/src/git/dir.c

Source
/*
 * This handles recursive filename detection with exclude
 * files, index knowledge etc..
 *
 * Copyright (C) Linus Torvalds, 2005-2006
 *     Junio Hamano, 2005-2006
 */

#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "abspath.h"
#include "config.h"
#include "convert.h"
#include "dir.h"
#include "environment.h"
#include "gettext.h"
#include "name-hash.h"
#include "object-file.h"
#include "path.h"
#include "refs.h"
#include "repository.h"
#include "wildmatch.h"
#include "pathspec.h"
#include "utf8.h"
#include "varint.h"
#include "ewah/ewok.h"
#include "fsmonitor-ll.h"
#include "read-cache-ll.h"
#include "setup.h"
#include "sparse-index.h"
#include "strbuf.h"
#include "submodule-config.h"
#include "symlinks.h"
#include "trace2.h"
#include "tree.h"
#include "hex.h"

 /*
  * The maximum size of a pattern/exclude file. If the file exceeds this size
  * we will ignore it.
  */
#define PATTERN_MAX_FILE_SIZE (100 * 1024 * 1024)

/*
 * Tells read_directory_recursive how a file or directory should be treated.
 * Values are ordered by significance, e.g. if a directory contains both
 * excluded and untracked files, it is listed as untracked because
 * path_untracked > path_excluded.
 */
enum path_treatment {
  path_none = 0,
  path_recurse,
  path_excluded,
  path_untracked
};

/*
 * Support data structure for our opendir/readdir/closedir wrappers
 */
struct cached_dir {
  DIR *fdir;
  struct untracked_cache_dir *untracked;
  int nr_files;
  int nr_dirs;

  const char *d_name;
  int d_type;
  const char *file;
  struct untracked_cache_dir *ucd;
};

static enum path_treatment read_directory_recursive(struct dir_struct *dir,
  struct index_state *istate, const char *path, int len,
  struct untracked_cache_dir *untracked,
  int check_only, int stop_at_first_file, const struct pathspec *pathspec);
static int resolve_dtype(int dtype, struct index_state *istate,
       const char *path, int len);
struct dirent *readdir_skip_dot_and_dotdot(DIR *dirp)
{
  struct dirent *e;

  while ((e = readdir(dirp)) != NULL) {
    if (!is_dot_or_dotdot(e->d_name))
      break;
  }
  return e;
}

int for_each_file_in_dir(struct strbuf *path, file_iterator fn, const void *data)
{
  struct dirent *e;
  int res = 0;
  size_t baselen = path->len;
  DIR *dir = opendir(path->buf);

  if (!dir)
    return 0;

  while (!res && (e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
    unsigned char dtype = get_dtype(e, path, 0);
    strbuf_setlen(path, baselen);
    strbuf_addstr(path, e->d_name);

    if (dtype == DT_REG) {
      res = fn(path->buf, data);
    } else if (dtype == DT_DIR) {
      strbuf_addch(path, '/');
      res = for_each_file_in_dir(path, fn, data);
    }
  }

  closedir(dir);
  return res;
}

int count_slashes(const char *s)
{
  int cnt = 0;
  while (*s)
    if (*s++ == '/')
      cnt++;
  return cnt;
}

int git_fspathcmp(const char *a, const char *b)
{
  return repo_ignore_case(the_repository) ? strcasecmp(a, b) : strcmp(a, b);
}

int fspatheq(const char *a, const char *b)
{
  return !fspathcmp(a, b);
}

int git_fspathncmp(const char *a, const char *b, size_t count)
{
  return repo_ignore_case(the_repository) ? strncasecmp(a, b, count) : strncmp(a, b, count);
}

int paths_collide(const char *a, const char *b)
{
  size_t len_a = strlen(a), len_b = strlen(b);

  if (len_a == len_b)
    return fspatheq(a, b);

  if (len_a < len_b)
    return is_dir_sep(b[len_a]) && !fspathncmp(a, b, len_a);
  return is_dir_sep(a[len_b]) && !fspathncmp(a, b, len_b);
}

unsigned int fspathhash(const char *str)
{
  return repo_ignore_case(the_repository) ? strihash(str) : strhash(str);
}

int git_fnmatch(const struct pathspec_item *item,
    const char *pattern, const char *string,
    int prefix)
{
  if (prefix > 0) {
    if (ps_strncmp(item, pattern, string, prefix))
      return WM_NOMATCH;
    pattern += prefix;
    string += prefix;
  }
  if (item->flags & PATHSPEC_ONESTAR) {
    int pattern_len = strlen(++pattern);
    int string_len = strlen(string);
    return string_len < pattern_len ||
      ps_strcmp(item, pattern,
          string + string_len - pattern_len);
  }
  if (item->magic & PATHSPEC_GLOB)
    return wildmatch(pattern, string,
         WM_PATHNAME |
         (item->magic & PATHSPEC_ICASE ? WM_CASEFOLD : 0));
  else
    /* wildmatch has not learned no FNM_PATHNAME mode yet */
    return wildmatch(pattern, string,
         item->magic & PATHSPEC_ICASE ? WM_CASEFOLD : 0);
}

static int fnmatch_icase_mem(const char *pattern, int patternlen,
           const char *string, int stringlen,
           int flags)
{
  int match_status;
  struct strbuf pat_buf = STRBUF_INIT;
  struct strbuf str_buf = STRBUF_INIT;
  const char *use_pat = pattern;
  const char *use_str = string;

  if (pattern[patternlen]) {
    strbuf_add(&pat_buf, pattern, patternlen);
    use_pat = pat_buf.buf;
  }
  if (string[stringlen]) {
    strbuf_add(&str_buf, string, stringlen);
    use_str = str_buf.buf;
  }

  if (repo_ignore_case(the_repository))
    flags |= WM_CASEFOLD;
  match_status = wildmatch(use_pat, use_str, flags);

  strbuf_release(&pat_buf);
  strbuf_release(&str_buf);

  return match_status;
}

static size_t common_prefix_len(const struct pathspec *pathspec,
        const char **matched_prefix)
{
  int n, first = -1;
  size_t max = 0;

  /*
   * ":(icase)path" is treated as a pathspec full of
   * wildcard. In other words, only prefix is considered common
   * prefix. If the pathspec is abc/foo abc/bar, running in
   * subdir xyz, the common prefix is still xyz, not xyz/abc as
   * in non-:(icase).
   */
  GUARD_PATHSPEC(pathspec,
           PATHSPEC_FROMTOP |
           PATHSPEC_MAXDEPTH |
           PATHSPEC_LITERAL |
           PATHSPEC_GLOB |
           PATHSPEC_ICASE |
           PATHSPEC_EXCLUDE |
           PATHSPEC_ATTR);

  for (n = 0; n < pathspec->nr; n++) {
    size_t i = 0, len = 0, item_len;
    if (pathspec->items[n].magic & PATHSPEC_EXCLUDE)
      continue;
    if (first < 0)
      first = n;
    if (pathspec->items[n].magic & PATHSPEC_ICASE)
      item_len = pathspec->items[n].prefix;
    else
      item_len = pathspec->items[n].nowildcard_len;
    while (i < item_len && (n == first || i < max)) {
      char c = pathspec->items[n].match[i];
      if (c != pathspec->items[first].match[i])
        break;
      if (c == '/')
        len = i + 1;
      i++;
    }
    if (n == first || len < max) {
      max = len;
      if (!max)
        break;
    }
  }
  *matched_prefix = first < 0 ? NULL : pathspec->items[first].match;
  return max;
}

/*
 * Returns a copy of the longest leading path common among all pathspec
 * items that are not excluded.
 */
char *common_prefix(const struct pathspec *pathspec)
{
  const char *matched_prefix;
  size_t len = common_prefix_len(pathspec, &matched_prefix);

  return len ? xmemdupz(matched_prefix, len) : NULL;
}

int fill_directory(struct dir_struct *dir,
       struct index_state *istate,
       const struct pathspec *pathspec)
{
  const char *matched_prefix;
  size_t prefix_len;

  unsigned exclusive_flags = DIR_SHOW_IGNORED | DIR_SHOW_IGNORED_TOO;
  if ((dir->flags & exclusive_flags) == exclusive_flags)
    BUG("DIR_SHOW_IGNORED and DIR_SHOW_IGNORED_TOO are exclusive");

  /*
   * Calculate common prefix for the pathspec, and
   * use that to optimize the directory walk
   */
  prefix_len = common_prefix_len(pathspec, &matched_prefix);

  /* Read the directory and prune it */
  read_directory(dir, istate, prefix_len ? matched_prefix : "",
           prefix_len, pathspec);

  return prefix_len;
}

int within_depth(const char *name, int namelen,
      int depth, int max_depth)
{
  const char *cp = name, *cpe = name + namelen;

  while (cp < cpe) {
    if (*cp++ != '/')
      continue;
    depth++;
    if (depth > max_depth)
      return 0;
  }
  return depth <= max_depth;
}

/*
 * Read the contents of the blob with the given OID into a buffer.
 * Append a trailing LF to the end if the last line doesn't have one.
 *
 * Returns:
 *    -1 when the OID is invalid or unknown or does not refer to a blob.
 *     0 when the blob is empty.
 *     1 along with { data, size } of the (possibly augmented) buffer
 *       when successful.
 *
 * Optionally updates the given oid_stat with the given OID (when valid).
 */
static int do_read_blob(const struct object_id *oid, struct oid_stat *oid_stat,
      size_t *size_out, char **data_out)
{
  enum object_type type;
  size_t sz;
  char *data;

  *size_out = 0;
  *data_out = NULL;

  data = odb_read_object(the_repository->objects, oid, &type, &sz);
  if (!data || type != OBJ_BLOB) {
    free(data);
    return -1;
  }

  if (oid_stat) {
    memset(&oid_stat->stat, 0, sizeof(oid_stat->stat));
    oidcpy(&oid_stat->oid, oid);
  }

  if (sz == 0) {
    free(data);
    return 0;
  }

  if (data[sz - 1] != '\n') {
    data = xrealloc(data, st_add(sz, 1));
    data[sz++] = '\n';
  }

  *size_out = xsize_t(sz);
  *data_out = data;

  return 1;
}

#define DO_MATCH_EXCLUDE   (1<<0)
#define DO_MATCH_DIRECTORY (1<<1)
#define DO_MATCH_LEADING_PATHSPEC (1<<2)

/*
 * Does the given pathspec match the given name?  A match is found if
 *
 * (1) the pathspec string is leading directory of 'name' ("RECURSIVELY"), or
 * (2) the pathspec string has a leading part matching 'name' ("LEADING"), or
 * (3) the pathspec string is a wildcard and matches 'name' ("WILDCARD"), or
 * (4) the pathspec string is exactly the same as 'name' ("EXACT").
 *
 * Return value tells which case it was (1-4), or 0 when there is no match.
 *
 * It may be instructive to look at a small table of concrete examples
 * to understand the differences between 1, 2, and 4:
 *
 *                              Pathspecs
 *                |    a/b    |   a/b/    |   a/b/c
 *          ------+-----------+-----------+------------
 *          a/b   |  EXACT    |  EXACT[1] | LEADING[2]
 *  Names   a/b/  | RECURSIVE |   EXACT   | LEADING[2]
 *          a/b/c | RECURSIVE | RECURSIVE |   EXACT
 *
 * [1] Only if DO_MATCH_DIRECTORY is passed; otherwise, this is NOT a match.
 * [2] Only if DO_MATCH_LEADING_PATHSPEC is passed; otherwise, not a match.
 */
static int match_pathspec_item(struct index_state *istate,
             const struct pathspec_item *item, int prefix,
             const char *name, int namelen, unsigned flags)
{
  /* name/namelen has prefix cut off by caller */
  const char *match = item->match + prefix;
  int matchlen = item->len - prefix;

  /*
   * The normal call pattern is:
   * 1. prefix = common_prefix_len(ps, &matched_prefix);
   * 2. prune something, or fill_directory
   * 3. match_pathspec()
   *
   * 'prefix' at #1 may be shorter than the command's prefix and
   * it's ok for #2 to match extra files. Those extras will be
   * trimmed at #3.
   *
   * Suppose the pathspec is 'foo' and '../bar' running from
   * subdir 'xyz'. The common prefix at #1 will be empty, thanks
   * to "../". We may have xyz/foo _and_ XYZ/foo after #2. The
   * user does not want XYZ/foo, only the "foo" part should be
   * case-insensitive. We need to filter out XYZ/foo here. In
   * other words, we do not trust the caller on comparing the
   * prefix part when :(icase) is involved. We do exact
   * comparison ourselves.
   *
   * Normally the caller (common_prefix_len() in fact) does
   * _exact_ matching on name[-prefix+1..-1] and we do not need
   * to check that part. Be defensive and check it anyway, in
   * case common_prefix_len() is changed, or a new caller is
   * introduced that does not use common_prefix_len().
   *
   * If the penalty turns out too high when prefix is really
   * long, maybe change it to
   * strncmp(match, name, item->prefix - prefix)
   */
  if (item->prefix && (item->magic & PATHSPEC_ICASE) &&
      strncmp(item->match, name - prefix, item->prefix))
    return 0;

  if (item->attr_match_nr) {
    if (!istate)
      BUG("magic PATHSPEC_ATTR requires an index");
    if (!match_pathspec_attrs(istate, name - prefix, namelen + prefix, item))
      return 0;
  }

  /* If the match was just the prefix, we matched */
  if (!*match)
    return MATCHED_RECURSIVELY;

  if (matchlen <= namelen && !ps_strncmp(item, match, name, matchlen)) {
    if (matchlen == namelen)
      return MATCHED_EXACTLY;

    if (match[matchlen-1] == '/' || name[matchlen] == '/')
      return MATCHED_RECURSIVELY;
  } else if ((flags & DO_MATCH_DIRECTORY) &&
       match[matchlen - 1] == '/' &&
       namelen == matchlen - 1 &&
       !ps_strncmp(item, match, name, namelen))
    return MATCHED_EXACTLY;

  if (item->nowildcard_len < item->len &&
      !git_fnmatch(item, match, name,
       item->nowildcard_len - prefix))
    return MATCHED_FNMATCH;

  /* Perform checks to see if "name" is a leading string of the pathspec */
  if ( (flags & DO_MATCH_LEADING_PATHSPEC) &&
      !(flags & DO_MATCH_EXCLUDE)) {
    /* name is a literal prefix of the pathspec */
    int offset = name[namelen-1] == '/' ? 1 : 0;
    if ((namelen < matchlen) &&
        (match[namelen-offset] == '/') &&
        !ps_strncmp(item, match, name, namelen))
      return MATCHED_RECURSIVELY_LEADING_PATHSPEC;

    /* name doesn't match up to the first wild character */
    if (item->nowildcard_len < item->len &&
        ps_strncmp(item, match, name,
             item->nowildcard_len - prefix))
      return 0;

    /*
     * name has no wildcard, and it didn't match as a leading
     * pathspec so return.
     */
    if (item->nowildcard_len == item->len)
      return 0;

    /*
     * Here is where we would perform a wildmatch to check if
     * "name" can be matched as a directory (or a prefix) against
     * the pathspec.  Since wildmatch doesn't have this capability
     * at the present we have to punt and say that it is a match,
     * potentially returning a false positive
     * The submodules themselves will be able to perform more
     * accurate matching to determine if the pathspec matches.
     */
    return MATCHED_RECURSIVELY_LEADING_PATHSPEC;
  }

  return 0;
}

/*
 * do_match_pathspec() is meant to ONLY be called by
 * match_pathspec_with_flags(); calling it directly risks pathspecs
 * like ':!unwanted_path' being ignored.
 *
 * Given a name and a list of pathspecs, returns the nature of the
 * closest (i.e. most specific) match of the name to any of the
 * pathspecs.
 *
 * The caller typically calls this multiple times with the same
 * pathspec and seen[] array but with different name/namelen
 * (e.g. entries from the index) and is interested in seeing if and
 * how each pathspec matches all the names it calls this function
 * with.  A mark is left in the seen[] array for each pathspec element
 * indicating the closest type of match that element achieved, so if
 * seen[n] remains zero after multiple invocations, that means the nth
 * pathspec did not match any names, which could indicate that the
 * user mistyped the nth pathspec.
 */
static int do_match_pathspec(struct index_state *istate,
           const struct pathspec *ps,
           const char *name, int namelen,
           int prefix, char *seen,
           unsigned flags)
{
  int i, retval = 0, exclude = flags & DO_MATCH_EXCLUDE;

  GUARD_PATHSPEC(ps,
           PATHSPEC_FROMTOP |
           PATHSPEC_MAXDEPTH |
           PATHSPEC_LITERAL |
           PATHSPEC_GLOB |
           PATHSPEC_ICASE |
           PATHSPEC_EXCLUDE |
           PATHSPEC_ATTR);

  if (!ps->nr) {
    if (!ps->recursive ||
        !(ps->magic & PATHSPEC_MAXDEPTH) ||
        ps->max_depth == -1)
      return MATCHED_RECURSIVELY;

    if (within_depth(name, namelen, 0, ps->max_depth))
      return MATCHED_EXACTLY;
    else
      return 0;
  }

  name += prefix;
  namelen -= prefix;

  for (i = ps->nr - 1; i >= 0; i--) {
    int how;

    if ((!exclude &&   ps->items[i].magic & PATHSPEC_EXCLUDE) ||
        ( exclude && !(ps->items[i].magic & PATHSPEC_EXCLUDE)))
      continue;

    if (seen && seen[i] == MATCHED_EXACTLY &&
        ps->items[i].nowildcard_len == ps->items[i].len)
      continue;
    /*
     * Make exclude patterns optional and never report
     * "pathspec ':(exclude)foo' matches no files"
     */
    if (seen && ps->items[i].magic & PATHSPEC_EXCLUDE)
      seen[i] = MATCHED_FNMATCH;
    how = match_pathspec_item(istate, ps->items+i, prefix, name,
            namelen, flags);
    if (ps->recursive &&
        (ps->magic & PATHSPEC_MAXDEPTH) &&
        ps->max_depth != -1 &&
        how && how != MATCHED_FNMATCH) {
      int len = ps->items[i].len;
      if (name[len] == '/')
        len++;
      if (within_depth(name+len, namelen-len, 0, ps->max_depth))
        how = MATCHED_EXACTLY;
      else
        how = 0;
    }
    if (how) {
      if (retval < how)
        retval = how;
      if (seen && seen[i] < how)
        seen[i] = how;
    }
  }
  return retval;
}

static int match_pathspec_with_flags(struct index_state *istate,
             const struct pathspec *ps,
             const char *name, int namelen,
             int prefix, char *seen, unsigned flags)
{
  int positive, negative;
  positive = do_match_pathspec(istate, ps, name, namelen,
             prefix, seen, flags);
  if (!(ps->magic & PATHSPEC_EXCLUDE) || !positive)
    return positive;
  negative = do_match_pathspec(istate, ps, name, namelen,
             0, seen,
             flags | DO_MATCH_EXCLUDE);
  return negative ? 0 : positive;
}

int match_pathspec(struct index_state *istate,
       const struct pathspec *ps,
       const char *name, int namelen,
       int prefix, char *seen, int is_dir)
{
  unsigned flags = is_dir ? DO_MATCH_DIRECTORY : 0;
  return match_pathspec_with_flags(istate, ps, name, namelen,
           prefix, seen, flags);
}

int match_leading_pathspec(struct index_state *istate,
         const struct pathspec *ps,
         const char *name, int namelen,
         int prefix, char *seen, int is_dir)
{
  unsigned flags = is_dir ? DO_MATCH_DIRECTORY | DO_MATCH_LEADING_PATHSPEC : 0;
  return match_pathspec_with_flags(istate, ps, name, namelen,
           prefix, seen, flags);
}

/**
 * Check if a submodule is a superset of the pathspec
 */
int submodule_path_match(struct index_state *istate,
       const struct pathspec *ps,
       const char *submodule_name,
       char *seen)
{
  int matched = match_pathspec_with_flags(istate, ps, submodule_name,
            strlen(submodule_name),
            0, seen,
            DO_MATCH_DIRECTORY |
            DO_MATCH_LEADING_PATHSPEC);
  return matched;
}

int report_path_error(const char *ps_matched,
          const struct pathspec *pathspec)
{
  /*
   * Make sure all pathspec matched; otherwise it is an error.
   */
  int num, errors = 0;
  for (num = 0; num < pathspec->nr; num++) {
    int other, found_dup;

    if (ps_matched[num])
      continue;
    /*
     * The caller might have fed identical pathspec
     * twice.  Do not barf on such a mistake.
     * FIXME: parse_pathspec should have eliminated
     * duplicate pathspec.
     */
    for (found_dup = other = 0;
         !found_dup && other < pathspec->nr;
         other++) {
      if (other == num || !ps_matched[other])
        continue;
      if (!strcmp(pathspec->items[other].original,
            pathspec->items[num].original))
        /*
         * Ok, we have a match already.
         */
        found_dup = 1;
    }
    if (found_dup)
      continue;

    error(_("pathspec '%s' did not match any file(s) known to git"),
          pathspec->items[num].original);
    errors++;
  }
  return errors;
}

/*
 * Return the length of the "simple" part of a path match limiter.
 */
int simple_length(const char *match)
{
  int len = -1;

  for (;;) {
    unsigned char c = *match++;
    len++;
    if (c == '\0' || is_glob_special(c))
      return len;
  }
}

int no_wildcard(const char *string)
{
  return string[simple_length(string)] == '\0';
}

void parse_path_pattern(const char **pattern,
         int *patternlen,
         unsigned *flags,
         int *nowildcardlen)
{
  const char *p = *pattern;
  size_t i, len;

  *flags = 0;
  if (*p == '!') {
    *flags |= PATTERN_FLAG_NEGATIVE;
    p++;
  }
  len = strlen(p);
  if (len && p[len - 1] == '/') {
    len--;
    *flags |= PATTERN_FLAG_MUSTBEDIR;
  }
  for (i = 0; i < len; i++) {
    if (p[i] == '/')
      break;
  }
  if (i == len)
    *flags |= PATTERN_FLAG_NODIR;
  *nowildcardlen = simple_length(p);
  /*
   * we should have excluded the trailing slash from 'p' too,
   * but that's one more allocation. Instead just make sure
   * nowildcardlen does not exceed real patternlen
   */
  if (*nowildcardlen > len)
    *nowildcardlen = len;
  if (*p == '*' && no_wildcard(p + 1))
    *flags |= PATTERN_FLAG_ENDSWITH;
  *pattern = p;
  *patternlen = len;
}

int pl_hashmap_cmp(const void *cmp_data UNUSED,
       const struct hashmap_entry *a,
       const struct hashmap_entry *b,
       const void *key UNUSED)
{
  const struct pattern_entry *ee1 =
      container_of(a, struct pattern_entry, ent);
  const struct pattern_entry *ee2 =
      container_of(b, struct pattern_entry, ent);

  size_t min_len = ee1->patternlen <= ee2->patternlen
       ? ee1->patternlen
       : ee2->patternlen;

  return fspathncmp(ee1->pattern, ee2->pattern, min_len);
}

static char *dup_and_filter_pattern(const char *pattern)
{
  char *set, *read;
  size_t count  = 0;
  char *result = xstrdup(pattern);

  set = result;
  read = result;

  while (*read) {
    /* skip escape characters (once) */
    if (*read == '\\')
      read++;

    *set = *read;

    set++;
    read++;
    count++;
  }
  *set = 0;

  if (count > 2 &&
      *(set - 1) == '*' &&
      *(set - 2) == '/')
    *(set - 2) = 0;

  return result;
}

static void clear_pattern_entry_hashmap(struct hashmap *map)
{
  struct hashmap_iter iter;
  struct pattern_entry *entry;

  hashmap_for_each_entry(map, &iter, entry, ent) {
    free(entry->pattern);
  }
  hashmap_clear_and_free(map, struct pattern_entry, ent);
}

static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern *given)
{
  struct pattern_entry *translated;
  char *truncated;
  char *data = NULL;
  const char *prev, *cur, *next;

  if (!pl->use_cone_patterns)
    return;

  if (given->flags & PATTERN_FLAG_NEGATIVE &&
      given->flags & PATTERN_FLAG_MUSTBEDIR &&
      !strcmp(given->pattern, "/*")) {
    pl->full_cone = 0;
    return;
  }

  if (!given->flags && !strcmp(given->pattern, "/*")) {
    pl->full_cone = 1;
    return;
  }

  if (given->patternlen < 2 ||
      *given->pattern != '/' ||
      strstr(given->pattern, "**")) {
    /* Not a cone pattern. */
    warning(_("unrecognized pattern: '%s'"), given->pattern);
    goto clear_hashmaps;
  }

  if (!(given->flags & PATTERN_FLAG_MUSTBEDIR) &&
      strcmp(given->pattern, "/*")) {
    /* Not a cone pattern. */
    warning(_("unrecognized pattern: '%s'"), given->pattern);
    goto clear_hashmaps;
  }

  prev = given->pattern;
  cur = given->pattern + 1;
  next = given->pattern + 2;

  while (*cur) {
    /* Watch for glob characters '*', '\', '[', '?' */
    if (!is_glob_special(*cur))
      goto increment;

    /* But only if *prev != '\\' */
    if (*prev == '\\')
      goto increment;

    /* But allow the initial '\' */
    if (*cur == '\\' &&
        is_glob_special(*next))
      goto increment;

    /* But a trailing '/' then '*' is fine */
    if (*prev == '/' &&
        *cur == '*' &&
        *next == 0)
      goto increment;

    /* Not a cone pattern. */
    warning(_("unrecognized pattern: '%s'"), given->pattern);
    goto clear_hashmaps;

  increment:
    prev++;
    cur++;
    next++;
  }

  if (given->patternlen > 2 &&
      !strcmp(given->pattern + given->patternlen - 2, "/*")) {
    struct pattern_entry *old;

    if (!(given->flags & PATTERN_FLAG_NEGATIVE)) {
      /* Not a cone pattern. */
      warning(_("unrecognized pattern: '%s'"), given->pattern);
      goto clear_hashmaps;
    }

    truncated = dup_and_filter_pattern(given->pattern);

    translated = xmalloc(sizeof(struct pattern_entry));
    translated->pattern = truncated;
    translated->patternlen = given->patternlen - 2;
    hashmap_entry_init(&translated->ent,
           fspathhash(translated->pattern));

    if (!hashmap_get_entry(&pl->recursive_hashmap,
               translated, ent, NULL)) {
      /* We did not see the "parent" included */
      warning(_("unrecognized negative pattern: '%s'"),
        given->pattern);
      free(truncated);
      free(translated);
      goto clear_hashmaps;
    }

    hashmap_add(&pl->parent_hashmap, &translated->ent);
    old = hashmap_remove_entry(&pl->recursive_hashmap, translated, ent, &data);
    if (old) {
      free(old->pattern);
      free(old);
    }
    free(data);
    return;
  }

  if (given->flags & PATTERN_FLAG_NEGATIVE) {
    warning(_("unrecognized negative pattern: '%s'"),
      given->pattern);
    goto clear_hashmaps;
  }

  translated = xmalloc(sizeof(struct pattern_entry));

  translated->pattern = dup_and_filter_pattern(given->pattern);
  translated->patternlen = given->patternlen;
  hashmap_entry_init(&translated->ent,
         fspathhash(translated->pattern));

  hashmap_add(&pl->recursive_hashmap, &translated->ent);

  if (hashmap_get_entry(&pl->parent_hashmap, translated, ent, NULL)) {
    /* we already included this at the parent level */
    warning(_("your sparse-checkout file may have issues: pattern '%s' is repeated"),
      given->pattern);
    goto clear_hashmaps;
  }

  return;

clear_hashmaps:
  warning(_("disabling cone pattern matching"));
  clear_pattern_entry_hashmap(&pl->recursive_hashmap);
  clear_pattern_entry_hashmap(&pl->parent_hashmap);
  pl->use_cone_patterns = 0;
}

static int hashmap_contains_path(struct hashmap *map,
         struct strbuf *pattern)
{
  struct pattern_entry p;

  /* Check straight mapping */
  p.pattern = pattern->buf;
  p.patternlen = pattern->len;
  hashmap_entry_init(&p.ent, fspathhash(p.pattern));
  return !!hashmap_get_entry(map, &p, ent, NULL);
}

int hashmap_contains_parent(struct hashmap *map,
          const char *path,
          struct strbuf *buffer)
{
  char *slash_pos;

  strbuf_setlen(buffer, 0);

  if (path[0] != '/')
    strbuf_addch(buffer, '/');

  strbuf_addstr(buffer, path);

  slash_pos = strrchr(buffer->buf, '/');

  while (slash_pos > buffer->buf) {
    strbuf_setlen(buffer, slash_pos - buffer->buf);

    if (hashmap_contains_path(map, buffer))
      return 1;

    slash_pos = strrchr(buffer->buf, '/');
  }

  return 0;
}

void add_pattern(const char *string, const char *base,
     int baselen, struct pattern_list *pl, int srcpos)
{
  struct path_pattern *pattern;
  int patternlen;
  unsigned flags;
  int nowildcardlen;

  parse_path_pattern(&string, &patternlen, &flags, &nowildcardlen);
  FLEX_ALLOC_MEM(pattern, pattern, string, patternlen);
  pattern->patternlen = patternlen;
  pattern->nowildcardlen = nowildcardlen;
  pattern->base = base;
  pattern->baselen = baselen;
  pattern->flags = flags;
  pattern->srcpos = srcpos;
  ALLOC_GROW(pl->patterns, pl->nr + 1, pl->alloc);
  pl->patterns[pl->nr++] = pattern;
  pattern->pl = pl;

  add_pattern_to_hashsets(pl, pattern);
}

static int read_skip_worktree_file_from_index(struct index_state *istate,
                const char *path,
                size_t *size_out, char **data_out,
                struct oid_stat *oid_stat)
{
  int pos, len;

  len = strlen(path);
  pos = index_name_pos(istate, path, len);
  if (pos < 0)
    return -1;
  if (!ce_skip_worktree(istate->cache[pos]))
    return -1;

  return do_read_blob(&istate->cache[pos]->oid, oid_stat, size_out, data_out);
}

/*
 * Frees memory within pl which was allocated for exclude patterns and
 * the file buffer.  Does not free pl itself.
 */
void clear_pattern_list(struct pattern_list *pl)
{
  int i;

  for (i = 0; i < pl->nr; i++)
    free(pl->patterns[i]);
  free(pl->patterns);
  clear_pattern_entry_hashmap(&pl->recursive_hashmap);
  clear_pattern_entry_hashmap(&pl->parent_hashmap);

  memset(pl, 0, sizeof(*pl));
}

static void trim_trailing_spaces(char *buf)
{
  char *p, *last_space = NULL;

  for (p = buf; *p; p++)
    switch (*p) {
    case ' ':
      if (!last_space)
        last_space = p;
      break;
    case '\\':
      p++;
      if (!*p)
        return;
      /* fallthrough */
    default:
      last_space = NULL;
    }

  if (last_space)
    *last_space = '\0';
}

/*
 * Given a subdirectory name and "dir" of the current directory,
 * search the subdir in "dir" and return it, or create a new one if it
 * does not exist in "dir".
 *
 * If "name" has the trailing slash, it'll be excluded in the search.
 */
static struct untracked_cache_dir *lookup_untracked(struct untracked_cache *uc,
                struct untracked_cache_dir *dir,
                const char *name, int len)
{
  int first, last;
  struct untracked_cache_dir *d;
  if (!dir)
    return NULL;
  if (len && name[len - 1] == '/')
    len--;
  first = 0;
  last = dir->dirs_nr;
  while (last > first) {
    int cmp, next = first + ((last - first) >> 1);
    d = dir->dirs[next];
    cmp = strncmp(name, d->name, len);
    if (!cmp && strlen(d->name) > len)
      cmp = -1;
    if (!cmp)
      return d;
    if (cmp < 0) {
      last = next;
      continue;
    }
    first = next+1;
  }

  uc->dir_created++;
  FLEX_ALLOC_MEM(d, name, name, len);

  ALLOC_GROW(dir->dirs, dir->dirs_nr + 1, dir->dirs_alloc);
  MOVE_ARRAY(dir->dirs + first + 1, dir->dirs + first,
       dir->dirs_nr - first);
  dir->dirs_nr++;
  dir->dirs[first] = d;
  return d;
}

static void do_invalidate_gitignore(struct untracked_cache_dir *dir)
{
  int i;
  dir->valid = 0;
  for (size_t i = 0; i < dir->untracked_nr; i++)
    free(dir->untracked[i]);
  dir->untracked_nr = 0;
  for (i = 0; i < dir->dirs_nr; i++)
    do_invalidate_gitignore(dir->dirs[i]);
}

static void invalidate_gitignore(struct untracked_cache *uc,
         struct untracked_cache_dir *dir)
{
  uc->gitignore_invalidated++;
  do_invalidate_gitignore(dir);
}

static void invalidate_directory(struct untracked_cache *uc,
         struct untracked_cache_dir *dir)
{
  int i;

  /*
   * Invalidation increment here is just roughly correct. If
   * untracked_nr or any of dirs[].recurse is non-zero, we
   * should increment dir_invalidated too. But that's more
   * expensive to do.
   */
  if (dir->valid)
    uc->dir_invalidated++;

  dir->valid = 0;
  for (size_t i = 0; i < dir->untracked_nr; i++)
    free(dir->untracked[i]);
  dir->untracked_nr = 0;
  for (i = 0; i < dir->dirs_nr; i++)
    dir->dirs[i]->recurse = 0;
}

/* Flags for add_patterns() */
#define PATTERN_NOFOLLOW (1<<0)

/*
 * Given a file with name "fname", read it (either from disk, or from
 * an index if 'istate' is non-null), parse it and store the
 * exclude rules in "pl".
 *
 * If "oid_stat" is not NULL, compute oid of the exclude file and fill
 * stat data from disk (only valid if add_patterns returns zero). If
 * oid_stat.valid is non-zero, "oid_stat" must contain good value as input.
 */
static int add_patterns(const char *fname, const char *base, int baselen,
      struct pattern_list *pl, struct index_state *istate,
      unsigned flags, struct oid_stat *oid_stat)
{
  struct stat st;
  int r;
  int fd;
  size_t size = 0;
  char *buf;

  if (flags & PATTERN_NOFOLLOW)
    fd = open_nofollow(fname, O_RDONLY);
  else
    fd = open(fname, O_RDONLY);

  if (fd < 0 || fstat(fd, &st) < 0) {
    if (fd < 0)
      warn_on_fopen_errors(fname);
    else
      close(fd);
    if (!istate)
      return -1;
    r = read_skip_worktree_file_from_index(istate, fname,
                   &size, &buf,
                   oid_stat);
    if (r != 1)
      return r;
  } else {
    size = xsize_t(st.st_size);
    if (size == 0) {
      if (oid_stat) {
        fill_stat_data(&oid_stat->stat, &st);
        oidcpy(&oid_stat->oid, the_hash_algo->empty_blob);
        oid_stat->valid = 1;
      }
      close(fd);
      return 0;
    }
    buf = xmallocz(size);
    if (read_in_full(fd, buf, size) != size) {
      free(buf);
      close(fd);
      return -1;
    }
    buf[size++] = '\n';
    close(fd);
    if (oid_stat) {
      int pos;
      if (oid_stat->valid &&
          !match_stat_data_racy(istate, &oid_stat->stat, &st))
        ; /* no content change, oid_stat->oid still good */
      else if (istate &&
         (pos = index_name_pos(istate, fname, strlen(fname))) >= 0 &&
         !ce_stage(istate->cache[pos]) &&
         ce_uptodate(istate->cache[pos]) &&
         !would_convert_to_git(istate, fname))
        oidcpy(&oid_stat->oid,
               &istate->cache[pos]->oid);
      else
        hash_object_file(the_hash_algo, buf, size,
             OBJ_BLOB, &oid_stat->oid);
      fill_stat_data(&oid_stat->stat, &st);
      oid_stat->valid = 1;
    }
  }

  if (size > PATTERN_MAX_FILE_SIZE) {
    warning("ignoring excessively large pattern file: %s", fname);
    free(buf);
    return -1;
  }

  add_patterns_from_buffer(buf, size, base, baselen, pl);
  free(buf);
  return 0;
}

int add_patterns_from_buffer(char *buf, size_t size,
           const char *base, int baselen,
           struct pattern_list *pl)
{
  char *orig = buf;
  int i, lineno = 1;
  char *entry;

  hashmap_init(&pl->recursive_hashmap, pl_hashmap_cmp, NULL, 0);
  hashmap_init(&pl->parent_hashmap, pl_hashmap_cmp, NULL, 0);

  if (skip_utf8_bom(&buf, size))
    size -= buf - orig;

  entry = buf;

  for (i = 0; i < size; i++) {
    if (buf[i] == '\n') {
      if (entry != buf + i && entry[0] != '#') {
        buf[i - (i && buf[i-1] == '\r')] = 0;
        trim_trailing_spaces(entry);
        add_pattern(entry, base, baselen, pl, lineno);
      }
      lineno++;
      entry = buf + i + 1;
    }
  }
  return 0;
}

int add_patterns_from_file_to_list(const char *fname, const char *base,
           int baselen, struct pattern_list *pl,
           struct index_state *istate,
           unsigned flags)
{
  return add_patterns(fname, base, baselen, pl, istate, flags, NULL);
}

int add_patterns_from_blob_to_list(
  struct object_id *oid,
  const char *base, int baselen,
  struct pattern_list *pl)
{
  char *buf;
  size_t size;
  int r;

  r = do_read_blob(oid, NULL, &size, &buf);
  if (r != 1)
    return r;

  if (size > PATTERN_MAX_FILE_SIZE) {
    warning("ignoring excessively large pattern blob: %s",
      oid_to_hex(oid));
    free(buf);
    return -1;
  }

  add_patterns_from_buffer(buf, size, base, baselen, pl);
  free(buf);
  return 0;
}

struct pattern_list *add_pattern_list(struct dir_struct *dir,
              int group_type, const char *src)
{
  struct pattern_list *pl;
  struct exclude_list_group *group;

  group = &dir->internal.exclude_list_group[group_type];
  ALLOC_GROW(group->pl, group->nr + 1, group->alloc);
  pl = &group->pl[group->nr++];
  memset(pl, 0, sizeof(*pl));
  pl->src = src;
  return pl;
}

/*
 * Used to set up core.excludesfile and .git/info/exclude lists.
 */
static void add_patterns_from_file_1(struct dir_struct *dir, const char *fname,
             struct oid_stat *oid_stat)
{
  struct pattern_list *pl;
  /*
   * catch setup_standard_excludes() that's called before
   * dir->untracked is assigned. That function behaves
   * differently when dir->untracked is non-NULL.
   */
  if (!dir->untracked)
    dir->internal.unmanaged_exclude_files++;
  pl = add_pattern_list(dir, EXC_FILE, fname);
  if (add_patterns(fname, "", 0, pl, NULL, 0, oid_stat) < 0)
    die(_("cannot use %s as an exclude file"), fname);
}

void add_patterns_from_file(struct dir_struct *dir, const char *fname)
{
  dir->internal.unmanaged_exclude_files++; /* see validate_untracked_cache() */
  add_patterns_from_file_1(dir, fname, NULL);
}

int match_basename(const char *basename, int basenamelen,
       const char *pattern, int prefix, int patternlen,
       unsigned flags)
{
  if (prefix == patternlen) {
    if (patternlen == basenamelen &&
        !fspathncmp(pattern, basename, basenamelen))
      return 1;
  } else if (flags & PATTERN_FLAG_ENDSWITH) {
    /* "*literal" matching against "fooliteral" */
    if (patternlen - 1 <= basenamelen &&
        !fspathncmp(pattern + 1,
           basename + basenamelen - (patternlen - 1),
           patternlen - 1))
      return 1;
  } else {
    if (fnmatch_icase_mem(pattern, patternlen,
              basename, basenamelen,
              0) == 0)
      return 1;
  }
  return 0;
}

int match_pathname(const char *pathname, int pathlen,
       const char *base, int baselen,
       const char *pattern, int prefix, int patternlen)
{
  const char *name;
  int namelen;

  /*
   * match with FNM_PATHNAME; the pattern has base implicitly
   * in front of it.
   */
  if (*pattern == '/') {
    pattern++;
    patternlen--;
    prefix--;
  }

  /*
   * baselen does not count the trailing slash. base[] may or
   * may not end with a trailing slash though.
   */
  if (pathlen < baselen + 1 ||
      (baselen && pathname[baselen] != '/') ||
      fspathncmp(pathname, base, baselen))
    return 0;

  namelen = baselen ? pathlen - baselen - 1 : pathlen;
  name = pathname + pathlen - namelen;

  if (prefix) {
    /*
     * if the non-wildcard part is longer than the
     * remaining pathname, surely it cannot match.
     */
    if (prefix > namelen)
      return 0;

    if (fspathncmp(pattern, name, prefix))
      return 0;

    /*
     * If the whole pattern did not have a wildcard,
     * then our prefix match is all we need; we
     * do not need to call fnmatch at all.
     */
    if (patternlen == prefix && namelen == prefix)
      return 1;

    /*
     * Retain one character of the prefix to
     * pass to fnmatch, which lets it distinguish
     * the start of a directory component correctly.
     */
    prefix--;
    pattern += prefix;
    patternlen -= prefix;
    name    += prefix;
    namelen -= prefix;
  }

  return fnmatch_icase_mem(pattern, patternlen,
         name, namelen,
         WM_PATHNAME) == 0;
}

/*
 * Scan the given exclude list in reverse to see whether pathname
 * should be ignored.  The first match (i.e. the last on the list), if
 * any, determines the fate.  Returns the exclude_list element which
 * matched, or NULL for undecided.
 */
static struct path_pattern *last_matching_pattern_from_list(const char *pathname,
                   int pathlen,
                   const char *basename,
                   int *dtype,
                   struct pattern_list *pl,
                   struct index_state *istate)
{
  struct path_pattern *res = NULL; /* undecided */
  int i;

  if (!pl->nr)
    return NULL; /* undefined */

  for (i = pl->nr - 1; 0 <= i; i--) {
    struct path_pattern *pattern = pl->patterns[i];
    const char *exclude = pattern->pattern;
    int prefix = pattern->nowildcardlen;

    if (pattern->flags & PATTERN_FLAG_MUSTBEDIR) {
      *dtype = resolve_dtype(*dtype, istate, pathname, pathlen);
      if (*dtype != DT_DIR)
        continue;
    }

    if (pattern->flags & PATTERN_FLAG_NODIR) {
      if (match_basename(basename,
             pathlen - (basename - pathname),
             exclude, prefix, pattern->patternlen,
             pattern->flags)) {
        res = pattern;
        break;
      }
      continue;
    }

    assert(pattern->baselen == 0 ||
           pattern->base[pattern->baselen - 1] == '/');
    if (match_pathname(pathname, pathlen,
           pattern->base,
           pattern->baselen ? pattern->baselen - 1 : 0,
           exclude, prefix, pattern->patternlen)) {
      res = pattern;
      break;
    }
  }
  return res;
}

/*
 * Scan the list of patterns to determine if the ordered list
 * of patterns matches on 'pathname'.
 *
 * Return 1 for a match, 0 for not matched and -1 for undecided.
 */
enum pattern_match_result path_matches_pattern_list(
        const char *pathname, int pathlen,
        const char *basename, int *dtype,
        struct pattern_list *pl,
        struct index_state *istate)
{
  struct path_pattern *pattern;
  struct strbuf parent_pathname = STRBUF_INIT;
  int result = NOT_MATCHED;
  size_t slash_pos;

  if (!pl->use_cone_patterns) {
    pattern = last_matching_pattern_from_list(pathname, pathlen, basename,
              dtype, pl, istate);
    if (pattern) {
      if (pattern->flags & PATTERN_FLAG_NEGATIVE)
        return NOT_MATCHED;
      else
        return MATCHED;
    }

    return UNDECIDED;
  }

  if (pl->full_cone)
    return MATCHED;

  strbuf_addch(&parent_pathname, '/');
  strbuf_add(&parent_pathname, pathname, pathlen);

  /*
   * Directory entries are matched if and only if a file
   * contained immediately within them is matched. For the
   * case of a directory entry, modify the path to create
   * a fake filename within this directory, allowing us to
   * use the file-base matching logic in an equivalent way.
   */
  if (parent_pathname.len > 0 &&
      parent_pathname.buf[parent_pathname.len - 1] == '/') {
    slash_pos = parent_pathname.len - 1;
    strbuf_add(&parent_pathname, "-", 1);
  } else {
    const char *slash_ptr = strrchr(parent_pathname.buf, '/');
    slash_pos = slash_ptr ? slash_ptr - parent_pathname.buf : 0;
  }

  if (hashmap_contains_path(&pl->recursive_hashmap,
          &parent_pathname)) {
    result = MATCHED_RECURSIVE;
    goto done;
  }

  if (!slash_pos) {
    /* include every file in root */
    result = MATCHED;
    goto done;
  }

  strbuf_setlen(&parent_pathname, slash_pos);

  if (hashmap_contains_path(&pl->parent_hashmap, &parent_pathname)) {
    result = MATCHED;
    goto done;
  }

  if (hashmap_contains_parent(&pl->recursive_hashmap,
            pathname,
            &parent_pathname))
    result = MATCHED_RECURSIVE;

done:
  strbuf_release(&parent_pathname);
  return result;
}

int init_sparse_checkout_patterns(struct index_state *istate)
{
  struct repo_config_values *cfg = repo_config_values(the_repository);

  if (!cfg->apply_sparse_checkout)
    return 1;
  if (istate->sparse_checkout_patterns)
    return 0;

  CALLOC_ARRAY(istate->sparse_checkout_patterns, 1);

  if (get_sparse_checkout_patterns(istate->sparse_checkout_patterns) < 0) {
    FREE_AND_NULL(istate->sparse_checkout_patterns);
    return -1;
  }

  return 0;
}

static int path_in_sparse_checkout_1(const char *path,
             struct index_state *istate,
             int require_cone_mode)
{
  int dtype = DT_REG;
  enum pattern_match_result match = UNDECIDED;
  const char *end, *slash;

  /*
   * We default to accepting a path if the path is empty, there are no
   * patterns, or the patterns are of the wrong type.
   */
  if (!*path ||
      init_sparse_checkout_patterns(istate) ||
      (require_cone_mode &&
       !istate->sparse_checkout_patterns->use_cone_patterns))
    return 1;

  /*
   * If UNDECIDED, use the match from the parent dir (recursively), or
   * fall back to NOT_MATCHED at the topmost level. Note that cone mode
   * never returns UNDECIDED, so we will execute only one iteration in
   * this case.
   */
  for (end = path + strlen(path);
       end > path && match == UNDECIDED;
       end = slash) {

    for (slash = end - 1; slash > path && *slash != '/'; slash--)
      ; /* do nothing */

    match = path_matches_pattern_list(path, end - path,
        slash > path ? slash + 1 : path, &dtype,
        istate->sparse_checkout_patterns, istate);

    /* We are going to match the parent dir now */
    dtype = DT_DIR;
  }
  return match > 0;
}

int path_in_sparse_checkout(const char *path,
          struct index_state *istate)
{
  return path_in_sparse_checkout_1(path, istate, 0);
}

int path_in_cone_mode_sparse_checkout(const char *path,
             struct index_state *istate)
{
  return path_in_sparse_checkout_1(path, istate, 1);
}

static struct path_pattern *last_matching_pattern_from_lists(
    struct dir_struct *dir, struct index_state *istate,
    const char *pathname, int pathlen,
    const char *basename, int *dtype_p)
{
  int i, j;
  struct exclude_list_group *group;
  struct path_pattern *pattern;
  for (i = EXC_CMDL; i <= EXC_FILE; i++) {
    group = &dir->internal.exclude_list_group[i];
    for (j = group->nr - 1; j >= 0; j--) {
      pattern = last_matching_pattern_from_list(
        pathname, pathlen, basename, dtype_p,
        &group->pl[j], istate);
      if (pattern)
        return pattern;
    }
  }
  return NULL;
}

/*
 * Loads the per-directory exclude list for the substring of base
 * which has a char length of baselen.
 */
static void prep_exclude(struct dir_struct *dir,
       struct index_state *istate,
       const char *base, int baselen)
{
  struct exclude_list_group *group;
  struct pattern_list *pl;
  struct exclude_stack *stk = NULL;
  struct untracked_cache_dir *untracked;
  int current;

  group = &dir->internal.exclude_list_group[EXC_DIRS];

  /*
   * Pop the exclude lists from the EXCL_DIRS exclude_list_group
   * which originate from directories not in the prefix of the
   * path being checked.
   */
  while ((stk = dir->internal.exclude_stack) != NULL) {
    if (stk->baselen <= baselen &&
        !strncmp(dir->internal.basebuf.buf, base, stk->baselen))
      break;
    pl = &group->pl[dir->internal.exclude_stack->exclude_ix];
    dir->internal.exclude_stack = stk->prev;
    dir->internal.pattern = NULL;
    free((char *)pl->src); /* see strbuf_detach() below */
    clear_pattern_list(pl);
    free(stk);
    group->nr--;
  }

  /* Skip traversing into sub directories if the parent is excluded */
  if (dir->internal.pattern)
    return;

  /*
   * Lazy initialization. All call sites currently just
   * memset(dir, 0, sizeof(*dir)) before use. Changing all of
   * them seems lots of work for little benefit.
   */
  if (!dir->internal.basebuf.buf)
    strbuf_init(&dir->internal.basebuf, PATH_MAX);

  /* Read from the parent directories and push them down. */
  current = stk ? stk->baselen : -1;
  strbuf_setlen(&dir->internal.basebuf, current < 0 ? 0 : current);
  if (dir->untracked)
    untracked = stk ? stk->ucd : dir->untracked->root;
  else
    untracked = NULL;

  while (current < baselen) {
    const char *cp;
    struct oid_stat oid_stat;

    CALLOC_ARRAY(stk, 1);
    if (current < 0) {
      cp = base;
      current = 0;
    } else {
      cp = strchr(base + current + 1, '/');
      if (!cp)
        die("oops in prep_exclude");
      cp++;
      untracked =
        lookup_untracked(dir->untracked,
             untracked,
             base + current,
             cp - base - current);
    }
    stk->prev = dir->internal.exclude_stack;
    stk->baselen = cp - base;
    stk->exclude_ix = group->nr;
    stk->ucd = untracked;
    pl = add_pattern_list(dir, EXC_DIRS, NULL);
    strbuf_add(&dir->internal.basebuf, base + current, stk->baselen - current);
    assert(stk->baselen == dir->internal.basebuf.len);

    /* Abort if the directory is excluded */
    if (stk->baselen) {
      int dt = DT_DIR;
      dir->internal.basebuf.buf[stk->baselen - 1] = 0;
      dir->internal.pattern = last_matching_pattern_from_lists(dir,
                  istate,
        dir->internal.basebuf.buf, stk->baselen - 1,
        dir->internal.basebuf.buf + current, &dt);
      dir->internal.basebuf.buf[stk->baselen - 1] = '/';
      if (dir->internal.pattern &&
          dir->internal.pattern->flags & PATTERN_FLAG_NEGATIVE)
        dir->internal.pattern = NULL;
      if (dir->internal.pattern) {
        dir->internal.exclude_stack = stk;
        return;
      }
    }

    /* Try to read per-directory file */
    oidclr(&oid_stat.oid, the_repository->hash_algo);
    oid_stat.valid = 0;
    if (dir->exclude_per_dir &&
        /*
         * If we know that no files have been added in
         * this directory (i.e. valid_cached_dir() has
         * been executed and set untracked->valid) ..
         */
        (!untracked || !untracked->valid ||
         /*
          * .. and .gitignore does not exist before
          * (i.e. null exclude_oid). Then we can skip
          * loading .gitignore, which would result in
          * ENOENT anyway.
          */
         !is_null_oid(&untracked->exclude_oid))) {
      /*
       * dir->internal.basebuf gets reused by the traversal,
       * but we need fname to remain unchanged to ensure the
       * src member of each struct path_pattern correctly
       * back-references its source file.  Other invocations
       * of add_pattern_list provide stable strings, so we
       * strbuf_detach() and free() here in the caller.
       */
      struct strbuf sb = STRBUF_INIT;
      strbuf_addbuf(&sb, &dir->internal.basebuf);
      strbuf_addstr(&sb, dir->exclude_per_dir);
      pl->src = strbuf_detach(&sb, NULL);
      add_patterns(pl->src, pl->src, stk->baselen, pl, istate,
             PATTERN_NOFOLLOW,
             untracked ? &oid_stat : NULL);
    }
    /*
     * NEEDSWORK: when untracked cache is enabled, prep_exclude()
     * will first be called in valid_cached_dir() then maybe many
     * times more in last_matching_pattern(). When the cache is
     * used, last_matching_pattern() will not be called and
     * reading .gitignore content will be a waste.
     *
     * So when it's called by valid_cached_dir() and we can get
     * .gitignore SHA-1 from the index (i.e. .gitignore is not
     * modified on work tree), we could delay reading the
     * .gitignore content until we absolutely need it in
     * last_matching_pattern(). Be careful about ignore rule
     * order, though, if you do that.
     */
    if (untracked &&
        !oideq(&oid_stat.oid, &untracked->exclude_oid)) {
      invalidate_gitignore(dir->untracked, untracked);
      oidcpy(&untracked->exclude_oid, &oid_stat.oid);
    }
    dir->internal.exclude_stack = stk;
    current = stk->baselen;
  }
  strbuf_setlen(&dir->internal.basebuf, baselen);
}

/*
 * Loads the exclude lists for the directory containing pathname, then
 * scans all exclude lists to determine whether pathname is excluded.
 * Returns the exclude_list element which matched, or NULL for
 * undecided.
 */
struct path_pattern *last_matching_pattern(struct dir_struct *dir,
              struct index_state *istate,
              const char *pathname,
              int *dtype_p)
{
  int pathlen = strlen(pathname);
  const char *basename = strrchr(pathname, '/');
  basename = (basename) ? basename+1 : pathname;

  prep_exclude(dir, istate, pathname, basename-pathname);

  if (dir->internal.pattern)
    return dir->internal.pattern;

  return last_matching_pattern_from_lists(dir, istate, pathname, pathlen,
      basename, dtype_p);
}

/*
 * Loads the exclude lists for the directory containing pathname, then
 * scans all exclude lists to determine whether pathname is excluded.
 * Returns 1 if true, otherwise 0.
 */
int is_excluded(struct dir_struct *dir, struct index_state *istate,
    const char *pathname, int *dtype_p)
{
  struct path_pattern *pattern =
    last_matching_pattern(dir, istate, pathname, dtype_p);
  if (pattern)
    return pattern->flags & PATTERN_FLAG_NEGATIVE ? 0 : 1;
  return 0;
}

static struct dir_entry *dir_entry_new(const char *pathname, int len)
{
  struct dir_entry *ent;

  FLEX_ALLOC_MEM(ent, name, pathname, len);
  ent->len = len;
  return ent;
}

static struct dir_entry *dir_add_name(struct dir_struct *dir,
              struct index_state *istate,
              const char *pathname, int len)
{
  if (index_file_exists(istate, pathname, len, repo_ignore_case(the_repository)))
    return NULL;

  ALLOC_GROW(dir->entries, dir->nr+1, dir->internal.alloc);
  return dir->entries[dir->nr++] = dir_entry_new(pathname, len);
}

struct dir_entry *dir_add_ignored(struct dir_struct *dir,
          struct index_state *istate,
          const char *pathname, int len)
{
  if (!index_name_is_other(istate, pathname, len))
    return NULL;

  ALLOC_GROW(dir->ignored, dir->ignored_nr+1, dir->internal.ignored_alloc);
  return dir->ignored[dir->ignored_nr++] = dir_entry_new(pathname, len);
}

enum exist_status {
  index_nonexistent = 0,
  index_directory,
  index_gitdir
};

/*
 * Do not use the alphabetically sorted index to look up
 * the directory name; instead, use the case insensitive
 * directory hash.
 */
static enum exist_status directory_exists_in_index_icase(struct index_state *istate,
               const char *dirname, int len)
{
  struct cache_entry *ce;

  if (index_dir_exists(istate, dirname, len))
    return index_directory;

  ce = index_file_exists(istate, dirname, len, repo_ignore_case(the_repository));
  if (ce && S_ISGITLINK(ce->ce_mode))
    return index_gitdir;

  return index_nonexistent;
}

/*
 * The index sorts alphabetically by entry name, which
 * means that a gitlink sorts as '\0' at the end, while
 * a directory (which is defined not as an entry, but as
 * the files it contains) will sort with the '/' at the
 * end.
 */
static enum exist_status directory_exists_in_index(struct index_state *istate,
               const char *dirname, int len)
{
  int pos;

  if (repo_ignore_case(the_repository))
    return directory_exists_in_index_icase(istate, dirname, len);

  pos = index_name_pos(istate, dirname, len);
  if (pos < 0)
    pos = -pos-1;
  while (pos < istate->cache_nr) {
    const struct cache_entry *ce = istate->cache[pos++];
    unsigned char endchar;

    if (strncmp(ce->name, dirname, len))
      break;
    endchar = ce->name[len];
    if (endchar > '/')
      break;
    if (endchar == '/')
      return index_directory;
    if (!endchar && S_ISGITLINK(ce->ce_mode))
      return index_gitdir;
  }
  return index_nonexistent;
}

static int dir_match(struct index_state *istate,
         const struct pathspec *pathspec,
         const char *dirname, int len)
{
  return match_pathspec_with_flags(istate, pathspec, dirname, len,
           0 /* prefix */,
           NULL /* seen */,
           DO_MATCH_LEADING_PATHSPEC);
}

/*
 * When we find a directory when traversing the filesystem, we
 * have three distinct cases:
 *
 *  - ignore it
 *  - see it as a directory
 *  - recurse into it
 *
 * and which one we choose depends on a combination of existing
 * git index contents and the flags passed into the directory
 * traversal routine.
 *
 * Case 1: If we *already* have entries in the index under that
 * directory name, we always recurse into the directory to see
 * all the files.
 *
 * Case 2: If we *already* have that directory name as a gitlink,
 * we always continue to see it as a gitlink, regardless of whether
 * there is an actual git directory there or not (it might not
 * be checked out as a subproject!)
 *
 * Case 3: if we didn't have it in the index previously, we
 * have a few sub-cases:
 *
 *  (a) if DIR_SHOW_OTHER_DIRECTORIES flag is set, we show it as
 *      just a directory, unless DIR_HIDE_EMPTY_DIRECTORIES is
 *      also true, in which case we need to check if it contains any
 *      untracked and / or ignored files.
 *  (b) if it looks like a git directory and we don't have the
 *      DIR_NO_GITLINKS flag, then we treat it as a gitlink, and
 *      show it as a directory.
 *  (c) otherwise, we recurse into it.
 */
static enum path_treatment treat_directory(struct dir_struct *dir,
  struct index_state *istate,
  struct untracked_cache_dir *untracked,
  const char *dirname, int len, int baselen, int excluded,
  const struct pathspec *pathspec)
{
  /*
   * WARNING: From this function, you can return path_recurse or you
   *          can call read_directory_recursive() (or neither), but
   *          you CAN'T DO BOTH.
   */
  enum path_treatment state;
  int matches_how = 0;
  int check_only, stop_early;
  int old_ignored_nr, old_untracked_nr;
  /* The "len-1" is to strip the final '/' */
  enum exist_status status = directory_exists_in_index(istate, dirname, len-1);

  if (status == index_directory)
    return path_recurse;
  if (status == index_gitdir)
    return path_none;
  if (status != index_nonexistent)
    BUG("Unhandled value for directory_exists_in_index: %d\n", status);

  /*
   * We don't want to descend into paths that don't match the necessary
   * patterns.  Clearly, if we don't have a pathspec, then we can't check
   * for matching patterns.  Also, if (excluded) then we know we matched
   * the exclusion patterns so as an optimization we can skip checking
   * for matching patterns.
   */
  if (pathspec && !excluded) {
    matches_how = dir_match(istate, pathspec, dirname, len);
    if (!matches_how)
      return path_none;
  }


  if ((dir->flags & DIR_SKIP_NESTED_GIT) ||
    !(dir->flags & DIR_NO_GITLINKS)) {
    /*
     * Determine if `dirname` is a nested repo by confirming that:
     * 1) we are in a nonbare repository, and
     * 2) `dirname` is not an immediate parent of `the_repository->gitdir`,
     *    which could occur if the git_dir or worktree location was
     *    manually configured by the user; see t2205 testcases 1-3 for
     *    examples where this matters
     */
    int nested_repo;
    struct strbuf sb = STRBUF_INIT;
    strbuf_addstr(&sb, dirname);
    nested_repo = is_nonbare_repository_dir(&sb);

    if (nested_repo) {
      char *real_dirname, *real_gitdir;
      strbuf_addstr(&sb, ".git");
      real_dirname = real_pathdup(sb.buf, 1);
      real_gitdir = real_pathdup(the_repository->gitdir, 1);

      nested_repo = !!strcmp(real_dirname, real_gitdir);
      free(real_gitdir);
      free(real_dirname);
    }
    strbuf_release(&sb);

    if (nested_repo) {
      if (dir->flags & DIR_SKIP_NESTED_GIT)
        return path_none;
      if (pathspec && !matches_how) {
        matches_how = dir_match(istate, pathspec,
              dirname, len);
        if (!matches_how)
          return path_none;
      }
      if (matches_how == MATCHED_RECURSIVELY_LEADING_PATHSPEC)
        return path_none;
      return excluded ? path_excluded : path_untracked;
    }
  }

  if (!(dir->flags & DIR_SHOW_OTHER_DIRECTORIES)) {
    if (excluded &&
        (dir->flags & DIR_SHOW_IGNORED_TOO) &&
        (dir->flags & DIR_SHOW_IGNORED_TOO_MODE_MATCHING)) {

      /*
       * This is an excluded directory and we are
       * showing ignored paths that match an exclude
       * pattern.  (e.g. show directory as ignored
       * only if it matches an exclude pattern).
       * This path will either be 'path_excluded`
       * (if we are showing empty directories or if
       * the directory is not empty), or will be
       * 'path_none' (empty directory, and we are
       * not showing empty directories).
       */
      if (!(dir->flags & DIR_HIDE_EMPTY_DIRECTORIES))
        return path_excluded;

      if (read_directory_recursive(dir, istate, dirname, len,
                 untracked, 1, 1, pathspec) == path_excluded)
        return path_excluded;

      return path_none;
    }
    return path_recurse;
  }

  assert(dir->flags & DIR_SHOW_OTHER_DIRECTORIES);

  /*
   * If we have a pathspec which could match something _below_ this
   * directory (e.g. when checking 'subdir/' having a pathspec like
   * 'subdir/some/deep/path/file' or 'subdir/widget-*.c'), then we
   * need to recurse.
   */
  if (matches_how == MATCHED_RECURSIVELY_LEADING_PATHSPEC)
    return path_recurse;

  /* Special cases for where this directory is excluded/ignored */
  if (excluded) {
    /*
     * If DIR_SHOW_OTHER_DIRECTORIES is set and we're not
     * hiding empty directories, there is no need to
     * recurse into an ignored directory.
     */
    if (!(dir->flags & DIR_HIDE_EMPTY_DIRECTORIES))
      return path_excluded;

    /*
     * Even if we are hiding empty directories, we can still avoid
     * recursing into ignored directories for DIR_SHOW_IGNORED_TOO
     * if DIR_SHOW_IGNORED_TOO_MODE_MATCHING is also set.
     */
    if ((dir->flags & DIR_SHOW_IGNORED_TOO) &&
        (dir->flags & DIR_SHOW_IGNORED_TOO_MODE_MATCHING))
      return path_excluded;
  }

  /*
   * Other than the path_recurse case above, we only need to
   * recurse into untracked directories if any of the following
   * bits is set:
   *   - DIR_SHOW_IGNORED (because then we need to determine if
   *                       there are ignored entries below)
   *   - DIR_SHOW_IGNORED_TOO (same as above)
   *   - DIR_HIDE_EMPTY_DIRECTORIES (because we have to determine if
   *                                 the directory is empty)
   */
  if (!excluded &&
      !(dir->flags & (DIR_SHOW_IGNORED |
          DIR_SHOW_IGNORED_TOO |
          DIR_HIDE_EMPTY_DIRECTORIES))) {
    return path_untracked;
  }

  /*
   * Even if we don't want to know all the paths under an untracked or
   * ignored directory, we may still need to go into the directory to
   * determine if it is empty (because with DIR_HIDE_EMPTY_DIRECTORIES,
   * an empty directory should be path_none instead of path_excluded or
   * path_untracked).
   */
  check_only = ((dir->flags & DIR_HIDE_EMPTY_DIRECTORIES) &&
          !(dir->flags & DIR_SHOW_IGNORED_TOO));

  /*
   * However, there's another optimization possible as a subset of
   * check_only, based on the cases we have to consider:
   *   A) Directory matches no exclude patterns:
   *     * Directory is empty => path_none
   *     * Directory has an untracked file under it => path_untracked
   *     * Directory has only ignored files under it => path_excluded
   *   B) Directory matches an exclude pattern:
   *     * Directory is empty => path_none
   *     * Directory has an untracked file under it => path_excluded
   *     * Directory has only ignored files under it => path_excluded
   * In case A, we can exit as soon as we've found an untracked
   * file but otherwise have to walk all files.  In case B, though,
   * we can stop at the first file we find under the directory.
   */
  stop_early = check_only && excluded;

  /*
   * If /every/ file within an untracked directory is ignored, then
   * we want to treat the directory as ignored (for e.g. status
   * --porcelain), without listing the individual ignored files
   * underneath.  To do so, we'll save the current ignored_nr, and
   * pop all the ones added after it if it turns out the entire
   * directory is ignored.  Also, when DIR_SHOW_IGNORED_TOO and
   * !DIR_KEEP_UNTRACKED_CONTENTS then we don't want to show
   * untracked paths so will need to pop all those off the last
   * after we traverse.
   */
  old_ignored_nr = dir->ignored_nr;
  old_untracked_nr = dir->nr;

  /* Actually recurse into dirname now, we'll fixup the state later. */
  untracked = lookup_untracked(dir->untracked, untracked,
             dirname + baselen, len - baselen);
  state = read_directory_recursive(dir, istate, dirname, len, untracked,
           check_only, stop_early, pathspec);

  /* There are a variety of reasons we may need to fixup the state... */
  if (state == path_excluded) {
    /* state == path_excluded implies all paths under
     * dirname were ignored...
     *
     * if running e.g. `git status --porcelain --ignored=matching`,
     * then we want to see the subpaths that are ignored.
     *
     * if running e.g. just `git status --porcelain`, then
     * we just want the directory itself to be listed as ignored
     * and not the individual paths underneath.
     */
    int want_ignored_subpaths =
      ((dir->flags & DIR_SHOW_IGNORED_TOO) &&
       (dir->flags & DIR_SHOW_IGNORED_TOO_MODE_MATCHING));

    if (want_ignored_subpaths) {
      /*
       * with --ignored=matching, we want the subpaths
       * INSTEAD of the directory itself.
       */
      state = path_none;
    } else {
      for (int i = old_ignored_nr; i < dir->ignored_nr; i++)
        FREE_AND_NULL(dir->ignored[i]);
      dir->ignored_nr = old_ignored_nr;
    }
  }

  /*
   * We may need to ignore some of the untracked paths we found while
   * traversing subdirectories.
   */
  if ((dir->flags & DIR_SHOW_IGNORED_TOO) &&
      !(dir->flags & DIR_KEEP_UNTRACKED_CONTENTS)) {
    for (int i = old_untracked_nr; i < dir->nr; i++)
      FREE_AND_NULL(dir->entries[i]);
    dir->nr = old_untracked_nr;
  }

  /*
   * If there is nothing under the current directory and we are not
   * hiding empty directories, then we need to report on the
   * untracked or ignored status of the directory itself.
   */
  if (state == path_none && !(dir->flags & DIR_HIDE_EMPTY_DIRECTORIES))
    state = excluded ? path_excluded : path_untracked;

  return state;
}

/*
 * This is an inexact early pruning of any recursive directory
 * reading - if the path cannot possibly be in the pathspec,
 * return true, and we'll skip it early.
 */
static int simplify_away(const char *path, int pathlen,
       const struct pathspec *pathspec)
{
  int i;

  if (!pathspec || !pathspec->nr)
    return 0;

  GUARD_PATHSPEC(pathspec,
           PATHSPEC_FROMTOP |
           PATHSPEC_MAXDEPTH |
           PATHSPEC_LITERAL |
           PATHSPEC_GLOB |
           PATHSPEC_ICASE |
           PATHSPEC_EXCLUDE |
           PATHSPEC_ATTR);

  for (i = 0; i < pathspec->nr; i++) {
    const struct pathspec_item *item = &pathspec->items[i];
    int len = item->nowildcard_len;

    if (len > pathlen)
      len = pathlen;
    if (!ps_strncmp(item, item->match, path, len))
      return 0;
  }

  return 1;
}

/*
 * This function tells us whether an excluded path matches a
 * list of "interesting" pathspecs. That is, whether a path matched
 * by any of the pathspecs could possibly be ignored by excluding
 * the specified path. This can happen if:
 *
 *   1. the path is mentioned explicitly in the pathspec
 *
 *   2. the path is a directory prefix of some element in the
 *      pathspec
 */
static int exclude_matches_pathspec(const char *path, int pathlen,
            const struct pathspec *pathspec)
{
  int i;

  if (!pathspec || !pathspec->nr)
    return 0;

  GUARD_PATHSPEC(pathspec,
           PATHSPEC_FROMTOP |
           PATHSPEC_MAXDEPTH |
           PATHSPEC_LITERAL |
           PATHSPEC_GLOB |
           PATHSPEC_ICASE |
           PATHSPEC_EXCLUDE |
           PATHSPEC_ATTR);

  for (i = 0; i < pathspec->nr; i++) {
    const struct pathspec_item *item = &pathspec->items[i];
    int len = item->nowildcard_len;

    if (len == pathlen &&
        !ps_strncmp(item, item->match, path, pathlen))
      return 1;
    if (len > pathlen &&
        item->match[pathlen] == '/' &&
        !ps_strncmp(item, item->match, path, pathlen))
      return 1;
  }
  return 0;
}

static int get_index_dtype(struct index_state *istate,
         const char *path, int len)
{
  int pos;
  const struct cache_entry *ce;

  ce = index_file_exists(istate, path, len, 0);
  if (ce) {
    if (!ce_uptodate(ce))
      return DT_UNKNOWN;
    if (S_ISGITLINK(ce->ce_mode))
      return DT_DIR;
    /*
     * Nobody actually cares about the
     * difference between DT_LNK and DT_REG
     */
    return DT_REG;
  }

  /* Try to look it up as a directory */
  pos = index_name_pos(istate, path, len);
  if (pos >= 0)
    return DT_UNKNOWN;
  pos = -pos-1;
  while (pos < istate->cache_nr) {
    ce = istate->cache[pos++];
    if (strncmp(ce->name, path, len))
      break;
    if (ce->name[len] > '/')
      break;
    if (ce->name[len] < '/')
      continue;
    if (!ce_uptodate(ce))
      break; /* continue? */
    return DT_DIR;
  }
  return DT_UNKNOWN;
}

unsigned char get_dtype(struct dirent *e, struct strbuf *path,
      int follow_symlink)
{
  struct stat st;
  unsigned char dtype = DTYPE(e);
  size_t base_path_len;

  if (dtype != DT_UNKNOWN && !(follow_symlink && dtype == DT_LNK))
    return dtype;

  /*
   * d_type unknown or unfollowed symlink, try to fall back on [l]stat
   * results. If [l]stat fails, explicitly set DT_UNKNOWN.
   */
  base_path_len = path->len;
  strbuf_addstr(path, e->d_name);
  if ((follow_symlink && stat(path->buf, &st)) ||
      (!follow_symlink && lstat(path->buf, &st)))
    goto cleanup;

  /* determine d_type from st_mode */
  if (S_ISREG(st.st_mode))
    dtype = DT_REG;
  else if (S_ISDIR(st.st_mode))
    dtype = DT_DIR;
  else if (S_ISLNK(st.st_mode))
    dtype = DT_LNK;

cleanup:
  strbuf_setlen(path, base_path_len);
  return dtype;
}

static int resolve_dtype(int dtype, struct index_state *istate,
       const char *path, int len)
{
  struct stat st;

  if (dtype != DT_UNKNOWN)
    return dtype;
  dtype = get_index_dtype(istate, path, len);
  if (dtype != DT_UNKNOWN)
    return dtype;
  if (lstat(path, &st))
    return dtype;
  if (S_ISREG(st.st_mode))
    return DT_REG;
  if (S_ISDIR(st.st_mode))
    return DT_DIR;
  if (S_ISLNK(st.st_mode))
    return DT_LNK;
  return dtype;
}

static enum path_treatment treat_path_fast(struct dir_struct *dir,
             struct cached_dir *cdir,
             struct index_state *istate,
             struct strbuf *path,
             int baselen,
             const struct pathspec *pathspec)
{
  /*
   * WARNING: From this function, you can return path_recurse or you
   *          can call read_directory_recursive() (or neither), but
   *          you CAN'T DO BOTH.
   */
  strbuf_setlen(path, baselen);
  if (!cdir->ucd) {
    strbuf_addstr(path, cdir->file);
    return path_untracked;
  }
  strbuf_addstr(path, cdir->ucd->name);
  /* treat_one_path() does this before it calls treat_directory() */
  strbuf_complete(path, '/');
  if (cdir->ucd->check_only)
    /*
     * check_only is set as a result of treat_directory() getting
     * to its bottom. Verify again the same set of directories
     * with check_only set.
     */
    return read_directory_recursive(dir, istate, path->buf, path->len,
            cdir->ucd, 1, 0, pathspec);
  /*
   * We get path_recurse in the first run when
   * directory_exists_in_index() returns index_nonexistent. We
   * are sure that new changes in the index does not impact the
   * outcome. Return now.
   */
  return path_recurse;
}

static enum path_treatment treat_path(struct dir_struct *dir,
              struct untracked_cache_dir *untracked,
              struct cached_dir *cdir,
              struct index_state *istate,
              struct strbuf *path,
              int baselen,
              const struct pathspec *pathspec)
{
  int has_path_in_index, dtype, excluded;

  if (!cdir->d_name)
    return treat_path_fast(dir, cdir, istate, path,
               baselen, pathspec);
  if (is_dot_or_dotdot(cdir->d_name) || !fspathcmp(cdir->d_name, ".git"))
    return path_none;
  strbuf_setlen(path, baselen);
  strbuf_addstr(path, cdir->d_name);
  if (simplify_away(path->buf, path->len, pathspec))
    return path_none;

  dtype = resolve_dtype(cdir->d_type, istate, path->buf, path->len);

  /* Always exclude indexed files */
  has_path_in_index = !!index_file_exists(istate, path->buf, path->len,
            repo_ignore_case(the_repository));
  if (dtype != DT_DIR && has_path_in_index)
    return path_none;

  /*
   * When we are looking at a directory P in the working tree,
   * there are three cases:
   *
   * (1) P exists in the index.  Everything inside the directory P in
   * the working tree needs to go when P is checked out from the
   * index.
   *
   * (2) P does not exist in the index, but there is P/Q in the index.
   * We know P will stay a directory when we check out the contents
   * of the index, but we do not know yet if there is a directory
   * P/Q in the working tree to be killed, so we need to recurse.
   *
   * (3) P does not exist in the index, and there is no P/Q in the index
   * to require P to be a directory, either.  Only in this case, we
   * know that everything inside P will not be killed without
   * recursing.
   */
  if ((dir->flags & DIR_COLLECT_KILLED_ONLY) &&
      (dtype == DT_DIR) &&
      !has_path_in_index &&
      (directory_exists_in_index(istate, path->buf, path->len) == index_nonexistent))
    return path_none;

  excluded = is_excluded(dir, istate, path->buf, &dtype);

  /*
   * Excluded? If we don't explicitly want to show
   * ignored files, ignore it
   */
  if (excluded && !(dir->flags & (DIR_SHOW_IGNORED|DIR_SHOW_IGNORED_TOO)))
    return path_excluded;

  switch (dtype) {
  default:
    return path_none;
  case DT_DIR:
    /*
     * WARNING: Do not ignore/amend the return value from
     * treat_directory(), and especially do not change it to return
     * path_recurse as that can cause exponential slowdown.
     * Instead, modify treat_directory() to return the right value.
     */
    strbuf_addch(path, '/');
    return treat_directory(dir, istate, untracked,
               path->buf, path->len,
               baselen, excluded, pathspec);
  case DT_REG:
  case DT_LNK:
    if (pathspec &&
        !match_pathspec(istate, pathspec, path->buf, path->len,
            0 /* prefix */, NULL /* seen */,
            0 /* is_dir */))
      return path_none;
    if (excluded)
      return path_excluded;
    return path_untracked;
  }
}

static void add_untracked(struct untracked_cache_dir *dir, const char *name)
{
  if (!dir)
    return;
  ALLOC_GROW(dir->untracked, dir->untracked_nr + 1,
       dir->untracked_alloc);
  dir->untracked[dir->untracked_nr++] = xstrdup(name);
}

static int valid_cached_dir(struct dir_struct *dir,
          struct untracked_cache_dir *untracked,
          struct index_state *istate,
          struct strbuf *path,
          int check_only)
{
  struct stat st;

  if (!untracked)
    return 0;

  /*
   * With fsmonitor, we can trust the untracked cache's valid field.
   */
  refresh_fsmonitor(istate);
  if (!(dir->untracked->use_fsmonitor && untracked->valid)) {
    if (lstat(path->len ? path->buf : ".", &st)) {
      memset(&untracked->stat_data, 0, sizeof(untracked->stat_data));
      return 0;
    }
    if (!untracked->valid ||
      match_stat_data_racy(istate, &untracked->stat_data, &st)) {
      fill_stat_data(&untracked->stat_data, &st);
      return 0;
    }
  }

  if (untracked->check_only != !!check_only)
    return 0;

  /*
   * prep_exclude will be called eventually on this directory,
   * but it's called much later in last_matching_pattern(). We
   * need it now to determine the validity of the cache for this
   * path. The next calls will be nearly no-op, the way
   * prep_exclude() is designed.
   */
  if (path->len && path->buf[path->len - 1] != '/') {
    strbuf_addch(path, '/');
    prep_exclude(dir, istate, path->buf, path->len);
    strbuf_setlen(path, path->len - 1);
  } else
    prep_exclude(dir, istate, path->buf, path->len);

  /* hopefully prep_exclude() haven't invalidated this entry... */
  return untracked->valid;
}

static int open_cached_dir(struct cached_dir *cdir,
         struct dir_struct *dir,
         struct untracked_cache_dir *untracked,
         struct index_state *istate,
         struct strbuf *path,
         int check_only)
{
  const char *c_path;

  memset(cdir, 0, sizeof(*cdir));
  cdir->untracked = untracked;
  if (valid_cached_dir(dir, untracked, istate, path, check_only))
    return 0;
  c_path = path->len ? path->buf : ".";
  cdir->fdir = opendir(c_path);
  if (!cdir->fdir)
    warning_errno(_("could not open directory '%s'"), c_path);
  if (dir->untracked) {
    invalidate_directory(dir->untracked, untracked);
    dir->untracked->dir_opened++;
  }
  if (!cdir->fdir)
    return -1;
  return 0;
}

static int read_cached_dir(struct cached_dir *cdir)
{
  struct dirent *de;

  if (cdir->fdir) {
    de = readdir_skip_dot_and_dotdot(cdir->fdir);
    if (!de) {
      cdir->d_name = NULL;
      cdir->d_type = DT_UNKNOWN;
      return -1;
    }
    cdir->d_name = de->d_name;
    cdir->d_type = DTYPE(de);
    return 0;
  }
  while (cdir->nr_dirs < cdir->untracked->dirs_nr) {
    struct untracked_cache_dir *d = cdir->untracked->dirs[cdir->nr_dirs];
    if (!d->recurse) {
      cdir->nr_dirs++;
      continue;
    }
    cdir->ucd = d;
    cdir->nr_dirs++;
    return 0;
  }
  cdir->ucd = NULL;
  if (cdir->nr_files < cdir->untracked->untracked_nr) {
    struct untracked_cache_dir *d = cdir->untracked;
    cdir->file = d->untracked[cdir->nr_files++];
    return 0;
  }
  return -1;
}

static void close_cached_dir(struct cached_dir *cdir)
{
  if (cdir->fdir)
    closedir(cdir->fdir);
  /*
   * We have gone through this directory and found no untracked
   * entries. Mark it valid.
   */
  if (cdir->untracked) {
    cdir->untracked->valid = 1;
    cdir->untracked->recurse = 1;
  }
}

static void add_path_to_appropriate_result_list(struct dir_struct *dir,
  struct untracked_cache_dir *untracked,
  struct cached_dir *cdir,
  struct index_state *istate,
  struct strbuf *path,
  int baselen,
  const struct pathspec *pathspec,
  enum path_treatment state)
{
  /* add the path to the appropriate result list */
  switch (state) {
  case path_excluded:
    if (dir->flags & DIR_SHOW_IGNORED)
      dir_add_name(dir, istate, path->buf, path->len);
    else if ((dir->flags & DIR_SHOW_IGNORED_TOO) ||
      ((dir->flags & DIR_COLLECT_IGNORED) &&
      exclude_matches_pathspec(path->buf, path->len,
             pathspec)))
      dir_add_ignored(dir, istate, path->buf, path->len);
    break;

  case path_untracked:
    if (dir->flags & DIR_SHOW_IGNORED)
      break;
    dir_add_name(dir, istate, path->buf, path->len);
    if (cdir->fdir)
      add_untracked(untracked, path->buf + baselen);
    break;

  default:
    break;
  }
}

/*
 * Read a directory tree. We currently ignore anything but
 * directories, regular files and symlinks. That's because git
 * doesn't handle them at all yet. Maybe that will change some
 * day.
 *
 * Also, we ignore the name ".git" (even if it is not a directory).
 * That likely will not change.
 *
 * If 'stop_at_first_file' is specified, 'path_excluded' is returned
 * to signal that a file was found. This is the least significant value that
 * indicates that a file was encountered that does not depend on the order of
 * whether an untracked or excluded path was encountered first.
 *
 * Returns the most significant path_treatment value encountered in the scan.
 * If 'stop_at_first_file' is specified, `path_excluded` is the most
 * significant path_treatment value that will be returned.
 */

static enum path_treatment read_directory_recursive(struct dir_struct *dir,
  struct index_state *istate, const char *base, int baselen,
  struct untracked_cache_dir *untracked, int check_only,
  int stop_at_first_file, const struct pathspec *pathspec)
{
  /*
   * WARNING: Do NOT recurse unless path_recurse is returned from
   *          treat_path().  Recursing on any other return value
   *          can result in exponential slowdown.
   */
  struct cached_dir cdir;
  enum path_treatment state, subdir_state, dir_state = path_none;
  struct strbuf path = STRBUF_INIT;

  strbuf_add(&path, base, baselen);

  if (open_cached_dir(&cdir, dir, untracked, istate, &path, check_only))
    goto out;
  dir->internal.visited_directories++;

  if (untracked)
    untracked->check_only = !!check_only;

  while (!read_cached_dir(&cdir)) {
    /* check how the file or directory should be treated */
    state = treat_path(dir, untracked, &cdir, istate, &path,
           baselen, pathspec);
    dir->internal.visited_paths++;

    if (state > dir_state)
      dir_state = state;

    /* recurse into subdir if instructed by treat_path */
    if (state == path_recurse) {
      struct untracked_cache_dir *ud;
      ud = lookup_untracked(dir->untracked,
                untracked,
                path.buf + baselen,
                path.len - baselen);
      subdir_state =
        read_directory_recursive(dir, istate, path.buf,
               path.len, ud,
               check_only, stop_at_first_file, pathspec);
      if (subdir_state > dir_state)
        dir_state = subdir_state;

      if (pathspec &&
          !match_pathspec(istate, pathspec, path.buf, path.len,
              0 /* prefix */, NULL,
              0 /* do NOT special case dirs */))
        state = path_none;
    }

    if (check_only) {
      if (stop_at_first_file) {
        /*
         * If stopping at first file, then
         * signal that a file was found by
         * returning `path_excluded`. This is
         * to return a consistent value
         * regardless of whether an ignored or
         * excluded file happened to be
         * encountered 1st.
         *
         * In current usage, the
         * `stop_at_first_file` is passed when
         * an ancestor directory has matched
         * an exclude pattern, so any found
         * files will be excluded.
         */
        if (dir_state >= path_excluded) {
          dir_state = path_excluded;
          break;
        }
      }

      /* abort early if maximum state has been reached */
      if (dir_state == path_untracked) {
        if (cdir.fdir)
          add_untracked(untracked, path.buf + baselen);
        break;
      }
      /* skip the add_path_to_appropriate_result_list() */
      continue;
    }

    add_path_to_appropriate_result_list(dir, untracked, &cdir,
                istate, &path, baselen,
                pathspec, state);
  }
  close_cached_dir(&cdir);
 out:
  strbuf_release(&path);

  return dir_state;
}

int cmp_dir_entry(const void *p1, const void *p2)
{
  const struct dir_entry *e1 = *(const struct dir_entry **)p1;
  const struct dir_entry *e2 = *(const struct dir_entry **)p2;

  return name_compare(e1->name, e1->len, e2->name, e2->len);
}

/* check if *out lexically strictly contains *in */
int check_dir_entry_contains(const struct dir_entry *out, const struct dir_entry *in)
{
  return (out->len < in->len) &&
    (out->name[out->len - 1] == '/') &&
    !memcmp(out->name, in->name, out->len);
}

static int treat_leading_path(struct dir_struct *dir,
            struct index_state *istate,
            const char *path, int len,
            const struct pathspec *pathspec)
{
  struct strbuf sb = STRBUF_INIT;
  struct strbuf subdir = STRBUF_INIT;
  int prevlen, baselen;
  const char *cp;
  struct cached_dir cdir;
  enum path_treatment state = path_none;

  /*
   * For each directory component of path, we are going to check whether
   * that path is relevant given the pathspec.  For example, if path is
   *    foo/bar/baz/
   * then we will ask treat_path() whether we should go into foo, then
   * whether we should go into bar, then whether baz is relevant.
   * Checking each is important because e.g. if path is
   *    .git/info/
   * then we need to check .git to know we shouldn't traverse it.
   * If the return from treat_path() is:
   *    * path_none, for any path, we return false.
   *    * path_recurse, for all path components, we return true
   *    * <anything else> for some intermediate component, we make sure
   *        to add that path to the relevant list but return false
   *        signifying that we shouldn't recurse into it.
   */

  while (len && path[len - 1] == '/')
    len--;
  if (!len)
    return 1;

  memset(&cdir, 0, sizeof(cdir));
  cdir.d_type = DT_DIR;
  baselen = 0;
  prevlen = 0;
  while (1) {
    prevlen = baselen + !!baselen;
    cp = path + prevlen;
    cp = memchr(cp, '/', path + len - cp);
    if (!cp)
      baselen = len;
    else
      baselen = cp - path;
    strbuf_reset(&sb);
    strbuf_add(&sb, path, baselen);
    if (!is_directory(sb.buf))
      break;
    strbuf_reset(&sb);
    strbuf_add(&sb, path, prevlen);
    strbuf_reset(&subdir);
    strbuf_add(&subdir, path+prevlen, baselen-prevlen);
    cdir.d_name = subdir.buf;
    state = treat_path(dir, NULL, &cdir, istate, &sb, prevlen, pathspec);

    if (state != path_recurse)
      break; /* do not recurse into it */
    if (len <= baselen)
      break; /* finished checking */
  }
  add_path_to_appropriate_result_list(dir, NULL, &cdir, istate,
              &sb, baselen, pathspec,
              state);

  strbuf_release(&subdir);
  strbuf_release(&sb);
  return state == path_recurse;
}

static const char *get_ident_string(void)
{
  static struct strbuf sb = STRBUF_INIT;
  struct utsname uts;

  if (sb.len)
    return sb.buf;
  if (uname(&uts) < 0)
    die_errno(_("failed to get kernel name and information"));
  strbuf_addf(&sb, "Location %s, system %s", repo_get_work_tree(the_repository),
        uts.sysname);
  return sb.buf;
}

static int ident_in_untracked(const struct untracked_cache *uc)
{
  /*
   * Previous git versions may have saved many NUL separated
   * strings in the "ident" field, but it is insane to manage
   * many locations, so just take care of the first one.
   */

  return !strcmp(uc->ident.buf, get_ident_string());
}

static void set_untracked_ident(struct untracked_cache *uc)
{
  strbuf_reset(&uc->ident);
  strbuf_addstr(&uc->ident, get_ident_string());

  /*
   * This strbuf used to contain a list of NUL separated
   * strings, so save NUL too for backward compatibility.
   */
  strbuf_addch(&uc->ident, 0);
}

static unsigned new_untracked_cache_flags(struct index_state *istate)
{
  struct repository *repo = istate->repo;
  const char *val;

  /*
   * This logic is coordinated with the setting of these flags in
   * wt-status.c#wt_status_collect_untracked(), and the evaluation
   * of the config setting in commit.c#git_status_config()
   */
  if (!repo_config_get_string_tmp(repo, "status.showuntrackedfiles", &val) &&
      !strcmp(val, "all"))
    return 0;

  /*
   * The default, if "all" is not set, is "normal" - leading us here.
   * If the value is "none" then it really doesn't matter.
   */
  return DIR_SHOW_OTHER_DIRECTORIES | DIR_HIDE_EMPTY_DIRECTORIES;
}

static void new_untracked_cache(struct index_state *istate, int flags)
{
  struct untracked_cache *uc = xcalloc(1, sizeof(*uc));
  strbuf_init(&uc->ident, 100);
  uc->exclude_per_dir = ".gitignore";
  uc->dir_flags = flags >= 0 ? flags : new_untracked_cache_flags(istate);
  set_untracked_ident(uc);
  istate->untracked = uc;
  istate->cache_changed |= UNTRACKED_CHANGED;
}

void add_untracked_cache(struct index_state *istate)
{
  if (!istate->untracked) {
    new_untracked_cache(istate, -1);
  } else {
    if (!ident_in_untracked(istate->untracked)) {
      free_untracked_cache(istate->untracked);
      new_untracked_cache(istate, -1);
    }
  }
}

void remove_untracked_cache(struct index_state *istate)
{
  if (istate->untracked) {
    free_untracked_cache(istate->untracked);
    istate->untracked = NULL;
    istate->cache_changed |= UNTRACKED_CHANGED;
  }
}

static struct untracked_cache_dir *validate_untracked_cache(struct dir_struct *dir,
                  int base_len,
                  const struct pathspec *pathspec,
                  struct index_state *istate)
{
  struct untracked_cache_dir *root;
  static int untracked_cache_disabled = -1;

  if (!dir->untracked)
    return NULL;
  if (untracked_cache_disabled < 0)
    untracked_cache_disabled = git_env_bool("GIT_DISABLE_UNTRACKED_CACHE", 0);
  if (untracked_cache_disabled)
    return NULL;

  /*
   * We only support $GIT_COMMON_DIR/info/exclude and core.excludesfile
   * as the global ignore rule files. Any other additions
   * (e.g. from command line) invalidate the cache. This
   * condition also catches running setup_standard_excludes()
   * before setting dir->untracked!
   */
  if (dir->internal.unmanaged_exclude_files)
    return NULL;

  /*
   * Optimize for the main use case only: whole-tree git
   * status. More work involved in treat_leading_path() if we
   * use cache on just a subset of the worktree. pathspec
   * support could make the matter even worse.
   */
  if (base_len || (pathspec && pathspec->nr))
    return NULL;

  /* We don't support collecting ignore files */
  if (dir->flags & (DIR_SHOW_IGNORED | DIR_SHOW_IGNORED_TOO |
      DIR_COLLECT_IGNORED))
    return NULL;

  /*
   * If we use .gitignore in the cache and now you change it to
   * .gitexclude, everything will go wrong.
   */
  if (dir->exclude_per_dir != dir->untracked->exclude_per_dir &&
      strcmp(dir->exclude_per_dir, dir->untracked->exclude_per_dir))
    return NULL;

  /*
   * EXC_CMDL is not considered in the cache. If people set it,
   * skip the cache.
   */
  if (dir->internal.exclude_list_group[EXC_CMDL].nr)
    return NULL;

  if (!ident_in_untracked(dir->untracked)) {
    warning(_("untracked cache is disabled on this system or location"));
    return NULL;
  }

  /*
   * If the untracked structure we received does not have the same flags
   * as requested in this run, we're going to need to either discard the
   * existing structure (and potentially later recreate), or bypass the
   * untracked cache mechanism for this run.
   */
  if (dir->flags != dir->untracked->dir_flags) {
    /*
     * If the untracked structure we received does not have the same flags
     * as configured, then we need to reset / create a new "untracked"
     * structure to match the new config.
     *
     * Keeping the saved and used untracked cache consistent with the
     * configuration provides an opportunity for frequent users of
     * "git status -uall" to leverage the untracked cache by aligning their
     * configuration - setting "status.showuntrackedfiles" to "all" or
     * "normal" as appropriate.
     *
     * Previously using -uall (or setting "status.showuntrackedfiles" to
     * "all") was incompatible with untracked cache and *consistently*
     * caused surprisingly bad performance (with fscache and fsmonitor
     * enabled) on Windows.
     *
     * IMPROVEMENT OPPORTUNITY: If we reworked the untracked cache storage
     * to not be as bound up with the desired output in a given run,
     * and instead iterated through and stored enough information to
     * correctly serve both "modes", then users could get peak performance
     * with or without '-uall' regardless of their
     * "status.showuntrackedfiles" config.
     */
    if (dir->untracked->dir_flags != new_untracked_cache_flags(istate)) {
      free_untracked_cache(istate->untracked);
      new_untracked_cache(istate, dir->flags);
      dir->untracked = istate->untracked;
    }
    else {
      /*
       * Current untracked cache data is consistent with config, but not
       * usable in this request/run; just bypass untracked cache.
       */
      return NULL;
    }
  }

  if (!dir->untracked->root) {
    /* Untracked cache existed but is not initialized; fix that */
    FLEX_ALLOC_STR(dir->untracked->root, name, "");
    istate->cache_changed |= UNTRACKED_CHANGED;
  }

  /* Validate $GIT_COMMON_DIR/info/exclude and core.excludesfile */
  root = dir->untracked->root;
  if (!oideq(&dir->internal.ss_info_exclude.oid,
       &dir->untracked->ss_info_exclude.oid)) {
    invalidate_gitignore(dir->untracked, root);
    dir->untracked->ss_info_exclude = dir->internal.ss_info_exclude;
  }
  if (!oideq(&dir->internal.ss_excludes_file.oid,
       &dir->untracked->ss_excludes_file.oid)) {
    invalidate_gitignore(dir->untracked, root);
    dir->untracked->ss_excludes_file = dir->internal.ss_excludes_file;
  }

  /* Make sure this directory is not dropped out at saving phase */
  root->recurse = 1;
  return root;
}

static void emit_traversal_statistics(struct dir_struct *dir,
              struct repository *repo,
              const char *path,
              int path_len)
{
  if (!trace2_is_enabled())
    return;

  if (!path_len) {
    trace2_data_string("read_directory", repo, "path", "");
  } else {
    struct strbuf tmp = STRBUF_INIT;
    strbuf_add(&tmp, path, path_len);
    trace2_data_string("read_directory", repo, "path", tmp.buf);
    strbuf_release(&tmp);
  }

  trace2_data_intmax("read_directory", repo,
         "directories-visited", dir->internal.visited_directories);
  trace2_data_intmax("read_directory", repo,
         "paths-visited", dir->internal.visited_paths);

  if (!dir->untracked)
    return;
  trace2_data_intmax("read_directory", repo,
         "node-creation", dir->untracked->dir_created);
  trace2_data_intmax("read_directory", repo,
         "gitignore-invalidation",
         dir->untracked->gitignore_invalidated);
  trace2_data_intmax("read_directory", repo,
         "directory-invalidation",
         dir->untracked->dir_invalidated);
  trace2_data_intmax("read_directory", repo,
         "opendir", dir->untracked->dir_opened);
}

int read_directory(struct dir_struct *dir, struct index_state *istate,
       const char *path, int len, const struct pathspec *pathspec)
{
  struct untracked_cache_dir *untracked;

  trace2_region_enter("dir", "read_directory", istate->repo);
  dir->internal.visited_paths = 0;
  dir->internal.visited_directories = 0;

  if (has_symlink_leading_path(path, len)) {
    trace2_region_leave("dir", "read_directory", istate->repo);
    return dir->nr;
  }

  untracked = validate_untracked_cache(dir, len, pathspec, istate);
  if (!untracked)
    /*
     * make sure untracked cache code path is disabled,
     * e.g. prep_exclude()
     */
    dir->untracked = NULL;
  if (!len || treat_leading_path(dir, istate, path, len, pathspec))
    read_directory_recursive(dir, istate, path, len, untracked, 0, 0, pathspec);
  QSORT(dir->entries, dir->nr, cmp_dir_entry);
  QSORT(dir->ignored, dir->ignored_nr, cmp_dir_entry);

  emit_traversal_statistics(dir, istate->repo, path, len);

  trace2_region_leave("dir", "read_directory", istate->repo);
  if (dir->untracked) {
    static int force_untracked_cache = -1;

    if (force_untracked_cache < 0)
      force_untracked_cache =
        git_env_bool("GIT_FORCE_UNTRACKED_CACHE", -1);
    if (force_untracked_cache < 0)
      force_untracked_cache = (istate->repo->settings.core_untracked_cache == UNTRACKED_CACHE_WRITE);
    if (force_untracked_cache &&
      dir->untracked == istate->untracked &&
        (dir->untracked->dir_opened ||
         dir->untracked->gitignore_invalidated ||
         dir->untracked->dir_invalidated))
      istate->cache_changed |= UNTRACKED_CHANGED;
    if (dir->untracked != istate->untracked) {
      FREE_AND_NULL(dir->untracked);
    }
  }

  return dir->nr;
}

int file_exists(const char *f)
{
  struct stat sb;
  return lstat(f, &sb) == 0;
}

int repo_file_exists(struct repository *repo, const char *path)
{
  if (repo != the_repository)
    BUG("do not know how to check file existence in arbitrary repo");

  return file_exists(path);
}

static int cmp_icase(char a, char b)
{
  if (a == b)
    return 0;
  if (repo_ignore_case(the_repository))
    return toupper(a) - toupper(b);
  return a - b;
}

/*
 * Given two normalized paths (a trailing slash is ok), if subdir is
 * outside dir, return -1.  Otherwise return the offset in subdir that
 * can be used as relative path to dir.
 */
int dir_inside_of(const char *subdir, const char *dir)
{
  int offset = 0;

  assert(dir && subdir && *dir && *subdir);

  while (*dir && *subdir && !cmp_icase(*dir, *subdir)) {
    dir++;
    subdir++;
    offset++;
  }

  /* hel[p]/me vs hel[l]/yeah */
  if (*dir && *subdir)
    return -1;

  if (!*subdir)
    return !*dir ? offset : -1; /* same dir */

  /* foo/[b]ar vs foo/[] */
  if (is_dir_sep(dir[-1]))
    return is_dir_sep(subdir[-1]) ? offset : -1;

  /* foo[/]bar vs foo[] */
  return is_dir_sep(*subdir) ? offset + 1 : -1;
}

int is_inside_dir(const char *dir)
{
  char *cwd;
  int rc;

  if (!dir)
    return 0;

  cwd = xgetcwd();
  rc = (dir_inside_of(cwd, dir) >= 0);
  free(cwd);
  return rc;
}

int is_empty_dir(const char *path)
{
  DIR *dir = opendir(path);
  struct dirent *e;
  int ret = 1;

  if (!dir)
    return 0;

  e = readdir_skip_dot_and_dotdot(dir);
  if (e)
    ret = 0;

  closedir(dir);
  return ret;
}

char *git_url_basename(const char *repo, int is_bundle, int is_bare)
{
  const char *end = repo + strlen(repo), *start, *ptr;
  size_t len;
  char *dir;

  /*
   * Skip scheme.
   */
  start = strstr(repo, "://");
  if (!start)
    start = repo;
  else
    start += 3;

  /*
   * Skip authentication data. The stripping does happen
   * greedily, such that we strip up to the last '@' inside
   * the host part.
   */
  for (ptr = start; ptr < end && !is_dir_sep(*ptr); ptr++) {
    if (*ptr == '@')
      start = ptr + 1;
  }

  /*
   * Strip trailing spaces, slashes and /.git
   */
  while (start < end && (is_dir_sep(end[-1]) || isspace(end[-1])))
    end--;
  if (end - start > 5 && is_dir_sep(end[-5]) &&
      !strncmp(end - 4, ".git", 4)) {
    end -= 5;
    while (start < end && is_dir_sep(end[-1]))
      end--;
  }

  /*
   * It should not be possible to overflow `ptrdiff_t` by passing in an
   * insanely long URL, but GCC does not know that and will complain
   * without this check.
   */
  if (end - start < 0)
    die(_("No directory name could be guessed.\n"
          "Please specify a directory on the command line"));

  /*
   * Strip trailing port number if we've got only a
   * hostname (that is, there is no dir separator but a
   * colon). This check is required such that we do not
   * strip URI's like '/foo/bar:2222.git', which should
   * result in a dir '2222' being guessed due to backwards
   * compatibility.
   */
  if (memchr(start, '/', end - start) == NULL
      && memchr(start, ':', end - start) != NULL) {
    ptr = end;
    while (start < ptr && isdigit(ptr[-1]) && ptr[-1] != ':')
      ptr--;
    if (start < ptr && ptr[-1] == ':')
      end = ptr - 1;
  }

  /*
   * Find last component. To remain backwards compatible we
   * also regard colons as path separators, such that
   * cloning a repository 'foo:bar.git' would result in a
   * directory 'bar' being guessed.
   */
  ptr = end;
  while (start < ptr && !is_dir_sep(ptr[-1]) && ptr[-1] != ':')
    ptr--;
  start = ptr;

  /*
   * Strip .{bundle,git}.
   */
  len = end - start;
  strip_suffix_mem(start, &len, is_bundle ? ".bundle" : ".git");

  if (!len || (len == 1 && *start == '/'))
    die(_("No directory name could be guessed.\n"
          "Please specify a directory on the command line"));

  if (is_bare)
    dir = xstrfmt("%.*s.git", (int)len, start);
  else
    dir = xstrndup(start, len);
  /*
   * Replace sequences of 'control' characters and whitespace
   * with one ascii space, remove leading and trailing spaces.
   */
  if (*dir) {
    char *out = dir;
    int prev_space = 1 /* strip leading whitespace */;
    for (end = dir; *end; ++end) {
      char ch = *end;
      if ((unsigned char)ch < '\x20')
        ch = '\x20';
      if (isspace(ch)) {
        if (prev_space)
          continue;
        prev_space = 1;
      } else
        prev_space = 0;
      *out++ = ch;
    }
    *out = '\0';
    if (out > dir && prev_space)
      out[-1] = '\0';
  }
  return dir;
}

void strip_dir_trailing_slashes(char *dir)
{
  char *end = dir + strlen(dir);

  while (dir < end - 1 && is_dir_sep(end[-1]))
    end--;
  *end = '\0';
}

static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
{
  DIR *dir;
  struct dirent *e;
  int ret = 0, original_len = path->len, len, kept_down = 0;
  int only_empty = (flag & REMOVE_DIR_EMPTY_ONLY);
  int keep_toplevel = (flag & REMOVE_DIR_KEEP_TOPLEVEL);
  int purge_original_cwd = (flag & REMOVE_DIR_PURGE_ORIGINAL_CWD);
  struct object_id submodule_head;

  if ((flag & REMOVE_DIR_KEEP_NESTED_GIT) &&
      !repo_resolve_gitlink_ref(the_repository, path->buf,
              "HEAD", &submodule_head)) {
    /* Do not descend and nuke a nested git work tree. */
    if (kept_up)
      *kept_up = 1;
    return 0;
  }

  flag &= ~REMOVE_DIR_KEEP_TOPLEVEL;
  dir = opendir(path->buf);
  if (!dir) {
    if (errno == ENOENT)
      return keep_toplevel ? -1 : 0;
    else if (errno == EACCES && !keep_toplevel)
      /*
       * An empty dir could be removable even if it
       * is unreadable:
       */
      return rmdir(path->buf);
    else
      return -1;
  }
  strbuf_complete(path, '/');

  len = path->len;
  while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
    struct stat st;

    strbuf_setlen(path, len);
    strbuf_addstr(path, e->d_name);
    if (lstat(path->buf, &st)) {
      if (errno == ENOENT)
        /*
         * file disappeared, which is what we
         * wanted anyway
         */
        continue;
      /* fall through */
    } else if (S_ISDIR(st.st_mode)) {
      if (!remove_dir_recurse(path, flag, &kept_down))
        continue; /* happy */
    } else if (!only_empty &&
         (!unlink(path->buf) || errno == ENOENT)) {
      continue; /* happy, too */
    }

    /* path too long, stat fails, or non-directory still exists */
    ret = -1;
    break;
  }
  closedir(dir);

  strbuf_setlen(path, original_len);
  if (!ret && !keep_toplevel && !kept_down) {
    if (!purge_original_cwd &&
        startup_info->original_cwd &&
        !strcmp(startup_info->original_cwd, path->buf))
      ret = -1; /* Do not remove current working directory */
    else
      ret = (!rmdir(path->buf) || errno == ENOENT) ? 0 : -1;
  } else if (kept_up)
    /*
     * report the uplevel that it is not an error that we
     * did not rmdir() our directory.
     */
    *kept_up = !ret;
  return ret;
}

int remove_dir_recursively(struct strbuf *path, int flag)
{
  return remove_dir_recurse(path, flag, NULL);
}

static GIT_PATH_FUNC(git_path_info_exclude, "info/exclude")

void setup_standard_excludes(struct dir_struct *dir)
{
  const char *excludes_file = repo_excludes_file(the_repository);

  dir->exclude_per_dir = ".gitignore";

  /* core.excludesfile defaulting to $XDG_CONFIG_HOME/git/ignore */
  if (excludes_file && !access_or_warn(excludes_file, R_OK, 0))
    add_patterns_from_file_1(dir, excludes_file,
           dir->untracked ? &dir->internal.ss_excludes_file : NULL);

  /* per repository user preference */
  if (startup_info->have_repository) {
    const char *path = git_path_info_exclude();
    if (!access_or_warn(path, R_OK, 0))
      add_patterns_from_file_1(dir, path,
             dir->untracked ? &dir->internal.ss_info_exclude : NULL);
  }
}

char *get_sparse_checkout_filename(void)
{
  return repo_git_path(the_repository, "info/sparse-checkout");
}

int get_sparse_checkout_patterns(struct pattern_list *pl)
{
  int res;
  char *sparse_filename = get_sparse_checkout_filename();
  struct repo_config_values *cfg = repo_config_values(the_repository);

  pl->use_cone_patterns = cfg->core_sparse_checkout_cone;
  res = add_patterns_from_file_to_list(sparse_filename, "", 0, pl, NULL, 0);

  free(sparse_filename);
  return res;
}

int remove_path(const char *name)
{
  const char *last;

  if (unlink(name) && !is_missing_file_error(errno))
    return -1;

  last = strrchr(name, '/');
  if (last) {
    char *dirs = xstrdup(name);
    char *slash = dirs + (last - name);
    do {
      *slash = '\0';
      if (startup_info->original_cwd &&
          !strcmp(startup_info->original_cwd, dirs))
        break;
    } while (rmdir(dirs) == 0 && (slash = strrchr(dirs, '/')));
    free(dirs);
  }
  return 0;
}

/*
 * Frees memory within dir which was allocated, and resets fields for further
 * use.  Does not free dir itself.
 */
void dir_clear(struct dir_struct *dir)
{
  int i, j;
  struct exclude_list_group *group;
  struct pattern_list *pl;
  struct exclude_stack *stk;
  struct dir_struct new = DIR_INIT;

  for (i = EXC_CMDL; i <= EXC_FILE; i++) {
    group = &dir->internal.exclude_list_group[i];
    for (j = 0; j < group->nr; j++) {
      pl = &group->pl[j];
      if (i == EXC_DIRS)
        free((char *)pl->src);
      clear_pattern_list(pl);
    }
    free(group->pl);
  }

  for (i = 0; i < dir->ignored_nr; i++)
    free(dir->ignored[i]);
  for (i = 0; i < dir->nr; i++)
    free(dir->entries[i]);
  free(dir->ignored);
  free(dir->entries);

  stk = dir->internal.exclude_stack;
  while (stk) {
    struct exclude_stack *prev = stk->prev;
    free(stk);
    stk = prev;
  }
  strbuf_release(&dir->internal.basebuf);

  memcpy(dir, &new, sizeof(*dir));
}

struct ondisk_untracked_cache {
  struct stat_data info_exclude_stat;
  struct stat_data excludes_file_stat;
  uint32_t dir_flags;
};

#define ouc_offset(x) offsetof(struct ondisk_untracked_cache, x)

struct write_data {
  int index;     /* number of written untracked_cache_dir */
  struct ewah_bitmap *check_only; /* from untracked_cache_dir */
  struct ewah_bitmap *valid;  /* from untracked_cache_dir */
  struct ewah_bitmap *sha1_valid; /* set if exclude_sha1 is not null */
  struct strbuf out;
  struct strbuf sb_stat;
  struct strbuf sb_sha1;
};

static void stat_data_to_disk(struct stat_data *to, const struct stat_data *from)
{
  to->sd_ctime.sec  = htonl(from->sd_ctime.sec);
  to->sd_ctime.nsec = htonl(from->sd_ctime.nsec);
  to->sd_mtime.sec  = htonl(from->sd_mtime.sec);
  to->sd_mtime.nsec = htonl(from->sd_mtime.nsec);
  to->sd_dev    = htonl(from->sd_dev);
  to->sd_ino    = htonl(from->sd_ino);
  to->sd_uid    = htonl(from->sd_uid);
  to->sd_gid    = htonl(from->sd_gid);
  to->sd_size   = htonl(from->sd_size);
}

static void write_one_dir(struct untracked_cache_dir *untracked,
        struct write_data *wd)
{
  struct stat_data stat_data;
  struct strbuf *out = &wd->out;
  unsigned char intbuf[16];
  unsigned int value;
  uint8_t intlen;
  int i = wd->index++;

  /*
   * untracked_nr should be reset whenever valid is clear, but
   * for safety..
   */
  if (!untracked->valid) {
    for (size_t i = 0; i < untracked->untracked_nr; i++)
      free(untracked->untracked[i]);
    untracked->untracked_nr = 0;
    untracked->check_only = 0;
  }

  if (untracked->check_only)
    ewah_set(wd->check_only, i);
  if (untracked->valid) {
    ewah_set(wd->valid, i);
    stat_data_to_disk(&stat_data, &untracked->stat_data);
    strbuf_add(&wd->sb_stat, &stat_data, sizeof(stat_data));
  }
  if (!is_null_oid(&untracked->exclude_oid)) {
    ewah_set(wd->sha1_valid, i);
    strbuf_add(&wd->sb_sha1, untracked->exclude_oid.hash,
         the_hash_algo->rawsz);
  }

  intlen = encode_varint(untracked->untracked_nr, intbuf);
  strbuf_add(out, intbuf, intlen);

  /* skip non-recurse directories */
  for (i = 0, value = 0; i < untracked->dirs_nr; i++)
    if (untracked->dirs[i]->recurse)
      value++;
  intlen = encode_varint(value, intbuf);
  strbuf_add(out, intbuf, intlen);

  strbuf_add(out, untracked->name, strlen(untracked->name) + 1);

  for (i = 0; i < untracked->untracked_nr; i++)
    strbuf_add(out, untracked->untracked[i],
         strlen(untracked->untracked[i]) + 1);

  for (i = 0; i < untracked->dirs_nr; i++)
    if (untracked->dirs[i]->recurse)
      write_one_dir(untracked->dirs[i], wd);
}

void write_untracked_extension(struct strbuf *out, struct untracked_cache *untracked)
{
  struct ondisk_untracked_cache *ouc;
  struct write_data wd;
  unsigned char varbuf[16];
  uint8_t varint_len;
  const unsigned hashsz = the_hash_algo->rawsz;

  CALLOC_ARRAY(ouc, 1);
  stat_data_to_disk(&ouc->info_exclude_stat, &untracked->ss_info_exclude.stat);
  stat_data_to_disk(&ouc->excludes_file_stat, &untracked->ss_excludes_file.stat);
  ouc->dir_flags = htonl(untracked->dir_flags);

  varint_len = encode_varint(untracked->ident.len, varbuf);
  strbuf_add(out, varbuf, varint_len);
  strbuf_addbuf(out, &untracked->ident);

  strbuf_add(out, ouc, sizeof(*ouc));
  strbuf_add(out, untracked->ss_info_exclude.oid.hash, hashsz);
  strbuf_add(out, untracked->ss_excludes_file.oid.hash, hashsz);
  strbuf_add(out, untracked->exclude_per_dir, strlen(untracked->exclude_per_dir) + 1);
  FREE_AND_NULL(ouc);

  if (!untracked->root) {
    varint_len = encode_varint(0, varbuf);
    strbuf_add(out, varbuf, varint_len);
    return;
  }

  wd.index      = 0;
  wd.check_only = ewah_new();
  wd.valid      = ewah_new();
  wd.sha1_valid = ewah_new();
  strbuf_init(&wd.out, 1024);
  strbuf_init(&wd.sb_stat, 1024);
  strbuf_init(&wd.sb_sha1, 1024);
  write_one_dir(untracked->root, &wd);

  varint_len = encode_varint(wd.index, varbuf);
  strbuf_add(out, varbuf, varint_len);
  strbuf_addbuf(out, &wd.out);
  ewah_serialize_strbuf(wd.valid, out);
  ewah_serialize_strbuf(wd.check_only, out);
  ewah_serialize_strbuf(wd.sha1_valid, out);
  strbuf_addbuf(out, &wd.sb_stat);
  strbuf_addbuf(out, &wd.sb_sha1);
  strbuf_addch(out, '\0'); /* safe guard for string lists */

  ewah_free(wd.valid);
  ewah_free(wd.check_only);
  ewah_free(wd.sha1_valid);
  strbuf_release(&wd.out);
  strbuf_release(&wd.sb_stat);
  strbuf_release(&wd.sb_sha1);
}

static void free_untracked(struct untracked_cache_dir *ucd)
{
  int i;
  if (!ucd)
    return;
  for (i = 0; i < ucd->dirs_nr; i++)
    free_untracked(ucd->dirs[i]);
  for (i = 0; i < ucd->untracked_nr; i++)
    free(ucd->untracked[i]);
  free(ucd->untracked);
  free(ucd->dirs);
  free(ucd);
}

void free_untracked_cache(struct untracked_cache *uc)
{
  if (!uc)
    return;

  free(uc->exclude_per_dir_to_free);
  strbuf_release(&uc->ident);
  free_untracked(uc->root);
  free(uc);
}

struct read_data {
  int index;
  struct untracked_cache_dir **ucd;
  struct ewah_bitmap *check_only;
  struct ewah_bitmap *valid;
  struct ewah_bitmap *sha1_valid;
  const unsigned char *data;
  const unsigned char *end;
};

static void stat_data_from_disk(struct stat_data *to, const unsigned char *data)
{
  memcpy(to, data, sizeof(*to));
  to->sd_ctime.sec  = ntohl(to->sd_ctime.sec);
  to->sd_ctime.nsec = ntohl(to->sd_ctime.nsec);
  to->sd_mtime.sec  = ntohl(to->sd_mtime.sec);
  to->sd_mtime.nsec = ntohl(to->sd_mtime.nsec);
  to->sd_dev    = ntohl(to->sd_dev);
  to->sd_ino    = ntohl(to->sd_ino);
  to->sd_uid    = ntohl(to->sd_uid);
  to->sd_gid    = ntohl(to->sd_gid);
  to->sd_size   = ntohl(to->sd_size);
}

static int read_one_dir(struct untracked_cache_dir **untracked_,
      struct read_data *rd)
{
  struct untracked_cache_dir ud, *untracked;
  const unsigned char *data = rd->data, *end = rd->end;
  const unsigned char *eos;
  uint64_t value;
  int i;

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

  value = decode_varint(&data);
  if (data > end)
    return -1;
  ud.recurse     = 1;
  ud.untracked_alloc = value;
  ud.untracked_nr    = value;
  if (ud.untracked_nr)
    ALLOC_ARRAY(ud.untracked, ud.untracked_nr);

  ud.dirs_alloc = ud.dirs_nr = decode_varint(&data);
  if (data > end) {
    free(ud.untracked);
    return -1;
  }
  ALLOC_ARRAY(ud.dirs, ud.dirs_nr);

  eos = memchr(data, '\0', end - data);
  if (!eos || eos == end) {
    free(ud.untracked);
    free(ud.dirs);
    return -1;
  }

  *untracked_ = untracked = xmalloc(st_add3(sizeof(*untracked), eos - data, 1));
  memcpy(untracked, &ud, sizeof(ud));
  memcpy(untracked->name, data, eos - data + 1);
  data = eos + 1;

  for (i = 0; i < untracked->untracked_nr; i++) {
    eos = memchr(data, '\0', end - data);
    if (!eos || eos == end)
      return -1;
    untracked->untracked[i] = xmemdupz(data, eos - data);
    data = eos + 1;
  }

  rd->ucd[rd->index++] = untracked;
  rd->data = data;

  for (i = 0; i < untracked->dirs_nr; i++) {
    if (read_one_dir(untracked->dirs + i, rd) < 0)
      return -1;
  }
  return 0;
}

static void set_check_only(size_t pos, void *cb)
{
  struct read_data *rd = cb;
  struct untracked_cache_dir *ud = rd->ucd[pos];
  ud->check_only = 1;
}

static void read_stat(size_t pos, void *cb)
{
  struct read_data *rd = cb;
  struct untracked_cache_dir *ud = rd->ucd[pos];
  if (rd->data + sizeof(struct stat_data) > rd->end) {
    rd->data = rd->end + 1;
    return;
  }
  stat_data_from_disk(&ud->stat_data, rd->data);
  rd->data += sizeof(struct stat_data);
  ud->valid = 1;
}

static void read_oid(size_t pos, void *cb)
{
  struct read_data *rd = cb;
  struct untracked_cache_dir *ud = rd->ucd[pos];
  if (rd->data + the_hash_algo->rawsz > rd->end) {
    rd->data = rd->end + 1;
    return;
  }
  oidread(&ud->exclude_oid, rd->data, the_repository->hash_algo);
  rd->data += the_hash_algo->rawsz;
}

static void load_oid_stat(struct oid_stat *oid_stat, const unsigned char *data,
        const unsigned char *sha1)
{
  stat_data_from_disk(&oid_stat->stat, data);
  oidread(&oid_stat->oid, sha1, the_repository->hash_algo);
  oid_stat->valid = 1;
}

struct untracked_cache *read_untracked_extension(const void *data, unsigned long sz)
{
  struct untracked_cache *uc;
  struct read_data rd;
  const unsigned char *next = data, *end = (const unsigned char *)data + sz;
  const char *ident;
  uint64_t ident_len;
  uint64_t varint_len;
  ssize_t len;
  const char *exclude_per_dir;
  const unsigned hashsz = the_hash_algo->rawsz;
  const unsigned offset = sizeof(struct ondisk_untracked_cache);
  const unsigned exclude_per_dir_offset = offset + 2 * hashsz;

  if (sz <= 1 || end[-1] != '\0')
    return NULL;
  end--;

  ident_len = decode_varint(&next);
  if (next + ident_len > end)
    return NULL;
  ident = (const char *)next;
  next += ident_len;

  if (next + exclude_per_dir_offset + 1 > end)
    return NULL;

  CALLOC_ARRAY(uc, 1);
  strbuf_init(&uc->ident, ident_len);
  strbuf_add(&uc->ident, ident, ident_len);
  load_oid_stat(&uc->ss_info_exclude,
          next + ouc_offset(info_exclude_stat),
          next + offset);
  load_oid_stat(&uc->ss_excludes_file,
          next + ouc_offset(excludes_file_stat),
          next + offset + hashsz);
  uc->dir_flags = get_be32(next + ouc_offset(dir_flags));
  exclude_per_dir = (const char *)next + exclude_per_dir_offset;
  uc->exclude_per_dir = uc->exclude_per_dir_to_free = xstrdup(exclude_per_dir);
  /* NUL after exclude_per_dir is covered by sizeof(*ouc) */
  next += exclude_per_dir_offset + strlen(exclude_per_dir) + 1;
  if (next >= end)
    goto done2;

  varint_len = decode_varint(&next);
  if (next > end || varint_len == 0)
    goto done2;

  rd.valid      = ewah_new();
  rd.check_only = ewah_new();
  rd.sha1_valid = ewah_new();
  rd.data       = next;
  rd.end        = end;
  rd.index      = 0;
  ALLOC_ARRAY(rd.ucd, varint_len);

  if (read_one_dir(&uc->root, &rd) || rd.index != varint_len)
    goto done;

  next = rd.data;
  len = ewah_read_mmap(rd.valid, next, end - next);
  if (len < 0)
    goto done;

  next += len;
  len = ewah_read_mmap(rd.check_only, next, end - next);
  if (len < 0)
    goto done;

  next += len;
  len = ewah_read_mmap(rd.sha1_valid, next, end - next);
  if (len < 0)
    goto done;

  ewah_each_bit(rd.check_only, set_check_only, &rd);
  rd.data = next + len;
  ewah_each_bit(rd.valid, read_stat, &rd);
  ewah_each_bit(rd.sha1_valid, read_oid, &rd);
  next = rd.data;

done:
  free(rd.ucd);
  ewah_free(rd.valid);
  ewah_free(rd.check_only);
  ewah_free(rd.sha1_valid);
done2:
  if (next != end) {
    free_untracked_cache(uc);
    uc = NULL;
  }
  return uc;
}

static void invalidate_one_directory(struct untracked_cache *uc,
             struct untracked_cache_dir *ucd)
{
  uc->dir_invalidated++;
  ucd->valid = 0;
  for (size_t i = 0; i < ucd->untracked_nr; i++)
    free(ucd->untracked[i]);
  ucd->untracked_nr = 0;
}

/*
 * Normally when an entry is added or removed from a directory,
 * invalidating that directory is enough. No need to touch its
 * ancestors. When a directory is shown as "foo/bar/" in git-status
 * however, deleting or adding an entry may have cascading effect.
 *
 * Say the "foo/bar/file" has become untracked, we need to tell the
 * untracked_cache_dir of "foo" that "bar/" is not an untracked
 * directory any more (because "bar" is managed by foo as an untracked
 * "file").
 *
 * Similarly, if "foo/bar/file" moves from untracked to tracked and it
 * was the last untracked entry in the entire "foo", we should show
 * "foo/" instead. Which means we have to invalidate past "bar" up to
 * "foo".
 *
 * This function traverses all directories from root to leaf. If there
 * is a chance of one of the above cases happening, we invalidate back
 * to root. Otherwise we just invalidate the leaf. There may be a more
 * sophisticated way than checking for SHOW_OTHER_DIRECTORIES to
 * detect these cases and avoid unnecessary invalidation, for example,
 * checking for the untracked entry named "bar/" in "foo", but for now
 * stick to something safe and simple.
 */
static int invalidate_one_component(struct untracked_cache *uc,
            struct untracked_cache_dir *dir,
            const char *path, int len)
{
  const char *rest = strchr(path, '/');

  if (rest) {
    int component_len = rest - path;
    struct untracked_cache_dir *d =
      lookup_untracked(uc, dir, path, component_len);
    int ret =
      invalidate_one_component(uc, d, rest + 1,
             len - (component_len + 1));
    if (ret)
      invalidate_one_directory(uc, dir);
    return ret;
  }

  invalidate_one_directory(uc, dir);
  return uc->dir_flags & DIR_SHOW_OTHER_DIRECTORIES;
}

void untracked_cache_invalidate_path(struct index_state *istate,
             const char *path, int safe_path)
{
  if (!istate->untracked || !istate->untracked->root)
    return;
  if (!safe_path && !verify_path(path, 0))
    return;
  invalidate_one_component(istate->untracked, istate->untracked->root,
         path, strlen(path));
}

void untracked_cache_invalidate_trimmed_path(struct index_state *istate,
               const char *path,
               int safe_path)
{
  size_t len = strlen(path);

  if (!len)
    BUG("untracked_cache_invalidate_trimmed_path given zero length path");

  if (path[len - 1] != '/') {
    untracked_cache_invalidate_path(istate, path, safe_path);
  } else {
    struct strbuf tmp = STRBUF_INIT;

    strbuf_add(&tmp, path, len - 1);
    untracked_cache_invalidate_path(istate, tmp.buf, safe_path);
    strbuf_release(&tmp);
  }
}

void untracked_cache_remove_from_index(struct index_state *istate,
               const char *path)
{
  untracked_cache_invalidate_path(istate, path, 1);
}

void untracked_cache_add_to_index(struct index_state *istate,
          const char *path)
{
  untracked_cache_invalidate_path(istate, path, 1);
}

static void connect_wt_gitdir_in_nested(const char *sub_worktree,
          const char *sub_gitdir)
{
  int i;
  struct repository subrepo;
  struct strbuf sub_wt = STRBUF_INIT;
  struct strbuf sub_gd = STRBUF_INIT;

  const struct submodule *sub;

  /* If the submodule has no working tree, we can ignore it. */
  if (repo_init(&subrepo, sub_gitdir, sub_worktree))
    return;

  if (repo_read_index(&subrepo) < 0)
    die(_("index file corrupt in repo %s"), subrepo.gitdir);

  /* TODO: audit for interaction with sparse-index. */
  ensure_full_index(subrepo.index);
  for (i = 0; i < subrepo.index->cache_nr; i++) {
    const struct cache_entry *ce = subrepo.index->cache[i];

    if (!S_ISGITLINK(ce->ce_mode))
      continue;

    while (i + 1 < subrepo.index->cache_nr &&
           !strcmp(ce->name, subrepo.index->cache[i + 1]->name))
      /*
       * Skip entries with the same name in different stages
       * to make sure an entry is returned only once.
       */
      i++;

    sub = submodule_from_path(&subrepo, null_oid(the_hash_algo), ce->name);
    if (!sub || !is_submodule_active(&subrepo, ce->name))
      /* .gitmodules broken or inactive sub */
      continue;

    strbuf_reset(&sub_wt);
    strbuf_reset(&sub_gd);
    strbuf_addf(&sub_wt, "%s/%s", sub_worktree, sub->path);
    submodule_name_to_gitdir(&sub_gd, &subrepo, sub->name);

    connect_work_tree_and_git_dir(sub_wt.buf, sub_gd.buf, 1);
  }
  strbuf_release(&sub_wt);
  strbuf_release(&sub_gd);
  repo_clear(&subrepo);
}

void connect_work_tree_and_git_dir(const char *work_tree_,
           const char *git_dir_,
           int recurse_into_nested)
{
  struct strbuf gitfile_sb = STRBUF_INIT;
  struct strbuf cfg_sb = STRBUF_INIT;
  struct strbuf rel_path = STRBUF_INIT;
  char *git_dir, *work_tree;

  /* Prepare .git file */
  strbuf_addf(&gitfile_sb, "%s/.git", work_tree_);
  if (safe_create_leading_directories_const(the_repository, gitfile_sb.buf))
    die(_("could not create directories for %s"), gitfile_sb.buf);

  /* Prepare config file */
  strbuf_addf(&cfg_sb, "%s/config", git_dir_);
  if (safe_create_leading_directories_const(the_repository, cfg_sb.buf))
    die(_("could not create directories for %s"), cfg_sb.buf);

  git_dir = real_pathdup(git_dir_, 1);
  work_tree = real_pathdup(work_tree_, 1);

  /* Write .git file */
  write_file(gitfile_sb.buf, "gitdir: %s",
       relative_path(git_dir, work_tree, &rel_path));
  /* Update core.worktree setting */
  repo_config_set_in_file(the_repository, cfg_sb.buf, "core.worktree",
        relative_path(work_tree, git_dir, &rel_path));

  strbuf_release(&gitfile_sb);
  strbuf_release(&cfg_sb);
  strbuf_release(&rel_path);

  if (recurse_into_nested)
    connect_wt_gitdir_in_nested(work_tree, git_dir);

  free(work_tree);
  free(git_dir);
}

/*
 * Migrate the git directory of the given path from old_git_dir to new_git_dir.
 */
void relocate_gitdir(const char *path, const char *old_git_dir, const char *new_git_dir)
{
  if (rename(old_git_dir, new_git_dir) < 0)
    die_errno(_("could not migrate git directory from '%s' to '%s'"),
      old_git_dir, new_git_dir);

  connect_work_tree_and_git_dir(path, new_git_dir, 0);
}

int path_match_flags(const char *const str, const enum path_match_flags flags)
{
  const char *p = str;

  if (flags & PATH_MATCH_NATIVE &&
      flags & PATH_MATCH_XPLATFORM)
    BUG("path_match_flags() must get one match kind, not multiple!");
  else if (!(flags & PATH_MATCH_KINDS_MASK))
    BUG("path_match_flags() must get at least one match kind!");

  if (flags & PATH_MATCH_STARTS_WITH_DOT_SLASH &&
      flags & PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH)
    BUG("path_match_flags() must get one platform kind, not multiple!");
  else if (!(flags & PATH_MATCH_PLATFORM_MASK))
    BUG("path_match_flags() must get at least one platform kind!");

  if (*p++ != '.')
    return 0;
  if (flags & PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH &&
      *p++ != '.')
    return 0;

  if (flags & PATH_MATCH_NATIVE)
    return is_dir_sep(*p);
  else if (flags & PATH_MATCH_XPLATFORM)
    return is_xplatform_dir_sep(*p);
  BUG("unreachable");
}

Coverage Report

Created: 2026-11-12 06:03