(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  return gitdiff_verify_name(state, line,
           patch->is_delete, &patch->new_name,
           DIFF_NEW_NAME);
}

static int parse_mode_line(const char *line,
         const char *patch_input_file,
         int linenr,
         unsigned int *mode)
{
  char *end;
  *mode = strtoul(line, &end, 8);
  if (end == line || !isspace(*end)) {
    if (patch_input_file)
      return error(_("invalid mode at %s:%d: %s"),
             patch_input_file, linenr, line);
    return error(_("invalid mode on line %d: %s"), linenr, line);
  }
  *mode = canon_mode(*mode);
  return 0;
}

static int gitdiff_oldmode(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  return parse_mode_line(line, state->patch_input_file, state->linenr,
             &patch->old_mode);
}

static int gitdiff_newmode(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  return parse_mode_line(line, state->patch_input_file, state->linenr,
             &patch->new_mode);
}

static int gitdiff_delete(struct gitdiff_data *state,
        const char *line,
        struct patch *patch)
{
  patch->is_delete = 1;
  free(patch->old_name);
  patch->old_name = xstrdup_or_null(patch->def_name);
  return gitdiff_oldmode(state, line, patch);
}

static int gitdiff_newfile(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  patch->is_new = 1;
  free(patch->new_name);
  patch->new_name = xstrdup_or_null(patch->def_name);
  return gitdiff_newmode(state, line, patch);
}

static int gitdiff_copysrc(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  patch->is_copy = 1;
  free(patch->old_name);
  patch->old_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
  return 0;
}

static int gitdiff_copydst(struct gitdiff_data *state,
         const char *line,
         struct patch *patch)
{
  patch->is_copy = 1;
  free(patch->new_name);
  patch->new_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
  return 0;
}

static int gitdiff_renamesrc(struct gitdiff_data *state,
           const char *line,
           struct patch *patch)
{
  patch->is_rename = 1;
  free(patch->old_name);
  patch->old_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
  return 0;
}

static int gitdiff_renamedst(struct gitdiff_data *state,
           const char *line,
           struct patch *patch)
{
  patch->is_rename = 1;
  free(patch->new_name);
  patch->new_name = find_name(state->root, line, NULL, state->p_value ? state->p_value - 1 : 0, 0);
  return 0;
}

static int gitdiff_similarity(struct gitdiff_data *state UNUSED,
            const char *line,
            struct patch *patch)
{
  unsigned long val = strtoul(line, NULL, 10);
  if (val <= 100)
    patch->score = val;
  return 0;
}

static int gitdiff_dissimilarity(struct gitdiff_data *state UNUSED,
         const char *line,
         struct patch *patch)
{
  unsigned long val = strtoul(line, NULL, 10);
  if (val <= 100)
    patch->score = val;
  return 0;
}

static int gitdiff_index(struct gitdiff_data *state,
       const char *line,
       struct patch *patch)
{
  /*
   * index line is N hexadecimal, "..", N hexadecimal,
   * and optional space with octal mode.
   */
  const char *ptr, *eol;
  int len;
  const unsigned hexsz = the_hash_algo->hexsz;

  ptr = strchr(line, '.');
  if (!ptr || ptr[1] != '.' || hexsz < ptr - line)
    return 0;
  len = ptr - line;
  memcpy(patch->old_oid_prefix, line, len);
  patch->old_oid_prefix[len] = 0;

  line = ptr + 2;
  ptr = strchr(line, ' ');
  eol = strchrnul(line, '\n');

  if (!ptr || eol < ptr)
    ptr = eol;
  len = ptr - line;

  if (hexsz < len)
    return 0;
  memcpy(patch->new_oid_prefix, line, len);
  patch->new_oid_prefix[len] = 0;
  if (*ptr == ' ')
    return gitdiff_oldmode(state, ptr + 1, patch);
  return 0;
}

/*
 * This is normal for a diff that doesn't change anything: we'll fall through
 * into the next diff. Tell the parser to break out.
 */
static int gitdiff_unrecognized(struct gitdiff_data *state UNUSED,
        const char *line UNUSED,
        struct patch *patch UNUSED)
{
  return 1;
}

/*
 * Skip p_value leading components from "line"; as we do not accept
 * absolute paths, return NULL in that case.
 */
static const char *skip_tree_prefix(int p_value,
            const char *line,
            int llen)
{
  int nslash;
  int i;

  if (!p_value)
    return (llen && line[0] == '/') ? NULL : line;

  nslash = p_value;
  for (i = 0; i < llen; i++) {
    int ch = line[i];
    if (ch == '/' && --nslash <= 0)
      return (i == 0) ? NULL : &line[i + 1];
  }
  return NULL;
}

/*
 * This is to extract the same name that appears on "diff --git"
 * line.  We do not find and return anything if it is a rename
 * patch, and it is OK because we will find the name elsewhere.
 * We need to reliably find name only when it is mode-change only,
 * creation or deletion of an empty file.  In any of these cases,
 * both sides are the same name under a/ and b/ respectively.
 */
static char *git_header_name(int p_value,
           const char *line,
           int llen)
{
  const char *name;
  const char *second = NULL;
  size_t len, line_len;

  line += strlen("diff --git ");
  llen -= strlen("diff --git ");

  if (*line == '"') {
    const char *cp;
    struct strbuf first = STRBUF_INIT;
    struct strbuf sp = STRBUF_INIT;

    if (unquote_c_style(&first, line, &second))
      goto free_and_fail1;

    /* strip the a/b prefix including trailing slash */
    cp = skip_tree_prefix(p_value, first.buf, first.len);
    if (!cp)
      goto free_and_fail1;
    strbuf_remove(&first, 0, cp - first.buf);

    /*
     * second points at one past closing dq of name.
     * find the second name.
     */
    while ((second < line + llen) && isspace(*second))
      second++;

    if (line + llen <= second)
      goto free_and_fail1;
    if (*second == '"') {
      if (unquote_c_style(&sp, second, NULL))
        goto free_and_fail1;
      cp = skip_tree_prefix(p_value, sp.buf, sp.len);
      if (!cp)
        goto free_and_fail1;
      /* They must match, otherwise ignore */
      if (strcmp(cp, first.buf))
        goto free_and_fail1;
      strbuf_release(&sp);
      return strbuf_detach(&first, NULL);
    }

    /* unquoted second */
    cp = skip_tree_prefix(p_value, second, line + llen - second);
    if (!cp)
      goto free_and_fail1;
    if (line + llen - cp != first.len ||
        memcmp(first.buf, cp, first.len))
      goto free_and_fail1;
    return strbuf_detach(&first, NULL);

  free_and_fail1:
    strbuf_release(&first);
    strbuf_release(&sp);
    return NULL;
  }

  /* unquoted first name */
  name = skip_tree_prefix(p_value, line, llen);
  if (!name)
    return NULL;

  /*
   * since the first name is unquoted, a dq if exists must be
   * the beginning of the second name.
   */
  for (second = name; second < line + llen; second++) {
    if (*second == '"') {
      struct strbuf sp = STRBUF_INIT;
      const char *np;

      if (unquote_c_style(&sp, second, NULL))
        goto free_and_fail2;

      np = skip_tree_prefix(p_value, sp.buf, sp.len);
      if (!np)
        goto free_and_fail2;

      len = sp.buf + sp.len - np;
      if (len < second - name &&
          !strncmp(np, name, len) &&
          isspace(name[len])) {
        /* Good */
        strbuf_remove(&sp, 0, np - sp.buf);
        return strbuf_detach(&sp, NULL);
      }

    free_and_fail2:
      strbuf_release(&sp);
      return NULL;
    }
  }

  /*
   * Accept a name only if it shows up twice, exactly the same
   * form.
   */
  second = strchr(name, '\n');
  if (!second)
    return NULL;
  line_len = second - name;
  for (len = 0 ; ; len++) {
    switch (name[len]) {
    default:
      continue;
    case '\n':
      return NULL;
    case '\t': case ' ':
      /*
       * Is this the separator between the preimage
       * and the postimage pathname?  Again, we are
       * only interested in the case where there is
       * no rename, as this is only to set def_name
       * and a rename patch has the names elsewhere
       * in an unambiguous form.
       */
      if (!name[len + 1])
        return NULL; /* no postimage name */
      second = skip_tree_prefix(p_value, name + len + 1,
              line_len - (len + 1));
      /*
       * If we are at the SP at the end of a directory,
       * skip_tree_prefix() may return NULL as that makes
       * it appears as if we have an absolute path.
       * Keep going to find another SP.
       */
      if (!second)
        continue;

      /*
       * Does len bytes starting at "name" and "second"
       * (that are separated by one HT or SP we just
       * found) exactly match?
       */
      if (second[len] == '\n' && !strncmp(name, second, len))
        return xmemdupz(name, len);
    }
  }
}

static int check_header_line(int linenr, struct patch *patch)
{
  int extensions = (patch->is_delete == 1) + (patch->is_new == 1) +
       (patch->is_rename == 1) + (patch->is_copy == 1);
  if (extensions > 1)
    return error(_("inconsistent header lines %d and %d"),
           patch->extension_linenr, linenr);
  if (extensions && !patch->extension_linenr)
    patch->extension_linenr = linenr;
  return 0;
}

int parse_git_diff_header(struct strbuf *root,
        const char *patch_input_file,
        int *linenr,
        int p_value,
        const char *line,
        int len,
        unsigned int size,
        struct patch *patch)
{
  unsigned long offset;
  struct gitdiff_data parse_hdr_state;

  /* A git diff has explicit new/delete information, so we don't guess */
  patch->is_new = 0;
  patch->is_delete = 0;

  /*
   * Some things may not have the old name in the
   * rest of the headers anywhere (pure mode changes,
   * or removing or adding empty files), so we get
   * the default name from the header.
   */
  patch->def_name = git_header_name(p_value, line, len);
  if (patch->def_name && root->len) {
    char *s = xstrfmt("%s%s", root->buf, patch->def_name);
    free(patch->def_name);
    patch->def_name = s;
  }

  line += len;
  size -= len;
  (*linenr)++;
  parse_hdr_state.root = root;
  parse_hdr_state.patch_input_file = patch_input_file;
  parse_hdr_state.linenr = *linenr;
  parse_hdr_state.p_value = p_value;

  for (offset = len ; size > 0 ; offset += len, size -= len, line += len, (*linenr)++) {
    static const struct opentry {
      const char *str;
      int (*fn)(struct gitdiff_data *, const char *, struct patch *);
    } optable[] = {
      { "@@ -", gitdiff_hdrend },
      { "--- ", gitdiff_oldname },
      { "+++ ", gitdiff_newname },
      { "old mode ", gitdiff_oldmode },
      { "new mode ", gitdiff_newmode },
      { "deleted file mode ", gitdiff_delete },
      { "new file mode ", gitdiff_newfile },
      { "copy from ", gitdiff_copysrc },
      { "copy to ", gitdiff_copydst },
      { "rename old ", gitdiff_renamesrc },
      { "rename new ", gitdiff_renamedst },
      { "rename from ", gitdiff_renamesrc },
      { "rename to ", gitdiff_renamedst },
      { "similarity index ", gitdiff_similarity },
      { "dissimilarity index ", gitdiff_dissimilarity },
      { "index ", gitdiff_index },
      { "", gitdiff_unrecognized },
    };
    int i;

    len = linelen(line, size);
    if (!len || line[len-1] != '\n')
      break;
    for (i = 0; i < ARRAY_SIZE(optable); i++) {
      const struct opentry *p = optable + i;
      int oplen = strlen(p->str);
      int res;
      if (len < oplen || memcmp(p->str, line, oplen))
        continue;
      parse_hdr_state.linenr = *linenr;
      res = p->fn(&parse_hdr_state, line + oplen, patch);
      if (res < 0)
        return -1;
      if (check_header_line(*linenr, patch))
        return -1;
      if (res > 0)
        goto done;
      break;
    }
  }

done:
  if (!patch->old_name && !patch->new_name) {
    if (!patch->def_name) {
      if (patch_input_file)
        error(Q_("git diff header lacks filename information when removing "
           "%d leading pathname component at %s:%d",
           "git diff header lacks filename information when removing "
           "%d leading pathname components at %s:%d",
           parse_hdr_state.p_value),
              parse_hdr_state.p_value, patch_input_file, *linenr);
      else
        error(Q_("git diff header lacks filename information when removing "
           "%d leading pathname component (line %d)",
           "git diff header lacks filename information when removing "
           "%d leading pathname components (line %d)",
           parse_hdr_state.p_value),
              parse_hdr_state.p_value, *linenr);
      return -128;
    }
    patch->old_name = xstrdup(patch->def_name);
    patch->new_name = xstrdup(patch->def_name);
  }
  if ((!patch->new_name && !patch->is_delete) ||
      (!patch->old_name && !patch->is_new)) {
    if (patch_input_file)
      error(_("git diff header lacks filename information at %s:%d"),
            patch_input_file, *linenr);
    else
      error(_("git diff header lacks filename information (line %d)"),
            *linenr);
    return -128;
  }
  patch->is_toplevel_relative = 1;
  return offset;
}

static int parse_num(const char *line, unsigned long *p)
{
  char *ptr;

  if (!isdigit(*line))
    return 0;
  errno = 0;
  *p = strtoul(line, &ptr, 10);
  if (errno)
    return 0;
  return ptr - line;
}

static int parse_range(const char *line, int len, int offset, const char *expect,
           unsigned long *p1, unsigned long *p2)
{
  int digits, ex;

  if (offset < 0 || offset >= len)
    return -1;
  line += offset;
  len -= offset;

  digits = parse_num(line, p1);
  if (!digits)
    return -1;

  offset += digits;
  line += digits;
  len -= digits;

  *p2 = 1;
  if (*line == ',') {
    digits = parse_num(line+1, p2);
    if (!digits)
      return -1;

    offset += digits+1;
    line += digits+1;
    len -= digits+1;
  }

  ex = strlen(expect);
  if (ex > len)
    return -1;
  if (memcmp(line, expect, ex))
    return -1;

  return offset + ex;
}

static void recount_diff(const char *line, int size, struct fragment *fragment)
{
  int oldlines = 0, newlines = 0, ret = 0;

  if (size < 1) {
    warning("recount: ignore empty hunk");
    return;
  }

  for (;;) {
    int len = linelen(line, size);
    size -= len;
    line += len;

    if (size < 1)
      break;

    switch (*line) {
    case ' ': case '\n':
      newlines++;
      /* fall through */
    case '-':
      oldlines++;
      continue;
    case '+':
      newlines++;
      continue;
    case '\\':
      continue;
    case '@':
      ret = size < 3 || !starts_with(line, "@@ ");
      break;
    case 'd':
      ret = size < 5 || !starts_with(line, "diff ");
      break;
    default:
      ret = -1;
      break;
    }
    if (ret) {
      warning(_("recount: unexpected line: %.*s"),
        (int)linelen(line, size), line);
      return;
    }
    break;
  }
  fragment->oldlines = oldlines;
  fragment->newlines = newlines;
}

/*
 * Parse a unified diff fragment header of the
 * form "@@ -a,b +c,d @@"
 */
static int parse_fragment_header(const char *line, int len, struct fragment *fragment)
{
  int offset;

  if (!len || line[len-1] != '\n')
    return -1;

  /* Figure out the number of lines in a fragment */
  offset = parse_range(line, len, 4, " +", &fragment->oldpos, &fragment->oldlines);
  offset = parse_range(line, len, offset, " @@", &fragment->newpos, &fragment->newlines);

  return offset;
}

/*
 * Find file diff header
 *
 * Returns:
 *  -1 if no header was found
 *  -128 in case of error
 *   the size of the header in bytes (called "offset") otherwise
 */
static int find_header(struct apply_state *state,
           const char *line,
           unsigned long size,
           int *hdrsize,
           struct patch *patch)
{
  unsigned long offset, len;

  patch->is_toplevel_relative = 0;
  patch->is_rename = patch->is_copy = 0;
  patch->is_new = patch->is_delete = -1;
  patch->old_mode = patch->new_mode = 0;
  patch->old_name = patch->new_name = NULL;
  for (offset = 0; size > 0; offset += len, size -= len, line += len, state->linenr++) {
    unsigned long nextlen;

    len = linelen(line, size);
    if (!len)
      break;

    /* Testing this early allows us to take a few shortcuts.. */
    if (len < 6)
      continue;

    /*
     * Make sure we don't find any unconnected patch fragments.
     * That's a sign that we didn't find a header, and that a
     * patch has become corrupted/broken up.
     */
    if (!memcmp("@@ -", line, 4)) {
      struct fragment dummy;
      if (parse_fragment_header(line, len, &dummy) < 0)
        continue;
      error(_("patch fragment without header at %s:%d: %.*s"),
            state->patch_input_file, state->linenr,
            (int)len-1, line);
      return -128;
    }

    if (size < len + 6)
      break;

    /*
     * Git patch? It might not have a real patch, just a rename
     * or mode change, so we handle that specially
     */
    if (!memcmp("diff --git ", line, 11)) {
      int git_hdr_len = parse_git_diff_header(&state->root,
                state->patch_input_file,
                &state->linenr,
                state->p_value, line, len,
                size, patch);
      if (git_hdr_len < 0)
        return -128;
      if (git_hdr_len <= len)
        continue;
      *hdrsize = git_hdr_len;
      return offset;
    }

    /* --- followed by +++ ? */
    if (memcmp("--- ", line,  4) || memcmp("+++ ", line + len, 4))
      continue;

    /*
     * We only accept unified patches, so we want it to
     * at least have "@@ -a,b +c,d @@\n", which is 14 chars
     * minimum ("@@ -0,0 +1 @@\n" is the shortest).
     */
    nextlen = linelen(line + len, size - len);
    if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
      continue;

    /* Ok, we'll consider it a patch */
    if (parse_traditional_patch(state, line, line+len, patch))
      return -128;
    *hdrsize = len + nextlen;
    state->linenr += 2;
    return offset;
  }
  return -1;
}

static void record_ws_error(struct apply_state *state,
          unsigned result,
          const char *line,
          int len,
          int linenr)
{
  char *err;

  if (!result)
    return;

  state->whitespace_error++;
  if (state->squelch_whitespace_errors &&
      state->squelch_whitespace_errors < state->whitespace_error)
    return;

  /*
   * line[len] for an incomplete line points at the "\n" at the end
   * of patch input line, so "%.*s" would drop the last letter on line;
   * compensate for it.
   */
  if (result & WS_INCOMPLETE_LINE)
    len++;

  err = whitespace_error_string(result);
  if (state->apply_verbosity > verbosity_silent)
    fprintf(stderr, "%s:%d: %s.\n%.*s\n",
      state->patch_input_file, linenr, err, len, line);
  free(err);
}

static void check_whitespace(struct apply_state *state,
           const char *line,
           int len,
           unsigned ws_rule)
{
  unsigned result = ws_check(line + 1, len - 1, ws_rule);

  record_ws_error(state, result, line + 1, len - 2, state->linenr);
}

/*
 * Check if the patch has context lines with CRLF or
 * the patch wants to remove lines with CRLF.
 */
static void check_old_for_crlf(struct patch *patch, const char *line, int len)
{
  if (len >= 2 && line[len-1] == '\n' && line[len-2] == '\r') {
    patch->ws_rule |= WS_CR_AT_EOL;
    patch->crlf_in_old = 1;
  }
}


/*
 * Just saw a single line in a fragment.  If it is a part of this hunk
 * that is a context " ", an added "+", or a removed "-" line, it may
 * be followed by "\\ No newline..." to signal that the last "\n" on
 * this line needs to be dropped.  Depending on locale settings when
 * the patch was produced we don't know what this line would exactly
 * say. The only thing we do know is that it begins with "\ ".
 * Checking for 12 is just for sanity check; "\ No newline..." would
 * be at least that long in any l10n.
 *
 * Return 0 if the line we saw is not followed by "\ No newline...",
 * or length of that line.  The caller will use it to skip over the
 * "\ No newline..." line.
 */
static int adjust_incomplete(const char *line, int len,
           unsigned long size)
{
  int nextlen;

  if (*line != '\n' && *line != ' ' && *line != '+' && *line != '-')
    return 0;
  if (size - len < 12 || memcmp(line + len, "\\ ", 2))
    return 0;
  nextlen = linelen(line + len, size - len);
  if (nextlen < 12)
    return 0;
  return nextlen;
}

/*
 * Parse a unified diff. Note that this really needs to parse each
 * fragment separately, since the only way to know the difference
 * between a "---" that is part of a patch, and a "---" that starts
 * the next patch is to look at the line counts..
 */
static int parse_fragment(struct apply_state *state,
        const char *line,
        unsigned long size,
        struct patch *patch,
        struct fragment *fragment)
{
  int added, deleted;
  int len = linelen(line, size), offset;
  int skip_len = 0;
  unsigned long oldlines, newlines;
  unsigned long leading, trailing;

  /* do not complain a symbolic link being an incomplete line */
  if (patch->ws_rule & WS_INCOMPLETE_LINE) {
    /*
     * We want to figure out if the postimage is a
     * symbolic link when applying the patch normally, or
     * if the preimage is a symbolic link when applying
     * the patch in reverse.  A normal patch only has
     * old_mode without new_mode.  If it changes the
     * filemode, new_mode has value, which is different
     * from old_mode.
     */
    unsigned mode = (state->apply_in_reverse
         ? patch->old_mode
         : patch->new_mode
         ? patch->new_mode
         : patch->old_mode);
    if (mode && S_ISLNK(mode))
      patch->ws_rule &= ~WS_INCOMPLETE_LINE;
  }

  offset = parse_fragment_header(line, len, fragment);
  if (offset < 0)
    return -1;
  if (offset > 0 && patch->recount)
    recount_diff(line + offset, size - offset, fragment);
  oldlines = fragment->oldlines;
  newlines = fragment->newlines;
  leading = 0;
  trailing = 0;

  /* Parse the thing.. */
  line += len;
  size -= len;
  state->linenr++;
  added = deleted = 0;
  for (offset = len;
       0 < size;
       offset += len, size -= len, line += len, state->linenr++) {
    if (!oldlines && !newlines)
      break;
    len = linelen(line, size);
    if (!len || line[len-1] != '\n')
      return -1;

    /*
     * For an incomplete line, skip_len counts the bytes
     * on "\\ No newline..." marker line that comes next
     * to the current line.
     *
     * Reduce "len" to drop the newline at the end of
     * line[], but add one to "skip_len", which will be
     * added back to "len" for the next iteration, to
     * compensate.
     */
    skip_len = adjust_incomplete(line, len, size);
    if (skip_len) {
      len--;
      skip_len++;
    }
    switch (*line) {
    default:
      return -1;
    case '\n': /* newer GNU diff, an empty context line */
    case ' ':
      oldlines--;
      newlines--;
      if (!deleted && !added)
        leading++;
      trailing++;
      check_old_for_crlf(patch, line, len);
      if (!state->apply_in_reverse &&
          state->ws_error_action == correct_ws_error)
        check_whitespace(state, line, len, patch->ws_rule);
      break;
    case '-':
      if (!state->apply_in_reverse)
        check_old_for_crlf(patch, line, len);
      if (state->apply_in_reverse &&
          state->ws_error_action != nowarn_ws_error)
        check_whitespace(state, line, len, patch->ws_rule);
      deleted++;
      oldlines--;
      trailing = 0;
      break;
    case '+':
      if (state->apply_in_reverse)
        check_old_for_crlf(patch, line, len);
      if (!state->apply_in_reverse &&
          state->ws_error_action != nowarn_ws_error)
        check_whitespace(state, line, len, patch->ws_rule);
      added++;
      newlines--;
      trailing = 0;
      break;
    }

    /* eat the "\\ No newline..." as well, if exists */
    if (skip_len) {
      len += skip_len;
      state->linenr++;
    }
  }
  if (oldlines || newlines)
    return -1;
  if (!patch->recount && !deleted && !added)
    return -1;

  fragment->leading = leading;
  fragment->trailing = trailing;

  patch->lines_added += added;
  patch->lines_deleted += deleted;

  if (0 < patch->is_new && oldlines)
    return error(_("new file depends on old contents"));
  if (0 < patch->is_delete && newlines)
    return error(_("deleted file still has contents"));
  return offset;
}

/*
 * We have seen "diff --git a/... b/..." header (or a traditional patch
 * header).  Read hunks that belong to this patch into fragments and hang
 * them to the given patch structure.
 *
 * The (fragment->patch, fragment->size) pair points into the memory given
 * by the caller, not a copy, when we return.
 *
 * Returns:
 *   -1 in case of error,
 *   the number of bytes in the patch otherwise.
 */
static int parse_single_patch(struct apply_state *state,
            const char *line,
            unsigned long size,
            struct patch *patch)
{
  unsigned long offset = 0;
  unsigned long oldlines = 0, newlines = 0, context = 0;
  struct fragment **fragp = &patch->fragments;

  while (size > 4 && !memcmp(line, "@@ -", 4)) {
    struct fragment *fragment;
    int len;

    CALLOC_ARRAY(fragment, 1);
    fragment->linenr = state->linenr;
    len = parse_fragment(state, line, size, patch, fragment);
    if (len <= 0) {
      free(fragment);
      return error(_("corrupt patch at %s:%d"),
             state->patch_input_file, state->linenr);
    }
    fragment->patch = line;
    fragment->size = len;
    oldlines += fragment->oldlines;
    newlines += fragment->newlines;
    context += fragment->leading + fragment->trailing;

    *fragp = fragment;
    fragp = &fragment->next;

    offset += len;
    line += len;
    size -= len;
  }

  /*
   * If something was removed (i.e. we have old-lines) it cannot
   * be creation, and if something was added it cannot be
   * deletion.  However, the reverse is not true; --unified=0
   * patches that only add are not necessarily creation even
   * though they do not have any old lines, and ones that only
   * delete are not necessarily deletion.
   *
   * Unfortunately, a real creation/deletion patch do _not_ have
   * any context line by definition, so we cannot safely tell it
   * apart with --unified=0 insanity.  At least if the patch has
   * more than one hunk it is not creation or deletion.
   */
  if (patch->is_new < 0 &&
      (oldlines || (patch->fragments && patch->fragments->next)))
    patch->is_new = 0;
  if (patch->is_delete < 0 &&
      (newlines || (patch->fragments && patch->fragments->next)))
    patch->is_delete = 0;

  if (0 < patch->is_new && oldlines)
    return error(_("new file %s depends on old contents"), patch->new_name);
  if (0 < patch->is_delete && newlines)
    return error(_("deleted file %s still has contents"), patch->old_name);
  if (!patch->is_delete && !newlines && context && state->apply_verbosity > verbosity_silent)
    fprintf_ln(stderr,
         _("** warning: "
           "file %s becomes empty but is not deleted"),
         patch->new_name);

  return offset;
}

static inline int metadata_changes(struct patch *patch)
{
  return  patch->is_rename > 0 ||
    patch->is_copy > 0 ||
    patch->is_new > 0 ||
    patch->is_delete ||
    (patch->old_mode && patch->new_mode &&
     patch->old_mode != patch->new_mode);
}

static char *inflate_it(const void *data, unsigned long size,
      unsigned long inflated_size)
{
  git_zstream stream;
  void *out;
  int st;

  memset(&stream, 0, sizeof(stream));

  stream.next_in = (unsigned char *)data;
  stream.avail_in = size;
  stream.next_out = out = xmalloc(inflated_size);
  stream.avail_out = inflated_size;
  git_inflate_init(&stream);
  st = git_inflate(&stream, Z_FINISH);
  git_inflate_end(&stream);
  if ((st != Z_STREAM_END) || stream.total_out != inflated_size) {
    free(out);
    return NULL;
  }
  return out;
}

/*
 * Read a binary hunk and return a new fragment; fragment->patch
 * points at an allocated memory that the caller must free, so
 * it is marked as "->free_patch = 1".
 */
static struct fragment *parse_binary_hunk(struct apply_state *state,
            char **buf_p,
            unsigned long *sz_p,
            int *status_p,
            int *used_p)
{
  /*
   * Expect a line that begins with binary patch method ("literal"
   * or "delta"), followed by the length of data before deflating.
   * a sequence of 'length-byte' followed by base-85 encoded data
   * should follow, terminated by a newline.
   *
   * Each 5-byte sequence of base-85 encodes up to 4 bytes,
   * and we would limit the patch line to 66 characters,
   * so one line can fit up to 13 groups that would decode
   * to 52 bytes max.  The length byte 'A'-'Z' corresponds
   * to 1-26 bytes, and 'a'-'z' corresponds to 27-52 bytes.
   */
  int llen, used;
  unsigned long size = *sz_p;
  char *buffer = *buf_p;
  int patch_method;
  unsigned long origlen;
  char *data = NULL;
  int hunk_size = 0;
  struct fragment *frag;

  llen = linelen(buffer, size);
  used = llen;

  *status_p = 0;

  if (starts_with(buffer, "delta ")) {
    patch_method = BINARY_DELTA_DEFLATED;
    origlen = strtoul(buffer + 6, NULL, 10);
  }
  else if (starts_with(buffer, "literal ")) {
    patch_method = BINARY_LITERAL_DEFLATED;
    origlen = strtoul(buffer + 8, NULL, 10);
  }
  else
    return NULL;

  state->linenr++;
  buffer += llen;
  size -= llen;
  while (1) {
    int byte_length, max_byte_length, newsize;
    llen = linelen(buffer, size);
    used += llen;
    state->linenr++;
    if (llen == 1) {
      /* consume the blank line */
      buffer++;
      size--;
      break;
    }
    /*
     * Minimum line is "A00000\n" which is 7-byte long,
     * and the line length must be multiple of 5 plus 2.
     */
    if ((llen < 7) || (llen-2) % 5)
      goto corrupt;
    max_byte_length = (llen - 2) / 5 * 4;
    byte_length = *buffer;
    if ('A' <= byte_length && byte_length <= 'Z')
      byte_length = byte_length - 'A' + 1;
    else if ('a' <= byte_length && byte_length <= 'z')
      byte_length = byte_length - 'a' + 27;
    else
      goto corrupt;
    /* if the input length was not multiple of 4, we would
     * have filler at the end but the filler should never
     * exceed 3 bytes
     */
    if (max_byte_length < byte_length ||
        byte_length <= max_byte_length - 4)
      goto corrupt;
    newsize = hunk_size + byte_length;
    data = xrealloc(data, newsize);
    if (decode_85(data + hunk_size, buffer + 1, byte_length))
      goto corrupt;
    hunk_size = newsize;
    buffer += llen;
    size -= llen;
  }

  CALLOC_ARRAY(frag, 1);
  frag->patch = inflate_it(data, hunk_size, origlen);
  frag->free_patch = 1;
  if (!frag->patch)
    goto corrupt;
  free(data);
  frag->size = origlen;
  *buf_p = buffer;
  *sz_p = size;
  *used_p = used;
  frag->binary_patch_method = patch_method;
  return frag;

 corrupt:
  free(data);
  *status_p = -1;
  error(_("corrupt binary patch at %s:%d: %.*s"),
        state->patch_input_file, state->linenr-1, llen-1, buffer);
  return NULL;
}

/*
 * Returns:
 *   -1 in case of error,
 *   the length of the parsed binary patch otherwise
 */
static int parse_binary(struct apply_state *state,
      char *buffer,
      unsigned long size,
      struct patch *patch)
{
  /*
   * We have read "GIT binary patch\n"; what follows is a line
   * that says the patch method (currently, either "literal" or
   * "delta") and the length of data before deflating; a
   * sequence of 'length-byte' followed by base-85 encoded data
   * follows.
   *
   * When a binary patch is reversible, there is another binary
   * hunk in the same format, starting with patch method (either
   * "literal" or "delta") with the length of data, and a sequence
   * of length-byte + base-85 encoded data, terminated with another
   * empty line.  This data, when applied to the postimage, produces
   * the preimage.
   */
  struct fragment *forward;
  struct fragment *reverse;
  int status;
  int used, used_1;

  forward = parse_binary_hunk(state, &buffer, &size, &status, &used);
  if (!forward && !status)
    /* there has to be one hunk (forward hunk) */
    return error(_("unrecognized binary patch at %s:%d"),
           state->patch_input_file, state->linenr-1);
  if (status)
    /* otherwise we already gave an error message */
    return status;

  reverse = parse_binary_hunk(state, &buffer, &size, &status, &used_1);
  if (reverse)
    used += used_1;
  else if (status) {
    /*
     * Not having reverse hunk is not an error, but having
     * a corrupt reverse hunk is.
     */
    free((void*) forward->patch);
    free(forward);
    return status;
  }
  forward->next = reverse;
  patch->fragments = forward;
  patch->is_binary = 1;
  return used;
}

static void prefix_one(struct apply_state *state, char **name)
{
  char *old_name = *name;
  if (!old_name)
    return;
  *name = prefix_filename(state->prefix, *name);
  free(old_name);
}

static void prefix_patch(struct apply_state *state, struct patch *p)
{
  if (!state->prefix || p->is_toplevel_relative)
    return;
  prefix_one(state, &p->new_name);
  prefix_one(state, &p->old_name);
}

/*
 * include/exclude
 */

static void add_name_limit(struct apply_state *state,
         const char *name,
         int exclude)
{
  struct string_list_item *it;

  it = string_list_append(&state->limit_by_name, name);
  it->util = exclude ? NULL : (void *) 1;
}

static int use_patch(struct apply_state *state, struct patch *p)
{
  const char *pathname = p->new_name ? p->new_name : p->old_name;
  int i;

  /* Paths outside are not touched regardless of "--include" */
  if (state->prefix && *state->prefix) {
    const char *rest;
    if (!skip_prefix(pathname, state->prefix, &rest) || !*rest)
      return 0;
  }

  /* See if it matches any of exclude/include rule */
  for (i = 0; i < state->limit_by_name.nr; i++) {
    struct string_list_item *it = &state->limit_by_name.items[i];
    if (!wildmatch(it->string, pathname, 0))
      return (it->util != NULL);
  }

  /*
   * If we had any include, a path that does not match any rule is
   * not used.  Otherwise, we saw bunch of exclude rules (or none)
   * and such a path is used.
   */
  return !state->has_include;
}

/*
 * Read the patch text in "buffer" that extends for "size" bytes; stop
 * reading after seeing a single patch (i.e. changes to a single file).
 * Create fragments (i.e. patch hunks) and hang them to the given patch.
 *
 * Returns:
 *   -1 if no header was found or parse_binary() failed,
 *   -128 on another error,
 *   the number of bytes consumed otherwise,
 *     so that the caller can call us again for the next patch.
 */
static int parse_chunk(struct apply_state *state, char *buffer, unsigned long size, struct patch *patch)
{
  int hdrsize, patchsize;
  int offset = find_header(state, buffer, size, &hdrsize, patch);

  if (offset < 0)
    return offset;

  prefix_patch(state, patch);

  if (!use_patch(state, patch))
    patch->ws_rule = 0;
  else if (patch->new_name)
    patch->ws_rule = whitespace_rule(state->repo->index,
             patch->new_name);
  else
    patch->ws_rule = whitespace_rule(state->repo->index,
             patch->old_name);

  patchsize = parse_single_patch(state,
               buffer + offset + hdrsize,
               size - offset - hdrsize,
               patch);

  if (patchsize < 0)
    return -128;

  if (!patchsize) {
    static const char git_binary[] = "GIT binary patch\n";
    int hd = hdrsize + offset;
    unsigned long llen = linelen(buffer + hd, size - hd);

    if (llen == sizeof(git_binary) - 1 &&
        !memcmp(git_binary, buffer + hd, llen)) {
      int used;
      state->linenr++;
      used = parse_binary(state, buffer + hd + llen,
              size - hd - llen, patch);
      if (used < 0)
        return -1;
      if (used)
        patchsize = used + llen;
      else
        patchsize = 0;
    }
    else if (!memcmp(" differ\n", buffer + hd + llen - 8, 8)) {
      static const char *binhdr[] = {
        "Binary files ",
        "Files ",
        NULL,
      };
      int i;
      for (i = 0; binhdr[i]; i++) {
        int len = strlen(binhdr[i]);
        if (len < size - hd &&
            !memcmp(binhdr[i], buffer + hd, len)) {
          state->linenr++;
          patch->is_binary = 1;
          patchsize = llen;
          break;
        }
      }
    }

    /* Empty patch cannot be applied if it is a text patch
     * without metadata change.  A binary patch appears
     * empty to us here.
     */
    if ((state->apply || state->check) &&
        (!patch->is_binary && !metadata_changes(patch))) {
      error(_("patch with only garbage at %s:%d"),
            state->patch_input_file, state->linenr);
      return -128;
    }
  }

  return offset + hdrsize + patchsize;
}

static void reverse_patches(struct patch *p)
{
  for (; p; p = p->next) {
    struct fragment *frag = p->fragments;

    SWAP(p->new_name, p->old_name);
    if (p->new_mode || p->is_delete)
      SWAP(p->new_mode, p->old_mode);
    SWAP(p->is_new, p->is_delete);
    SWAP(p->lines_added, p->lines_deleted);
    SWAP(p->old_oid_prefix, p->new_oid_prefix);

    for (; frag; frag = frag->next) {
      SWAP(frag->newpos, frag->oldpos);
      SWAP(frag->newlines, frag->oldlines);
    }
  }
}

static const char pluses[] =
"++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
static const char minuses[]=
"----------------------------------------------------------------------";

static void show_stats(struct apply_state *state, struct patch *patch)
{
  struct strbuf qname = STRBUF_INIT;
  char *cp = patch->new_name ? patch->new_name : patch->old_name;
  int max, add, del;

  quote_c_style(cp, &qname, NULL, 0);

  /*
   * "scale" the filename
   */
  max = state->max_len;
  if (max > 50)
    max = 50;

  if (qname.len > max) {
    cp = strchr(qname.buf + qname.len + 3 - max, '/');
    if (!cp)
      cp = qname.buf + qname.len + 3 - max;
    strbuf_splice(&qname, 0, cp - qname.buf, "...", 3);
  }

  if (patch->is_binary) {
    printf(" %-*s |  Bin\n", max, qname.buf);
    strbuf_release(&qname);
    return;
  }

  printf(" %-*s |", max, qname.buf);
  strbuf_release(&qname);

  /*
   * scale the add/delete
   */
  max = max + state->max_change > 70 ? 70 - max : state->max_change;
  add = patch->lines_added;
  del = patch->lines_deleted;

  if (state->max_change > 0) {
    int total = ((add + del) * max + state->max_change / 2) / state->max_change;
    add = (add * max + state->max_change / 2) / state->max_change;
    del = total - add;
  }
  printf("%5d %.*s%.*s\n", patch->lines_added + patch->lines_deleted,
    add, pluses, del, minuses);
}

static int read_old_data(struct stat *st, struct patch *patch,
       const char *path, struct strbuf *buf)
{
  int conv_flags = patch->crlf_in_old ?
    CONV_EOL_KEEP_CRLF : CONV_EOL_RENORMALIZE;
  switch (st->st_mode & S_IFMT) {
  case S_IFLNK:
    if (strbuf_readlink(buf, path, st->st_size) < 0)
      return error(_("unable to read symlink %s"), path);
    return 0;
  case S_IFREG:
    if (strbuf_read_file(buf, path, st->st_size) != st->st_size)
      return error(_("unable to open or read %s"), path);
    /*
     * "git apply" without "--index/--cached" should never look
     * at the index; the target file may not have been added to
     * the index yet, and we may not even be in any Git repository.
     * Pass NULL to convert_to_git() to stress this; the function
     * should never look at the index when explicit crlf option
     * is given.
     */
    convert_to_git(NULL, path, buf->buf, buf->len, buf, conv_flags);
    return 0;
  default:
    return -1;
  }
}

/*
 * Update the preimage, and the common lines in postimage,
 * from buffer buf of length len.
 */
static void update_pre_post_images(struct image *preimage,
           struct image *postimage,
           char *buf, size_t len)
{
  struct image fixed_preimage = IMAGE_INIT;
  size_t insert_pos = 0;
  int i, ctx, reduced;
  const char *fixed;

  /*
   * Update the preimage with whitespace fixes.  Note that we
   * are not losing preimage->buf -- apply_one_fragment() will
   * free "oldlines".
   */
  image_prepare(&fixed_preimage, buf, len, 1);
  for (i = 0; i < fixed_preimage.line_nr; i++)
    fixed_preimage.line[i].flag = preimage->line[i].flag;
  image_clear(preimage);
  *preimage = fixed_preimage;
  fixed = preimage->buf.buf;

  /*
   * Adjust the common context lines in postimage.
   */
  for (i = reduced = ctx = 0; i < postimage->line_nr; i++) {
    size_t l_len = postimage->line[i].len;

    if (!(postimage->line[i].flag & LINE_COMMON)) {
      /* an added line -- no counterparts in preimage */
      insert_pos += l_len;
      continue;
    }

    /* and find the corresponding one in the fixed preimage */
    while (ctx < preimage->line_nr &&
           !(preimage->line[ctx].flag & LINE_COMMON)) {
      fixed += preimage->line[ctx].len;
      ctx++;
    }

    /*
     * preimage is expected to run out, if the caller
     * fixed addition of trailing blank lines.
     */
    if (preimage->line_nr <= ctx) {
      reduced++;
      continue;
    }

    /* and copy it in, while fixing the line length */
    l_len = preimage->line[ctx].len;
    strbuf_splice(&postimage->buf, insert_pos, postimage->line[i].len,
            fixed, l_len);
    insert_pos += l_len;
    fixed += l_len;
    postimage->line[i].len = l_len;
    ctx++;
  }

  /* Fix the length of the whole thing */
  postimage->line_nr -= reduced;
}

/*
 * Compare lines s1 of length n1 and s2 of length n2, ignoring
 * whitespace difference. Returns 1 if they match, 0 otherwise
 */
static int fuzzy_matchlines(const char *s1, size_t n1,
          const char *s2, size_t n2)
{
  const char *end1 = s1 + n1;
  const char *end2 = s2 + n2;

  /* ignore line endings */
  while (s1 < end1 && (end1[-1] == '\r' || end1[-1] == '\n'))
    end1--;
  while (s2 < end2 && (end2[-1] == '\r' || end2[-1] == '\n'))
    end2--;

  while (s1 < end1 && s2 < end2) {
    if (isspace(*s1)) {
      /*
       * Skip whitespace. We check on both buffers
       * because we don't want "a b" to match "ab".
       */
      if (!isspace(*s2))
        return 0;
      while (s1 < end1 && isspace(*s1))
        s1++;
      while (s2 < end2 && isspace(*s2))
        s2++;
    } else if (*s1++ != *s2++)
      return 0;
  }

  /* If we reached the end on one side only, lines don't match. */
  return s1 == end1 && s2 == end2;
}

static int line_by_line_fuzzy_match(struct image *img,
            struct image *preimage,
            struct image *postimage,
            unsigned long current,
            int current_lno,
            int preimage_limit)
{
  int i;
  size_t imgoff = 0;
  size_t preoff = 0;
  size_t extra_chars;
  char *buf;
  char *preimage_eof;
  char *preimage_end;
  struct strbuf fixed;
  char *fixed_buf;
  size_t fixed_len;

  for (i = 0; i < preimage_limit; i++) {
    size_t prelen = preimage->line[i].len;
    size_t imglen = img->line[current_lno+i].len;

    if (!fuzzy_matchlines(img->buf.buf + current + imgoff, imglen,
              preimage->buf.buf + preoff, prelen))
      return 0;
    imgoff += imglen;
    preoff += prelen;
  }

  /*
   * Ok, the preimage matches with whitespace fuzz.
   *
   * imgoff now holds the true length of the target that
   * matches the preimage before the end of the file.
   *
   * Count the number of characters in the preimage that fall
   * beyond the end of the file and make sure that all of them
   * are whitespace characters. (This can only happen if
   * we are removing blank lines at the end of the file.)
   */
  buf = preimage_eof = preimage->buf.buf + preoff;
  for ( ; i < preimage->line_nr; i++)
    preoff += preimage->line[i].len;
  preimage_end = preimage->buf.buf + preoff;
  for ( ; buf < preimage_end; buf++)
    if (!isspace(*buf))
      return 0;

  /*
   * Update the preimage and the common postimage context
   * lines to use the same whitespace as the target.
   * If whitespace is missing in the target (i.e.
   * if the preimage extends beyond the end of the file),
   * use the whitespace from the preimage.
   */
  extra_chars = preimage_end - preimage_eof;
  strbuf_init(&fixed, imgoff + extra_chars);
  strbuf_add(&fixed, img->buf.buf + current, imgoff);
  strbuf_add(&fixed, preimage_eof, extra_chars);
  fixed_buf = strbuf_detach(&fixed, &fixed_len);
  update_pre_post_images(preimage, postimage,
             fixed_buf, fixed_len);
  return 1;
}

static int match_fragment(struct apply_state *state,
        struct image *img,
        struct image *preimage,
        struct image *postimage,
        unsigned long current,
        int current_lno,
        unsigned ws_rule,
        int match_beginning, int match_end)
{
  int i;
  const char *orig, *target;
  struct strbuf fixed = STRBUF_INIT;
  char *fixed_buf;
  size_t fixed_len;
  int preimage_limit;
  int ret;

  if (preimage->line_nr + current_lno <= img->line_nr) {
    /*
     * The hunk falls within the boundaries of img.
     */
    preimage_limit = preimage->line_nr;
    if (match_end && (preimage->line_nr + current_lno != img->line_nr)) {
      ret = 0;
      goto out;
    }
  } else if (state->ws_error_action == correct_ws_error &&
       (ws_rule & WS_BLANK_AT_EOF)) {
    /*
     * This hunk extends beyond the end of img, and we are
     * removing blank lines at the end of the file.  This
     * many lines from the beginning of the preimage must
     * match with img, and the remainder of the preimage
     * must be blank.
     */
    preimage_limit = img->line_nr - current_lno;
  } else {
    /*
     * The hunk extends beyond the end of the img and
     * we are not removing blanks at the end, so we
     * should reject the hunk at this position.
     */
    ret = 0;
    goto out;
  }

  if (match_beginning && current_lno) {
    ret = 0;
    goto out;
  }

  /* Quick hash check */
  for (i = 0; i < preimage_limit; i++) {
    if ((img->line[current_lno + i].flag & LINE_PATCHED) ||
        (preimage->line[i].hash != img->line[current_lno + i].hash)) {
      ret = 0;
      goto out;
    }
  }

  if (preimage_limit == preimage->line_nr) {
    /*
     * Do we have an exact match?  If we were told to match
     * at the end, size must be exactly at current+fragsize,
     * otherwise current+fragsize must be still within the preimage,
     * and either case, the old piece should match the preimage
     * exactly.
     */
    if ((match_end
         ? (current + preimage->buf.len == img->buf.len)
         : (current + preimage->buf.len <= img->buf.len)) &&
        !memcmp(img->buf.buf + current, preimage->buf.buf, preimage->buf.len)) {
      ret = 1;
      goto out;
    }
  } else {
    /*
     * The preimage extends beyond the end of img, so
     * there cannot be an exact match.
     *
     * There must be one non-blank context line that match
     * a line before the end of img.
     */
    const char *buf, *buf_end;

    buf = preimage->buf.buf;
    buf_end = buf;
    for (i = 0; i < preimage_limit; i++)
      buf_end += preimage->line[i].len;

    for ( ; buf < buf_end; buf++)
      if (!isspace(*buf))
        break;
    if (buf == buf_end) {
      ret = 0;
      goto out;
    }
  }

  /*
   * No exact match. If we are ignoring whitespace, run a line-by-line
   * fuzzy matching. We collect all the line length information because
   * we need it to adjust whitespace if we match.
   */
  if (state->ws_ignore_action == ignore_ws_change) {
    ret = line_by_line_fuzzy_match(img, preimage, postimage,
                 current, current_lno, preimage_limit);
    goto out;
  }

  if (state->ws_error_action != correct_ws_error) {
    ret = 0;
    goto out;
  }

  /*
   * The hunk does not apply byte-by-byte, but the hash says
   * it might with whitespace fuzz. We weren't asked to
   * ignore whitespace, we were asked to correct whitespace
   * errors, so let's try matching after whitespace correction.
   *
   * While checking the preimage against the target, whitespace
   * errors in both fixed, we count how large the corresponding
   * postimage needs to be.  The postimage prepared by
   * apply_one_fragment() has whitespace errors fixed on added
   * lines already, but the common lines were propagated as-is,
   * which may become longer when their whitespace errors are
   * fixed.
   */

  /*
   * The preimage may extend beyond the end of the file,
   * but in this loop we will only handle the part of the
   * preimage that falls within the file.
   */
  strbuf_grow(&fixed, preimage->buf.len + 1);
  orig = preimage->buf.buf;
  target = img->buf.buf + current;
  for (i = 0; i < preimage_limit; i++) {
    size_t oldlen = preimage->line[i].len;
    size_t tgtlen = img->line[current_lno + i].len;
    size_t fixstart = fixed.len;
    struct strbuf tgtfix;
    int match;

    /* Try fixing the line in the preimage */
    ws_fix_copy(&fixed, orig, oldlen, ws_rule, NULL);

    /* Try fixing the line in the target */
    strbuf_init(&tgtfix, tgtlen);
    ws_fix_copy(&tgtfix, target, tgtlen, ws_rule, NULL);

    /*
     * If they match, either the preimage was based on
     * a version before our tree fixed whitespace breakage,
     * or we are lacking a whitespace-fix patch the tree
     * the preimage was based on already had (i.e. target
     * has whitespace breakage, the preimage doesn't).
     * In either case, we are fixing the whitespace breakages
     * so we might as well take the fix together with their
     * real change.
     */
    match = (tgtfix.len == fixed.len - fixstart &&
       !memcmp(tgtfix.buf, fixed.buf + fixstart,
               fixed.len - fixstart));

    strbuf_release(&tgtfix);
    if (!match) {
      ret = 0;
      goto out;
    }

    orig += oldlen;
    target += tgtlen;
  }


  /*
   * Now handle the lines in the preimage that falls beyond the
   * end of the file (if any). They will only match if they are
   * empty or only contain whitespace (if WS_BLANK_AT_EOL is
   * false).
   */
  for ( ; i < preimage->line_nr; i++) {
    size_t fixstart = fixed.len; /* start of the fixed preimage */
    size_t oldlen = preimage->line[i].len;
    int j;

    /* Try fixing the line in the preimage */
    ws_fix_copy(&fixed, orig, oldlen, ws_rule, NULL);

    for (j = fixstart; j < fixed.len; j++) {
      if (!isspace(fixed.buf[j])) {
        ret = 0;
        goto out;
      }
    }


    orig += oldlen;
  }

  /*
   * Yes, the preimage is based on an older version that still
   * has whitespace breakages unfixed, and fixing them makes the
   * hunk match.  Update the context lines in the postimage.
   */
  fixed_buf = strbuf_detach(&fixed, &fixed_len);
  update_pre_post_images(preimage, postimage,
             fixed_buf, fixed_len);

  ret = 1;

out:
  strbuf_release(&fixed);
  return ret;
}

static int find_pos(struct apply_state *state,
        struct image *img,
        struct image *preimage,
        struct image *postimage,
        int line,
        unsigned ws_rule,
        int match_beginning, int match_end)
{
  int i;
  unsigned long backwards, forwards, current;
  int backwards_lno, forwards_lno, current_lno;

  /*
   * When running with --allow-overlap, it is possible that a hunk is
   * seen that pretends to start at the beginning (but no longer does),
   * and that *still* needs to match the end. So trust `match_end` more
   * than `match_beginning`.
   */
  if (state->allow_overlap && match_beginning && match_end &&
      img->line_nr - preimage->line_nr != 0)
    match_beginning = 0;

  /*
   * If match_beginning or match_end is specified, there is no
   * point starting from a wrong line that will never match and
   * wander around and wait for a match at the specified end.
   */
  if (match_beginning)
    line = 0;
  else if (match_end)
    line = img->line_nr - preimage->line_nr;

  /*
   * Because the comparison is unsigned, the following test
   * will also take care of a negative line number that can
   * result when match_end and preimage is larger than the target.
   */
  if ((size_t) line > img->line_nr)
    line = img->line_nr;

  current = 0;
  for (i = 0; i < line; i++)
    current += img->line[i].len;

  /*
   * There's probably some smart way to do this, but I'll leave
   * that to the smart and beautiful people. I'm simple and stupid.
   */
  backwards = current;
  backwards_lno = line;
  forwards = current;
  forwards_lno = line;
  current_lno = line;

  for (i = 0; ; i++) {
    if (match_fragment(state, img, preimage, postimage,
           current, current_lno, ws_rule,
           match_beginning, match_end))
      return current_lno;

  again:
    if (backwards_lno == 0 && forwards_lno == img->line_nr)
      break;

    if (i & 1) {
      if (backwards_lno == 0) {
        i++;
        goto again;
      }
      backwards_lno--;
      backwards -= img->line[backwards_lno].len;
      current = backwards;
      current_lno = backwards_lno;
    } else {
      if (forwards_lno == img->line_nr) {
        i++;
        goto again;
      }
      forwards += img->line[forwards_lno].len;
      forwards_lno++;
      current = forwards;
      current_lno = forwards_lno;
    }

  }
  return -1;
}

/*
 * The change from "preimage" and "postimage" has been found to
 * apply at applied_pos (counts in line numbers) in "img".
 * Update "img" to remove "preimage" and replace it with "postimage".
 */
static void update_image(struct apply_state *state,
       struct image *img,
       int applied_pos,
       struct image *preimage,
       struct image *postimage)
{
  /*
   * remove the copy of preimage at offset in img
   * and replace it with postimage
   */
  int i, nr;
  size_t remove_count, insert_count, applied_at = 0;
  size_t result_alloc;
  char *result;
  int preimage_limit;

  /*
   * If we are removing blank lines at the end of img,
   * the preimage may extend beyond the end.
   * If that is the case, we must be careful only to
   * remove the part of the preimage that falls within
   * the boundaries of img. Initialize preimage_limit
   * to the number of lines in the preimage that falls
   * within the boundaries.
   */
  preimage_limit = preimage->line_nr;
  if (preimage_limit > img->line_nr - applied_pos)
    preimage_limit = img->line_nr - applied_pos;

  for (i = 0; i < applied_pos; i++)
    applied_at += img->line[i].len;

  remove_count = 0;
  for (i = 0; i < preimage_limit; i++)
    remove_count += img->line[applied_pos + i].len;
  insert_count = postimage->buf.len;

  /* Adjust the contents */
  result_alloc = st_add3(st_sub(img->buf.len, remove_count), insert_count, 1);
  result = xmalloc(result_alloc);
  memcpy(result, img->buf.buf, applied_at);
  memcpy(result + applied_at, postimage->buf.buf, postimage->buf.len);
  memcpy(result + applied_at + postimage->buf.len,
         img->buf.buf + (applied_at + remove_count),
         img->buf.len - (applied_at + remove_count));
  strbuf_attach(&img->buf, result, postimage->buf.len + img->buf.len - remove_count,
          result_alloc);

  /* Adjust the line table */
  nr = img->line_nr + postimage->line_nr - preimage_limit;
  if (preimage_limit < postimage->line_nr)
    /*
     * NOTE: this knows that we never call image_remove_first_line()
     * on anything other than pre/post image.
     */
    REALLOC_ARRAY(img->line, nr);
  if (preimage_limit != postimage->line_nr)
    MOVE_ARRAY(img->line + applied_pos + postimage->line_nr,
         img->line + applied_pos + preimage_limit,
         img->line_nr - (applied_pos + preimage_limit));
  COPY_ARRAY(img->line + applied_pos, postimage->line, postimage->line_nr);
  if (!state->allow_overlap)
    for (i = 0; i < postimage->line_nr; i++)
      img->line[applied_pos + i].flag |= LINE_PATCHED;
  img->line_nr = nr;
}

/*
 * Use the patch-hunk text in "frag" to prepare two images (preimage and
 * postimage) for the hunk.  Find lines that match "preimage" in "img" and
 * replace the part of "img" with "postimage" text.
 */
static int apply_one_fragment(struct apply_state *state,
            struct image *img, struct fragment *frag,
            int inaccurate_eof, unsigned ws_rule,
            int nth_fragment)
{
  int match_beginning, match_end;
  const char *patch = frag->patch;
  int size = frag->size;
  char *old, *oldlines;
  struct strbuf newlines;
  int new_blank_lines_at_end = 0;
  int found_new_blank_lines_at_end = 0;
  int hunk_linenr = frag->linenr;
  unsigned long leading, trailing;
  int pos, applied_pos;
  struct image preimage = IMAGE_INIT;
  struct image postimage = IMAGE_INIT;

  oldlines = xmalloc(size);
  strbuf_init(&newlines, size);

  old = oldlines;
  while (size > 0) {
    char first;
    int len = linelen(patch, size);
    int plen;
    int added_blank_line = 0;
    int is_blank_context = 0;
    size_t start;

    if (!len)
      break;

    /*
     * "plen" is how much of the line we should use for
     * the actual patch data. Normally we just remove the
     * first character on the line, but if the line is
     * followed by "\ No newline", then we also remove the
     * last one (which is the newline, of course).
     */
    plen = len - 1;
    if (len < size && patch[len] == '\\')
      plen--;
    first = *patch;
    if (state->apply_in_reverse) {
      if (first == '-')
        first = '+';
      else if (first == '+')
        first = '-';
    }

    switch (first) {
    case '\n':
      /* Newer GNU diff, empty context line */
      if (plen < 0)
        /* ... followed by '\No newline'; nothing */
        break;
      *old++ = '\n';
      strbuf_addch(&newlines, '\n');
      image_add_line(&preimage, "\n", 1, LINE_COMMON);
      image_add_line(&postimage, "\n", 1, LINE_COMMON);
      is_blank_context = 1;
      break;
    case ' ':
      if (plen && (ws_rule & WS_BLANK_AT_EOF) &&
          ws_blank_line(patch + 1, plen))
        is_blank_context = 1;
      /* fallthrough */
    case '-':
      memcpy(old, patch + 1, plen);
      image_add_line(&preimage, old, plen,
              (first == ' ' ? LINE_COMMON : 0));
      old += plen;
      if (first == '-')
        break;
      /* fallthrough */
    case '+':
      /* --no-add does not add new lines */
      if (first == '+' && state->no_add)
        break;

      start = newlines.len;
      if (first != '+' ||
          !state->whitespace_error ||
          state->ws_error_action != correct_ws_error) {
        strbuf_add(&newlines, patch + 1, plen);
      }
      else {
        ws_fix_copy(&newlines, patch + 1, plen, ws_rule, &state->applied_after_fixing_ws);
      }
      image_add_line(&postimage, newlines.buf + start, newlines.len - start,
              (first == '+' ? 0 : LINE_COMMON));
      if (first == '+' &&
          (ws_rule & WS_BLANK_AT_EOF) &&
          ws_blank_line(patch + 1, plen))
        added_blank_line = 1;
      break;
    case '@': case '\\':
      /* Ignore it, we already handled it */
      break;
    default:
      if (state->apply_verbosity > verbosity_normal)
        error(_("invalid start of line: '%c'"), first);
      applied_pos = -1;
      goto out;
    }
    if (added_blank_line) {
      if (!new_blank_lines_at_end)
        found_new_blank_lines_at_end = hunk_linenr;
      new_blank_lines_at_end++;
    }
    else if (is_blank_context)
      ;
    else
      new_blank_lines_at_end = 0;
    patch += len;
    size -= len;
    hunk_linenr++;
  }
  if (inaccurate_eof &&
      old > oldlines && old[-1] == '\n' &&
      newlines.len > 0 && newlines.buf[newlines.len - 1] == '\n') {
    old--;
    strbuf_setlen(&newlines, newlines.len - 1);
    preimage.line[preimage.line_nr - 1].len--;
    postimage.line[postimage.line_nr - 1].len--;
  }

  leading = frag->leading;
  trailing = frag->trailing;

  /*
   * A hunk to change lines at the beginning would begin with
   * @@ -1,L +N,M @@
   * but we need to be careful.  -U0 that inserts before the second
   * line also has this pattern.
   *
   * And a hunk to add to an empty file would begin with
   * @@ -0,0 +N,M @@
   *
   * In other words, a hunk that is (frag->oldpos <= 1) with or
   * without leading context must match at the beginning.
   */
  match_beginning = (!frag->oldpos ||
         (frag->oldpos == 1 && !state->unidiff_zero));

  /*
   * A hunk without trailing lines must match at the end.
   * However, we simply cannot tell if a hunk must match end
   * from the lack of trailing lines if the patch was generated
   * with unidiff without any context.
   */
  match_end = !state->unidiff_zero && !trailing;

  pos = frag->newpos ? (frag->newpos - 1) : 0;
  strbuf_add(&preimage.buf, oldlines, old - oldlines);
  strbuf_swap(&postimage.buf, &newlines);

  for (;;) {

    applied_pos = find_pos(state, img, &preimage, &postimage, pos,
               ws_rule, match_beginning, match_end);

    if (applied_pos >= 0)
      break;

    /* Am I at my context limits? */
    if ((leading <= state->p_context) && (trailing <= state->p_context))
      break;
    if (match_beginning || match_end) {
      match_beginning = match_end = 0;
      continue;
    }

    /*
     * Reduce the number of context lines; reduce both
     * leading and trailing if they are equal otherwise
     * just reduce the larger context.
     */
    if (leading >= trailing) {
      image_remove_first_line(&preimage);
      image_remove_first_line(&postimage);
      pos--;
      leading--;
    }
    if (trailing > leading) {
      image_remove_last_line(&preimage);
      image_remove_last_line(&postimage);
      trailing--;
    }
  }

  if (applied_pos >= 0) {
    if (new_blank_lines_at_end &&
        preimage.line_nr + applied_pos >= img->line_nr &&
        (ws_rule & WS_BLANK_AT_EOF) &&
        state->ws_error_action != nowarn_ws_error) {
      record_ws_error(state, WS_BLANK_AT_EOF, "+", 1,
          found_new_blank_lines_at_end);
      if (state->ws_error_action == correct_ws_error) {
        while (new_blank_lines_at_end--)
          image_remove_last_line(&postimage);
      }
      /*
       * We would want to prevent write_out_results()
       * from taking place in apply_patch() that follows
       * the callchain led us here, which is:
       * apply_patch->check_patch_list->check_patch->
       * apply_data->apply_fragments->apply_one_fragment
       */
      if (state->ws_error_action == die_on_ws_error)
        state->apply = 0;
    }

    if (state->apply_verbosity > verbosity_normal && applied_pos != pos) {
      int offset = applied_pos - pos;
      if (state->apply_in_reverse)
        offset = 0 - offset;
      fprintf_ln(stderr,
           Q_("Hunk #%d succeeded at %d (offset %d line).",
              "Hunk #%d succeeded at %d (offset %d lines).",
              offset),
           nth_fragment, applied_pos + 1, offset);
    }

    /*
     * Warn if it was necessary to reduce the number
     * of context lines.
     */
    if ((leading != frag->leading ||
         trailing != frag->trailing) && state->apply_verbosity > verbosity_silent)
      fprintf_ln(stderr, _("Context reduced to (%ld/%ld)"
               " to apply fragment at %d"),
           leading, trailing, applied_pos+1);
    update_image(state, img, applied_pos, &preimage, &postimage);
  } else {
    if (state->apply_verbosity > verbosity_normal)
      error(_("while searching for:\n%.*s"),
            (int)(old - oldlines), oldlines);
  }

out:
  free(oldlines);
  strbuf_release(&newlines);
  image_clear(&preimage);
  image_clear(&postimage);

  return (applied_pos < 0);
}

static int apply_binary_fragment(struct apply_state *state,
         struct image *img,
         struct patch *patch)
{
  struct fragment *fragment = patch->fragments;
  unsigned long len;
  void *dst;

  if (!fragment)
    return error(_("missing binary patch data for '%s'"),
           patch->new_name ?
           patch->new_name :
           patch->old_name);

  /* Binary patch is irreversible without the optional second hunk */
  if (state->apply_in_reverse) {
    if (!fragment->next)
      return error(_("cannot reverse-apply a binary patch "
               "without the reverse hunk to '%s'"),
             patch->new_name
             ? patch->new_name : patch->old_name);
    fragment = fragment->next;
  }
  switch (fragment->binary_patch_method) {
  case BINARY_DELTA_DEFLATED:
    dst = patch_delta(img->buf.buf, img->buf.len, fragment->patch,
          fragment->size, &len);
    if (!dst)
      return -1;
    image_clear(img);
    strbuf_attach(&img->buf, dst, len, len + 1);
    return 0;
  case BINARY_LITERAL_DEFLATED:
    image_clear(img);
    strbuf_add(&img->buf, fragment->patch, fragment->size);
    return 0;
  }
  return -1;
}

/*
 * Replace "img" with the result of applying the binary patch.
 * The binary patch data itself in patch->fragment is still kept
 * but the preimage prepared by the caller in "img" is freed here
 * or in the helper function apply_binary_fragment() this calls.
 */
static int apply_binary(struct apply_state *state,
      struct image *img,
      struct patch *patch)
{
  const char *name = patch->old_name ? patch->old_name : patch->new_name;
  struct object_id oid;
  const unsigned hexsz = the_hash_algo->hexsz;

  /*
   * For safety, we require patch index line to contain
   * full hex textual object ID for old and new, at least for now.
   */
  if (strlen(patch->old_oid_prefix) != hexsz ||
      strlen(patch->new_oid_prefix) != hexsz ||
      get_oid_hex(patch->old_oid_prefix, &oid) ||
      get_oid_hex(patch->new_oid_prefix, &oid))
    return error(_("cannot apply binary patch to '%s' "
             "without full index line"), name);

  if (patch->old_name) {
    /*
     * See if the old one matches what the patch
     * applies to.
     */
    hash_object_file(the_hash_algo, img->buf.buf, img->buf.len,
         OBJ_BLOB, &oid);
    if (strcmp(oid_to_hex(&oid), patch->old_oid_prefix))
      return error(_("the patch applies to '%s' (%s), "
               "which does not match the "
               "current contents."),
             name, oid_to_hex(&oid));
  }
  else {
    /* Otherwise, the old one must be empty. */
    if (img->buf.len)
      return error(_("the patch applies to an empty "
               "'%s' but it is not empty"), name);
  }

  get_oid_hex(patch->new_oid_prefix, &oid);
  if (is_null_oid(&oid)) {
    image_clear(img);
    return 0; /* deletion patch */
  }

  if (odb_has_object(the_repository->objects, &oid, 0)) {
    /* We already have the postimage */
    enum object_type type;
    unsigned long size;
    char *result;

    result = odb_read_object(the_repository->objects, &oid,
           &type, &size);
    if (!result)
      return error(_("the necessary postimage %s for "
               "'%s' cannot be read"),
             patch->new_oid_prefix, name);
    image_clear(img);
    strbuf_attach(&img->buf, result, size, size + 1);
  } else {
    /*
     * We have verified buf matches the preimage;
     * apply the patch data to it, which is stored
     * in the patch->fragments->{patch,size}.
     */
    if (apply_binary_fragment(state, img, patch))
      return error(_("binary patch does not apply to '%s'"),
             name);

    /* verify that the result matches */
    hash_object_file(the_hash_algo, img->buf.buf, img->buf.len, OBJ_BLOB,
         &oid);
    if (strcmp(oid_to_hex(&oid), patch->new_oid_prefix))
      return error(_("binary patch to '%s' creates incorrect result (expecting %s, got %s)"),
        name, patch->new_oid_prefix, oid_to_hex(&oid));
  }

  return 0;
}

static int apply_fragments(struct apply_state *state, struct image *img, struct patch *patch)
{
  struct fragment *frag = patch->fragments;
  const char *name = patch->old_name ? patch->old_name : patch->new_name;
  unsigned ws_rule = patch->ws_rule;
  unsigned inaccurate_eof = patch->inaccurate_eof;
  int nth = 0;

  if (patch->is_binary)
    return apply_binary(state, img, patch);

  while (frag) {
    nth++;
    if (apply_one_fragment(state, img, frag, inaccurate_eof, ws_rule, nth)) {
      error(_("patch failed: %s:%ld"), name, frag->oldpos);
      if (!state->apply_with_reject)
        return -1;
      frag->rejected = 1;
    }
    frag = frag->next;
  }
  return 0;
}

static int read_blob_object(struct strbuf *buf, const struct object_id *oid, unsigned mode)
{
  if (S_ISGITLINK(mode)) {
    strbuf_grow(buf, 100);
    strbuf_addf(buf, "Subproject commit %s\n", oid_to_hex(oid));
  } else {
    enum object_type type;
    unsigned long sz;
    char *result;

    result = odb_read_object(the_repository->objects, oid,
           &type, &sz);
    if (!result)
      return -1;
    /* XXX read_sha1_file NUL-terminates */
    strbuf_attach(buf, result, sz, sz + 1);
  }
  return 0;
}

static int read_file_or_gitlink(const struct cache_entry *ce, struct strbuf *buf)
{
  if (!ce)
    return 0;
  return read_blob_object(buf, &ce->oid, ce->ce_mode);
}

static struct patch *in_fn_table(struct apply_state *state, const char *name)
{
  struct string_list_item *item;

  if (!name)
    return NULL;

  item = string_list_lookup(&state->fn_table, name);
  if (item)
    return (struct patch *)item->util;

  return NULL;
}

/*
 * item->util in the filename table records the status of the path.
 * Usually it points at a patch (whose result records the contents
 * of it after applying it), but it could be PATH_WAS_DELETED for a
 * path that a previously applied patch has already removed, or
 * PATH_TO_BE_DELETED for a path that a later patch would remove.
 *
 * The latter is needed to deal with a case where two paths A and B
 * are swapped by first renaming A to B and then renaming B to A;
 * moving A to B should not be prevented due to presence of B as we
 * will remove it in a later patch.
 */
#define PATH_TO_BE_DELETED ((struct patch *) -2)
#define PATH_WAS_DELETED ((struct patch *) -1)

static int to_be_deleted(struct patch *patch)
{
  return patch == PATH_TO_BE_DELETED;
}

static int was_deleted(struct patch *patch)
{
  return patch == PATH_WAS_DELETED;
}

static void add_to_fn_table(struct apply_state *state, struct patch *patch)
{
  struct string_list_item *item;

  /*
   * Always add new_name unless patch is a deletion
   * This should cover the cases for normal diffs,
   * file creations and copies
   */
  if (patch->new_name) {
    item = string_list_insert(&state->fn_table, patch->new_name);
    item->util = patch;
  }

  /*
   * store a failure on rename/deletion cases because
   * later chunks shouldn't patch old names
   */
  if ((patch->new_name == NULL) || (patch->is_rename)) {
    item = string_list_insert(&state->fn_table, patch->old_name);
    item->util = PATH_WAS_DELETED;
  }
}

static void prepare_fn_table(struct apply_state *state, struct patch *patch)
{
  /*
   * store information about incoming file deletion
   */
  while (patch) {
    if ((patch->new_name == NULL) || (patch->is_rename)) {
      struct string_list_item *item;
      item = string_list_insert(&state->fn_table, patch->old_name);
      item->util = PATH_TO_BE_DELETED;
    }
    patch = patch->next;
  }
}

static int checkout_target(struct index_state *istate,
         struct cache_entry *ce, struct stat *st)
{
  struct checkout costate = CHECKOUT_INIT;

  costate.refresh_cache = 1;
  costate.istate = istate;
  if (checkout_entry(ce, &costate, NULL, NULL) ||
      lstat(ce->name, st))
    return error(_("cannot checkout %s"), ce->name);
  return 0;
}

static struct patch *previous_patch(struct apply_state *state,
            struct patch *patch,
            int *gone)
{
  struct patch *previous;

  *gone = 0;
  if (patch->is_copy || patch->is_rename)
    return NULL; /* "git" patches do not depend on the order */

  previous = in_fn_table(state, patch->old_name);
  if (!previous)
    return NULL;

  if (to_be_deleted(previous))
    return NULL; /* the deletion hasn't happened yet */

  if (was_deleted(previous))
    *gone = 1;

  return previous;
}

static int verify_index_match(struct apply_state *state,
            const struct cache_entry *ce,
            struct stat *st)
{
  if (S_ISGITLINK(ce->ce_mode)) {
    if (!S_ISDIR(st->st_mode))
      return -1;
    return 0;
  }
  return ie_match_stat(state->repo->index, ce, st,
           CE_MATCH_IGNORE_VALID | CE_MATCH_IGNORE_SKIP_WORKTREE);
}

#define SUBMODULE_PATCH_WITHOUT_INDEX 1

static int load_patch_target(struct apply_state *state,
           struct strbuf *buf,
           const struct cache_entry *ce,
           struct stat *st,
           struct patch *patch,
           const char *name,
           unsigned expected_mode)
{
  if (state->cached || state->check_index) {
    if (read_file_or_gitlink(ce, buf))
      return error(_("failed to read %s"), name);
  } else if (name) {
    if (S_ISGITLINK(expected_mode)) {
      if (ce)
        return read_file_or_gitlink(ce, buf);
      else
        return SUBMODULE_PATCH_WITHOUT_INDEX;
    } else if (has_symlink_leading_path(name, strlen(name))) {
      return error(_("reading from '%s' beyond a symbolic link"), name);
    } else {
      if (read_old_data(st, patch, name, buf))
        return error(_("failed to read %s"), name);
    }
  }
  return 0;
}

/*
 * We are about to apply "patch"; populate the "image" with the
 * current version we have, from the working tree or from the index,
 * depending on the situation e.g. --cached/--index.  If we are
 * applying a non-git patch that incrementally updates the tree,
 * we read from the result of a previous diff.
 */
static int load_preimage(struct apply_state *state,
       struct image *image,
       struct patch *patch, struct stat *st,
       const struct cache_entry *ce)
{
  struct strbuf buf = STRBUF_INIT;
  size_t len;
  char *img;
  struct patch *previous;
  int status;

  previous = previous_patch(state, patch, &status);
  if (status)
    return error(_("path %s has been renamed/deleted"),
           patch->old_name);
  if (previous) {
    /* We have a patched copy in memory; use that. */
    strbuf_add(&buf, previous->result, previous->resultsize);
  } else {
    status = load_patch_target(state, &buf, ce, st, patch,
             patch->old_name, patch->old_mode);
    if (status < 0)
      return status;
    else if (status == SUBMODULE_PATCH_WITHOUT_INDEX) {
      /*
       * There is no way to apply subproject
       * patch without looking at the index.
       * NEEDSWORK: shouldn't this be flagged
       * as an error???
       */
      free_fragment_list(patch->fragments);
      patch->fragments = NULL;
    } else if (status) {
      return error(_("failed to read %s"), patch->old_name);
    }
  }

  img = strbuf_detach(&buf, &len);
  image_prepare(image, img, len, !patch->is_binary);
  return 0;
}

static int resolve_to(struct image *image, const struct object_id *result_id)
{
  unsigned long size;
  enum object_type type;
  char *data;

  image_clear(image);

  data = odb_read_object(the_repository->objects, result_id, &type, &size);
  if (!data || type != OBJ_BLOB)
    die("unable to read blob object %s", oid_to_hex(result_id));
  strbuf_attach(&image->buf, data, size, size + 1);

  return 0;
}

static int three_way_merge(struct apply_state *state,
         struct image *image,
         char *path,
         const struct object_id *base,
         const struct object_id *ours,
         const struct object_id *theirs)
{
  mmfile_t base_file, our_file, their_file;
  struct ll_merge_options merge_opts = LL_MERGE_OPTIONS_INIT;
  mmbuffer_t result = { NULL };
  enum ll_merge_result status;

  /* resolve trivial cases first */
  if (oideq(base, ours))
    return resolve_to(image, theirs);
  else if (oideq(base, theirs) || oideq(ours, theirs))
    return resolve_to(image, ours);

  read_mmblob(&base_file, the_repository->objects, base);
  read_mmblob(&our_file, the_repository->objects, ours);
  read_mmblob(&their_file, the_repository->objects, theirs);
  merge_opts.variant = state->merge_variant;
  status = ll_merge(&result, path,
        &base_file, "base",
        &our_file, "ours",
        &their_file, "theirs",
        state->repo->index,
        &merge_opts);
  if (status == LL_MERGE_BINARY_CONFLICT)
    warning("Cannot merge binary files: %s (%s vs. %s)",
      path, "ours", "theirs");
  free(base_file.ptr);
  free(our_file.ptr);
  free(their_file.ptr);
  if (status < 0 || !result.ptr) {
    free(result.ptr);
    return -1;
  }
  image_clear(image);
  strbuf_attach(&image->buf, result.ptr, result.size, result.size);

  return status;
}

/*
 * When directly falling back to add/add three-way merge, we read from
 * the current contents of the new_name.  In no cases other than that
 * this function will be called.
 */
static int load_current(struct apply_state *state,
      struct image *image,
      struct patch *patch)
{
  struct strbuf buf = STRBUF_INIT;
  int status, pos;
  size_t len;
  char *img;
  struct stat st;
  struct cache_entry *ce;
  char *name = patch->new_name;
  unsigned mode = patch->new_mode;

  if (!patch->is_new)
    BUG("patch to %s is not a creation", patch->old_name);

  pos = index_name_pos(state->repo->index, name, strlen(name));
  if (pos < 0)
    return error(_("%s: does not exist in index"), name);
  ce = state->repo->index->cache[pos];
  if (lstat(name, &st)) {
    if (errno != ENOENT)
      return error_errno("%s", name);
    if (checkout_target(state->repo->index, ce, &st))
      return -1;
  }
  if (verify_index_match(state, ce, &st))
    return error(_("%s: does not match index"), name);

  status = load_patch_target(state, &buf, ce, &st, patch, name, mode);
  if (status < 0)
    return status;
  else if (status)
    return -1;
  img = strbuf_detach(&buf, &len);
  image_prepare(image, img, len, !patch->is_binary);
  return 0;
}

static int try_threeway(struct apply_state *state,
      struct image *image,
      struct patch *patch,
      struct stat *st,
      const struct cache_entry *ce)
{
  struct object_id pre_oid, post_oid, our_oid;
  struct strbuf buf = STRBUF_INIT;
  size_t len;
  int status;
  char *img;
  struct image tmp_image = IMAGE_INIT;

  /* No point falling back to 3-way merge in these cases */
  if (patch->is_delete ||
      S_ISGITLINK(patch->old_mode) || S_ISGITLINK(patch->new_mode) ||
      (patch->is_new && !patch->direct_to_threeway) ||
      (patch->is_rename && !patch->lines_added && !patch->lines_deleted))
    return -1;

  /* Preimage the patch was prepared for */
  if (patch->is_new)
    odb_write_object(the_repository->objects, "", 0, OBJ_BLOB, &pre_oid);
  else if (repo_get_oid(the_repository, patch->old_oid_prefix, &pre_oid) ||
     read_blob_object(&buf, &pre_oid, patch->old_mode))
    return error(_("repository lacks the necessary blob to perform 3-way merge."));

  if (state->apply_verbosity > verbosity_silent && patch->direct_to_threeway)
    fprintf(stderr, _("Performing three-way merge...\n"));

  img = strbuf_detach(&buf, &len);
  image_prepare(&tmp_image, img, len, 1);
  /* Apply the patch to get the post image */
  if (apply_fragments(state, &tmp_image, patch) < 0) {
    image_clear(&tmp_image);
    return -1;
  }
  /* post_oid is theirs */
  odb_write_object(the_repository->objects, tmp_image.buf.buf,
       tmp_image.buf.len, OBJ_BLOB, &post_oid);
  image_clear(&tmp_image);

  /* our_oid is ours */
  if (patch->is_new) {
    if (load_current(state, &tmp_image, patch))
      return error(_("cannot read the current contents of '%s'"),
             patch->new_name);
  } else {
    if (load_preimage(state, &tmp_image, patch, st, ce))
      return error(_("cannot read the current contents of '%s'"),
             patch->old_name);
  }
  odb_write_object(the_repository->objects, tmp_image.buf.buf,
       tmp_image.buf.len, OBJ_BLOB, &our_oid);
  image_clear(&tmp_image);

  /* in-core three-way merge between post and our using pre as base */
  status = three_way_merge(state, image, patch->new_name,
         &pre_oid, &our_oid, &post_oid);
  if (status < 0) {
    if (state->apply_verbosity > verbosity_silent)
      fprintf(stderr,
        _("Failed to perform three-way merge...\n"));
    return status;
  }

  if (status) {
    patch->conflicted_threeway = 1;
    if (patch->is_new)
      oidclr(&patch->threeway_stage[0], the_repository->hash_algo);
    else
      oidcpy(&patch->threeway_stage[0], &pre_oid);
    oidcpy(&patch->threeway_stage[1], &our_oid);
    oidcpy(&patch->threeway_stage[2], &post_oid);
    if (state->apply_verbosity > verbosity_silent)
      fprintf(stderr,
        _("Applied patch to '%s' with conflicts.\n"),
        patch->new_name);
  } else {
    if (state->apply_verbosity > verbosity_silent)
      fprintf(stderr,
        _("Applied patch to '%s' cleanly.\n"),
        patch->new_name);
  }
  return 0;
}

static int apply_data(struct apply_state *state, struct patch *patch,
          struct stat *st, const struct cache_entry *ce)
{
  struct image image = IMAGE_INIT;

  if (load_preimage(state, &image, patch, st, ce) < 0)
    return -1;

  if (!state->threeway || try_threeway(state, &image, patch, st, ce) < 0) {
    if (state->apply_verbosity > verbosity_silent &&
        state->threeway && !patch->direct_to_threeway)
      fprintf(stderr, _("Falling back to direct application...\n"));

    /* Note: with --reject, apply_fragments() returns 0 */
    if (patch->direct_to_threeway || apply_fragments(state, &image, patch) < 0) {
      image_clear(&image);
      return -1;
    }
  }
  patch->result = strbuf_detach(&image.buf, &patch->resultsize);
  add_to_fn_table(state, patch);
  free(image.line);

  if (0 < patch->is_delete && patch->resultsize)
    return error(_("removal patch leaves file contents"));

  return 0;
}

/*
 * If "patch" that we are looking at modifies or deletes what we have,
 * we would want it not to lose any local modification we have, either
 * in the working tree or in the index.
 *
 * This also decides if a non-git patch is a creation patch or a
 * modification to an existing empty file.  We do not check the state
 * of the current tree for a creation patch in this function; the caller
 * check_patch() separately makes sure (and errors out otherwise) that
 * the path the patch creates does not exist in the current tree.
 */
static int check_preimage(struct apply_state *state,
        struct patch *patch,
        struct cache_entry **ce,
        struct stat *st)
{
  const char *old_name = patch->old_name;
  struct patch *previous = NULL;
  int stat_ret = 0, status;
  unsigned st_mode = 0;

  if (!old_name)
    return 0;

  assert(patch->is_new <= 0);
  previous = previous_patch(state, patch, &status);

  if (status)
    return error(_("path %s has been renamed/deleted"), old_name);
  if (previous) {
    st_mode = previous->new_mode;
  } else if (!state->cached) {
    stat_ret = lstat(old_name, st);
    if (stat_ret && errno != ENOENT)
      return error_errno("%s", old_name);
  }

  if (state->check_index && !previous) {
    int pos = index_name_pos(state->repo->index, old_name,
           strlen(old_name));
    if (pos < 0) {
      if (patch->is_new < 0)
        goto is_new;
      return error(_("%s: does not exist in index"), old_name);
    }
    *ce = state->repo->index->cache[pos];
    if (stat_ret < 0) {
      if (checkout_target(state->repo->index, *ce, st))
        return -1;
    }
    if (!state->cached && verify_index_match(state, *ce, st))
      return error(_("%s: does not match index"), old_name);
    if (state->cached)
      st_mode = (*ce)->ce_mode;
  } else if (stat_ret < 0) {
    if (patch->is_new < 0)
      goto is_new;
    return error_errno("%s", old_name);
  }

  if (!state->cached && !previous) {
    if (*ce && !(*ce)->ce_mode)
      BUG("ce_mode == 0 for path '%s'", old_name);

    if (trust_executable_bit || !S_ISREG(st->st_mode))
      st_mode = ce_mode_from_stat(*ce, st->st_mode);
    else if (*ce)
      st_mode = (*ce)->ce_mode;
    else
      st_mode = patch->old_mode;
  }

  if (patch->is_new < 0)
    patch->is_new = 0;
  if (!patch->old_mode)
    patch->old_mode = st_mode;
  if ((st_mode ^ patch->old_mode) & S_IFMT)
    return error(_("%s: wrong type"), old_name);
  if (st_mode != patch->old_mode)
    warning(_("%s has type %o, expected %o"),
      old_name, st_mode, patch->old_mode);
  if (!patch->new_mode && !patch->is_delete)
    patch->new_mode = st_mode;
  return 0;

 is_new:
  patch->is_new = 1;
  patch->is_delete = 0;
  FREE_AND_NULL(patch->old_name);
  return 0;
}


#define EXISTS_IN_INDEX 1
#define EXISTS_IN_WORKTREE 2
#define EXISTS_IN_INDEX_AS_ITA 3

static int check_to_create(struct apply_state *state,
         const char *new_name,
         int ok_if_exists)
{
  struct stat nst;

  if (state->check_index && (!ok_if_exists || !state->cached)) {
    int pos;

    pos = index_name_pos(state->repo->index, new_name, strlen(new_name));
    if (pos >= 0) {
      struct cache_entry *ce = state->repo->index->cache[pos];

      /* allow ITA, as they do not yet exist in the index */
      if (!ok_if_exists && !(ce->ce_flags & CE_INTENT_TO_ADD))
        return EXISTS_IN_INDEX;

      /* ITA entries can never match working tree files */
      if (!state->cached && (ce->ce_flags & CE_INTENT_TO_ADD))
        return EXISTS_IN_INDEX_AS_ITA;
    }
  }

  if (state->cached)
    return 0;

  if (!lstat(new_name, &nst)) {
    if (S_ISDIR(nst.st_mode) || ok_if_exists)
      return 0;
    /*
     * A leading component of new_name might be a symlink
     * that is going to be removed with this patch, but
     * still pointing at somewhere that has the path.
     * In such a case, path "new_name" does not exist as
     * far as git is concerned.
     */
    if (has_symlink_leading_path(new_name, strlen(new_name)))
      return 0;

    return EXISTS_IN_WORKTREE;
  } else if (!is_missing_file_error(errno)) {
    return error_errno("%s", new_name);
  }
  return 0;
}

static void prepare_symlink_changes(struct apply_state *state, struct patch *patch)
{
  for ( ; patch; patch = patch->next) {
    if ((patch->old_name && S_ISLNK(patch->old_mode)) &&
        (patch->is_rename || patch->is_delete))
      /* the symlink at patch->old_name is removed */
      strset_add(&state->removed_symlinks, patch->old_name);

    if (patch->new_name && S_ISLNK(patch->new_mode))
      /* the symlink at patch->new_name is created or remains */
      strset_add(&state->kept_symlinks, patch->new_name);
  }
}

static int path_is_beyond_symlink_1(struct apply_state *state, struct strbuf *name)
{
  do {
    while (--name->len && name->buf[name->len] != '/')
      ; /* scan backwards */
    if (!name->len)
      break;
    name->buf[name->len] = '\0';
    if (strset_contains(&state->kept_symlinks, name->buf))
      return 1;
    if (strset_contains(&state->removed_symlinks, name->buf))
      /*
       * This cannot be "return 0", because we may
       * see a new one created at a higher level.
       */
      continue;

    /* otherwise, check the preimage */
    if (state->check_index) {
      struct cache_entry *ce;

      ce = index_file_exists(state->repo->index, name->buf,
                 name->len, ignore_case);
      if (ce && S_ISLNK(ce->ce_mode))
        return 1;
    } else {
      struct stat st;
      if (!lstat(name->buf, &st) && S_ISLNK(st.st_mode))
        return 1;
    }
  } while (1);
  return 0;
}

static int path_is_beyond_symlink(struct apply_state *state, const char *name_)
{
  int ret;
  struct strbuf name = STRBUF_INIT;

  assert(*name_ != '\0');
  strbuf_addstr(&name, name_);
  ret = path_is_beyond_symlink_1(state, &name);
  strbuf_release(&name);

  return ret;
}

static int check_unsafe_path(struct patch *patch)
{
  const char *old_name = NULL;
  const char *new_name = NULL;
  if (patch->is_delete)
    old_name = patch->old_name;
  else if (!patch->is_new && !patch->is_copy)
    old_name = patch->old_name;
  if (!patch->is_delete)
    new_name = patch->new_name;

  if (old_name && !verify_path(old_name, patch->old_mode))
    return error(_("invalid path '%s'"), old_name);
  if (new_name && !verify_path(new_name, patch->new_mode))
    return error(_("invalid path '%s'"), new_name);
  return 0;
}

/*
 * Check and apply the patch in-core; leave the result in patch->result
 * for the caller to write it out to the final destination.
 */
static int check_patch(struct apply_state *state, struct patch *patch)
{
  struct stat st;
  const char *old_name = patch->old_name;
  const char *new_name = patch->new_name;
  const char *name = old_name ? old_name : new_name;
  struct cache_entry *ce = NULL;
  struct patch *tpatch;
  int ok_if_exists;
  int status;

  patch->rejected = 1; /* we will drop this after we succeed */

  status = check_preimage(state, patch, &ce, &st);
  if (status)
    return status;
  old_name = patch->old_name;

  /*
   * A type-change diff is always split into a patch to delete
   * old, immediately followed by a patch to create new (see
   * diff.c::run_diff()); in such a case it is Ok that the entry
   * to be deleted by the previous patch is still in the working
   * tree and in the index.
   *
   * A patch to swap-rename between A and B would first rename A
   * to B and then rename B to A.  While applying the first one,
   * the presence of B should not stop A from getting renamed to
   * B; ask to_be_deleted() about the later rename.  Removal of
   * B and rename from A to B is handled the same way by asking
   * was_deleted().
   */
  if ((tpatch = in_fn_table(state, new_name)) &&
      (was_deleted(tpatch) || to_be_deleted(tpatch)))
    ok_if_exists = 1;
  else
    ok_if_exists = 0;

  if (new_name &&
      ((0 < patch->is_new) || patch->is_rename || patch->is_copy)) {
    int err = check_to_create(state, new_name, ok_if_exists);

    if (err && state->threeway) {
      patch->direct_to_threeway = 1;
    } else switch (err) {
    case 0:
      break; /* happy */
    case EXISTS_IN_INDEX:
      return error(_("%s: already exists in index"), new_name);
    case EXISTS_IN_INDEX_AS_ITA:
      return error(_("%s: does not match index"), new_name);
    case EXISTS_IN_WORKTREE:
      return error(_("%s: already exists in working directory"),
             new_name);
    default:
      return err;
    }

    if (!patch->new_mode) {
      if (0 < patch->is_new)
        patch->new_mode = S_IFREG | 0644;
      else
        patch->new_mode = patch->old_mode;
    }
  }

  if (new_name && old_name) {
    int same = !strcmp(old_name, new_name);
    if (!patch->new_mode)
      patch->new_mode = patch->old_mode;
    if ((patch->old_mode ^ patch->new_mode) & S_IFMT) {
      if (same)
        return error(_("new mode (%o) of %s does not "
                 "match old mode (%o)"),
          patch->new_mode, new_name,
          patch->old_mode);
      else
        return error(_("new mode (%o) of %s does not "
                 "match old mode (%o) of %s"),
          patch->new_mode, new_name,
          patch->old_mode, old_name);
    }
  }

  if (!state->unsafe_paths && check_unsafe_path(patch))
    return -128;

  /*
   * An attempt to read from or delete a path that is beyond a
   * symbolic link will be prevented by load_patch_target() that
   * is called at the beginning of apply_data() so we do not
   * have to worry about a patch marked with "is_delete" bit
   * here.  We however need to make sure that the patch result
   * is not deposited to a path that is beyond a symbolic link
   * here.
   */
  if (!patch->is_delete && path_is_beyond_symlink(state, patch->new_name))
    return error(_("affected file '%s' is beyond a symbolic link"),
           patch->new_name);

  if (apply_data(state, patch, &st, ce) < 0)
    return error(_("%s: patch does not apply"), name);
  patch->rejected = 0;
  return 0;
}

static int check_patch_list(struct apply_state *state, struct patch *patch)
{
  int err = 0;

  prepare_symlink_changes(state, patch);
  prepare_fn_table(state, patch);
  while (patch) {
    int res;
    if (state->apply_verbosity > verbosity_normal)
      say_patch_name(stderr,
               _("Checking patch %s..."), patch);
    res = check_patch(state, patch);
    if (res == -128)
      return -128;
    err |= res;
    patch = patch->next;
  }
  return err;
}

static int read_apply_cache(struct apply_state *state)
{
  if (state->index_file)
    return read_index_from(state->repo->index, state->index_file,
               repo_get_git_dir(the_repository));
  else
    return repo_read_index(state->repo);
}

/* This function tries to read the object name from the current index */
static int get_current_oid(struct apply_state *state, const char *path,
         struct object_id *oid)
{
  int pos;

  if (read_apply_cache(state) < 0)
    return -1;
  pos = index_name_pos(state->repo->index, path, strlen(path));
  if (pos < 0)
    return -1;
  oidcpy(oid, &state->repo->index->cache[pos]->oid);
  return 0;
}

static int preimage_oid_in_gitlink_patch(struct patch *p, struct object_id *oid)
{
  /*
   * A usable gitlink patch has only one fragment (hunk) that looks like:
   * @@ -1 +1 @@
   * -Subproject commit <old sha1>
   * +Subproject commit <new sha1>
   * or
   * @@ -1 +0,0 @@
   * -Subproject commit <old sha1>
   * for a removal patch.
   */
  struct fragment *hunk = p->fragments;
  static const char heading[] = "-Subproject commit ";
  const char *preimage;

  if (/* does the patch have only one hunk? */
      hunk && !hunk->next &&
      /* is its preimage one line? */
      hunk->oldpos == 1 && hunk->oldlines == 1 &&
      /* does preimage begin with the heading? */
      (preimage = memchr(hunk->patch, '\n', hunk->size)) != NULL &&
      starts_with(++preimage, heading) &&
      /* does it record full SHA-1? */
      !get_oid_hex(preimage + sizeof(heading) - 1, oid) &&
      preimage[sizeof(heading) + the_hash_algo->hexsz - 1] == '\n' &&
      /* does the abbreviated name on the index line agree with it? */
      starts_with(preimage + sizeof(heading) - 1, p->old_oid_prefix))
    return 0; /* it all looks fine */

  /* we may have full object name on the index line */
  return get_oid_hex(p->old_oid_prefix, oid);
}

/* Build an index that contains just the files needed for a 3way merge */
static int build_fake_ancestor(struct apply_state *state, struct patch *list)
{
  struct patch *patch;
  struct index_state result = INDEX_STATE_INIT(state->repo);
  struct lock_file lock = LOCK_INIT;
  int res;

  /* Once we start supporting the reverse patch, it may be
   * worth showing the new sha1 prefix, but until then...
   */
  for (patch = list; patch; patch = patch->next) {
    struct object_id oid;
    struct cache_entry *ce;
    const char *name;

    name = patch->old_name ? patch->old_name : patch->new_name;
    if (0 < patch->is_new)
      continue;

    if (S_ISGITLINK(patch->old_mode)) {
      if (!preimage_oid_in_gitlink_patch(patch, &oid))
        ; /* ok, the textual part looks sane */
      else
        return error(_("sha1 information is lacking or "
                 "useless for submodule %s"), name);
    } else if (!repo_get_oid_blob(the_repository, patch->old_oid_prefix, &oid)) {
      ; /* ok */
    } else if (!patch->lines_added && !patch->lines_deleted) {
      /* mode-only change: update the current */
      if (get_current_oid(state, patch->old_name, &oid))
        return error(_("mode change for %s, which is not "
                 "in current HEAD"), name);
    } else
      return error(_("sha1 information is lacking or useless "
               "(%s)."), name);

    ce = make_cache_entry(&result, patch->old_mode, &oid, name, 0, 0);
    if (!ce)
      return error(_("make_cache_entry failed for path '%s'"),
             name);
    if (add_index_entry(&result, ce, ADD_CACHE_OK_TO_ADD)) {
      discard_cache_entry(ce);
      return error(_("could not add %s to temporary index"),
             name);
    }
  }

  hold_lock_file_for_update(&lock, state->fake_ancestor, LOCK_DIE_ON_ERROR);
  res = write_locked_index(&result, &lock, COMMIT_LOCK);
  discard_index(&result);

  if (res)
    return error(_("could not write temporary index to %s"),
           state->fake_ancestor);

  return 0;
}

static void stat_patch_list(struct apply_state *state, struct patch *patch)
{
  int files, adds, dels;

  for (files = adds = dels = 0 ; patch ; patch = patch->next) {
    files++;
    adds += patch->lines_added;
    dels += patch->lines_deleted;
    show_stats(state, patch);
  }

  print_stat_summary(stdout, files, adds, dels);
}

static void numstat_patch_list(struct apply_state *state,
             struct patch *patch)
{
  for ( ; patch; patch = patch->next) {
    const char *name;
    name = patch->new_name ? patch->new_name : patch->old_name;
    if (patch->is_binary)
      printf("-\t-\t");
    else
      printf("%d\t%d\t", patch->lines_added, patch->lines_deleted);
    write_name_quoted(name, stdout, state->line_termination);
  }
}

static void show_file_mode_name(const char *newdelete, unsigned int mode, const char *name)
{
  if (mode)
    printf(" %s mode %06o %s\n", newdelete, mode, name);
  else
    printf(" %s %s\n", newdelete, name);
}

static void show_mode_change(struct patch *p, int show_name)
{
  if (p->old_mode && p->new_mode && p->old_mode != p->new_mode) {
    if (show_name)
      printf(" mode change %06o => %06o %s\n",
             p->old_mode, p->new_mode, p->new_name);
    else
      printf(" mode change %06o => %06o\n",
             p->old_mode, p->new_mode);
  }
}

static void show_rename_copy(struct patch *p)
{
  const char *renamecopy = p->is_rename ? "rename" : "copy";
  const char *old_name, *new_name;

  /* Find common prefix */
  old_name = p->old_name;
  new_name = p->new_name;
  while (1) {
    const char *slash_old, *slash_new;
    slash_old = strchr(old_name, '/');
    slash_new = strchr(new_name, '/');
    if (!slash_old ||
        !slash_new ||
        slash_old - old_name != slash_new - new_name ||
        memcmp(old_name, new_name, slash_new - new_name))
      break;
    old_name = slash_old + 1;
    new_name = slash_new + 1;
  }
  /* p->old_name through old_name is the common prefix, and old_name and
   * new_name through the end of names are renames
   */
  if (old_name != p->old_name)
    printf(" %s %.*s{%s => %s} (%d%%)\n", renamecopy,
           (int)(old_name - p->old_name), p->old_name,
           old_name, new_name, p->score);
  else
    printf(" %s %s => %s (%d%%)\n", renamecopy,
           p->old_name, p->new_name, p->score);
  show_mode_change(p, 0);
}

static void summary_patch_list(struct patch *patch)
{
  struct patch *p;

  for (p = patch; p; p = p->next) {
    if (p->is_new)
      show_file_mode_name("create", p->new_mode, p->new_name);
    else if (p->is_delete)
      show_file_mode_name("delete", p->old_mode, p->old_name);
    else {
      if (p->is_rename || p->is_copy)
        show_rename_copy(p);
      else {
        if (p->score) {
          printf(" rewrite %s (%d%%)\n",
                 p->new_name, p->score);
          show_mode_change(p, 0);
        }
        else
          show_mode_change(p, 1);
      }
    }
  }
}

static void patch_stats(struct apply_state *state, struct patch *patch)
{
  int lines = patch->lines_added + patch->lines_deleted;

  if (lines > state->max_change)
    state->max_change = lines;
  if (patch->old_name) {
    int len = quote_c_style(patch->old_name, NULL, NULL, 0);
    if (!len)
      len = strlen(patch->old_name);
    if (len > state->max_len)
      state->max_len = len;
  }
  if (patch->new_name) {
    int len = quote_c_style(patch->new_name, NULL, NULL, 0);
    if (!len)
      len = strlen(patch->new_name);
    if (len > state->max_len)
      state->max_len = len;
  }
}

static int remove_file(struct apply_state *state, struct patch *patch, int rmdir_empty)
{
  if (state->update_index && !state->ita_only) {
    if (remove_file_from_index(state->repo->index, patch->old_name) < 0)
      return error(_("unable to remove %s from index"), patch->old_name);
  }
  if (!state->cached) {
    if (!remove_or_warn(patch->old_mode, patch->old_name) && rmdir_empty) {
      remove_path(patch->old_name);
    }
  }
  return 0;
}

static int add_index_file(struct apply_state *state,
        const char *path,
        unsigned mode,
        void *buf,
        unsigned long size)
{
  struct stat st;
  struct cache_entry *ce;
  int namelen = strlen(path);

  ce = make_empty_cache_entry(state->repo->index, namelen);
  memcpy(ce->name, path, namelen);
  ce->ce_mode = create_ce_mode(mode);
  ce->ce_flags = create_ce_flags(0);
  ce->ce_namelen = namelen;
  if (state->ita_only) {
    ce->ce_flags |= CE_INTENT_TO_ADD;
    set_object_name_for_intent_to_add_entry(ce);
  } else if (S_ISGITLINK(mode)) {
    const char *s;

    if (!skip_prefix(buf, "Subproject commit ", &s) ||
        get_oid_hex(s, &ce->oid)) {
      discard_cache_entry(ce);
      return error(_("corrupt patch for submodule %s"), path);
    }
  } else {
    if (!state->cached) {
      if (lstat(path, &st) < 0) {
        discard_cache_entry(ce);
        return error_errno(_("unable to stat newly "
                 "created file '%s'"),
               path);
      }
      fill_stat_cache_info(state->repo->index, ce, &st);
    }
    if (odb_write_object(the_repository->objects, buf, size,
             OBJ_BLOB, &ce->oid) < 0) {
      discard_cache_entry(ce);
      return error(_("unable to create backing store "
               "for newly created file %s"), path);
    }
  }
  if (add_index_entry(state->repo->index, ce, ADD_CACHE_OK_TO_ADD) < 0) {
    discard_cache_entry(ce);
    return error(_("unable to add cache entry for %s"), path);
  }

  return 0;
}

/*
 * Returns:
 *  -1 if an unrecoverable error happened
 *   0 if everything went well
 *   1 if a recoverable error happened
 */
static int try_create_file(struct apply_state *state, const char *path,
         unsigned int mode, const char *buf,
         unsigned long size)
{
  int fd, res;
  struct strbuf nbuf = STRBUF_INIT;

  if (S_ISGITLINK(mode)) {
    struct stat st;
    if (!lstat(path, &st) && S_ISDIR(st.st_mode))
      return 0;
    return !!mkdir(path, 0777);
  }

  if (has_symlinks && S_ISLNK(mode))
    /* Although buf:size is counted string, it also is NUL
     * terminated.
     */
    return !!symlink(buf, path);

  fd = open(path, O_CREAT | O_EXCL | O_WRONLY, (mode & 0100) ? 0777 : 0666);
  if (fd < 0)
    return 1;

  if (convert_to_working_tree(state->repo->index, path, buf, size, &nbuf, NULL)) {
    size = nbuf.len;
    buf  = nbuf.buf;
  }

  res = write_in_full(fd, buf, size) < 0;
  if (res)
    error_errno(_("failed to write to '%s'"), path);
  strbuf_release(&nbuf);

  if (close(fd) < 0 && !res)
    return error_errno(_("closing file '%s'"), path);

  return res ? -1 : 0;
}

/*
 * We optimistically assume that the directories exist,
 * which is true 99% of the time anyway. If they don't,
 * we create them and try again.
 *
 * Returns:
 *   -1 on error
 *   0 otherwise
 */
static int create_one_file(struct apply_state *state,
         char *path,
         unsigned mode,
         const char *buf,
         unsigned long size)
{
  char *newpath = NULL;
  int res;

  if (state->cached)
    return 0;

  /*
   * We already try to detect whether files are beyond a symlink in our
   * up-front checks. But in the case where symlinks are created by any
   * of the intermediate hunks it can happen that our up-front checks
   * didn't yet see the symlink, but at the point of arriving here there
   * in fact is one. We thus repeat the check for symlinks here.
   *
   * Note that this does not make the up-front check obsolete as the
   * failure mode is different:
   *
   * - The up-front checks cause us to abort before we have written
   *   anything into the working directory. So when we exit this way the
   *   working directory remains clean.
   *
   * - The checks here happen in the middle of the action where we have
   *   already started to apply the patch. The end result will be a dirty
   *   working directory.
   *
   * Ideally, we should update the up-front checks to catch what would
   * happen when we apply the patch before we damage the working tree.
   * We have all the information necessary to do so.  But for now, as a
   * part of embargoed security work, having this check would serve as a
   * reasonable first step.
   */
  if (path_is_beyond_symlink(state, path))
    return error(_("affected file '%s' is beyond a symbolic link"), path);

  res = try_create_file(state, path, mode, buf, size);
  if (res < 0)
    return -1;
  if (!res)
    return 0;

  if (errno == ENOENT) {
    if (safe_create_leading_directories_no_share(path))
      return 0;
    res = try_create_file(state, path, mode, buf, size);
    if (res < 0)
      return -1;
    if (!res)
      return 0;
  }

  if (errno == EEXIST || errno == EACCES) {
    /* We may be trying to create a file where a directory
     * used to be.
     */
    struct stat st;
    if (!lstat(path, &st) && (!S_ISDIR(st.st_mode) || !rmdir(path)))
      errno = EEXIST;
  }

  if (errno == EEXIST) {
    unsigned int nr = getpid();

    for (;;) {
      newpath = mkpathdup("%s~%u", path, nr);
      res = try_create_file(state, newpath, mode, buf, size);
      if (res < 0)
        goto out;
      if (!res) {
        if (!rename(newpath, path))
          goto out;
        unlink_or_warn(newpath);
        break;
      }
      if (errno != EEXIST)
        break;
      ++nr;
      FREE_AND_NULL(newpath);
    }
  }
  res = error_errno(_("unable to write file '%s' mode %o"), path, mode);
out:
  free(newpath);
  return res;
}

static int add_conflicted_stages_file(struct apply_state *state,
               struct patch *patch)
{
  int stage, namelen;
  unsigned mode;
  struct cache_entry *ce;

  if (!state->update_index)
    return 0;
  namelen = strlen(patch->new_name);
  mode = patch->new_mode ? patch->new_mode : (S_IFREG | 0644);

  remove_file_from_index(state->repo->index, patch->new_name);
  for (stage = 1; stage < 4; stage++) {
    if (is_null_oid(&patch->threeway_stage[stage - 1]))
      continue;
    ce = make_empty_cache_entry(state->repo->index, namelen);
    memcpy(ce->name, patch->new_name, namelen);
    ce->ce_mode = create_ce_mode(mode);
    ce->ce_flags = create_ce_flags(stage);
    ce->ce_namelen = namelen;
    oidcpy(&ce->oid, &patch->threeway_stage[stage - 1]);
    if (add_index_entry(state->repo->index, ce, ADD_CACHE_OK_TO_ADD) < 0) {
      discard_cache_entry(ce);
      return error(_("unable to add cache entry for %s"),
             patch->new_name);
    }
  }

  return 0;
}

static int create_file(struct apply_state *state, struct patch *patch)
{
  char *path = patch->new_name;
  unsigned mode = patch->new_mode;
  unsigned long size = patch->resultsize;
  char *buf = patch->result;

  if (!mode)
    mode = S_IFREG | 0644;
  if (create_one_file(state, path, mode, buf, size))
    return -1;

  if (patch->conflicted_threeway)
    return add_conflicted_stages_file(state, patch);
  else if (state->check_index || (state->ita_only && patch->is_new > 0))
    return add_index_file(state, path, mode, buf, size);
  return 0;
}

/* phase zero is to remove, phase one is to create */
static int write_out_one_result(struct apply_state *state,
        struct patch *patch,
        int phase)
{
  if (patch->is_delete > 0) {
    if (phase == 0)
      return remove_file(state, patch, 1);
    return 0;
  }
  if (patch->is_new > 0 || patch->is_copy) {
    if (phase == 1)
      return create_file(state, patch);
    return 0;
  }
  /*
   * Rename or modification boils down to the same
   * thing: remove the old, write the new
   */
  if (phase == 0)
    return remove_file(state, patch, patch->is_rename);
  if (phase == 1)
    return create_file(state, patch);
  return 0;
}

static int write_out_one_reject(struct apply_state *state, struct patch *patch)
{
  FILE *rej;
  char *namebuf;
  struct fragment *frag;
  int fd, cnt = 0;
  struct strbuf sb = STRBUF_INIT;

  for (cnt = 0, frag = patch->fragments; frag; frag = frag->next) {
    if (!frag->rejected)
      continue;
    cnt++;
  }

  if (!cnt) {
    if (state->apply_verbosity > verbosity_normal)
      say_patch_name(stderr,
               _("Applied patch %s cleanly."), patch);
    return 0;
  }

  /* This should not happen, because a removal patch that leaves
   * contents are marked "rejected" at the patch level.
   */
  if (!patch->new_name)
    die(_("internal error"));

  /* Say this even without --verbose */
  strbuf_addf(&sb, Q_("Applying patch %%s with %d reject...",
          "Applying patch %%s with %d rejects...",
          cnt),
        cnt);
  if (state->apply_verbosity > verbosity_silent)
    say_patch_name(stderr, sb.buf, patch);
  strbuf_release(&sb);

  namebuf = xstrfmt("%s.rej", patch->new_name);

  fd = open(namebuf, O_CREAT | O_EXCL | O_WRONLY, 0666);
  if (fd < 0) {
    if (errno != EEXIST) {
      error_errno(_("cannot open %s"), namebuf);
      goto error;
    }
    if (unlink(namebuf)) {
      error_errno(_("cannot unlink '%s'"), namebuf);
      goto error;
    }
    fd = open(namebuf, O_CREAT | O_EXCL | O_WRONLY, 0666);
    if (fd < 0) {
      error_errno(_("cannot open %s"), namebuf);
      goto error;
    }
  }
  rej = fdopen(fd, "w");
  if (!rej) {
    error_errno(_("cannot open %s"), namebuf);
    close(fd);
    goto error;
  }

  /* Normal git tools never deal with .rej, so do not pretend
   * this is a git patch by saying --git or giving extended
   * headers.  While at it, maybe please "kompare" that wants
   * the trailing TAB and some garbage at the end of line ;-).
   */
  fprintf(rej, "diff a/%s b/%s\t(rejected hunks)\n",
    patch->new_name, patch->new_name);
  for (cnt = 1, frag = patch->fragments;
       frag;
       cnt++, frag = frag->next) {
    if (!frag->rejected) {
      if (state->apply_verbosity > verbosity_silent)
        fprintf_ln(stderr, _("Hunk #%d applied cleanly."), cnt);
      continue;
    }
    if (state->apply_verbosity > verbosity_silent)
      fprintf_ln(stderr, _("Rejected hunk #%d."), cnt);
    fprintf(rej, "%.*s", frag->size, frag->patch);
    if (frag->patch[frag->size-1] != '\n')
      fputc('\n', rej);
  }
  fclose(rej);
error:
  free(namebuf);
  return -1;
}

/*
 * Returns:
 *  -1 if an error happened
 *   0 if the patch applied cleanly
 *   1 if the patch did not apply cleanly
 */
static int write_out_results(struct apply_state *state, struct patch *list)
{
  int phase;
  int errs = 0;
  struct patch *l;
  struct string_list cpath = STRING_LIST_INIT_DUP;

  for (phase = 0; phase < 2; phase++) {
    l = list;
    while (l) {
      if (l->rejected)
        errs = 1;
      else {
        if (write_out_one_result(state, l, phase)) {
          string_list_clear(&cpath, 0);
          return -1;
        }
        if (phase == 1) {
          if (write_out_one_reject(state, l))
            errs = 1;
          if (l->conflicted_threeway) {
            string_list_append(&cpath, l->new_name);
            errs = 1;
          }
        }
      }
      l = l->next;
    }
  }

  if (cpath.nr) {
    struct string_list_item *item;

    string_list_sort(&cpath);
    if (state->apply_verbosity > verbosity_silent) {
      for_each_string_list_item(item, &cpath)
        fprintf(stderr, "U %s\n", item->string);
    }
    string_list_clear(&cpath, 0);

    /*
     * rerere relies on the partially merged result being in the working
     * tree with conflict markers, but that isn't written with --cached.
     */
    if (!state->cached)
      repo_rerere(state->repo, 0);
  }

  return errs;
}

/*
 * Try to apply a patch.
 *
 * Returns:
 *  -128 if a bad error happened (like patch unreadable)
 *  -1 if patch did not apply and user cannot deal with it
 *   0 if the patch applied
 *   1 if the patch did not apply but user might fix it
 */
static int apply_patch(struct apply_state *state,
           int fd,
           const char *filename,
           int options)
{
  size_t offset;
  struct strbuf buf = STRBUF_INIT; /* owns the patch text */
  struct patch *list = NULL, **listp = &list;
  int skipped_patch = 0;
  int res = 0;
  int flush_attributes = 0;

  state->patch_input_file = filename;
  state->linenr = 1;
  if (read_patch_file(&buf, fd) < 0)
    return -128;
  offset = 0;
  while (offset < buf.len) {
    struct patch *patch;
    int nr;

    CALLOC_ARRAY(patch, 1);
    patch->inaccurate_eof = !!(options & APPLY_OPT_INACCURATE_EOF);
    patch->recount =  !!(options & APPLY_OPT_RECOUNT);
    nr = parse_chunk(state, buf.buf + offset, buf.len - offset, patch);
    if (nr < 0) {
      free_patch(patch);
      if (nr == -128) {
        res = -128;
        goto end;
      }
      break;
    }
    if (state->apply_in_reverse)
      reverse_patches(patch);
    if (use_patch(state, patch)) {
      patch_stats(state, patch);
      if (!list || !state->apply_in_reverse) {
        *listp = patch;
        listp = &patch->next;
      } else {
        patch->next = list;
        list = patch;
      }

      if ((patch->new_name &&
           ends_with_path_components(patch->new_name,
                   GITATTRIBUTES_FILE)) ||
          (patch->old_name &&
           ends_with_path_components(patch->old_name,
                   GITATTRIBUTES_FILE)))
        flush_attributes = 1;
    }
    else {
      if (state->apply_verbosity > verbosity_normal)
        say_patch_name(stderr, _("Skipped patch '%s'."), patch);
      free_patch(patch);
      skipped_patch++;
    }
    offset += nr;
  }

  if (!list && !skipped_patch) {
    if (!state->allow_empty) {
      error(_("No valid patches in input (allow with \"--allow-empty\")"));
      res = -128;
    }
    goto end;
  }

  if (state->whitespace_error && (state->ws_error_action == die_on_ws_error))
    state->apply = 0;

  state->update_index = (state->check_index || state->ita_only) && state->apply;
  if (state->update_index && !is_lock_file_locked(&state->lock_file)) {
    if (state->index_file)
      hold_lock_file_for_update(&state->lock_file,
              state->index_file,
              LOCK_DIE_ON_ERROR);
    else
      repo_hold_locked_index(state->repo, &state->lock_file,
                 LOCK_DIE_ON_ERROR);
  }

  if ((state->check_index || state->update_index) && read_apply_cache(state) < 0) {
    error(_("unable to read index file"));
    res = -128;
    goto end;
  }

  if (state->check || state->apply) {
    int r = check_patch_list(state, list);
    if (r == -128) {
      res = -128;
      goto end;
    }
    if (r < 0 && !state->apply_with_reject) {
      res = -1;
      goto end;
    }
  }

  if (state->apply) {
    int write_res = write_out_results(state, list);
    if (write_res < 0) {
      res = -128;
      goto end;
    }
    if (write_res > 0) {
      /* with --3way, we still need to write the index out */
      res = state->apply_with_reject ? -1 : 1;
      goto end;
    }
  }

  if (state->fake_ancestor &&
      build_fake_ancestor(state, list)) {
    res = -128;
    goto end;
  }

  if (state->diffstat && state->apply_verbosity > verbosity_silent)
    stat_patch_list(state, list);

  if (state->numstat && state->apply_verbosity > verbosity_silent)
    numstat_patch_list(state, list);

  if (state->summary && state->apply_verbosity > verbosity_silent)
    summary_patch_list(list);

  if (flush_attributes)
    reset_parsed_attributes();
end:
  free_patch_list(list);
  strbuf_release(&buf);
  string_list_clear(&state->fn_table, 0);
  return res;
}

static int apply_option_parse_exclude(const struct option *opt,
              const char *arg, int unset)
{
  struct apply_state *state = opt->value;

  BUG_ON_OPT_NEG(unset);

  add_name_limit(state, arg, 1);
  return 0;
}

static int apply_option_parse_include(const struct option *opt,
              const char *arg, int unset)
{
  struct apply_state *state = opt->value;

  BUG_ON_OPT_NEG(unset);

  add_name_limit(state, arg, 0);
  state->has_include = 1;
  return 0;
}

static int apply_option_parse_p(const struct option *opt,
        const char *arg,
        int unset)
{
  struct apply_state *state = opt->value;

  BUG_ON_OPT_NEG(unset);

  if (strtol_i(arg, 10, &state->p_value) < 0 || state->p_value < 0)
    die(_("option -p expects a non-negative integer, got '%s'"), arg);
  state->p_value_known = 1;
  return 0;
}

static int apply_option_parse_space_change(const struct option *opt,
             const char *arg, int unset)
{
  struct apply_state *state = opt->value;

  BUG_ON_OPT_ARG(arg);

  if (unset)
    state->ws_ignore_action = ignore_ws_none;
  else
    state->ws_ignore_action = ignore_ws_change;
  return 0;
}

static int apply_option_parse_whitespace(const struct option *opt,
           const char *arg, int unset)
{
  struct apply_state *state = opt->value;

  BUG_ON_OPT_NEG(unset);

  state->whitespace_option = arg;
  if (parse_whitespace_option(state, arg))
    return -1;
  return 0;
}

static int apply_option_parse_directory(const struct option *opt,
          const char *arg, int unset)
{
  struct apply_state *state = opt->value;

  BUG_ON_OPT_NEG(unset);

  strbuf_reset(&state->root);
  strbuf_addstr(&state->root, arg);

  if (strbuf_normalize_path(&state->root) < 0)
    return error(_("unable to normalize directory: '%s'"), arg);

  strbuf_complete(&state->root, '/');
  return 0;
}

int apply_all_patches(struct apply_state *state,
          int argc,
          const char **argv,
          int options)
{
  int i;
  int res;
  int errs = 0;
  int read_stdin = 1;

  for (i = 0; i < argc; i++) {
    const char *arg = argv[i];
    char *to_free = NULL;
    int fd;

    if (!strcmp(arg, "-")) {
      res = apply_patch(state, 0, "<stdin>", options);
      if (res < 0)
        goto end;
      errs |= res;
      read_stdin = 0;
      continue;
    } else
      arg = to_free = prefix_filename(state->prefix, arg);

    fd = open(arg, O_RDONLY);
    if (fd < 0) {
      error(_("can't open patch '%s': %s"), arg, strerror(errno));
      res = -128;
      free(to_free);
      goto end;
    }
    read_stdin = 0;
    set_default_whitespace_mode(state);
    res = apply_patch(state, fd, arg, options);
    close(fd);
    free(to_free);
    if (res < 0)
      goto end;
    errs |= res;
  }
  set_default_whitespace_mode(state);
  if (read_stdin) {
    res = apply_patch(state, 0, "<stdin>", options);
    if (res < 0)
      goto end;
    errs |= res;
  }

  if (state->whitespace_error) {
    if (state->squelch_whitespace_errors &&
        state->squelch_whitespace_errors < state->whitespace_error) {
      int squelched =
        state->whitespace_error - state->squelch_whitespace_errors;
      warning(Q_("squelched %d whitespace error",
           "squelched %d whitespace errors",
           squelched),
        squelched);
    }
    if (state->ws_error_action == die_on_ws_error) {
      error(Q_("%d line adds whitespace errors.",
         "%d lines add whitespace errors.",
         state->whitespace_error),
            state->whitespace_error);
      res = -128;
      goto end;
    }
    if (state->applied_after_fixing_ws && state->apply)
      warning(Q_("%d line applied after"
           " fixing whitespace errors.",
           "%d lines applied after"
           " fixing whitespace errors.",
           state->applied_after_fixing_ws),
        state->applied_after_fixing_ws);
    else if (state->whitespace_error)
      warning(Q_("%d line adds whitespace errors.",
           "%d lines add whitespace errors.",
           state->whitespace_error),
        state->whitespace_error);
  }

  if (state->update_index) {
    res = write_locked_index(state->repo->index, &state->lock_file, COMMIT_LOCK);
    if (res) {
      error(_("Unable to write new index file"));
      res = -128;
      goto end;
    }
  }

  res = !!errs;

end:
  rollback_lock_file(&state->lock_file);

  if (state->apply_verbosity <= verbosity_silent) {
    set_error_routine(state->saved_error_routine);
    set_warn_routine(state->saved_warn_routine);
  }

  if (res > -1)
    return res;
  return (res == -1 ? 1 : 128);
}

int apply_parse_options(int argc, const char **argv,
      struct apply_state *state,
      int *force_apply, int *options,
      const char * const *apply_usage)
{
  struct option builtin_apply_options[] = {
    OPT_CALLBACK_F(0, "exclude", state, N_("path"),
      N_("don't apply changes matching the given path"),
      PARSE_OPT_NONEG, apply_option_parse_exclude),
    OPT_CALLBACK_F(0, "include", state, N_("path"),
      N_("apply changes matching the given path"),
      PARSE_OPT_NONEG, apply_option_parse_include),
    OPT_CALLBACK('p', NULL, state, N_("num"),
      N_("remove <num> leading slashes from traditional diff paths"),
      apply_option_parse_p),
    OPT_BOOL(0, "no-add", &state->no_add,
      N_("ignore additions made by the patch")),
    OPT_BOOL(0, "stat", &state->diffstat,
      N_("instead of applying the patch, output diffstat for the input")),
    OPT_NOOP_NOARG(0, "allow-binary-replacement"),
    OPT_NOOP_NOARG(0, "binary"),
    OPT_BOOL(0, "numstat", &state->numstat,
      N_("show number of added and deleted lines in decimal notation")),
    OPT_BOOL(0, "summary", &state->summary,
      N_("instead of applying the patch, output a summary for the input")),
    OPT_BOOL(0, "check", &state->check,
      N_("instead of applying the patch, see if the patch is applicable")),
    OPT_BOOL(0, "index", &state->check_index,
      N_("make sure the patch is applicable to the current index")),
    OPT_BOOL('N', "intent-to-add", &state->ita_only,
      N_("mark new files with `git add --intent-to-add`")),
    OPT_BOOL(0, "cached", &state->cached,
      N_("apply a patch without touching the working tree")),
    OPT_BOOL_F(0, "unsafe-paths", &state->unsafe_paths,
         N_("accept a patch that touches outside the working area"),
         PARSE_OPT_NOCOMPLETE),
    OPT_BOOL(0, "apply", force_apply,
      N_("also apply the patch (use with --stat/--summary/--check)")),
    OPT_BOOL('3', "3way", &state->threeway,
       N_( "attempt three-way merge, fall back on normal patch if that fails")),
    OPT_SET_INT_F(0, "ours", &state->merge_variant,
      N_("for conflicts, use our version"),
      XDL_MERGE_FAVOR_OURS, PARSE_OPT_NONEG),
    OPT_SET_INT_F(0, "theirs", &state->merge_variant,
      N_("for conflicts, use their version"),
      XDL_MERGE_FAVOR_THEIRS, PARSE_OPT_NONEG),
    OPT_SET_INT_F(0, "union", &state->merge_variant,
      N_("for conflicts, use a union version"),
      XDL_MERGE_FAVOR_UNION, PARSE_OPT_NONEG),
    OPT_FILENAME(0, "build-fake-ancestor", &state->fake_ancestor,
      N_("build a temporary index based on embedded index information")),
    /* Think twice before adding "--nul" synonym to this */
    OPT_SET_INT('z', NULL, &state->line_termination,
      N_("paths are separated with NUL character"), '\0'),
    OPT_UNSIGNED('C', NULL, &state->p_context,
           N_("ensure at least <n> lines of context match")),
    OPT_CALLBACK(0, "whitespace", state, N_("action"),
      N_("detect new or modified lines that have whitespace errors"),
      apply_option_parse_whitespace),
    OPT_CALLBACK_F(0, "ignore-space-change", state, NULL,
      N_("ignore changes in whitespace when finding context"),
      PARSE_OPT_NOARG, apply_option_parse_space_change),
    OPT_CALLBACK_F(0, "ignore-whitespace", state, NULL,
      N_("ignore changes in whitespace when finding context"),
      PARSE_OPT_NOARG, apply_option_parse_space_change),
    OPT_BOOL('R', "reverse", &state->apply_in_reverse,
      N_("apply the patch in reverse")),
    OPT_BOOL(0, "unidiff-zero", &state->unidiff_zero,
      N_("don't expect at least one line of context")),
    OPT_BOOL(0, "reject", &state->apply_with_reject,
      N_("leave the rejected hunks in corresponding *.rej files")),
    OPT_BOOL(0, "allow-overlap", &state->allow_overlap,
      N_("allow overlapping hunks")),
    OPT__VERBOSITY(&state->apply_verbosity),
    OPT_BIT(0, "inaccurate-eof", options,
      N_("tolerate incorrectly detected missing new-line at the end of file"),
      APPLY_OPT_INACCURATE_EOF),
    OPT_BIT(0, "recount", options,
      N_("do not trust the line counts in the hunk headers"),
      APPLY_OPT_RECOUNT),
    OPT_CALLBACK(0, "directory", state, N_("root"),
      N_("prepend <root> to all filenames"),
      apply_option_parse_directory),
    OPT_BOOL(0, "allow-empty", &state->allow_empty,
      N_("don't return error for empty patches")),
    OPT_END()
  };

  argc = parse_options(argc, argv, state->prefix, builtin_apply_options, apply_usage, 0);

  if (state->merge_variant && !state->threeway)
    die(_("--ours, --theirs, and --union require --3way"));

  return argc;
}

Coverage Report

Created: 2026-03-31 06:24