/src/git/convert.c

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#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"
#include "advice.h"
#include "config.h"
#include "convert.h"
#include "copy.h"
#include "gettext.h"
#include "hex.h"
#include "object-store-ll.h"
#include "attr.h"
#include "run-command.h"
#include "quote.h"
#include "read-cache-ll.h"
#include "sigchain.h"
#include "pkt-line.h"
#include "sub-process.h"
#include "trace.h"
#include "utf8.h"
#include "merge-ll.h"

/*
 * convert.c - convert a file when checking it out and checking it in.
 *
 * This should use the pathname to decide on whether it wants to do some
 * more interesting conversions (automatic gzip/unzip, general format
 * conversions etc etc), but by default it just does automatic CRLF<->LF
 * translation when the "text" attribute or "auto_crlf" option is set.
 */

/* Stat bits: When BIN is set, the txt bits are unset */
#define CONVERT_STAT_BITS_TXT_LF    0x1
#define CONVERT_STAT_BITS_TXT_CRLF  0x2
#define CONVERT_STAT_BITS_BIN       0x4

struct text_stat {
  /* NUL, CR, LF and CRLF counts */
  unsigned nul, lonecr, lonelf, crlf;

  /* These are just approximations! */
  unsigned printable, nonprintable;
};

static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
{
  unsigned long i;

  memset(stats, 0, sizeof(*stats));

  for (i = 0; i < size; i++) {
    unsigned char c = buf[i];
    if (c == '\r') {
      if (i+1 < size && buf[i+1] == '\n') {
        stats->crlf++;
        i++;
      } else
        stats->lonecr++;
      continue;
    }
    if (c == '\n') {
      stats->lonelf++;
      continue;
    }
    if (c == 127)
      /* DEL */
      stats->nonprintable++;
    else if (c < 32) {
      switch (c) {
        /* BS, HT, ESC and FF */
      case '\b': case '\t': case '\033': case '\014':
        stats->printable++;
        break;
      case 0:
        stats->nul++;
        /* fall through */
      default:
        stats->nonprintable++;
      }
    }
    else
      stats->printable++;
  }

  /* If file ends with EOF then don't count this EOF as non-printable. */
  if (size >= 1 && buf[size-1] == '\032')
    stats->nonprintable--;
}

/*
 * The same heuristics as diff.c::mmfile_is_binary()
 * We treat files with bare CR as binary
 */
static int convert_is_binary(const struct text_stat *stats)
{
  if (stats->lonecr)
    return 1;
  if (stats->nul)
    return 1;
  if ((stats->printable >> 7) < stats->nonprintable)
    return 1;
  return 0;
}

static unsigned int gather_convert_stats(const char *data, unsigned long size)
{
  struct text_stat stats;
  int ret = 0;
  if (!data || !size)
    return 0;
  gather_stats(data, size, &stats);
  if (convert_is_binary(&stats))
    ret |= CONVERT_STAT_BITS_BIN;
  if (stats.crlf)
    ret |= CONVERT_STAT_BITS_TXT_CRLF;
  if (stats.lonelf)
    ret |=  CONVERT_STAT_BITS_TXT_LF;

  return ret;
}

static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
{
  unsigned int convert_stats = gather_convert_stats(data, size);

  if (convert_stats & CONVERT_STAT_BITS_BIN)
    return "-text";
  switch (convert_stats) {
  case CONVERT_STAT_BITS_TXT_LF:
    return "lf";
  case CONVERT_STAT_BITS_TXT_CRLF:
    return "crlf";
  case CONVERT_STAT_BITS_TXT_LF | CONVERT_STAT_BITS_TXT_CRLF:
    return "mixed";
  default:
    return "none";
  }
}

const char *get_cached_convert_stats_ascii(struct index_state *istate,
             const char *path)
{
  const char *ret;
  unsigned long sz;
  void *data = read_blob_data_from_index(istate, path, &sz);
  ret = gather_convert_stats_ascii(data, sz);
  free(data);
  return ret;
}

const char *get_wt_convert_stats_ascii(const char *path)
{
  const char *ret = "";
  struct strbuf sb = STRBUF_INIT;
  if (strbuf_read_file(&sb, path, 0) >= 0)
    ret = gather_convert_stats_ascii(sb.buf, sb.len);
  strbuf_release(&sb);
  return ret;
}

static int text_eol_is_crlf(void)
{
  if (auto_crlf == AUTO_CRLF_TRUE)
    return 1;
  else if (auto_crlf == AUTO_CRLF_INPUT)
    return 0;
  if (core_eol == EOL_CRLF)
    return 1;
  if (core_eol == EOL_UNSET && EOL_NATIVE == EOL_CRLF)
    return 1;
  return 0;
}

static enum eol output_eol(enum convert_crlf_action crlf_action)
{
  switch (crlf_action) {
  case CRLF_BINARY:
    return EOL_UNSET;
  case CRLF_TEXT_CRLF:
    return EOL_CRLF;
  case CRLF_TEXT_INPUT:
    return EOL_LF;
  case CRLF_UNDEFINED:
  case CRLF_AUTO_CRLF:
    return EOL_CRLF;
  case CRLF_AUTO_INPUT:
    return EOL_LF;
  case CRLF_TEXT:
  case CRLF_AUTO:
    /* fall through */
    return text_eol_is_crlf() ? EOL_CRLF : EOL_LF;
  }
  warning(_("illegal crlf_action %d"), (int)crlf_action);
  return core_eol;
}

static void check_global_conv_flags_eol(const char *path,
          struct text_stat *old_stats, struct text_stat *new_stats,
          int conv_flags)
{
  if (old_stats->crlf && !new_stats->crlf ) {
    /*
     * CRLFs would not be restored by checkout
     */
    if (conv_flags & CONV_EOL_RNDTRP_DIE)
      die(_("CRLF would be replaced by LF in %s"), path);
    else if (conv_flags & CONV_EOL_RNDTRP_WARN)
      warning(_("in the working copy of '%s', CRLF will be"
          " replaced by LF the next time Git touches"
          " it"), path);
  } else if (old_stats->lonelf && !new_stats->lonelf ) {
    /*
     * CRLFs would be added by checkout
     */
    if (conv_flags & CONV_EOL_RNDTRP_DIE)
      die(_("LF would be replaced by CRLF in %s"), path);
    else if (conv_flags & CONV_EOL_RNDTRP_WARN)
      warning(_("in the working copy of '%s', LF will be"
          " replaced by CRLF the next time Git touches"
          " it"), path);
  }
}

static int has_crlf_in_index(struct index_state *istate, const char *path)
{
  unsigned long sz;
  void *data;
  const char *crp;
  int has_crlf = 0;

  data = read_blob_data_from_index(istate, path, &sz);
  if (!data)
    return 0;

  crp = memchr(data, '\r', sz);
  if (crp) {
    unsigned int ret_stats;
    ret_stats = gather_convert_stats(data, sz);
    if (!(ret_stats & CONVERT_STAT_BITS_BIN) &&
        (ret_stats & CONVERT_STAT_BITS_TXT_CRLF))
      has_crlf = 1;
  }
  free(data);
  return has_crlf;
}

static int will_convert_lf_to_crlf(struct text_stat *stats,
           enum convert_crlf_action crlf_action)
{
  if (output_eol(crlf_action) != EOL_CRLF)
    return 0;
  /* No "naked" LF? Nothing to convert, regardless. */
  if (!stats->lonelf)
    return 0;

  if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
    /* If we have any CR or CRLF line endings, we do not touch it */
    /* This is the new safer autocrlf-handling */
    if (stats->lonecr || stats->crlf)
      return 0;

    if (convert_is_binary(stats))
      return 0;
  }
  return 1;

}

static int validate_encoding(const char *path, const char *enc,
          const char *data, size_t len, int die_on_error)
{
  const char *stripped;

  /* We only check for UTF here as UTF?? can be an alias for UTF-?? */
  if (skip_iprefix(enc, "UTF", &stripped)) {
    skip_prefix(stripped, "-", &stripped);

    /*
     * Check for detectable errors in UTF encodings
     */
    if (has_prohibited_utf_bom(enc, data, len)) {
      const char *error_msg = _(
        "BOM is prohibited in '%s' if encoded as %s");
      /*
       * This advice is shown for UTF-??BE and UTF-??LE encodings.
       * We cut off the last two characters of the encoding name
       * to generate the encoding name suitable for BOMs.
       */
      const char *advise_msg = _(
        "The file '%s' contains a byte order "
        "mark (BOM). Please use UTF-%.*s as "
        "working-tree-encoding.");
      int stripped_len = strlen(stripped) - strlen("BE");
      advise(advise_msg, path, stripped_len, stripped);
      if (die_on_error)
        die(error_msg, path, enc);
      else {
        return error(error_msg, path, enc);
      }

    } else if (is_missing_required_utf_bom(enc, data, len)) {
      const char *error_msg = _(
        "BOM is required in '%s' if encoded as %s");
      const char *advise_msg = _(
        "The file '%s' is missing a byte order "
        "mark (BOM). Please use UTF-%sBE or UTF-%sLE "
        "(depending on the byte order) as "
        "working-tree-encoding.");
      advise(advise_msg, path, stripped, stripped);
      if (die_on_error)
        die(error_msg, path, enc);
      else {
        return error(error_msg, path, enc);
      }
    }

  }
  return 0;
}

static void trace_encoding(const char *context, const char *path,
         const char *encoding, const char *buf, size_t len)
{
  static struct trace_key coe = TRACE_KEY_INIT(WORKING_TREE_ENCODING);
  struct strbuf trace = STRBUF_INIT;
  int i;

  if (!trace_want(&coe))
    return;

  strbuf_addf(&trace, "%s (%s, considered %s):\n", context, path, encoding);
  for (i = 0; i < len && buf; ++i) {
    strbuf_addf(
      &trace, "| \033[2m%2i:\033[0m %2x \033[2m%c\033[0m%c",
      i,
      (unsigned char) buf[i],
      (buf[i] > 32 && buf[i] < 127 ? buf[i] : ' '),
      ((i+1) % 8 && (i+1) < len ? ' ' : '\n')
    );
  }
  strbuf_addchars(&trace, '\n', 1);

  trace_strbuf(&coe, &trace);
  strbuf_release(&trace);
}

static int check_roundtrip(const char *enc_name)
{
  /*
   * check_roundtrip_encoding contains a string of comma and/or
   * space separated encodings (eg. "UTF-16, ASCII, CP1125").
   * Search for the given encoding in that string.
   */
  const char *encoding = check_roundtrip_encoding ?
    check_roundtrip_encoding : "SHIFT-JIS";
  const char *found = strcasestr(encoding, enc_name);
  const char *next;
  int len;
  if (!found)
    return 0;
  next = found + strlen(enc_name);
  len = strlen(encoding);
  return (found && (
      /*
       * Check that the found encoding is at the beginning of
       * encoding or that it is prefixed with a space or
       * comma.
       */
      found == encoding || (
        (isspace(found[-1]) || found[-1] == ',')
      )
    ) && (
      /*
       * Check that the found encoding is at the end of
       * encoding or that it is suffixed with a space
       * or comma.
       */
      next == encoding + len || (
        next < encoding + len &&
        (isspace(next[0]) || next[0] == ',')
      )
    ));
}

static const char *default_encoding = "UTF-8";

static int encode_to_git(const char *path, const char *src, size_t src_len,
       struct strbuf *buf, const char *enc, int conv_flags)
{
  char *dst;
  size_t dst_len;
  int die_on_error = conv_flags & CONV_WRITE_OBJECT;

  /*
   * No encoding is specified or there is nothing to encode.
   * Tell the caller that the content was not modified.
   */
  if (!enc || (src && !src_len))
    return 0;

  /*
   * Looks like we got called from "would_convert_to_git()".
   * This means Git wants to know if it would encode (= modify!)
   * the content. Let's answer with "yes", since an encoding was
   * specified.
   */
  if (!buf && !src)
    return 1;

  if (validate_encoding(path, enc, src, src_len, die_on_error))
    return 0;

  trace_encoding("source", path, enc, src, src_len);
  dst = reencode_string_len(src, src_len, default_encoding, enc,
          &dst_len);
  if (!dst) {
    /*
     * We could add the blob "as-is" to Git. However, on checkout
     * we would try to re-encode to the original encoding. This
     * would fail and we would leave the user with a messed-up
     * working tree. Let's try to avoid this by screaming loud.
     */
    const char* msg = _("failed to encode '%s' from %s to %s");
    if (die_on_error)
      die(msg, path, enc, default_encoding);
    else {
      error(msg, path, enc, default_encoding);
      return 0;
    }
  }
  trace_encoding("destination", path, default_encoding, dst, dst_len);

  /*
   * UTF supports lossless conversion round tripping [1] and conversions
   * between UTF and other encodings are mostly round trip safe as
   * Unicode aims to be a superset of all other character encodings.
   * However, certain encodings (e.g. SHIFT-JIS) are known to have round
   * trip issues [2]. Check the round trip conversion for all encodings
   * listed in core.checkRoundtripEncoding.
   *
   * The round trip check is only performed if content is written to Git.
   * This ensures that no information is lost during conversion to/from
   * the internal UTF-8 representation.
   *
   * Please note, the code below is not tested because I was not able to
   * generate a faulty round trip without an iconv error. Iconv errors
   * are already caught above.
   *
   * [1] http://unicode.org/faq/utf_bom.html#gen2
   * [2] https://support.microsoft.com/en-us/help/170559/prb-conversion-problem-between-shift-jis-and-unicode
   */
  if (die_on_error && check_roundtrip(enc)) {
    char *re_src;
    size_t re_src_len;

    re_src = reencode_string_len(dst, dst_len,
               enc, default_encoding,
               &re_src_len);

    trace_printf("Checking roundtrip encoding for %s...\n", enc);
    trace_encoding("reencoded source", path, enc,
             re_src, re_src_len);

    if (!re_src || src_len != re_src_len ||
        memcmp(src, re_src, src_len)) {
      const char* msg = _("encoding '%s' from %s to %s and "
              "back is not the same");
      die(msg, path, enc, default_encoding);
    }

    free(re_src);
  }

  strbuf_attach(buf, dst, dst_len, dst_len + 1);
  return 1;
}

static int encode_to_worktree(const char *path, const char *src, size_t src_len,
            struct strbuf *buf, const char *enc)
{
  char *dst;
  size_t dst_len;

  /*
   * No encoding is specified or there is nothing to encode.
   * Tell the caller that the content was not modified.
   */
  if (!enc || (src && !src_len))
    return 0;

  dst = reencode_string_len(src, src_len, enc, default_encoding,
          &dst_len);
  if (!dst) {
    error(_("failed to encode '%s' from %s to %s"),
          path, default_encoding, enc);
    return 0;
  }

  strbuf_attach(buf, dst, dst_len, dst_len + 1);
  return 1;
}

static int crlf_to_git(struct index_state *istate,
           const char *path, const char *src, size_t len,
           struct strbuf *buf,
           enum convert_crlf_action crlf_action, int conv_flags)
{
  struct text_stat stats;
  char *dst;
  int convert_crlf_into_lf;

  if (crlf_action == CRLF_BINARY ||
      (src && !len))
    return 0;

  /*
   * If we are doing a dry-run and have no source buffer, there is
   * nothing to analyze; we must assume we would convert.
   */
  if (!buf && !src)
    return 1;

  gather_stats(src, len, &stats);
  /* Optimization: No CRLF? Nothing to convert, regardless. */
  convert_crlf_into_lf = !!stats.crlf;

  if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
    if (convert_is_binary(&stats))
      return 0;
    /*
     * If the file in the index has any CR in it, do not
     * convert.  This is the new safer autocrlf handling,
     * unless we want to renormalize in a merge or
     * cherry-pick.
     */
    if ((!(conv_flags & CONV_EOL_RENORMALIZE)) &&
        has_crlf_in_index(istate, path))
      convert_crlf_into_lf = 0;
  }
  if (((conv_flags & CONV_EOL_RNDTRP_WARN) ||
       ((conv_flags & CONV_EOL_RNDTRP_DIE) && len))) {
    struct text_stat new_stats;
    memcpy(&new_stats, &stats, sizeof(new_stats));
    /* simulate "git add" */
    if (convert_crlf_into_lf) {
      new_stats.lonelf += new_stats.crlf;
      new_stats.crlf = 0;
    }
    /* simulate "git checkout" */
    if (will_convert_lf_to_crlf(&new_stats, crlf_action)) {
      new_stats.crlf += new_stats.lonelf;
      new_stats.lonelf = 0;
    }
    check_global_conv_flags_eol(path, &stats, &new_stats, conv_flags);
  }
  if (!convert_crlf_into_lf)
    return 0;

  /*
   * At this point all of our source analysis is done, and we are sure we
   * would convert. If we are in dry-run mode, we can give an answer.
   */
  if (!buf)
    return 1;

  /* only grow if not in place */
  if (strbuf_avail(buf) + buf->len < len)
    strbuf_grow(buf, len - buf->len);
  dst = buf->buf;
  if (crlf_action == CRLF_AUTO || crlf_action == CRLF_AUTO_INPUT || crlf_action == CRLF_AUTO_CRLF) {
    /*
     * If we guessed, we already know we rejected a file with
     * lone CR, and we can strip a CR without looking at what
     * follow it.
     */
    do {
      unsigned char c = *src++;
      if (c != '\r')
        *dst++ = c;
    } while (--len);
  } else {
    do {
      unsigned char c = *src++;
      if (! (c == '\r' && (1 < len && *src == '\n')))
        *dst++ = c;
    } while (--len);
  }
  strbuf_setlen(buf, dst - buf->buf);
  return 1;
}

static int crlf_to_worktree(const char *src, size_t len, struct strbuf *buf,
          enum convert_crlf_action crlf_action)
{
  char *to_free = NULL;
  struct text_stat stats;

  if (!len || output_eol(crlf_action) != EOL_CRLF)
    return 0;

  gather_stats(src, len, &stats);
  if (!will_convert_lf_to_crlf(&stats, crlf_action))
    return 0;

  /* are we "faking" in place editing ? */
  if (src == buf->buf)
    to_free = strbuf_detach(buf, NULL);

  strbuf_grow(buf, len + stats.lonelf);
  for (;;) {
    const char *nl = memchr(src, '\n', len);
    if (!nl)
      break;
    if (nl > src && nl[-1] == '\r') {
      strbuf_add(buf, src, nl + 1 - src);
    } else {
      strbuf_add(buf, src, nl - src);
      strbuf_addstr(buf, "\r\n");
    }
    len -= nl + 1 - src;
    src  = nl + 1;
  }
  strbuf_add(buf, src, len);

  free(to_free);
  return 1;
}

struct filter_params {
  const char *src;
  size_t size;
  int fd;
  const char *cmd;
  const char *path;
};

static int filter_buffer_or_fd(int in UNUSED, int out, void *data)
{
  /*
   * Spawn cmd and feed the buffer contents through its stdin.
   */
  struct child_process child_process = CHILD_PROCESS_INIT;
  struct filter_params *params = (struct filter_params *)data;
  const char *format = params->cmd;
  int write_err, status;

  /* apply % substitution to cmd */
  struct strbuf cmd = STRBUF_INIT;

  /* expand all %f with the quoted path; quote to preserve space, etc. */
  while (strbuf_expand_step(&cmd, &format)) {
    if (skip_prefix(format, "%", &format))
      strbuf_addch(&cmd, '%');
    else if (skip_prefix(format, "f", &format))
      sq_quote_buf(&cmd, params->path);
    else
      strbuf_addch(&cmd, '%');
  }

  strvec_push(&child_process.args, cmd.buf);
  child_process.use_shell = 1;
  child_process.in = -1;
  child_process.out = out;

  if (start_command(&child_process)) {
    strbuf_release(&cmd);
    return error(_("cannot fork to run external filter '%s'"),
           params->cmd);
  }

  sigchain_push(SIGPIPE, SIG_IGN);

  if (params->src) {
    write_err = (write_in_full(child_process.in,
             params->src, params->size) < 0);
    if (errno == EPIPE)
      write_err = 0;
  } else {
    write_err = copy_fd(params->fd, child_process.in);
    if (write_err == COPY_WRITE_ERROR && errno == EPIPE)
      write_err = 0;
  }

  if (close(child_process.in))
    write_err = 1;
  if (write_err)
    error(_("cannot feed the input to external filter '%s'"),
          params->cmd);

  sigchain_pop(SIGPIPE);

  status = finish_command(&child_process);
  if (status)
    error(_("external filter '%s' failed %d"), params->cmd, status);

  strbuf_release(&cmd);
  return (write_err || status);
}

static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
            struct strbuf *dst, const char *cmd)
{
  /*
   * Create a pipeline to have the command filter the buffer's
   * contents.
   *
   * (child --> cmd) --> us
   */
  int err = 0;
  struct strbuf nbuf = STRBUF_INIT;
  struct async async;
  struct filter_params params;

  memset(&async, 0, sizeof(async));
  async.proc = filter_buffer_or_fd;
  async.data = &params;
  async.out = -1;
  params.src = src;
  params.size = len;
  params.fd = fd;
  params.cmd = cmd;
  params.path = path;

  fflush(NULL);
  if (start_async(&async))
    return 0; /* error was already reported */

  if (strbuf_read(&nbuf, async.out, 0) < 0) {
    err = error(_("read from external filter '%s' failed"), cmd);
  }
  if (close(async.out)) {
    err = error(_("read from external filter '%s' failed"), cmd);
  }
  if (finish_async(&async)) {
    err = error(_("external filter '%s' failed"), cmd);
  }

  if (!err) {
    strbuf_swap(dst, &nbuf);
  }
  strbuf_release(&nbuf);
  return !err;
}

#define CAP_CLEAN    (1u<<0)
#define CAP_SMUDGE   (1u<<1)
#define CAP_DELAY    (1u<<2)

struct cmd2process {
  struct subprocess_entry subprocess; /* must be the first member! */
  unsigned int supported_capabilities;
};

static int subprocess_map_initialized;
static struct hashmap subprocess_map;

static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
{
  static int versions[] = {2, 0};
  static struct subprocess_capability capabilities[] = {
    { "clean",  CAP_CLEAN  },
    { "smudge", CAP_SMUDGE },
    { "delay",  CAP_DELAY  },
    { NULL, 0 }
  };
  struct cmd2process *entry = (struct cmd2process *)subprocess;
  return subprocess_handshake(subprocess, "git-filter", versions, NULL,
            capabilities,
            &entry->supported_capabilities);
}

static void handle_filter_error(const struct strbuf *filter_status,
        struct cmd2process *entry,
        const unsigned int wanted_capability)
{
  if (!strcmp(filter_status->buf, "error"))
    ; /* The filter signaled a problem with the file. */
  else if (!strcmp(filter_status->buf, "abort") && wanted_capability) {
    /*
     * The filter signaled a permanent problem. Don't try to filter
     * files with the same command for the lifetime of the current
     * Git process.
     */
     entry->supported_capabilities &= ~wanted_capability;
  } else {
    /*
     * Something went wrong with the protocol filter.
     * Force shutdown and restart if another blob requires filtering.
     */
    error(_("external filter '%s' failed"), entry->subprocess.cmd);
    subprocess_stop(&subprocess_map, &entry->subprocess);
    free(entry);
  }
}

static int apply_multi_file_filter(const char *path, const char *src, size_t len,
           int fd, struct strbuf *dst, const char *cmd,
           const unsigned int wanted_capability,
           const struct checkout_metadata *meta,
           struct delayed_checkout *dco)
{
  int err;
  int can_delay = 0;
  struct cmd2process *entry;
  struct child_process *process;
  struct strbuf nbuf = STRBUF_INIT;
  struct strbuf filter_status = STRBUF_INIT;
  const char *filter_type;

  if (!subprocess_map_initialized) {
    subprocess_map_initialized = 1;
    hashmap_init(&subprocess_map, cmd2process_cmp, NULL, 0);
    entry = NULL;
  } else {
    entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
  }

  fflush(NULL);

  if (!entry) {
    entry = xmalloc(sizeof(*entry));
    entry->supported_capabilities = 0;

    if (subprocess_start(&subprocess_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
      free(entry);
      return 0;
    }
  }
  process = &entry->subprocess.process;

  if (!(entry->supported_capabilities & wanted_capability))
    return 0;

  if (wanted_capability & CAP_CLEAN)
    filter_type = "clean";
  else if (wanted_capability & CAP_SMUDGE)
    filter_type = "smudge";
  else
    die(_("unexpected filter type"));

  sigchain_push(SIGPIPE, SIG_IGN);

  assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
  err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
  if (err)
    goto done;

  err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
  if (err) {
    error(_("path name too long for external filter"));
    goto done;
  }

  err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
  if (err)
    goto done;

  if (meta && meta->refname) {
    err = packet_write_fmt_gently(process->in, "ref=%s\n", meta->refname);
    if (err)
      goto done;
  }

  if (meta && !is_null_oid(&meta->treeish)) {
    err = packet_write_fmt_gently(process->in, "treeish=%s\n", oid_to_hex(&meta->treeish));
    if (err)
      goto done;
  }

  if (meta && !is_null_oid(&meta->blob)) {
    err = packet_write_fmt_gently(process->in, "blob=%s\n", oid_to_hex(&meta->blob));
    if (err)
      goto done;
  }

  if ((entry->supported_capabilities & CAP_DELAY) &&
      dco && dco->state == CE_CAN_DELAY) {
    can_delay = 1;
    err = packet_write_fmt_gently(process->in, "can-delay=1\n");
    if (err)
      goto done;
  }

  err = packet_flush_gently(process->in);
  if (err)
    goto done;

  if (fd >= 0)
    err = write_packetized_from_fd_no_flush(fd, process->in);
  else
    err = write_packetized_from_buf_no_flush(src, len, process->in);
  if (err)
    goto done;

  err = packet_flush_gently(process->in);
  if (err)
    goto done;

  err = subprocess_read_status(process->out, &filter_status);
  if (err)
    goto done;

  if (can_delay && !strcmp(filter_status.buf, "delayed")) {
    string_list_insert(&dco->filters, cmd);
    string_list_insert(&dco->paths, path);
  } else {
    /* The filter got the blob and wants to send us a response. */
    err = strcmp(filter_status.buf, "success");
    if (err)
      goto done;

    err = read_packetized_to_strbuf(process->out, &nbuf,
            PACKET_READ_GENTLE_ON_EOF) < 0;
    if (err)
      goto done;

    err = subprocess_read_status(process->out, &filter_status);
    if (err)
      goto done;

    err = strcmp(filter_status.buf, "success");
  }

done:
  sigchain_pop(SIGPIPE);

  if (err)
    handle_filter_error(&filter_status, entry, wanted_capability);
  else
    strbuf_swap(dst, &nbuf);
  strbuf_release(&nbuf);
  strbuf_release(&filter_status);
  return !err;
}


int async_query_available_blobs(const char *cmd, struct string_list *available_paths)
{
  int err;
  char *line;
  struct cmd2process *entry;
  struct child_process *process;
  struct strbuf filter_status = STRBUF_INIT;

  assert(subprocess_map_initialized);
  entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
  if (!entry) {
    error(_("external filter '%s' is not available anymore although "
      "not all paths have been filtered"), cmd);
    return 0;
  }
  process = &entry->subprocess.process;
  sigchain_push(SIGPIPE, SIG_IGN);

  err = packet_write_fmt_gently(
    process->in, "command=list_available_blobs\n");
  if (err)
    goto done;

  err = packet_flush_gently(process->in);
  if (err)
    goto done;

  while ((line = packet_read_line(process->out, NULL))) {
    const char *path;
    if (skip_prefix(line, "pathname=", &path))
      string_list_insert(available_paths, path);
    else
      ; /* ignore unknown keys */
  }

  err = subprocess_read_status(process->out, &filter_status);
  if (err)
    goto done;

  err = strcmp(filter_status.buf, "success");

done:
  sigchain_pop(SIGPIPE);

  if (err)
    handle_filter_error(&filter_status, entry, 0);
  strbuf_release(&filter_status);
  return !err;
}

static struct convert_driver {
  const char *name;
  struct convert_driver *next;
  char *smudge;
  char *clean;
  char *process;
  int required;
} *user_convert, **user_convert_tail;

static int apply_filter(const char *path, const char *src, size_t len,
      int fd, struct strbuf *dst, struct convert_driver *drv,
      const unsigned int wanted_capability,
      const struct checkout_metadata *meta,
      struct delayed_checkout *dco)
{
  const char *cmd = NULL;

  if (!drv)
    return 0;

  if (!dst)
    return 1;

  if ((wanted_capability & CAP_CLEAN) && !drv->process && drv->clean)
    cmd = drv->clean;
  else if ((wanted_capability & CAP_SMUDGE) && !drv->process && drv->smudge)
    cmd = drv->smudge;

  if (cmd && *cmd)
    return apply_single_file_filter(path, src, len, fd, dst, cmd);
  else if (drv->process && *drv->process)
    return apply_multi_file_filter(path, src, len, fd, dst,
      drv->process, wanted_capability, meta, dco);

  return 0;
}

static int read_convert_config(const char *var, const char *value,
             const struct config_context *ctx UNUSED,
             void *cb UNUSED)
{
  const char *key, *name;
  size_t namelen;
  struct convert_driver *drv;

  /*
   * External conversion drivers are configured using
   * "filter.<name>.variable".
   */
  if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
    return 0;
  for (drv = user_convert; drv; drv = drv->next)
    if (!xstrncmpz(drv->name, name, namelen))
      break;
  if (!drv) {
    CALLOC_ARRAY(drv, 1);
    drv->name = xmemdupz(name, namelen);
    *user_convert_tail = drv;
    user_convert_tail = &(drv->next);
  }

  /*
   * filter.<name>.smudge and filter.<name>.clean specifies
   * the command line:
   *
   *  command-line
   *
   * The command-line will not be interpolated in any way.
   */

  if (!strcmp("smudge", key)) {
    FREE_AND_NULL(drv->smudge);
    return git_config_string(&drv->smudge, var, value);
  }

  if (!strcmp("clean", key)) {
    FREE_AND_NULL(drv->clean);
    return git_config_string(&drv->clean, var, value);
  }

  if (!strcmp("process", key)) {
    FREE_AND_NULL(drv->process);
    return git_config_string(&drv->process, var, value);
  }

  if (!strcmp("required", key)) {
    drv->required = git_config_bool(var, value);
    return 0;
  }

  return 0;
}

static int count_ident(const char *cp, unsigned long size)
{
  /*
   * "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
   */
  int cnt = 0;
  char ch;

  while (size) {
    ch = *cp++;
    size--;
    if (ch != '$')
      continue;
    if (size < 3)
      break;
    if (memcmp("Id", cp, 2))
      continue;
    ch = cp[2];
    cp += 3;
    size -= 3;
    if (ch == '$')
      cnt++; /* $Id$ */
    if (ch != ':')
      continue;

    /*
     * "$Id: ... "; scan up to the closing dollar sign and discard.
     */
    while (size) {
      ch = *cp++;
      size--;
      if (ch == '$') {
        cnt++;
        break;
      }
      if (ch == '\n')
        break;
    }
  }
  return cnt;
}

static int ident_to_git(const char *src, size_t len,
      struct strbuf *buf, int ident)
{
  char *dst, *dollar;

  if (!ident || (src && !count_ident(src, len)))
    return 0;

  if (!buf)
    return 1;

  /* only grow if not in place */
  if (strbuf_avail(buf) + buf->len < len)
    strbuf_grow(buf, len - buf->len);
  dst = buf->buf;
  for (;;) {
    dollar = memchr(src, '$', len);
    if (!dollar)
      break;
    memmove(dst, src, dollar + 1 - src);
    dst += dollar + 1 - src;
    len -= dollar + 1 - src;
    src  = dollar + 1;

    if (len > 3 && !memcmp(src, "Id:", 3)) {
      dollar = memchr(src + 3, '$', len - 3);
      if (!dollar)
        break;
      if (memchr(src + 3, '\n', dollar - src - 3)) {
        /* Line break before the next dollar. */
        continue;
      }

      memcpy(dst, "Id$", 3);
      dst += 3;
      len -= dollar + 1 - src;
      src  = dollar + 1;
    }
  }
  memmove(dst, src, len);
  strbuf_setlen(buf, dst + len - buf->buf);
  return 1;
}

static int ident_to_worktree(const char *src, size_t len,
           struct strbuf *buf, int ident)
{
  struct object_id oid;
  char *to_free = NULL, *dollar, *spc;
  int cnt;

  if (!ident)
    return 0;

  cnt = count_ident(src, len);
  if (!cnt)
    return 0;

  /* are we "faking" in place editing ? */
  if (src == buf->buf)
    to_free = strbuf_detach(buf, NULL);
  hash_object_file(the_hash_algo, src, len, OBJ_BLOB, &oid);

  strbuf_grow(buf, len + cnt * (the_hash_algo->hexsz + 3));
  for (;;) {
    /* step 1: run to the next '$' */
    dollar = memchr(src, '$', len);
    if (!dollar)
      break;
    strbuf_add(buf, src, dollar + 1 - src);
    len -= dollar + 1 - src;
    src  = dollar + 1;

    /* step 2: does it looks like a bit like Id:xxx$ or Id$ ? */
    if (len < 3 || memcmp("Id", src, 2))
      continue;

    /* step 3: skip over Id$ or Id:xxxxx$ */
    if (src[2] == '$') {
      src += 3;
      len -= 3;
    } else if (src[2] == ':') {
      /*
       * It's possible that an expanded Id has crept its way into the
       * repository, we cope with that by stripping the expansion out.
       * This is probably not a good idea, since it will cause changes
       * on checkout, which won't go away by stash, but let's keep it
       * for git-style ids.
       */
      dollar = memchr(src + 3, '$', len - 3);
      if (!dollar) {
        /* incomplete keyword, no more '$', so just quit the loop */
        break;
      }

      if (memchr(src + 3, '\n', dollar - src - 3)) {
        /* Line break before the next dollar. */
        continue;
      }

      spc = memchr(src + 4, ' ', dollar - src - 4);
      if (spc && spc < dollar-1) {
        /* There are spaces in unexpected places.
         * This is probably an id from some other
         * versioning system. Keep it for now.
         */
        continue;
      }

      len -= dollar + 1 - src;
      src  = dollar + 1;
    } else {
      /* it wasn't a "Id$" or "Id:xxxx$" */
      continue;
    }

    /* step 4: substitute */
    strbuf_addstr(buf, "Id: ");
    strbuf_addstr(buf, oid_to_hex(&oid));
    strbuf_addstr(buf, " $");
  }
  strbuf_add(buf, src, len);

  free(to_free);
  return 1;
}

static const char *git_path_check_encoding(struct attr_check_item *check)
{
  const char *value = check->value;

  if (ATTR_UNSET(value) || !strlen(value))
    return NULL;

  if (ATTR_TRUE(value) || ATTR_FALSE(value)) {
    die(_("true/false are no valid working-tree-encodings"));
  }

  /* Don't encode to the default encoding */
  if (same_encoding(value, default_encoding))
    return NULL;

  return value;
}

static enum convert_crlf_action git_path_check_crlf(struct attr_check_item *check)
{
  const char *value = check->value;

  if (ATTR_TRUE(value))
    return CRLF_TEXT;
  else if (ATTR_FALSE(value))
    return CRLF_BINARY;
  else if (ATTR_UNSET(value))
    ;
  else if (!strcmp(value, "input"))
    return CRLF_TEXT_INPUT;
  else if (!strcmp(value, "auto"))
    return CRLF_AUTO;
  return CRLF_UNDEFINED;
}

static enum eol git_path_check_eol(struct attr_check_item *check)
{
  const char *value = check->value;

  if (ATTR_UNSET(value))
    ;
  else if (!strcmp(value, "lf"))
    return EOL_LF;
  else if (!strcmp(value, "crlf"))
    return EOL_CRLF;
  return EOL_UNSET;
}

static struct convert_driver *git_path_check_convert(struct attr_check_item *check)
{
  const char *value = check->value;
  struct convert_driver *drv;

  if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
    return NULL;
  for (drv = user_convert; drv; drv = drv->next)
    if (!strcmp(value, drv->name))
      return drv;
  return NULL;
}

static int git_path_check_ident(struct attr_check_item *check)
{
  const char *value = check->value;

  return !!ATTR_TRUE(value);
}

static struct attr_check *check;

void convert_attrs(struct index_state *istate,
       struct conv_attrs *ca, const char *path)
{
  struct attr_check_item *ccheck = NULL;

  if (!check) {
    check = attr_check_initl("crlf", "ident", "filter",
           "eol", "text", "working-tree-encoding",
           NULL);
    user_convert_tail = &user_convert;
    git_config(read_convert_config, NULL);
  }

  git_check_attr(istate, path, check);
  ccheck = check->items;
  ca->crlf_action = git_path_check_crlf(ccheck + 4);
  if (ca->crlf_action == CRLF_UNDEFINED)
    ca->crlf_action = git_path_check_crlf(ccheck + 0);
  ca->ident = git_path_check_ident(ccheck + 1);
  ca->drv = git_path_check_convert(ccheck + 2);
  if (ca->crlf_action != CRLF_BINARY) {
    enum eol eol_attr = git_path_check_eol(ccheck + 3);
    if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_LF)
      ca->crlf_action = CRLF_AUTO_INPUT;
    else if (ca->crlf_action == CRLF_AUTO && eol_attr == EOL_CRLF)
      ca->crlf_action = CRLF_AUTO_CRLF;
    else if (eol_attr == EOL_LF)
      ca->crlf_action = CRLF_TEXT_INPUT;
    else if (eol_attr == EOL_CRLF)
      ca->crlf_action = CRLF_TEXT_CRLF;
  }
  ca->working_tree_encoding = git_path_check_encoding(ccheck + 5);

  /* Save attr and make a decision for action */
  ca->attr_action = ca->crlf_action;
  if (ca->crlf_action == CRLF_TEXT)
    ca->crlf_action = text_eol_is_crlf() ? CRLF_TEXT_CRLF : CRLF_TEXT_INPUT;
  if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_FALSE)
    ca->crlf_action = CRLF_BINARY;
  if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_TRUE)
    ca->crlf_action = CRLF_AUTO_CRLF;
  if (ca->crlf_action == CRLF_UNDEFINED && auto_crlf == AUTO_CRLF_INPUT)
    ca->crlf_action = CRLF_AUTO_INPUT;
}

void reset_parsed_attributes(void)
{
  struct convert_driver *drv, *next;

  attr_check_free(check);
  check = NULL;
  reset_merge_attributes();

  for (drv = user_convert; drv; drv = next) {
    next = drv->next;
    free((void *)drv->name);
    free((void *)drv->smudge);
    free((void *)drv->clean);
    free((void *)drv->process);
    free(drv);
  }
  user_convert = NULL;
  user_convert_tail = NULL;
}

int would_convert_to_git_filter_fd(struct index_state *istate, const char *path)
{
  struct conv_attrs ca;

  convert_attrs(istate, &ca, path);
  if (!ca.drv)
    return 0;

  /*
   * Apply a filter to an fd only if the filter is required to succeed.
   * We must die if the filter fails, because the original data before
   * filtering is not available.
   */
  if (!ca.drv->required)
    return 0;

  return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN, NULL, NULL);
}

const char *get_convert_attr_ascii(struct index_state *istate, const char *path)
{
  struct conv_attrs ca;

  convert_attrs(istate, &ca, path);
  switch (ca.attr_action) {
  case CRLF_UNDEFINED:
    return "";
  case CRLF_BINARY:
    return "-text";
  case CRLF_TEXT:
    return "text";
  case CRLF_TEXT_INPUT:
    return "text eol=lf";
  case CRLF_TEXT_CRLF:
    return "text eol=crlf";
  case CRLF_AUTO:
    return "text=auto";
  case CRLF_AUTO_CRLF:
    return "text=auto eol=crlf";
  case CRLF_AUTO_INPUT:
    return "text=auto eol=lf";
  }
  return "";
}

int convert_to_git(struct index_state *istate,
       const char *path, const char *src, size_t len,
       struct strbuf *dst, int conv_flags)
{
  int ret = 0;
  struct conv_attrs ca;

  convert_attrs(istate, &ca, path);

  ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN, NULL, NULL);
  if (!ret && ca.drv && ca.drv->required)
    die(_("%s: clean filter '%s' failed"), path, ca.drv->name);

  if (ret && dst) {
    src = dst->buf;
    len = dst->len;
  }

  ret |= encode_to_git(path, src, len, dst, ca.working_tree_encoding, conv_flags);
  if (ret && dst) {
    src = dst->buf;
    len = dst->len;
  }

  if (!(conv_flags & CONV_EOL_KEEP_CRLF)) {
    ret |= crlf_to_git(istate, path, src, len, dst, ca.crlf_action, conv_flags);
    if (ret && dst) {
      src = dst->buf;
      len = dst->len;
    }
  }
  return ret | ident_to_git(src, len, dst, ca.ident);
}

void convert_to_git_filter_fd(struct index_state *istate,
            const char *path, int fd, struct strbuf *dst,
            int conv_flags)
{
  struct conv_attrs ca;
  convert_attrs(istate, &ca, path);

  assert(ca.drv);

  if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN, NULL, NULL))
    die(_("%s: clean filter '%s' failed"), path, ca.drv->name);

  encode_to_git(path, dst->buf, dst->len, dst, ca.working_tree_encoding, conv_flags);
  crlf_to_git(istate, path, dst->buf, dst->len, dst, ca.crlf_action, conv_flags);
  ident_to_git(dst->buf, dst->len, dst, ca.ident);
}

static int convert_to_working_tree_ca_internal(const struct conv_attrs *ca,
                 const char *path, const char *src,
                 size_t len, struct strbuf *dst,
                 int normalizing,
                 const struct checkout_metadata *meta,
                 struct delayed_checkout *dco)
{
  int ret = 0, ret_filter = 0;

  ret |= ident_to_worktree(src, len, dst, ca->ident);
  if (ret) {
    src = dst->buf;
    len = dst->len;
  }
  /*
   * CRLF conversion can be skipped if normalizing, unless there
   * is a smudge or process filter (even if the process filter doesn't
   * support smudge).  The filters might expect CRLFs.
   */
  if ((ca->drv && (ca->drv->smudge || ca->drv->process)) || !normalizing) {
    ret |= crlf_to_worktree(src, len, dst, ca->crlf_action);
    if (ret) {
      src = dst->buf;
      len = dst->len;
    }
  }

  ret |= encode_to_worktree(path, src, len, dst, ca->working_tree_encoding);
  if (ret) {
    src = dst->buf;
    len = dst->len;
  }

  ret_filter = apply_filter(
    path, src, len, -1, dst, ca->drv, CAP_SMUDGE, meta, dco);
  if (!ret_filter && ca->drv && ca->drv->required)
    die(_("%s: smudge filter %s failed"), path, ca->drv->name);

  return ret | ret_filter;
}

int async_convert_to_working_tree_ca(const struct conv_attrs *ca,
             const char *path, const char *src,
             size_t len, struct strbuf *dst,
             const struct checkout_metadata *meta,
             void *dco)
{
  return convert_to_working_tree_ca_internal(ca, path, src, len, dst, 0,
               meta, dco);
}

int convert_to_working_tree_ca(const struct conv_attrs *ca,
             const char *path, const char *src,
             size_t len, struct strbuf *dst,
             const struct checkout_metadata *meta)
{
  return convert_to_working_tree_ca_internal(ca, path, src, len, dst, 0,
               meta, NULL);
}

int renormalize_buffer(struct index_state *istate, const char *path,
           const char *src, size_t len, struct strbuf *dst)
{
  struct conv_attrs ca;
  int ret;

  convert_attrs(istate, &ca, path);
  ret = convert_to_working_tree_ca_internal(&ca, path, src, len, dst, 1,
              NULL, NULL);
  if (ret) {
    src = dst->buf;
    len = dst->len;
  }
  return ret | convert_to_git(istate, path, src, len, dst, CONV_EOL_RENORMALIZE);
}

/*****************************************************************
 *
 * Streaming conversion support
 *
 *****************************************************************/

typedef int (*filter_fn)(struct stream_filter *,
       const char *input, size_t *isize_p,
       char *output, size_t *osize_p);
typedef void (*free_fn)(struct stream_filter *);

struct stream_filter_vtbl {
  filter_fn filter;
  free_fn free;
};

struct stream_filter {
  struct stream_filter_vtbl *vtbl;
};

static int null_filter_fn(struct stream_filter *filter UNUSED,
        const char *input, size_t *isize_p,
        char *output, size_t *osize_p)
{
  size_t count;

  if (!input)
    return 0; /* we do not keep any states */
  count = *isize_p;
  if (*osize_p < count)
    count = *osize_p;
  if (count) {
    memmove(output, input, count);
    *isize_p -= count;
    *osize_p -= count;
  }
  return 0;
}

static void null_free_fn(struct stream_filter *filter UNUSED)
{
  ; /* nothing -- null instances are shared */
}

static struct stream_filter_vtbl null_vtbl = {
  .filter = null_filter_fn,
  .free = null_free_fn,
};

static struct stream_filter null_filter_singleton = {
  .vtbl = &null_vtbl,
};

int is_null_stream_filter(struct stream_filter *filter)
{
  return filter == &null_filter_singleton;
}


/*
 * LF-to-CRLF filter
 */

struct lf_to_crlf_filter {
  struct stream_filter filter;
  unsigned has_held:1;
  char held;
};

static int lf_to_crlf_filter_fn(struct stream_filter *filter,
        const char *input, size_t *isize_p,
        char *output, size_t *osize_p)
{
  size_t count, o = 0;
  struct lf_to_crlf_filter *lf_to_crlf = (struct lf_to_crlf_filter *)filter;

  /*
   * We may be holding onto the CR to see if it is followed by a
   * LF, in which case we would need to go to the main loop.
   * Otherwise, just emit it to the output stream.
   */
  if (lf_to_crlf->has_held && (lf_to_crlf->held != '\r' || !input)) {
    output[o++] = lf_to_crlf->held;
    lf_to_crlf->has_held = 0;
  }

  /* We are told to drain */
  if (!input) {
    *osize_p -= o;
    return 0;
  }

  count = *isize_p;
  if (count || lf_to_crlf->has_held) {
    size_t i;
    int was_cr = 0;

    if (lf_to_crlf->has_held) {
      was_cr = 1;
      lf_to_crlf->has_held = 0;
    }

    for (i = 0; o < *osize_p && i < count; i++) {
      char ch = input[i];

      if (ch == '\n') {
        output[o++] = '\r';
      } else if (was_cr) {
        /*
         * Previous round saw CR and it is not followed
         * by a LF; emit the CR before processing the
         * current character.
         */
        output[o++] = '\r';
      }

      /*
       * We may have consumed the last output slot,
       * in which case we need to break out of this
       * loop; hold the current character before
       * returning.
       */
      if (*osize_p <= o) {
        lf_to_crlf->has_held = 1;
        lf_to_crlf->held = ch;
        continue; /* break but increment i */
      }

      if (ch == '\r') {
        was_cr = 1;
        continue;
      }

      was_cr = 0;
      output[o++] = ch;
    }

    *osize_p -= o;
    *isize_p -= i;

    if (!lf_to_crlf->has_held && was_cr) {
      lf_to_crlf->has_held = 1;
      lf_to_crlf->held = '\r';
    }
  }
  return 0;
}

static void lf_to_crlf_free_fn(struct stream_filter *filter)
{
  free(filter);
}

static struct stream_filter_vtbl lf_to_crlf_vtbl = {
  .filter = lf_to_crlf_filter_fn,
  .free = lf_to_crlf_free_fn,
};

static struct stream_filter *lf_to_crlf_filter(void)
{
  struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));

  lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
  return (struct stream_filter *)lf_to_crlf;
}

/*
 * Cascade filter
 */
#define FILTER_BUFFER 1024
struct cascade_filter {
  struct stream_filter filter;
  struct stream_filter *one;
  struct stream_filter *two;
  char buf[FILTER_BUFFER];
  int end, ptr;
};

static int cascade_filter_fn(struct stream_filter *filter,
           const char *input, size_t *isize_p,
           char *output, size_t *osize_p)
{
  struct cascade_filter *cas = (struct cascade_filter *) filter;
  size_t filled = 0;
  size_t sz = *osize_p;
  size_t to_feed, remaining;

  /*
   * input -- (one) --> buf -- (two) --> output
   */
  while (filled < sz) {
    remaining = sz - filled;

    /* do we already have something to feed two with? */
    if (cas->ptr < cas->end) {
      to_feed = cas->end - cas->ptr;
      if (stream_filter(cas->two,
            cas->buf + cas->ptr, &to_feed,
            output + filled, &remaining))
        return -1;
      cas->ptr += (cas->end - cas->ptr) - to_feed;
      filled = sz - remaining;
      continue;
    }

    /* feed one from upstream and have it emit into our buffer */
    to_feed = input ? *isize_p : 0;
    if (input && !to_feed)
      break;
    remaining = sizeof(cas->buf);
    if (stream_filter(cas->one,
          input, &to_feed,
          cas->buf, &remaining))
      return -1;
    cas->end = sizeof(cas->buf) - remaining;
    cas->ptr = 0;
    if (input) {
      size_t fed = *isize_p - to_feed;
      *isize_p -= fed;
      input += fed;
    }

    /* do we know that we drained one completely? */
    if (input || cas->end)
      continue;

    /* tell two to drain; we have nothing more to give it */
    to_feed = 0;
    remaining = sz - filled;
    if (stream_filter(cas->two,
          NULL, &to_feed,
          output + filled, &remaining))
      return -1;
    if (remaining == (sz - filled))
      break; /* completely drained two */
    filled = sz - remaining;
  }
  *osize_p -= filled;
  return 0;
}

static void cascade_free_fn(struct stream_filter *filter)
{
  struct cascade_filter *cas = (struct cascade_filter *)filter;
  free_stream_filter(cas->one);
  free_stream_filter(cas->two);
  free(filter);
}

static struct stream_filter_vtbl cascade_vtbl = {
  .filter = cascade_filter_fn,
  .free = cascade_free_fn,
};

static struct stream_filter *cascade_filter(struct stream_filter *one,
              struct stream_filter *two)
{
  struct cascade_filter *cascade;

  if (!one || is_null_stream_filter(one))
    return two;
  if (!two || is_null_stream_filter(two))
    return one;

  cascade = xmalloc(sizeof(*cascade));
  cascade->one = one;
  cascade->two = two;
  cascade->end = cascade->ptr = 0;
  cascade->filter.vtbl = &cascade_vtbl;
  return (struct stream_filter *)cascade;
}

/*
 * ident filter
 */
#define IDENT_DRAINING (-1)
#define IDENT_SKIPPING (-2)
struct ident_filter {
  struct stream_filter filter;
  struct strbuf left;
  int state;
  char ident[GIT_MAX_HEXSZ + 5]; /* ": x40 $" */
};

static int is_foreign_ident(const char *str)
{
  int i;

  if (!skip_prefix(str, "$Id: ", &str))
    return 0;
  for (i = 0; str[i]; i++) {
    if (isspace(str[i]) && str[i+1] != '$')
      return 1;
  }
  return 0;
}

static void ident_drain(struct ident_filter *ident, char **output_p, size_t *osize_p)
{
  size_t to_drain = ident->left.len;

  if (*osize_p < to_drain)
    to_drain = *osize_p;
  if (to_drain) {
    memcpy(*output_p, ident->left.buf, to_drain);
    strbuf_remove(&ident->left, 0, to_drain);
    *output_p += to_drain;
    *osize_p -= to_drain;
  }
  if (!ident->left.len)
    ident->state = 0;
}

static int ident_filter_fn(struct stream_filter *filter,
         const char *input, size_t *isize_p,
         char *output, size_t *osize_p)
{
  struct ident_filter *ident = (struct ident_filter *)filter;
  static const char head[] = "$Id";

  if (!input) {
    /* drain upon eof */
    switch (ident->state) {
    default:
      strbuf_add(&ident->left, head, ident->state);
      /* fallthrough */
    case IDENT_SKIPPING:
      /* fallthrough */
    case IDENT_DRAINING:
      ident_drain(ident, &output, osize_p);
    }
    return 0;
  }

  while (*isize_p || (ident->state == IDENT_DRAINING)) {
    int ch;

    if (ident->state == IDENT_DRAINING) {
      ident_drain(ident, &output, osize_p);
      if (!*osize_p)
        break;
      continue;
    }

    ch = *(input++);
    (*isize_p)--;

    if (ident->state == IDENT_SKIPPING) {
      /*
       * Skipping until '$' or LF, but keeping them
       * in case it is a foreign ident.
       */
      strbuf_addch(&ident->left, ch);
      if (ch != '\n' && ch != '$')
        continue;
      if (ch == '$' && !is_foreign_ident(ident->left.buf)) {
        strbuf_setlen(&ident->left, sizeof(head) - 1);
        strbuf_addstr(&ident->left, ident->ident);
      }
      ident->state = IDENT_DRAINING;
      continue;
    }

    if (ident->state < sizeof(head) &&
        head[ident->state] == ch) {
      ident->state++;
      continue;
    }

    if (ident->state)
      strbuf_add(&ident->left, head, ident->state);
    if (ident->state == sizeof(head) - 1) {
      if (ch != ':' && ch != '$') {
        strbuf_addch(&ident->left, ch);
        ident->state = 0;
        continue;
      }

      if (ch == ':') {
        strbuf_addch(&ident->left, ch);
        ident->state = IDENT_SKIPPING;
      } else {
        strbuf_addstr(&ident->left, ident->ident);
        ident->state = IDENT_DRAINING;
      }
      continue;
    }

    strbuf_addch(&ident->left, ch);
    ident->state = IDENT_DRAINING;
  }
  return 0;
}

static void ident_free_fn(struct stream_filter *filter)
{
  struct ident_filter *ident = (struct ident_filter *)filter;
  strbuf_release(&ident->left);
  free(filter);
}

static struct stream_filter_vtbl ident_vtbl = {
  .filter = ident_filter_fn,
  .free = ident_free_fn,
};

static struct stream_filter *ident_filter(const struct object_id *oid)
{
  struct ident_filter *ident = xmalloc(sizeof(*ident));

  xsnprintf(ident->ident, sizeof(ident->ident),
      ": %s $", oid_to_hex(oid));
  strbuf_init(&ident->left, 0);
  ident->filter.vtbl = &ident_vtbl;
  ident->state = 0;
  return (struct stream_filter *)ident;
}

/*
 * Return an appropriately constructed filter for the given ca, or NULL if
 * the contents cannot be filtered without reading the whole thing
 * in-core.
 *
 * Note that you would be crazy to set CRLF, smudge/clean or ident to a
 * large binary blob you would want us not to slurp into the memory!
 */
struct stream_filter *get_stream_filter_ca(const struct conv_attrs *ca,
             const struct object_id *oid)
{
  struct stream_filter *filter = NULL;

  if (classify_conv_attrs(ca) != CA_CLASS_STREAMABLE)
    return NULL;

  if (ca->ident)
    filter = ident_filter(oid);

  if (output_eol(ca->crlf_action) == EOL_CRLF)
    filter = cascade_filter(filter, lf_to_crlf_filter());
  else
    filter = cascade_filter(filter, &null_filter_singleton);

  return filter;
}

struct stream_filter *get_stream_filter(struct index_state *istate,
          const char *path,
          const struct object_id *oid)
{
  struct conv_attrs ca;
  convert_attrs(istate, &ca, path);
  return get_stream_filter_ca(&ca, oid);
}

void free_stream_filter(struct stream_filter *filter)
{
  filter->vtbl->free(filter);
}

int stream_filter(struct stream_filter *filter,
      const char *input, size_t *isize_p,
      char *output, size_t *osize_p)
{
  return filter->vtbl->filter(filter, input, isize_p, output, osize_p);
}

void init_checkout_metadata(struct checkout_metadata *meta, const char *refname,
          const struct object_id *treeish,
          const struct object_id *blob)
{
  memset(meta, 0, sizeof(*meta));
  if (refname)
    meta->refname = refname;
  if (treeish)
    oidcpy(&meta->treeish, treeish);
  if (blob)
    oidcpy(&meta->blob, blob);
}

void clone_checkout_metadata(struct checkout_metadata *dst,
           const struct checkout_metadata *src,
           const struct object_id *blob)
{
  memcpy(dst, src, sizeof(*dst));
  if (blob)
    oidcpy(&dst->blob, blob);
}

enum conv_attrs_classification classify_conv_attrs(const struct conv_attrs *ca)
{
  if (ca->drv) {
    if (ca->drv->process)
      return CA_CLASS_INCORE_PROCESS;
    if (ca->drv->smudge || ca->drv->clean)
      return CA_CLASS_INCORE_FILTER;
  }

  if (ca->working_tree_encoding)
    return CA_CLASS_INCORE;

  if (ca->crlf_action == CRLF_AUTO || ca->crlf_action == CRLF_AUTO_CRLF)
    return CA_CLASS_INCORE;

  return CA_CLASS_STREAMABLE;
}

Coverage Report

Created: 2024-09-08 06:23