/src/git/object-name.c

Source
#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "object-name.h"
#include "advice.h"
#include "config.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "tree-walk.h"
#include "refs.h"
#include "remote.h"
#include "dir.h"
#include "oid-array.h"
#include "oidtree.h"
#include "packfile.h"
#include "pretty.h"
#include "object-file.h"
#include "read-cache-ll.h"
#include "repo-settings.h"
#include "repository.h"
#include "setup.h"
#include "midx.h"
#include "commit-reach.h"
#include "date.h"
#include "object-file-convert.h"
#include "prio-queue.h"

static int get_oid_oneline(struct repository *r, const char *, struct object_id *,
         const struct commit_list *);

typedef int (*disambiguate_hint_fn)(struct repository *, const struct object_id *, void *);

struct disambiguate_state {
  int len; /* length of prefix in hex chars */
  char hex_pfx[GIT_MAX_HEXSZ + 1];
  struct object_id bin_pfx;

  struct repository *repo;
  disambiguate_hint_fn fn;
  void *cb_data;
  struct object_id candidate;
  unsigned candidate_exists:1;
  unsigned candidate_checked:1;
  unsigned candidate_ok:1;
  unsigned disambiguate_fn_used:1;
  unsigned ambiguous:1;
  unsigned always_call_fn:1;
};

static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
{
  /* The hash algorithm of current has already been filtered */
  if (ds->always_call_fn) {
    ds->ambiguous = ds->fn(ds->repo, current, ds->cb_data) ? 1 : 0;
    return;
  }
  if (!ds->candidate_exists) {
    /* this is the first candidate */
    oidcpy(&ds->candidate, current);
    ds->candidate_exists = 1;
    return;
  } else if (oideq(&ds->candidate, current)) {
    /* the same as what we already have seen */
    return;
  }

  if (!ds->fn) {
    /* cannot disambiguate between ds->candidate and current */
    ds->ambiguous = 1;
    return;
  }

  if (!ds->candidate_checked) {
    ds->candidate_ok = ds->fn(ds->repo, &ds->candidate, ds->cb_data);
    ds->disambiguate_fn_used = 1;
    ds->candidate_checked = 1;
  }

  if (!ds->candidate_ok) {
    /* discard the candidate; we know it does not satisfy fn */
    oidcpy(&ds->candidate, current);
    ds->candidate_checked = 0;
    return;
  }

  /* if we reach this point, we know ds->candidate satisfies fn */
  if (ds->fn(ds->repo, current, ds->cb_data)) {
    /*
     * if both current and candidate satisfy fn, we cannot
     * disambiguate.
     */
    ds->candidate_ok = 0;
    ds->ambiguous = 1;
  }

  /* otherwise, current can be discarded and candidate is still good */
}

static int match_hash(unsigned, const unsigned char *, const unsigned char *);

static enum cb_next match_prefix(const struct object_id *oid, void *arg)
{
  struct disambiguate_state *ds = arg;
  /* no need to call match_hash, oidtree_each did prefix match */
  update_candidates(ds, oid);
  return ds->ambiguous ? CB_BREAK : CB_CONTINUE;
}

static void find_short_object_filename(struct disambiguate_state *ds)
{
  struct odb_source *source;

  for (source = ds->repo->objects->sources; source && !ds->ambiguous; source = source->next)
    oidtree_each(odb_source_loose_cache(source, &ds->bin_pfx),
        &ds->bin_pfx, ds->len, match_prefix, ds);
}

static int match_hash(unsigned len, const unsigned char *a, const unsigned char *b)
{
  do {
    if (*a != *b)
      return 0;
    a++;
    b++;
    len -= 2;
  } while (len > 1);
  if (len)
    if ((*a ^ *b) & 0xf0)
      return 0;
  return 1;
}

static void unique_in_midx(struct multi_pack_index *m,
         struct disambiguate_state *ds)
{
  for (; m; m = m->base_midx) {
    uint32_t num, i, first = 0;
    const struct object_id *current = NULL;
    int len = ds->len > ds->repo->hash_algo->hexsz ?
      ds->repo->hash_algo->hexsz : ds->len;

    if (!m->num_objects)
      continue;

    num = m->num_objects + m->num_objects_in_base;

    bsearch_one_midx(&ds->bin_pfx, m, &first);

    /*
     * At this point, "first" is the location of the lowest
     * object with an object name that could match
     * "bin_pfx".  See if we have 0, 1 or more objects that
     * actually match(es).
     */
    for (i = first; i < num && !ds->ambiguous; i++) {
      struct object_id oid;
      current = nth_midxed_object_oid(&oid, m, i);
      if (!match_hash(len, ds->bin_pfx.hash, current->hash))
        break;
      update_candidates(ds, current);
    }
  }
}

static void unique_in_pack(struct packed_git *p,
         struct disambiguate_state *ds)
{
  uint32_t num, i, first = 0;
  int len = ds->len > ds->repo->hash_algo->hexsz ?
    ds->repo->hash_algo->hexsz : ds->len;

  if (p->multi_pack_index)
    return;

  if (open_pack_index(p) || !p->num_objects)
    return;

  num = p->num_objects;
  bsearch_pack(&ds->bin_pfx, p, &first);

  /*
   * At this point, "first" is the location of the lowest object
   * with an object name that could match "bin_pfx".  See if we have
   * 0, 1 or more objects that actually match(es).
   */
  for (i = first; i < num && !ds->ambiguous; i++) {
    struct object_id oid;
    nth_packed_object_id(&oid, p, i);
    if (!match_hash(len, ds->bin_pfx.hash, oid.hash))
      break;
    update_candidates(ds, &oid);
  }
}

static void find_short_packed_object(struct disambiguate_state *ds)
{
  struct odb_source *source;
  struct packed_git *p;

  /* Skip, unless oids from the storage hash algorithm are wanted */
  if (ds->bin_pfx.algo && (&hash_algos[ds->bin_pfx.algo] != ds->repo->hash_algo))
    return;

  odb_prepare_alternates(ds->repo->objects);
  for (source = ds->repo->objects->sources; source && !ds->ambiguous; source = source->next) {
    struct multi_pack_index *m = get_multi_pack_index(source);
    if (m)
      unique_in_midx(m, ds);
  }

  repo_for_each_pack(ds->repo, p) {
    if (ds->ambiguous)
      break;
    unique_in_pack(p, ds);
  }
}

static int finish_object_disambiguation(struct disambiguate_state *ds,
          struct object_id *oid)
{
  if (ds->ambiguous)
    return SHORT_NAME_AMBIGUOUS;

  if (!ds->candidate_exists)
    return MISSING_OBJECT;

  if (!ds->candidate_checked)
    /*
     * If this is the only candidate, there is no point
     * calling the disambiguation hint callback.
     *
     * On the other hand, if the current candidate
     * replaced an earlier candidate that did _not_ pass
     * the disambiguation hint callback, then we do have
     * more than one objects that match the short name
     * given, so we should make sure this one matches;
     * otherwise, if we discovered this one and the one
     * that we previously discarded in the reverse order,
     * we would end up showing different results in the
     * same repository!
     */
    ds->candidate_ok = (!ds->disambiguate_fn_used ||
            ds->fn(ds->repo, &ds->candidate, ds->cb_data));

  if (!ds->candidate_ok)
    return SHORT_NAME_AMBIGUOUS;

  oidcpy(oid, &ds->candidate);
  return 0;
}

static int disambiguate_commit_only(struct repository *r,
            const struct object_id *oid,
            void *cb_data UNUSED)
{
  int kind = odb_read_object_info(r->objects, oid, NULL);
  return kind == OBJ_COMMIT;
}

static int disambiguate_committish_only(struct repository *r,
          const struct object_id *oid,
          void *cb_data UNUSED)
{
  struct object *obj;
  int kind;

  kind = odb_read_object_info(r->objects, oid, NULL);
  if (kind == OBJ_COMMIT)
    return 1;
  if (kind != OBJ_TAG)
    return 0;

  /* We need to do this the hard way... */
  obj = deref_tag(r, parse_object(r, oid), NULL, 0);
  if (obj && obj->type == OBJ_COMMIT)
    return 1;
  return 0;
}

static int disambiguate_tree_only(struct repository *r,
          const struct object_id *oid,
          void *cb_data UNUSED)
{
  int kind = odb_read_object_info(r->objects, oid, NULL);
  return kind == OBJ_TREE;
}

static int disambiguate_treeish_only(struct repository *r,
             const struct object_id *oid,
             void *cb_data UNUSED)
{
  struct object *obj;
  int kind;

  kind = odb_read_object_info(r->objects, oid, NULL);
  if (kind == OBJ_TREE || kind == OBJ_COMMIT)
    return 1;
  if (kind != OBJ_TAG)
    return 0;

  /* We need to do this the hard way... */
  obj = deref_tag(r, parse_object(r, oid), NULL, 0);
  if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
    return 1;
  return 0;
}

static int disambiguate_blob_only(struct repository *r,
          const struct object_id *oid,
          void *cb_data UNUSED)
{
  int kind = odb_read_object_info(r->objects, oid, NULL);
  return kind == OBJ_BLOB;
}

static disambiguate_hint_fn default_disambiguate_hint;

int set_disambiguate_hint_config(const char *var, const char *value)
{
  static const struct {
    const char *name;
    disambiguate_hint_fn fn;
  } hints[] = {
    { "none", NULL },
    { "commit", disambiguate_commit_only },
    { "committish", disambiguate_committish_only },
    { "tree", disambiguate_tree_only },
    { "treeish", disambiguate_treeish_only },
    { "blob", disambiguate_blob_only }
  };
  int i;

  if (!value)
    return config_error_nonbool(var);

  for (i = 0; i < ARRAY_SIZE(hints); i++) {
    if (!strcasecmp(value, hints[i].name)) {
      default_disambiguate_hint = hints[i].fn;
      return 0;
    }
  }

  return error("unknown hint type for '%s': %s", var, value);
}

static int init_object_disambiguation(struct repository *r,
              const char *name, int len,
              const struct git_hash_algo *algo,
              struct disambiguate_state *ds)
{
  int i;

  if (len < MINIMUM_ABBREV || len > GIT_MAX_HEXSZ)
    return -1;

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

  for (i = 0; i < len ;i++) {
    unsigned char c = name[i];
    unsigned char val;
    if (c >= '0' && c <= '9')
      val = c - '0';
    else if (c >= 'a' && c <= 'f')
      val = c - 'a' + 10;
    else if (c >= 'A' && c <='F') {
      val = c - 'A' + 10;
      c -= 'A' - 'a';
    }
    else
      return -1;
    ds->hex_pfx[i] = c;
    if (!(i & 1))
      val <<= 4;
    ds->bin_pfx.hash[i >> 1] |= val;
  }

  ds->len = len;
  ds->hex_pfx[len] = '\0';
  ds->repo = r;
  ds->bin_pfx.algo = algo ? hash_algo_by_ptr(algo) : GIT_HASH_UNKNOWN;
  odb_prepare_alternates(r->objects);
  return 0;
}

struct ambiguous_output {
  const struct disambiguate_state *ds;
  struct strbuf advice;
  struct strbuf sb;
};

static int show_ambiguous_object(const struct object_id *oid, void *data)
{
  struct ambiguous_output *state = data;
  const struct disambiguate_state *ds = state->ds;
  struct strbuf *advice = &state->advice;
  struct strbuf *sb = &state->sb;
  int type;
  const char *hash;

  if (ds->fn && !ds->fn(ds->repo, oid, ds->cb_data))
    return 0;

  hash = repo_find_unique_abbrev(ds->repo, oid, DEFAULT_ABBREV);
  type = odb_read_object_info(ds->repo->objects, oid, NULL);

  if (type < 0) {
    /*
     * TRANSLATORS: This is a line of ambiguous object
     * output shown when we cannot look up or parse the
     * object in question. E.g. "deadbeef [bad object]".
     */
    strbuf_addf(sb, _("%s [bad object]"), hash);
    goto out;
  }

  assert(type == OBJ_TREE || type == OBJ_COMMIT ||
         type == OBJ_BLOB || type == OBJ_TAG);

  if (type == OBJ_COMMIT) {
    struct strbuf date = STRBUF_INIT;
    struct strbuf msg = STRBUF_INIT;
    struct commit *commit = lookup_commit(ds->repo, oid);

    if (commit) {
      struct pretty_print_context pp = {0};
      pp.date_mode.type = DATE_SHORT;
      repo_format_commit_message(the_repository, commit,
               "%ad", &date, &pp);
      repo_format_commit_message(the_repository, commit,
               "%s", &msg, &pp);
    }

    /*
     * TRANSLATORS: This is a line of ambiguous commit
     * object output. E.g.:
     *
     *    "deadbeef commit 2021-01-01 - Some Commit Message"
     */
    strbuf_addf(sb, _("%s commit %s - %s"), hash, date.buf,
          msg.buf);

    strbuf_release(&date);
    strbuf_release(&msg);
  } else if (type == OBJ_TAG) {
    struct tag *tag = lookup_tag(ds->repo, oid);

    if (!parse_tag(tag) && tag->tag) {
      /*
       * TRANSLATORS: This is a line of ambiguous
       * tag object output. E.g.:
       *
       *    "deadbeef tag 2022-01-01 - Some Tag Message"
       *
       * The second argument is the YYYY-MM-DD found
       * in the tag.
       *
       * The third argument is the "tag" string
       * from object.c.
       */
      strbuf_addf(sb, _("%s tag %s - %s"), hash,
            show_date(tag->date, 0, DATE_MODE(SHORT)),
            tag->tag);
    } else {
      /*
       * TRANSLATORS: This is a line of ambiguous
       * tag object output where we couldn't parse
       * the tag itself. E.g.:
       *
       *    "deadbeef [bad tag, could not parse it]"
       */
      strbuf_addf(sb, _("%s [bad tag, could not parse it]"),
            hash);
    }
  } else if (type == OBJ_TREE) {
    /*
     * TRANSLATORS: This is a line of ambiguous <type>
     * object output. E.g. "deadbeef tree".
     */
    strbuf_addf(sb, _("%s tree"), hash);
  } else if (type == OBJ_BLOB) {
    /*
     * TRANSLATORS: This is a line of ambiguous <type>
     * object output. E.g. "deadbeef blob".
     */
    strbuf_addf(sb, _("%s blob"), hash);
  }


out:
  /*
   * TRANSLATORS: This is line item of ambiguous object output
   * from describe_ambiguous_object() above. For RTL languages
   * you'll probably want to swap the "%s" and leading " " space
   * around.
   */
  strbuf_addf(advice, _("  %s\n"), sb->buf);

  strbuf_reset(sb);
  return 0;
}

static int collect_ambiguous(const struct object_id *oid, void *data)
{
  oid_array_append(data, oid);
  return 0;
}

static int repo_collect_ambiguous(struct repository *r UNUSED,
          const struct object_id *oid,
          void *data)
{
  return collect_ambiguous(oid, data);
}

static int sort_ambiguous(const void *va, const void *vb, void *ctx)
{
  struct repository *sort_ambiguous_repo = ctx;
  const struct object_id *a = va, *b = vb;
  int a_type = odb_read_object_info(sort_ambiguous_repo->objects, a, NULL);
  int b_type = odb_read_object_info(sort_ambiguous_repo->objects, b, NULL);
  int a_type_sort;
  int b_type_sort;

  /*
   * Sorts by hash within the same object type, just as
   * oid_array_for_each_unique() would do.
   */
  if (a_type == b_type) {
    if (a->algo == b->algo)
      return oidcmp(a, b);
    else
      return a->algo > b->algo ? 1 : -1;
  }

  /*
   * Between object types show tags, then commits, and finally
   * trees and blobs.
   *
   * The object_type enum is commit, tree, blob, tag, but we
   * want tag, commit, tree blob. Cleverly (perhaps too
   * cleverly) do that with modulus, since the enum assigns 1 to
   * commit, so tag becomes 0.
   */
  a_type_sort = a_type % 4;
  b_type_sort = b_type % 4;
  return a_type_sort > b_type_sort ? 1 : -1;
}

static void sort_ambiguous_oid_array(struct repository *r, struct oid_array *a)
{
  QSORT_S(a->oid, a->nr, sort_ambiguous, r);
}

static enum get_oid_result get_short_oid(struct repository *r,
           const char *name, int len,
           struct object_id *oid,
           unsigned flags)
{
  int status;
  struct disambiguate_state ds;
  int quietly = !!(flags & GET_OID_QUIETLY);
  const struct git_hash_algo *algo = r->hash_algo;

  if (flags & GET_OID_HASH_ANY)
    algo = NULL;

  if (init_object_disambiguation(r, name, len, algo, &ds) < 0)
    return -1;

  if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
    BUG("multiple get_short_oid disambiguator flags");

  if (flags & GET_OID_COMMIT)
    ds.fn = disambiguate_commit_only;
  else if (flags & GET_OID_COMMITTISH)
    ds.fn = disambiguate_committish_only;
  else if (flags & GET_OID_TREE)
    ds.fn = disambiguate_tree_only;
  else if (flags & GET_OID_TREEISH)
    ds.fn = disambiguate_treeish_only;
  else if (flags & GET_OID_BLOB)
    ds.fn = disambiguate_blob_only;
  else
    ds.fn = default_disambiguate_hint;

  find_short_object_filename(&ds);
  find_short_packed_object(&ds);
  status = finish_object_disambiguation(&ds, oid);

  /*
   * If we didn't find it, do the usual reprepare() slow-path,
   * since the object may have recently been added to the repository
   * or migrated from loose to packed.
   */
  if (status == MISSING_OBJECT) {
    odb_reprepare(r->objects);
    find_short_object_filename(&ds);
    find_short_packed_object(&ds);
    status = finish_object_disambiguation(&ds, oid);
  }

  if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
    struct oid_array collect = OID_ARRAY_INIT;
    struct ambiguous_output out = {
      .ds = &ds,
      .sb = STRBUF_INIT,
      .advice = STRBUF_INIT,
    };

    error(_("short object ID %s is ambiguous"), ds.hex_pfx);

    /*
     * We may still have ambiguity if we simply saw a series of
     * candidates that did not satisfy our hint function. In
     * that case, we still want to show them, so disable the hint
     * function entirely.
     */
    if (!ds.ambiguous)
      ds.fn = NULL;

    repo_for_each_abbrev(r, ds.hex_pfx, algo, collect_ambiguous, &collect);
    sort_ambiguous_oid_array(r, &collect);

    if (oid_array_for_each(&collect, show_ambiguous_object, &out))
      BUG("show_ambiguous_object shouldn't return non-zero");

    /*
     * TRANSLATORS: The argument is the list of ambiguous
     * objects composed in show_ambiguous_object(). See
     * its "TRANSLATORS" comments for details.
     */
    advise(_("The candidates are:\n%s"), out.advice.buf);

    oid_array_clear(&collect);
    strbuf_release(&out.advice);
    strbuf_release(&out.sb);
  }

  return status;
}

int repo_for_each_abbrev(struct repository *r, const char *prefix,
       const struct git_hash_algo *algo,
       each_abbrev_fn fn, void *cb_data)
{
  struct oid_array collect = OID_ARRAY_INIT;
  struct disambiguate_state ds;
  int ret;

  if (init_object_disambiguation(r, prefix, strlen(prefix), algo, &ds) < 0)
    return -1;

  ds.always_call_fn = 1;
  ds.fn = repo_collect_ambiguous;
  ds.cb_data = &collect;
  find_short_object_filename(&ds);
  find_short_packed_object(&ds);

  ret = oid_array_for_each_unique(&collect, fn, cb_data);
  oid_array_clear(&collect);
  return ret;
}

/*
 * Return the slot of the most-significant bit set in "val". There are various
 * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 * probably not a big deal here.
 */
static unsigned msb(unsigned long val)
{
  unsigned r = 0;
  while (val >>= 1)
    r++;
  return r;
}

struct min_abbrev_data {
  unsigned int init_len;
  unsigned int cur_len;
  char *hex;
  struct repository *repo;
  const struct object_id *oid;
};

static inline char get_hex_char_from_oid(const struct object_id *oid,
           unsigned int pos)
{
  static const char hex[] = "0123456789abcdef";

  if ((pos & 1) == 0)
    return hex[oid->hash[pos >> 1] >> 4];
  else
    return hex[oid->hash[pos >> 1] & 0xf];
}

static int extend_abbrev_len(const struct object_id *oid,
           struct min_abbrev_data *mad)
{
  unsigned int i = mad->init_len;
  while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
    i++;

  if (mad->hex[i] && i >= mad->cur_len)
    mad->cur_len = i + 1;

  return 0;
}

static int repo_extend_abbrev_len(struct repository *r UNUSED,
          const struct object_id *oid,
          void *cb_data)
{
  return extend_abbrev_len(oid, cb_data);
}

static void find_abbrev_len_for_midx(struct multi_pack_index *m,
             struct min_abbrev_data *mad)
{
  for (; m; m = m->base_midx) {
    int match = 0;
    uint32_t num, first = 0;
    struct object_id oid;
    const struct object_id *mad_oid;

    if (!m->num_objects)
      continue;

    num = m->num_objects + m->num_objects_in_base;
    mad_oid = mad->oid;
    match = bsearch_one_midx(mad_oid, m, &first);

    /*
     * first is now the position in the packfile where we
     * would insert mad->hash if it does not exist (or the
     * position of mad->hash if it does exist). Hence, we
     * consider a maximum of two objects nearby for the
     * abbreviation length.
     */
    mad->init_len = 0;
    if (!match) {
      if (nth_midxed_object_oid(&oid, m, first))
        extend_abbrev_len(&oid, mad);
    } else if (first < num - 1) {
      if (nth_midxed_object_oid(&oid, m, first + 1))
        extend_abbrev_len(&oid, mad);
    }
    if (first > 0) {
      if (nth_midxed_object_oid(&oid, m, first - 1))
        extend_abbrev_len(&oid, mad);
    }
    mad->init_len = mad->cur_len;
  }
}

static void find_abbrev_len_for_pack(struct packed_git *p,
             struct min_abbrev_data *mad)
{
  int match = 0;
  uint32_t num, first = 0;
  struct object_id oid;
  const struct object_id *mad_oid;

  if (p->multi_pack_index)
    return;

  if (open_pack_index(p) || !p->num_objects)
    return;

  num = p->num_objects;
  mad_oid = mad->oid;
  match = bsearch_pack(mad_oid, p, &first);

  /*
   * first is now the position in the packfile where we would insert
   * mad->hash if it does not exist (or the position of mad->hash if
   * it does exist). Hence, we consider a maximum of two objects
   * nearby for the abbreviation length.
   */
  mad->init_len = 0;
  if (!match) {
    if (!nth_packed_object_id(&oid, p, first))
      extend_abbrev_len(&oid, mad);
  } else if (first < num - 1) {
    if (!nth_packed_object_id(&oid, p, first + 1))
      extend_abbrev_len(&oid, mad);
  }
  if (first > 0) {
    if (!nth_packed_object_id(&oid, p, first - 1))
      extend_abbrev_len(&oid, mad);
  }
  mad->init_len = mad->cur_len;
}

static void find_abbrev_len_packed(struct min_abbrev_data *mad)
{
  struct packed_git *p;

  odb_prepare_alternates(mad->repo->objects);
  for (struct odb_source *source = mad->repo->objects->sources; source; source = source->next) {
    struct multi_pack_index *m = get_multi_pack_index(source);
    if (m)
      find_abbrev_len_for_midx(m, mad);
  }

  repo_for_each_pack(mad->repo, p)
    find_abbrev_len_for_pack(p, mad);
}

void strbuf_repo_add_unique_abbrev(struct strbuf *sb, struct repository *repo,
           const struct object_id *oid, int abbrev_len)
{
  int r;
  strbuf_grow(sb, GIT_MAX_HEXSZ + 1);
  r = repo_find_unique_abbrev_r(repo, sb->buf + sb->len, oid, abbrev_len);
  strbuf_setlen(sb, sb->len + r);
}

void strbuf_add_unique_abbrev(struct strbuf *sb, const struct object_id *oid,
            int abbrev_len)
{
  strbuf_repo_add_unique_abbrev(sb, the_repository, oid, abbrev_len);
}

int repo_find_unique_abbrev_r(struct repository *r, char *hex,
            const struct object_id *oid, int len)
{
  const struct git_hash_algo *algo =
    oid->algo ? &hash_algos[oid->algo] : r->hash_algo;
  struct disambiguate_state ds;
  struct min_abbrev_data mad;
  struct object_id oid_ret;
  const unsigned hexsz = algo->hexsz;

  if (len < 0) {
    unsigned long count = repo_approximate_object_count(r);
    /*
     * Add one because the MSB only tells us the highest bit set,
     * not including the value of all the _other_ bits (so "15"
     * is only one off of 2^4, but the MSB is the 3rd bit.
     */
    len = msb(count) + 1;
    /*
     * We now know we have on the order of 2^len objects, which
     * expects a collision at 2^(len/2). But we also care about hex
     * chars, not bits, and there are 4 bits per hex. So all
     * together we need to divide by 2 and round up.
     */
    len = DIV_ROUND_UP(len, 2);
    /*
     * For very small repos, we stick with our regular fallback.
     */
    if (len < FALLBACK_DEFAULT_ABBREV)
      len = FALLBACK_DEFAULT_ABBREV;
  }

  oid_to_hex_r(hex, oid);
  if (len >= hexsz || !len)
    return hexsz;

  mad.repo = r;
  mad.init_len = len;
  mad.cur_len = len;
  mad.hex = hex;
  mad.oid = oid;

  find_abbrev_len_packed(&mad);

  if (init_object_disambiguation(r, hex, mad.cur_len, algo, &ds) < 0)
    return -1;

  ds.fn = repo_extend_abbrev_len;
  ds.always_call_fn = 1;
  ds.cb_data = (void *)&mad;

  find_short_object_filename(&ds);
  (void)finish_object_disambiguation(&ds, &oid_ret);

  hex[mad.cur_len] = 0;
  return mad.cur_len;
}

const char *repo_find_unique_abbrev(struct repository *r,
            const struct object_id *oid,
            int len)
{
  static int bufno;
  static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
  char *hex = hexbuffer[bufno];
  bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
  repo_find_unique_abbrev_r(r, hex, oid, len);
  return hex;
}

static int ambiguous_path(const char *path, int len)
{
  int slash = 1;
  int cnt;

  for (cnt = 0; cnt < len; cnt++) {
    switch (*path++) {
    case '\0':
      break;
    case '/':
      if (slash)
        break;
      slash = 1;
      continue;
    case '.':
      continue;
    default:
      slash = 0;
      continue;
    }
    break;
  }
  return slash;
}

static inline int at_mark(const char *string, int len,
        const char **suffix, int nr)
{
  int i;

  for (i = 0; i < nr; i++) {
    int suffix_len = strlen(suffix[i]);
    if (suffix_len <= len
        && !strncasecmp(string, suffix[i], suffix_len))
      return suffix_len;
  }
  return 0;
}

static inline int upstream_mark(const char *string, int len)
{
  const char *suffix[] = { "@{upstream}", "@{u}" };
  return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
}

static inline int push_mark(const char *string, int len)
{
  const char *suffix[] = { "@{push}" };
  return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
}

static enum get_oid_result get_oid_1(struct repository *r, const char *name, int len, struct object_id *oid, unsigned lookup_flags);
static int interpret_nth_prior_checkout(struct repository *r, const char *name, int namelen, struct strbuf *buf);

static int get_oid_basic(struct repository *r, const char *str, int len,
       struct object_id *oid, unsigned int flags)
{
  static const char *warn_msg = "refname '%.*s' is ambiguous.";
  static const char *object_name_msg = N_(
  "Git normally never creates a ref that ends with 40 hex characters\n"
  "because it will be ignored when you just specify 40-hex. These refs\n"
  "may be created by mistake. For example,\n"
  "\n"
  "  git switch -c $br $(git rev-parse ...)\n"
  "\n"
  "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
  "examine these refs and maybe delete them. Turn this message off by\n"
  "running \"git config set advice.objectNameWarning false\"");
  struct object_id tmp_oid;
  char *real_ref = NULL;
  int refs_found = 0;
  int at, reflog_len, nth_prior = 0;
  int fatal = !(flags & GET_OID_QUIETLY);

  if (len == r->hash_algo->hexsz && !get_oid_hex(str, oid)) {
    if (!(flags & GET_OID_SKIP_AMBIGUITY_CHECK) &&
        repo_settings_get_warn_ambiguous_refs(r) &&
        warn_on_object_refname_ambiguity) {
      refs_found = repo_dwim_ref(r, str, len, &tmp_oid, &real_ref, 0);
      if (refs_found > 0) {
        warning(warn_msg, len, str);
        if (advice_enabled(ADVICE_OBJECT_NAME_WARNING))
          fprintf(stderr, "%s\n", _(object_name_msg));
      }
      free(real_ref);
    }
    return 0;
  }

  /* basic@{time or number or -number} format to query ref-log */
  reflog_len = at = 0;
  if (len && str[len-1] == '}') {
    for (at = len-4; at >= 0; at--) {
      if (str[at] == '@' && str[at+1] == '{') {
        if (str[at+2] == '-') {
          if (at != 0)
            /* @{-N} not at start */
            return -1;
          nth_prior = 1;
          continue;
        }
        if (!upstream_mark(str + at, len - at) &&
            !push_mark(str + at, len - at)) {
          reflog_len = (len-1) - (at+2);
          len = at;
        }
        break;
      }
    }
  }

  /* Accept only unambiguous ref paths. */
  if (len && ambiguous_path(str, len))
    return -1;

  if (nth_prior) {
    struct strbuf buf = STRBUF_INIT;
    int detached;

    if (interpret_nth_prior_checkout(r, str, len, &buf) > 0) {
      detached = (buf.len == r->hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
      strbuf_release(&buf);
      if (detached)
        return 0;
    }
  }

  if (!len && reflog_len)
    /* allow "@{...}" to mean the current branch reflog */
    refs_found = repo_dwim_ref(r, "HEAD", 4, oid, &real_ref, !fatal);
  else if (reflog_len)
    refs_found = repo_dwim_log(r, str, len, oid, &real_ref);
  else
    refs_found = repo_dwim_ref(r, str, len, oid, &real_ref, !fatal);

  if (!refs_found)
    return -1;

  if (repo_settings_get_warn_ambiguous_refs(r) && !(flags & GET_OID_QUIETLY) &&
      (refs_found > 1 ||
       !get_short_oid(r, str, len, &tmp_oid, GET_OID_QUIETLY)))
    warning(warn_msg, len, str);

  if (reflog_len) {
    int nth, i;
    timestamp_t at_time;
    timestamp_t co_time;
    int co_tz, co_cnt;

    /* Is it asking for N-th entry, or approxidate? */
    for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
      char ch = str[at+2+i];
      if ('0' <= ch && ch <= '9')
        nth = nth * 10 + ch - '0';
      else
        nth = -1;
    }
    if (100000000 <= nth) {
      at_time = nth;
      nth = -1;
    } else if (0 <= nth)
      at_time = 0;
    else {
      int errors = 0;
      char *tmp = xstrndup(str + at + 2, reflog_len);
      at_time = approxidate_careful(tmp, &errors);
      free(tmp);
      if (errors) {
        free(real_ref);
        return -1;
      }
    }
    if (read_ref_at(get_main_ref_store(r),
        real_ref, flags, at_time, nth, oid, NULL,
        &co_time, &co_tz, &co_cnt)) {
      if (!len) {
        if (!skip_prefix(real_ref, "refs/heads/", &str))
          str = "HEAD";
        len = strlen(str);
      }
      if (at_time) {
        if (!(flags & GET_OID_QUIETLY)) {
          warning(_("log for '%.*s' only goes back to %s"),
            len, str,
            show_date(co_time, co_tz, DATE_MODE(RFC2822)));
        }
      } else if (nth == co_cnt && !is_null_oid(oid)) {
        /*
         * We were asked for the Nth reflog (counting
         * from 0), but there were only N entries.
         * read_ref_at() will have returned "1" to tell
         * us it did not find an entry, but it did
         * still fill in the oid with the "old" value,
         * which we can use.
         */
      } else if (!(flags & GET_OID_GENTLY)) {
        if (flags & GET_OID_QUIETLY) {
          exit(128);
        }
        die(_("log for '%.*s' only has %d entries"),
            len, str, co_cnt);
      }
      if (flags & GET_OID_GENTLY) {
        free(real_ref);
        return -1;
      }
    }
  }

  free(real_ref);
  return 0;
}

static enum get_oid_result get_parent(struct repository *r,
              const char *name, int len,
              struct object_id *result, int idx)
{
  struct object_id oid;
  enum get_oid_result ret = get_oid_1(r, name, len, &oid,
              GET_OID_COMMITTISH);
  struct commit *commit;
  struct commit_list *p;

  if (ret)
    return ret;
  commit = lookup_commit_reference(r, &oid);
  if (repo_parse_commit(r, commit))
    return MISSING_OBJECT;
  if (!idx) {
    oidcpy(result, &commit->object.oid);
    return FOUND;
  }
  p = commit->parents;
  while (p) {
    if (!--idx) {
      oidcpy(result, &p->item->object.oid);
      return FOUND;
    }
    p = p->next;
  }
  return MISSING_OBJECT;
}

static enum get_oid_result get_nth_ancestor(struct repository *r,
              const char *name, int len,
              struct object_id *result,
              int generation)
{
  struct object_id oid;
  struct commit *commit;
  int ret;

  ret = get_oid_1(r, name, len, &oid, GET_OID_COMMITTISH);
  if (ret)
    return ret;
  commit = lookup_commit_reference(r, &oid);
  if (!commit)
    return MISSING_OBJECT;

  while (generation--) {
    if (repo_parse_commit(r, commit) || !commit->parents)
      return MISSING_OBJECT;
    commit = commit->parents->item;
  }
  oidcpy(result, &commit->object.oid);
  return FOUND;
}

struct object *repo_peel_to_type(struct repository *r, const char *name, int namelen,
         struct object *o, enum object_type expected_type)
{
  if (name && !namelen)
    namelen = strlen(name);
  while (1) {
    if (!o || (!o->parsed && !parse_object(r, &o->oid)))
      return NULL;
    if (expected_type == OBJ_ANY || o->type == expected_type)
      return o;
    if (o->type == OBJ_TAG)
      o = ((struct tag*) o)->tagged;
    else if (o->type == OBJ_COMMIT)
      o = &(repo_get_commit_tree(r, ((struct commit *)o))->object);
    else {
      if (name)
        error("%.*s: expected %s type, but the object "
              "dereferences to %s type",
              namelen, name, type_name(expected_type),
              type_name(o->type));
      return NULL;
    }
  }
}

static int peel_onion(struct repository *r, const char *name, int len,
          struct object_id *oid, unsigned lookup_flags)
{
  struct object_id outer;
  const char *sp;
  unsigned int expected_type = 0;
  struct object *o;

  /*
   * "ref^{type}" dereferences ref repeatedly until you cannot
   * dereference anymore, or you get an object of given type,
   * whichever comes first.  "ref^{}" means just dereference
   * tags until you get a non-tag.  "ref^0" is a shorthand for
   * "ref^{commit}".  "commit^{tree}" could be used to find the
   * top-level tree of the given commit.
   */
  if (len < 4 || name[len-1] != '}')
    return -1;

  for (sp = name + len - 1; name <= sp; sp--) {
    int ch = *sp;
    if (ch == '{' && name < sp && sp[-1] == '^')
      break;
  }
  if (sp <= name)
    return -1;

  sp++; /* beginning of type name, or closing brace for empty */
  if (starts_with(sp, "commit}"))
    expected_type = OBJ_COMMIT;
  else if (starts_with(sp, "tag}"))
    expected_type = OBJ_TAG;
  else if (starts_with(sp, "tree}"))
    expected_type = OBJ_TREE;
  else if (starts_with(sp, "blob}"))
    expected_type = OBJ_BLOB;
  else if (starts_with(sp, "object}"))
    expected_type = OBJ_ANY;
  else if (sp[0] == '}')
    expected_type = OBJ_NONE;
  else if (sp[0] == '/')
    expected_type = OBJ_COMMIT;
  else
    return -1;

  lookup_flags &= ~GET_OID_DISAMBIGUATORS;
  if (expected_type == OBJ_COMMIT)
    lookup_flags |= GET_OID_COMMITTISH;
  else if (expected_type == OBJ_TREE)
    lookup_flags |= GET_OID_TREEISH;

  if (get_oid_1(r, name, sp - name - 2, &outer, lookup_flags))
    return -1;

  o = parse_object(r, &outer);
  if (!o)
    return -1;
  if (!expected_type) {
    o = deref_tag(r, o, name, sp - name - 2);
    if (!o || (!o->parsed && !parse_object(r, &o->oid)))
      return -1;
    oidcpy(oid, &o->oid);
    return 0;
  }

  /*
   * At this point, the syntax look correct, so
   * if we do not get the needed object, we should
   * barf.
   */
  o = repo_peel_to_type(r, name, len, o, expected_type);
  if (!o)
    return -1;

  oidcpy(oid, &o->oid);
  if (sp[0] == '/') {
    /* "$commit^{/foo}" */
    char *prefix;
    int ret;
    struct commit_list *list = NULL;

    /*
     * $commit^{/}. Some regex implementation may reject.
     * We don't need regex anyway. '' pattern always matches.
     */
    if (sp[1] == '}')
      return 0;

    prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
    commit_list_insert((struct commit *)o, &list);
    ret = get_oid_oneline(r, prefix, oid, list);

    free_commit_list(list);
    free(prefix);
    return ret;
  }
  return 0;
}

/*
 * Documentation/revisions.adoc says:
 *    '<describeOutput>', e.g. 'v1.7.4.2-679-g3bee7fb'::
 *      Output from `git describe`; i.e. a closest tag, optionally
 *      followed by a dash and a number of commits, followed by a dash, a
 *      'g', and an abbreviated object name.
 *
 * which means that the stuff before '-g${HASH}' needs to be a valid
 * refname, a dash, and a non-negative integer.  This function verifies
 * that.
 *
 * In particular, we do not want to treat
 *   branchname:path/to/file/named/i-gaffed
 * as a request for commit affed.
 *
 * More generally, we should probably not treat
 *   'refs/heads/./../.../ ~^:/?*[////\\\&}/busted.lock-g050e0ef6ead'
 * as a request for object 050e0ef6ead either.
 *
 * We are called with name[len] == '-' and name[len+1] == 'g', i.e.
 * we are verifying ${REFNAME}-{INTEGER} part of the name.
 */
static int ref_and_count_parts_valid(const char *name, int len)
{
  struct strbuf sb;
  const char *cp;
  int flags = REFNAME_ALLOW_ONELEVEL;
  int ret = 1;

  /* Ensure we have at least one digit */
  if (!isxdigit(name[len-1]))
    return 0;

  /* Skip over digits backwards until we get to the dash */
  for (cp = name + len - 2; name < cp; cp--) {
    if (*cp == '-')
      break;
    if (!isxdigit(*cp))
      return 0;
  }
  /* Ensure we found the leading dash */
  if (*cp != '-')
    return 0;

  len = cp - name;
  strbuf_init(&sb, len);
  strbuf_add(&sb, name, len);
  ret = !check_refname_format(sb.buf, flags);
  strbuf_release(&sb);
  return ret;
}

static int get_describe_name(struct repository *r,
           const char *name, int len,
           struct object_id *oid)
{
  const char *cp;
  unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;

  for (cp = name + len - 1; name + 2 <= cp; cp--) {
    char ch = *cp;
    if (!isxdigit(ch)) {
      /* We must be looking at g in "SOMETHING-g"
       * for it to be describe output.
       */
      if (ch == 'g' && cp[-1] == '-' &&
          ref_and_count_parts_valid(name, cp - 1 - name)) {
        cp++;
        len -= cp - name;
        return get_short_oid(r,
                 cp, len, oid, flags);
      }
    }
  }
  return -1;
}

static enum get_oid_result get_oid_1(struct repository *r,
             const char *name, int len,
             struct object_id *oid,
             unsigned lookup_flags)
{
  int ret, has_suffix;
  const char *cp;

  /*
   * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
   */
  has_suffix = 0;
  for (cp = name + len - 1; name <= cp; cp--) {
    int ch = *cp;
    if ('0' <= ch && ch <= '9')
      continue;
    if (ch == '~' || ch == '^')
      has_suffix = ch;
    break;
  }

  if (has_suffix) {
    unsigned int num = 0;
    int len1 = cp - name;
    cp++;
    while (cp < name + len) {
      unsigned int digit = *cp++ - '0';
      if (unsigned_mult_overflows(num, 10))
        return MISSING_OBJECT;
      num *= 10;
      if (unsigned_add_overflows(num, digit))
        return MISSING_OBJECT;
      num += digit;
    }
    if (!num && len1 == len - 1)
      num = 1;
    else if (num > INT_MAX)
      return MISSING_OBJECT;
    if (has_suffix == '^')
      return get_parent(r, name, len1, oid, num);
    /* else if (has_suffix == '~') -- goes without saying */
    return get_nth_ancestor(r, name, len1, oid, num);
  }

  ret = peel_onion(r, name, len, oid, lookup_flags);
  if (!ret)
    return FOUND;

  ret = get_oid_basic(r, name, len, oid, lookup_flags);
  if (!ret)
    return FOUND;

  /* It could be describe output that is "SOMETHING-gXXXX" */
  ret = get_describe_name(r, name, len, oid);
  if (!ret)
    return FOUND;

  return get_short_oid(r, name, len, oid, lookup_flags);
}

/*
 * This interprets names like ':/Initial revision of "git"' by searching
 * through history and returning the first commit whose message starts
 * the given regular expression.
 *
 * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 *
 * For a literal '!' character at the beginning of a pattern, you have to repeat
 * that, like: ':/!!foo'
 *
 * For future extension, all other sequences beginning with ':/!' are reserved.
 */

/* Remember to update object flag allocation in object.h */
#define ONELINE_SEEN (1u<<20)

struct handle_one_ref_cb {
  struct repository *repo;
  struct commit_list **list;
};

static int handle_one_ref(const struct reference *ref, void *cb_data)
{
  struct handle_one_ref_cb *cb = cb_data;
  struct commit_list **list = cb->list;
  struct object *object = parse_object(cb->repo, ref->oid);
  if (!object)
    return 0;
  if (object->type == OBJ_TAG) {
    object = deref_tag(cb->repo, object, ref->name,
           strlen(ref->name));
    if (!object)
      return 0;
  }
  if (object->type != OBJ_COMMIT)
    return 0;
  commit_list_insert((struct commit *)object, list);
  return 0;
}

static int get_oid_oneline(struct repository *r,
         const char *prefix, struct object_id *oid,
         const struct commit_list *list)
{
  struct prio_queue copy = { compare_commits_by_commit_date };
  const struct commit_list *l;
  int found = 0;
  int negative = 0;
  regex_t regex;

  if (prefix[0] == '!') {
    prefix++;

    if (prefix[0] == '-') {
      prefix++;
      negative = 1;
    } else if (prefix[0] != '!') {
      return -1;
    }
  }

  if (regcomp(&regex, prefix, REG_EXTENDED))
    return -1;

  for (l = list; l; l = l->next) {
    l->item->object.flags |= ONELINE_SEEN;
    prio_queue_put(&copy, l->item);
  }
  while (copy.nr) {
    const char *p, *buf;
    struct commit *commit;
    int matches;

    commit = pop_most_recent_commit(&copy, ONELINE_SEEN);
    if (!parse_object(r, &commit->object.oid))
      continue;
    buf = repo_get_commit_buffer(r, commit, NULL);
    p = strstr(buf, "\n\n");
    matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
    repo_unuse_commit_buffer(r, commit, buf);

    if (matches) {
      oidcpy(oid, &commit->object.oid);
      found = 1;
      break;
    }
  }
  regfree(&regex);
  for (l = list; l; l = l->next)
    clear_commit_marks(l->item, ONELINE_SEEN);
  clear_prio_queue(&copy);
  return found ? 0 : -1;
}

struct grab_nth_branch_switch_cbdata {
  int remaining;
  struct strbuf *sb;
};

static int grab_nth_branch_switch(const char *refname UNUSED,
          struct object_id *ooid UNUSED,
          struct object_id *noid UNUSED,
          const char *email UNUSED,
          timestamp_t timestamp UNUSED,
          int tz UNUSED,
          const char *message, void *cb_data)
{
  struct grab_nth_branch_switch_cbdata *cb = cb_data;
  const char *match = NULL, *target = NULL;
  size_t len;

  if (skip_prefix(message, "checkout: moving from ", &match))
    target = strstr(match, " to ");

  if (!match || !target)
    return 0;
  if (--(cb->remaining) == 0) {
    len = target - match;
    strbuf_reset(cb->sb);
    strbuf_add(cb->sb, match, len);
    return 1; /* we are done */
  }
  return 0;
}

/*
 * Parse @{-N} syntax, return the number of characters parsed
 * if successful; otherwise signal an error with negative value.
 */
static int interpret_nth_prior_checkout(struct repository *r,
          const char *name, int namelen,
          struct strbuf *buf)
{
  long nth;
  int retval;
  struct grab_nth_branch_switch_cbdata cb;
  const char *brace;
  char *num_end;

  if (namelen < 4)
    return -1;
  if (name[0] != '@' || name[1] != '{' || name[2] != '-')
    return -1;
  brace = memchr(name, '}', namelen);
  if (!brace)
    return -1;
  nth = strtol(name + 3, &num_end, 10);
  if (num_end != brace)
    return -1;
  if (nth <= 0)
    return -1;
  cb.remaining = nth;
  cb.sb = buf;

  retval = refs_for_each_reflog_ent_reverse(get_main_ref_store(r),
      "HEAD", grab_nth_branch_switch, &cb);
  if (0 < retval) {
    retval = brace - name + 1;
  } else
    retval = 0;

  return retval;
}

int repo_get_oid_mb(struct repository *r,
        const char *name,
        struct object_id *oid)
{
  struct commit *one, *two;
  struct commit_list *mbs = NULL;
  struct object_id oid_tmp;
  const char *dots;
  int st;

  dots = strstr(name, "...");
  if (!dots)
    return repo_get_oid(r, name, oid);
  if (dots == name)
    st = repo_get_oid(r, "HEAD", &oid_tmp);
  else {
    struct strbuf sb;
    strbuf_init(&sb, dots - name);
    strbuf_add(&sb, name, dots - name);
    st = repo_get_oid_committish(r, sb.buf, &oid_tmp);
    strbuf_release(&sb);
  }
  if (st)
    return st;
  one = lookup_commit_reference_gently(r, &oid_tmp, 0);
  if (!one)
    return -1;

  if (repo_get_oid_committish(r, dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
    return -1;
  two = lookup_commit_reference_gently(r, &oid_tmp, 0);
  if (!two)
    return -1;
  if (repo_get_merge_bases(r, one, two, &mbs) < 0) {
    free_commit_list(mbs);
    return -1;
  }
  if (!mbs || mbs->next)
    st = -1;
  else {
    st = 0;
    oidcpy(oid, &mbs->item->object.oid);
  }
  free_commit_list(mbs);
  return st;
}

/* parse @something syntax, when 'something' is not {.*} */
static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
{
  const char *next;

  if (len || name[1] == '{')
    return -1;

  /* make sure it's a single @, or @@{.*}, not @foo */
  next = memchr(name + len + 1, '@', namelen - len - 1);
  if (next && next[1] != '{')
    return -1;
  if (!next)
    next = name + namelen;
  if (next != name + 1)
    return -1;

  strbuf_reset(buf);
  strbuf_add(buf, "HEAD", 4);
  return 1;
}

static int reinterpret(struct repository *r,
           const char *name, int namelen, int len,
           struct strbuf *buf, unsigned allowed)
{
  /* we have extra data, which might need further processing */
  struct strbuf tmp = STRBUF_INIT;
  int used = buf->len;
  int ret;
  struct interpret_branch_name_options options = {
    .allowed = allowed
  };

  strbuf_add(buf, name + len, namelen - len);
  ret = repo_interpret_branch_name(r, buf->buf, buf->len, &tmp, &options);
  /* that data was not interpreted, remove our cruft */
  if (ret < 0) {
    strbuf_setlen(buf, used);
    return len;
  }
  strbuf_reset(buf);
  strbuf_addbuf(buf, &tmp);
  strbuf_release(&tmp);
  /* tweak for size of {-N} versus expanded ref name */
  return ret - used + len;
}

static void set_shortened_ref(struct repository *r, struct strbuf *buf, const char *ref)
{
  char *s = refs_shorten_unambiguous_ref(get_main_ref_store(r), ref, 0);
  strbuf_reset(buf);
  strbuf_addstr(buf, s);
  free(s);
}

static int branch_interpret_allowed(const char *refname, unsigned allowed)
{
  if (!allowed)
    return 1;

  if ((allowed & INTERPRET_BRANCH_LOCAL) &&
      starts_with(refname, "refs/heads/"))
    return 1;
  if ((allowed & INTERPRET_BRANCH_REMOTE) &&
      starts_with(refname, "refs/remotes/"))
    return 1;

  return 0;
}

static int interpret_branch_mark(struct repository *r,
         const char *name, int namelen,
         int at, struct strbuf *buf,
         int (*get_mark)(const char *, int),
         const char *(*get_data)(struct branch *,
               struct strbuf *),
         const struct interpret_branch_name_options *options)
{
  int len;
  struct branch *branch;
  struct strbuf err = STRBUF_INIT;
  const char *value;

  len = get_mark(name + at, namelen - at);
  if (!len)
    return -1;

  if (memchr(name, ':', at))
    return -1;

  if (at) {
    char *name_str = xmemdupz(name, at);
    branch = branch_get(name_str);
    free(name_str);
  } else
    branch = branch_get(NULL);

  value = get_data(branch, &err);
  if (!value) {
    if (options->nonfatal_dangling_mark) {
      strbuf_release(&err);
      return -1;
    } else {
      die("%s", err.buf);
    }
  }

  if (!branch_interpret_allowed(value, options->allowed))
    return -1;

  set_shortened_ref(r, buf, value);
  return len + at;
}

int repo_interpret_branch_name(struct repository *r,
             const char *name, int namelen,
             struct strbuf *buf,
             const struct interpret_branch_name_options *options)
{
  char *at;
  const char *start;
  int len;

  if (!namelen)
    namelen = strlen(name);

  if (!options->allowed || (options->allowed & INTERPRET_BRANCH_LOCAL)) {
    len = interpret_nth_prior_checkout(r, name, namelen, buf);
    if (!len) {
      return len; /* syntax Ok, not enough switches */
    } else if (len > 0) {
      if (len == namelen)
        return len; /* consumed all */
      else
        return reinterpret(r, name, namelen, len, buf,
               options->allowed);
    }
  }

  for (start = name;
       (at = memchr(start, '@', namelen - (start - name)));
       start = at + 1) {

    if (!options->allowed || (options->allowed & INTERPRET_BRANCH_HEAD)) {
      len = interpret_empty_at(name, namelen, at - name, buf);
      if (len > 0)
        return reinterpret(r, name, namelen, len, buf,
               options->allowed);
    }

    len = interpret_branch_mark(r, name, namelen, at - name, buf,
              upstream_mark, branch_get_upstream,
              options);
    if (len > 0)
      return len;

    len = interpret_branch_mark(r, name, namelen, at - name, buf,
              push_mark, branch_get_push,
              options);
    if (len > 0)
      return len;
  }

  return -1;
}

void object_context_release(struct object_context *ctx)
{
  free(ctx->path);
  strbuf_release(&ctx->symlink_path);
}

int repo_get_oid_with_flags(struct repository *r, const char *name,
          struct object_id *oid, unsigned flags)
{
  struct object_context unused;
  int ret = get_oid_with_context(r, name, flags, oid, &unused);
  object_context_release(&unused);
  return ret;
}

int repo_get_oid(struct repository *r, const char *name, struct object_id *oid)
{
  return repo_get_oid_with_flags(r, name, oid, 0);
}

/*
 * This returns a non-zero value if the string (built using printf
 * format and the given arguments) is not a valid object.
 */
int get_oidf(struct object_id *oid, const char *fmt, ...)
{
  va_list ap;
  int ret;
  struct strbuf sb = STRBUF_INIT;

  va_start(ap, fmt);
  strbuf_vaddf(&sb, fmt, ap);
  va_end(ap);

  ret = repo_get_oid(the_repository, sb.buf, oid);
  strbuf_release(&sb);

  return ret;
}

/*
 * Many callers know that the user meant to name a commit-ish by
 * syntactical positions where the object name appears.  Calling this
 * function allows the machinery to disambiguate shorter-than-unique
 * abbreviated object names between commit-ish and others.
 *
 * Note that this does NOT error out when the named object is not a
 * commit-ish. It is merely to give a hint to the disambiguation
 * machinery.
 */
int repo_get_oid_committish(struct repository *r,
          const char *name,
          struct object_id *oid)
{
  return repo_get_oid_with_flags(r, name, oid, GET_OID_COMMITTISH);
}

int repo_get_oid_treeish(struct repository *r,
       const char *name,
       struct object_id *oid)
{
  return repo_get_oid_with_flags(r, name, oid, GET_OID_TREEISH);
}

int repo_get_oid_commit(struct repository *r,
      const char *name,
      struct object_id *oid)
{
  return repo_get_oid_with_flags(r, name, oid, GET_OID_COMMIT);
}

int repo_get_oid_tree(struct repository *r,
          const char *name,
          struct object_id *oid)
{
  return repo_get_oid_with_flags(r, name, oid, GET_OID_TREE);
}

int repo_get_oid_blob(struct repository *r,
          const char *name,
          struct object_id *oid)
{
  return repo_get_oid_with_flags(r, name, oid, GET_OID_BLOB);
}

/* Must be called only when object_name:filename doesn't exist. */
static void diagnose_invalid_oid_path(struct repository *r,
              const char *prefix,
              const char *filename,
              const struct object_id *tree_oid,
              const char *object_name,
              int object_name_len)
{
  struct object_id oid;
  unsigned short mode;

  if (!prefix)
    prefix = "";

  if (file_exists(filename))
    die(_("path '%s' exists on disk, but not in '%.*s'"),
        filename, object_name_len, object_name);
  if (is_missing_file_error(errno)) {
    char *fullname = xstrfmt("%s%s", prefix, filename);

    if (!get_tree_entry(r, tree_oid, fullname, &oid, &mode)) {
      die(_("path '%s' exists, but not '%s'\n"
          "hint: Did you mean '%.*s:%s' aka '%.*s:./%s'?"),
          fullname,
          filename,
          object_name_len, object_name,
          fullname,
          object_name_len, object_name,
          filename);
    }
    die(_("path '%s' does not exist in '%.*s'"),
        filename, object_name_len, object_name);
  }
}

/* Must be called only when :stage:filename doesn't exist. */
static void diagnose_invalid_index_path(struct repository *r,
          int stage,
          const char *prefix,
          const char *filename)
{
  struct index_state *istate = r->index;
  const struct cache_entry *ce;
  int pos;
  unsigned namelen = strlen(filename);
  struct strbuf fullname = STRBUF_INIT;

  if (!prefix)
    prefix = "";

  /* Wrong stage number? */
  pos = index_name_pos(istate, filename, namelen);
  if (pos < 0)
    pos = -pos - 1;
  if (pos < istate->cache_nr) {
    ce = istate->cache[pos];
    if (!S_ISSPARSEDIR(ce->ce_mode) &&
        ce_namelen(ce) == namelen &&
        !memcmp(ce->name, filename, namelen))
      die(_("path '%s' is in the index, but not at stage %d\n"
          "hint: Did you mean ':%d:%s'?"),
          filename, stage,
          ce_stage(ce), filename);
  }

  /* Confusion between relative and absolute filenames? */
  strbuf_addstr(&fullname, prefix);
  strbuf_addstr(&fullname, filename);
  pos = index_name_pos(istate, fullname.buf, fullname.len);
  if (pos < 0)
    pos = -pos - 1;
  if (pos < istate->cache_nr) {
    ce = istate->cache[pos];
    if (!S_ISSPARSEDIR(ce->ce_mode) &&
        ce_namelen(ce) == fullname.len &&
        !memcmp(ce->name, fullname.buf, fullname.len))
      die(_("path '%s' is in the index, but not '%s'\n"
          "hint: Did you mean ':%d:%s' aka ':%d:./%s'?"),
          fullname.buf, filename,
          ce_stage(ce), fullname.buf,
          ce_stage(ce), filename);
  }

  if (repo_file_exists(r, filename))
    die(_("path '%s' exists on disk, but not in the index"), filename);
  if (is_missing_file_error(errno))
    die(_("path '%s' does not exist (neither on disk nor in the index)"),
        filename);

  strbuf_release(&fullname);
}


static char *resolve_relative_path(struct repository *r, const char *rel)
{
  if (!starts_with(rel, "./") && !starts_with(rel, "../"))
    return NULL;

  if (r != the_repository || !is_inside_work_tree())
    die(_("relative path syntax can't be used outside working tree"));

  /* die() inside prefix_path() if resolved path is outside worktree */
  return prefix_path(startup_info->prefix,
         startup_info->prefix ? strlen(startup_info->prefix) : 0,
         rel);
}

static int reject_tree_in_index(struct repository *repo,
        int only_to_die,
        const struct cache_entry *ce,
        int stage,
        const char *prefix,
        const char *cp)
{
  if (!S_ISSPARSEDIR(ce->ce_mode))
    return 0;
  if (only_to_die)
    diagnose_invalid_index_path(repo, stage, prefix, cp);
  return -1;
}

static enum get_oid_result get_oid_with_context_1(struct repository *repo,
          const char *name,
          unsigned flags,
          const char *prefix,
          struct object_id *oid,
          struct object_context *oc)
{
  int ret, bracket_depth;
  int namelen = strlen(name);
  const char *cp;
  int only_to_die = flags & GET_OID_ONLY_TO_DIE;

  memset(oc, 0, sizeof(*oc));
  oc->mode = S_IFINVALID;
  strbuf_init(&oc->symlink_path, 0);
  ret = get_oid_1(repo, name, namelen, oid, flags);
  if (!ret && flags & GET_OID_REQUIRE_PATH)
    die(_("<object>:<path> required, only <object> '%s' given"),
        name);
  if (!ret)
    return ret;
  /*
   * tree:path --> object name of path in tree
   * :path -> object name of absolute path in index
   * :./path -> object name of path relative to cwd in index
   * :[0-3]:path -> object name of path in index at stage
   * :/foo -> recent commit matching foo
   */
  if (name[0] == ':') {
    int stage = 0;
    const struct cache_entry *ce;
    char *new_path = NULL;
    int pos;
    if (!only_to_die && namelen > 2 && name[1] == '/') {
      struct handle_one_ref_cb cb;
      struct commit_list *list = NULL;

      cb.repo = repo;
      cb.list = &list;
      refs_for_each_ref(get_main_ref_store(repo), handle_one_ref, &cb);
      refs_head_ref(get_main_ref_store(repo), handle_one_ref, &cb);
      ret = get_oid_oneline(repo, name + 2, oid, list);

      free_commit_list(list);
      return ret;
    }
    if (namelen < 3 ||
        name[2] != ':' ||
        name[1] < '0' || '3' < name[1])
      cp = name + 1;
    else {
      stage = name[1] - '0';
      cp = name + 3;
    }
    new_path = resolve_relative_path(repo, cp);
    if (!new_path) {
      namelen = namelen - (cp - name);
    } else {
      cp = new_path;
      namelen = strlen(cp);
    }

    if (flags & GET_OID_RECORD_PATH)
      oc->path = xstrdup(cp);

    if (!repo->index || !repo->index->cache)
      repo_read_index(repo);
    pos = index_name_pos(repo->index, cp, namelen);
    if (pos < 0)
      pos = -pos - 1;
    while (pos < repo->index->cache_nr) {
      ce = repo->index->cache[pos];
      if (ce_namelen(ce) != namelen ||
          memcmp(ce->name, cp, namelen))
        break;
      if (ce_stage(ce) == stage) {
        free(new_path);
        if (reject_tree_in_index(repo, only_to_die, ce,
               stage, prefix, cp))
          return -1;
        oidcpy(oid, &ce->oid);
        oc->mode = ce->ce_mode;
        return 0;
      }
      pos++;
    }
    if (only_to_die && name[1] && name[1] != '/')
      diagnose_invalid_index_path(repo, stage, prefix, cp);
    free(new_path);
    return -1;
  }
  for (cp = name, bracket_depth = 0; *cp; cp++) {
    if (strchr("@^", *cp) && cp[1] == '{') {
      cp++;
      bracket_depth++;
    } else if (bracket_depth && *cp == '}') {
      bracket_depth--;
    } else if (!bracket_depth && *cp == ':') {
      break;
    }
  }
  if (*cp == ':') {
    struct object_id tree_oid;
    int len = cp - name;
    unsigned sub_flags = flags;

    sub_flags &= ~GET_OID_DISAMBIGUATORS;
    sub_flags |= GET_OID_TREEISH;

    if (!get_oid_1(repo, name, len, &tree_oid, sub_flags)) {
      const char *filename = cp+1;
      char *new_filename = NULL;

      new_filename = resolve_relative_path(repo, filename);
      if (new_filename)
        filename = new_filename;
      if (flags & GET_OID_FOLLOW_SYMLINKS) {
        ret = get_tree_entry_follow_symlinks(repo, &tree_oid,
          filename, oid, &oc->symlink_path,
          &oc->mode);
      } else {
        ret = get_tree_entry(repo, &tree_oid, filename, oid,
                 &oc->mode);
        if (ret && only_to_die) {
          diagnose_invalid_oid_path(repo, prefix,
                   filename,
                   &tree_oid,
                   name, len);
        }
      }
      if (flags & GET_OID_RECORD_PATH)
        oc->path = xstrdup(filename);

      free(new_filename);
      return ret;
    } else {
      if (only_to_die)
        die(_("invalid object name '%.*s'."), len, name);
    }
  }
  return ret;
}

/*
 * Call this function when you know "name" given by the end user must
 * name an object but it doesn't; the function _may_ die with a better
 * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
 * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
 * you have a chance to diagnose the error further.
 */
void maybe_die_on_misspelt_object_name(struct repository *r,
               const char *name,
               const char *prefix)
{
  struct object_context oc;
  struct object_id oid;
  get_oid_with_context_1(r, name, GET_OID_ONLY_TO_DIE | GET_OID_QUIETLY,
             prefix, &oid, &oc);
  object_context_release(&oc);
}

enum get_oid_result get_oid_with_context(struct repository *repo,
           const char *str,
           unsigned flags,
           struct object_id *oid,
           struct object_context *oc)
{
  if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
    BUG("incompatible flags for get_oid_with_context");
  return get_oid_with_context_1(repo, str, flags, NULL, oid, oc);
}

Coverage Report

Created: 2025-12-31 07:01