/src/git/commit.c

Source
#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"
#include "tag.h"
#include "commit.h"
#include "commit-graph.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "repository.h"
#include "object-name.h"
#include "odb.h"
#include "utf8.h"
#include "diff.h"
#include "revision.h"
#include "notes.h"
#include "alloc.h"
#include "gpg-interface.h"
#include "mergesort.h"
#include "commit-slab.h"
#include "prio-queue.h"
#include "hash-lookup.h"
#include "wt-status.h"
#include "advice.h"
#include "refs.h"
#include "commit-reach.h"
#include "setup.h"
#include "shallow.h"
#include "tree.h"
#include "hook.h"
#include "parse.h"
#include "object-file.h"
#include "object-file-convert.h"
#include "prio-queue.h"

static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);

int save_commit_buffer = 1;
int no_graft_file_deprecated_advice;

const char *commit_type = "commit";

struct commit *lookup_commit_reference_gently(struct repository *r,
    const struct object_id *oid, int quiet)
{
  struct object *obj = deref_tag(r,
               parse_object(r, oid),
               NULL, 0);

  if (!obj)
    return NULL;
  return object_as_type(obj, OBJ_COMMIT, quiet);
}

struct commit *lookup_commit_reference(struct repository *r, const struct object_id *oid)
{
  return lookup_commit_reference_gently(r, oid, 0);
}

struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref_name)
{
  struct commit *c = lookup_commit_reference(the_repository, oid);
  if (!c)
    die(_("could not parse %s"), ref_name);
  if (!oideq(oid, &c->object.oid)) {
    warning(_("%s %s is not a commit!"),
      ref_name, oid_to_hex(oid));
  }
  return c;
}

struct commit *lookup_commit_object(struct repository *r,
            const struct object_id *oid)
{
  struct object *obj = parse_object(r, oid);
  return obj ? object_as_type(obj, OBJ_COMMIT, 0) : NULL;

}

struct commit *lookup_commit(struct repository *r, const struct object_id *oid)
{
  struct object *obj = lookup_object(r, oid);
  if (!obj)
    return create_object(r, oid, alloc_commit_node(r));
  return object_as_type(obj, OBJ_COMMIT, 0);
}

struct commit *lookup_commit_reference_by_name(const char *name)
{
  return lookup_commit_reference_by_name_gently(name, 0);
}

struct commit *lookup_commit_reference_by_name_gently(const char *name,
                  int quiet)
{
  struct object_id oid;
  struct commit *commit;

  if (repo_get_oid_committish(the_repository, name, &oid))
    return NULL;
  commit = lookup_commit_reference_gently(the_repository, &oid, quiet);
  if (repo_parse_commit(the_repository, commit))
    return NULL;
  return commit;
}

static timestamp_t parse_commit_date(const char *buf, const char *tail)
{
  const char *dateptr;
  const char *eol;

  if (buf + 6 >= tail)
    return 0;
  if (memcmp(buf, "author", 6))
    return 0;
  while (buf < tail && *buf++ != '\n')
    /* nada */;
  if (buf + 9 >= tail)
    return 0;
  if (memcmp(buf, "committer", 9))
    return 0;

  /*
   * Jump to end-of-line so that we can walk backwards to find the
   * end-of-email ">". This is more forgiving of malformed cases
   * because unexpected characters tend to be in the name and email
   * fields.
   */
  eol = memchr(buf, '\n', tail - buf);
  if (!eol)
    return 0;
  dateptr = eol;
  while (dateptr > buf && dateptr[-1] != '>')
    dateptr--;
  if (dateptr == buf)
    return 0;

  /*
   * Trim leading whitespace, but make sure we have at least one
   * non-whitespace character, as parse_timestamp() will otherwise walk
   * right past the newline we found in "eol" when skipping whitespace
   * itself.
   *
   * In theory it would be sufficient to allow any character not matched
   * by isspace(), but there's a catch: our isspace() does not
   * necessarily match the behavior of parse_timestamp(), as the latter
   * is implemented by system routines which match more exotic control
   * codes, or even locale-dependent sequences.
   *
   * Since we expect the timestamp to be a number, we can check for that.
   * Anything else (e.g., a non-numeric token like "foo") would just
   * cause parse_timestamp() to return 0 anyway.
   */
  while (dateptr < eol && isspace(*dateptr))
    dateptr++;
  if (!isdigit(*dateptr) && *dateptr != '-')
    return 0;

  /*
   * We know there is at least one digit (or dash), so we'll begin
   * parsing there and stop at worst case at eol.
   *
   * Note that we may feed parse_timestamp() extra characters here if the
   * commit is malformed, and it will parse as far as it can. For
   * example, "123foo456" would return "123". That might be questionable
   * (versus returning "0"), but it would help in a hypothetical case
   * like "123456+0100", where the whitespace from the timezone is
   * missing. Since such syntactic errors may be baked into history and
   * hard to correct now, let's err on trying to make our best guess
   * here, rather than insist on perfect syntax.
   */
  return parse_timestamp(dateptr, NULL, 10);
}

static const struct object_id *commit_graft_oid_access(size_t index, const void *table)
{
  const struct commit_graft * const *commit_graft_table = table;
  return &commit_graft_table[index]->oid;
}

int commit_graft_pos(struct repository *r, const struct object_id *oid)
{
  return oid_pos(oid, r->parsed_objects->grafts,
           r->parsed_objects->grafts_nr,
           commit_graft_oid_access);
}

void unparse_commit(struct repository *r, const struct object_id *oid)
{
  struct commit *c = lookup_commit(r, oid);

  if (!c->object.parsed)
    return;
  free_commit_list(c->parents);
  c->parents = NULL;
  c->object.parsed = 0;
}

int register_commit_graft(struct repository *r, struct commit_graft *graft,
        int ignore_dups)
{
  int pos = commit_graft_pos(r, &graft->oid);

  if (0 <= pos) {
    if (ignore_dups)
      free(graft);
    else {
      free(r->parsed_objects->grafts[pos]);
      r->parsed_objects->grafts[pos] = graft;
    }
    return 1;
  }
  pos = -pos - 1;
  ALLOC_GROW(r->parsed_objects->grafts,
       r->parsed_objects->grafts_nr + 1,
       r->parsed_objects->grafts_alloc);
  r->parsed_objects->grafts_nr++;
  if (pos < r->parsed_objects->grafts_nr)
    memmove(r->parsed_objects->grafts + pos + 1,
      r->parsed_objects->grafts + pos,
      (r->parsed_objects->grafts_nr - pos - 1) *
      sizeof(*r->parsed_objects->grafts));
  r->parsed_objects->grafts[pos] = graft;
  unparse_commit(r, &graft->oid);
  return 0;
}

struct commit_graft *read_graft_line(struct strbuf *line)
{
  /* The format is just "Commit Parent1 Parent2 ...\n" */
  int i, phase;
  const char *tail = NULL;
  struct commit_graft *graft = NULL;
  struct object_id dummy_oid, *oid;

  strbuf_rtrim(line);
  if (!line->len || line->buf[0] == '#')
    return NULL;
  /*
   * phase 0 verifies line, counts hashes in line and allocates graft
   * phase 1 fills graft
   */
  for (phase = 0; phase < 2; phase++) {
    oid = graft ? &graft->oid : &dummy_oid;
    if (parse_oid_hex(line->buf, oid, &tail))
      goto bad_graft_data;
    for (i = 0; *tail != '\0'; i++) {
      oid = graft ? &graft->parent[i] : &dummy_oid;
      if (!isspace(*tail++) || parse_oid_hex(tail, oid, &tail))
        goto bad_graft_data;
    }
    if (!graft) {
      graft = xmalloc(st_add(sizeof(*graft),
                 st_mult(sizeof(struct object_id), i)));
      graft->nr_parent = i;
    }
  }
  return graft;

bad_graft_data:
  error("bad graft data: %s", line->buf);
  assert(!graft);
  return NULL;
}

static int read_graft_file(struct repository *r, const char *graft_file)
{
  FILE *fp = fopen_or_warn(graft_file, "r");
  struct strbuf buf = STRBUF_INIT;
  if (!fp)
    return -1;
  if (!no_graft_file_deprecated_advice &&
      advice_enabled(ADVICE_GRAFT_FILE_DEPRECATED))
    advise(_("Support for <GIT_DIR>/info/grafts is deprecated\n"
       "and will be removed in a future Git version.\n"
       "\n"
       "Please use \"git replace --convert-graft-file\"\n"
       "to convert the grafts into replace refs.\n"
       "\n"
       "Turn this message off by running\n"
       "\"git config set advice.graftFileDeprecated false\""));
  while (!strbuf_getwholeline(&buf, fp, '\n')) {
    /* The format is just "Commit Parent1 Parent2 ...\n" */
    struct commit_graft *graft = read_graft_line(&buf);
    if (!graft)
      continue;
    if (register_commit_graft(r, graft, 1))
      error("duplicate graft data: %s", buf.buf);
  }
  fclose(fp);
  strbuf_release(&buf);
  return 0;
}

void prepare_commit_graft(struct repository *r)
{
  const char *graft_file;

  if (r->parsed_objects->commit_graft_prepared)
    return;
  if (!startup_info->have_repository)
    return;

  graft_file = repo_get_graft_file(r);
  read_graft_file(r, graft_file);
  /* make sure shallows are read */
  is_repository_shallow(r);
  r->parsed_objects->commit_graft_prepared = 1;
}

struct commit_graft *lookup_commit_graft(struct repository *r, const struct object_id *oid)
{
  int pos;
  prepare_commit_graft(r);
  pos = commit_graft_pos(r, oid);
  if (pos < 0)
    return NULL;
  return r->parsed_objects->grafts[pos];
}

int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
{
  int i, ret;
  for (i = ret = 0; i < the_repository->parsed_objects->grafts_nr && !ret; i++)
    ret = fn(the_repository->parsed_objects->grafts[i], cb_data);
  return ret;
}

struct commit_buffer {
  void *buffer;
  unsigned long size;
};
define_commit_slab(buffer_slab, struct commit_buffer);

struct buffer_slab *allocate_commit_buffer_slab(void)
{
  struct buffer_slab *bs = xmalloc(sizeof(*bs));
  init_buffer_slab(bs);
  return bs;
}

void free_commit_buffer_slab(struct buffer_slab *bs)
{
  clear_buffer_slab(bs);
  free(bs);
}

void set_commit_buffer(struct repository *r, struct commit *commit, void *buffer, unsigned long size)
{
  struct commit_buffer *v = buffer_slab_at(
    r->parsed_objects->buffer_slab, commit);
  v->buffer = buffer;
  v->size = size;
}

const void *get_cached_commit_buffer(struct repository *r, const struct commit *commit, unsigned long *sizep)
{
  struct commit_buffer *v = buffer_slab_peek(
    r->parsed_objects->buffer_slab, commit);
  if (!v) {
    if (sizep)
      *sizep = 0;
    return NULL;
  }
  if (sizep)
    *sizep = v->size;
  return v->buffer;
}

const void *repo_get_commit_buffer(struct repository *r,
           const struct commit *commit,
           unsigned long *sizep)
{
  const void *ret = get_cached_commit_buffer(r, commit, sizep);
  if (!ret) {
    enum object_type type;
    unsigned long size;
    ret = odb_read_object(r->objects, &commit->object.oid, &type, &size);
    if (!ret)
      die("cannot read commit object %s",
          oid_to_hex(&commit->object.oid));
    if (type != OBJ_COMMIT)
      die("expected commit for %s, got %s",
          oid_to_hex(&commit->object.oid), type_name(type));
    if (sizep)
      *sizep = size;
  }
  return ret;
}

void repo_unuse_commit_buffer(struct repository *r,
            const struct commit *commit,
            const void *buffer)
{
  struct commit_buffer *v = buffer_slab_peek(
    r->parsed_objects->buffer_slab, commit);
  if (!(v && v->buffer == buffer))
    free((void *)buffer);
}

void free_commit_buffer(struct parsed_object_pool *pool, struct commit *commit)
{
  struct commit_buffer *v = buffer_slab_peek(
    pool->buffer_slab, commit);
  if (v) {
    FREE_AND_NULL(v->buffer);
    v->size = 0;
  }
}

static inline void set_commit_tree(struct commit *c, struct tree *t)
{
  c->maybe_tree = t;
}

struct tree *repo_get_commit_tree(struct repository *r,
          const struct commit *commit)
{
  if (commit->maybe_tree || !commit->object.parsed)
    return commit->maybe_tree;

  if (commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
    return get_commit_tree_in_graph(r, commit);

  return NULL;
}

struct object_id *get_commit_tree_oid(const struct commit *commit)
{
  struct tree *tree = repo_get_commit_tree(the_repository, commit);
  return tree ? &tree->object.oid : NULL;
}

void release_commit_memory(struct parsed_object_pool *pool, struct commit *c)
{
  set_commit_tree(c, NULL);
  free_commit_buffer(pool, c);
  c->index = 0;
  free_commit_list(c->parents);

  c->object.parsed = 0;
}

const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep)
{
  struct commit_buffer *v = buffer_slab_peek(
    the_repository->parsed_objects->buffer_slab, commit);
  void *ret;

  if (!v) {
    if (sizep)
      *sizep = 0;
    return NULL;
  }
  ret = v->buffer;
  if (sizep)
    *sizep = v->size;

  v->buffer = NULL;
  v->size = 0;
  return ret;
}

int parse_commit_buffer(struct repository *r, struct commit *item, const void *buffer, unsigned long size, int check_graph)
{
  const char *tail = buffer;
  const char *bufptr = buffer;
  struct object_id parent;
  struct commit_list **pptr;
  struct commit_graft *graft;
  const int tree_entry_len = the_hash_algo->hexsz + 5;
  const int parent_entry_len = the_hash_algo->hexsz + 7;
  struct tree *tree;

  if (item->object.parsed)
    return 0;
  /*
   * Presumably this is leftover from an earlier failed parse;
   * clear it out in preparation for us re-parsing (we'll hit the
   * same error, but that's good, since it lets our caller know
   * the result cannot be trusted.
   */
  free_commit_list(item->parents);
  item->parents = NULL;

  tail += size;
  if (tail <= bufptr + tree_entry_len + 1 || memcmp(bufptr, "tree ", 5) ||
      bufptr[tree_entry_len] != '\n')
    return error("bogus commit object %s", oid_to_hex(&item->object.oid));
  if (get_oid_hex(bufptr + 5, &parent) < 0)
    return error("bad tree pointer in commit %s",
           oid_to_hex(&item->object.oid));
  tree = lookup_tree(r, &parent);
  if (!tree)
    return error("bad tree pointer %s in commit %s",
           oid_to_hex(&parent),
           oid_to_hex(&item->object.oid));
  set_commit_tree(item, tree);
  bufptr += tree_entry_len + 1; /* "tree " + "hex sha1" + "\n" */
  pptr = &item->parents;

  graft = lookup_commit_graft(r, &item->object.oid);
  if (graft)
    r->parsed_objects->substituted_parent = 1;
  while (bufptr + parent_entry_len < tail && !memcmp(bufptr, "parent ", 7)) {
    struct commit *new_parent;

    if (tail <= bufptr + parent_entry_len + 1 ||
        get_oid_hex(bufptr + 7, &parent) ||
        bufptr[parent_entry_len] != '\n')
      return error("bad parents in commit %s", oid_to_hex(&item->object.oid));
    bufptr += parent_entry_len + 1;
    /*
     * The clone is shallow if nr_parent < 0, and we must
     * not traverse its real parents even when we unhide them.
     */
    if (graft && (graft->nr_parent < 0 || !grafts_keep_true_parents))
      continue;
    new_parent = lookup_commit(r, &parent);
    if (!new_parent)
      return error("bad parent %s in commit %s",
             oid_to_hex(&parent),
             oid_to_hex(&item->object.oid));
    pptr = &commit_list_insert(new_parent, pptr)->next;
  }
  if (graft) {
    int i;
    struct commit *new_parent;
    for (i = 0; i < graft->nr_parent; i++) {
      new_parent = lookup_commit(r,
               &graft->parent[i]);
      if (!new_parent)
        return error("bad graft parent %s in commit %s",
               oid_to_hex(&graft->parent[i]),
               oid_to_hex(&item->object.oid));
      pptr = &commit_list_insert(new_parent, pptr)->next;
    }
  }
  item->date = parse_commit_date(bufptr, tail);

  if (check_graph)
    load_commit_graph_info(r, item);

  item->object.parsed = 1;
  return 0;
}

int repo_parse_commit_internal(struct repository *r,
             struct commit *item,
             int quiet_on_missing,
             int use_commit_graph)
{
  enum object_type type;
  void *buffer;
  unsigned long size;
  struct object_info oi = {
    .typep = &type,
    .sizep = &size,
    .contentp = &buffer,
  };
  /*
   * Git does not support partial clones that exclude commits, so set
   * OBJECT_INFO_SKIP_FETCH_OBJECT to fail fast when an object is missing.
   */
  int flags = OBJECT_INFO_LOOKUP_REPLACE | OBJECT_INFO_SKIP_FETCH_OBJECT |
    OBJECT_INFO_DIE_IF_CORRUPT;
  int ret;

  if (!item)
    return -1;
  if (item->object.parsed)
    return 0;
  if (use_commit_graph && parse_commit_in_graph(r, item)) {
    static int commit_graph_paranoia = -1;

    if (commit_graph_paranoia == -1)
      commit_graph_paranoia = git_env_bool(GIT_COMMIT_GRAPH_PARANOIA, 0);

    if (commit_graph_paranoia && !odb_has_object(r->objects, &item->object.oid, 0)) {
      unparse_commit(r, &item->object.oid);
      return quiet_on_missing ? -1 :
        error(_("commit %s exists in commit-graph but not in the object database"),
              oid_to_hex(&item->object.oid));
    }

    return 0;
  }

  if (odb_read_object_info_extended(r->objects, &item->object.oid,
            &oi, flags) < 0)
    return quiet_on_missing ? -1 :
      error("Could not read %s",
           oid_to_hex(&item->object.oid));
  if (type != OBJ_COMMIT) {
    free(buffer);
    return error("Object %s not a commit",
           oid_to_hex(&item->object.oid));
  }

  ret = parse_commit_buffer(r, item, buffer, size, 0);
  if (save_commit_buffer && !ret &&
      !get_cached_commit_buffer(r, item, NULL)) {
    set_commit_buffer(r, item, buffer, size);
    return 0;
  }
  free(buffer);
  return ret;
}

int repo_parse_commit_gently(struct repository *r,
           struct commit *item, int quiet_on_missing)
{
  return repo_parse_commit_internal(r, item, quiet_on_missing, 1);
}

void parse_commit_or_die(struct commit *item)
{
  if (repo_parse_commit(the_repository, item))
    die("unable to parse commit %s",
        item ? oid_to_hex(&item->object.oid) : "(null)");
}

int find_commit_subject(const char *commit_buffer, const char **subject)
{
  const char *eol;
  const char *p = commit_buffer;

  while (*p && (*p != '\n' || p[1] != '\n'))
    p++;
  if (*p) {
    p = skip_blank_lines(p + 2);
    eol = strchrnul(p, '\n');
  } else
    eol = p;

  *subject = p;

  return eol - p;
}

size_t commit_subject_length(const char *body)
{
  const char *p = body;
  while (*p) {
    const char *next = skip_blank_lines(p);
    if (next != p)
      break;
    p = strchrnul(p, '\n');
    if (*p)
      p++;
  }
  return p - body;
}

struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
{
  struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
  new_list->item = item;
  new_list->next = *list_p;
  *list_p = new_list;
  return new_list;
}

int commit_list_contains(struct commit *item, struct commit_list *list)
{
  while (list) {
    if (list->item == item)
      return 1;
    list = list->next;
  }

  return 0;
}

unsigned commit_list_count(const struct commit_list *l)
{
  unsigned c = 0;
  for (; l; l = l->next )
    c++;
  return c;
}

struct commit_list *copy_commit_list(const struct commit_list *list)
{
  struct commit_list *head = NULL;
  struct commit_list **pp = &head;
  while (list) {
    pp = commit_list_append(list->item, pp);
    list = list->next;
  }
  return head;
}

struct commit_list *reverse_commit_list(struct commit_list *list)
{
  struct commit_list *next = NULL, *current, *backup;
  for (current = list; current; current = backup) {
    backup = current->next;
    current->next = next;
    next = current;
  }
  return next;
}

void free_commit_list(struct commit_list *list)
{
  while (list)
    pop_commit(&list);
}

struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
{
  struct commit_list **pp = list;
  struct commit_list *p;
  while ((p = *pp) != NULL) {
    if (p->item->date < item->date) {
      break;
    }
    pp = &p->next;
  }
  return commit_list_insert(item, pp);
}

static int commit_list_compare_by_date(const struct commit_list *a,
               const struct commit_list *b)
{
  timestamp_t a_date = a->item->date;
  timestamp_t b_date = b->item->date;
  if (a_date < b_date)
    return 1;
  if (a_date > b_date)
    return -1;
  return 0;
}

DEFINE_LIST_SORT(static, commit_list_sort, struct commit_list, next);

void commit_list_sort_by_date(struct commit_list **list)
{
  commit_list_sort(list, commit_list_compare_by_date);
}

struct commit *pop_most_recent_commit(struct prio_queue *queue,
              unsigned int mark)
{
  struct commit *ret = prio_queue_peek(queue);
  int get_pending = 1;
  struct commit_list *parents = ret->parents;

  while (parents) {
    struct commit *commit = parents->item;
    if (!repo_parse_commit(the_repository, commit) && !(commit->object.flags & mark)) {
      commit->object.flags |= mark;
      if (get_pending)
        prio_queue_replace(queue, commit);
      else
        prio_queue_put(queue, commit);
      get_pending = 0;
    }
    parents = parents->next;
  }
  if (get_pending)
    prio_queue_get(queue);
  return ret;
}

static void clear_commit_marks_1(struct commit_list **plist,
         struct commit *commit, unsigned int mark)
{
  while (commit) {
    struct commit_list *parents;

    if (!(mark & commit->object.flags))
      return;

    commit->object.flags &= ~mark;

    parents = commit->parents;
    if (!parents)
      return;

    while ((parents = parents->next)) {
      if (parents->item->object.flags & mark)
        commit_list_insert(parents->item, plist);
    }

    commit = commit->parents->item;
  }
}

void clear_commit_marks_many(size_t nr, struct commit **commit, unsigned int mark)
{
  for (size_t i = 0; i < nr; i++)
    clear_commit_marks(commit[i], mark);
}

void clear_commit_marks(struct commit *commit, unsigned int mark)
{
  struct commit_list *list = NULL;

  clear_commit_marks_1(&list, commit, mark);
  while (list)
    clear_commit_marks_1(&list, pop_commit(&list), mark);
}

struct commit *pop_commit(struct commit_list **stack)
{
  struct commit_list *top = *stack;
  struct commit *item = top ? top->item : NULL;

  if (top) {
    *stack = top->next;
    free(top);
  }
  return item;
}

/*
 * Topological sort support
 */

/* count number of children that have not been emitted */
define_commit_slab(indegree_slab, int);

define_commit_slab(author_date_slab, timestamp_t);

void record_author_date(struct author_date_slab *author_date,
      struct commit *commit)
{
  const char *buffer = repo_get_commit_buffer(the_repository, commit,
                NULL);
  struct ident_split ident;
  const char *ident_line;
  size_t ident_len;
  char *date_end;
  timestamp_t date;

  ident_line = find_commit_header(buffer, "author", &ident_len);
  if (!ident_line)
    goto fail_exit; /* no author line */
  if (split_ident_line(&ident, ident_line, ident_len) ||
      !ident.date_begin || !ident.date_end)
    goto fail_exit; /* malformed "author" line */

  date = parse_timestamp(ident.date_begin, &date_end, 10);
  if (date_end != ident.date_end)
    goto fail_exit; /* malformed date */
  *(author_date_slab_at(author_date, commit)) = date;

fail_exit:
  repo_unuse_commit_buffer(the_repository, commit, buffer);
}

int compare_commits_by_author_date(const void *a_, const void *b_,
           void *cb_data)
{
  const struct commit *a = a_, *b = b_;
  struct author_date_slab *author_date = cb_data;
  timestamp_t a_date = *(author_date_slab_at(author_date, a));
  timestamp_t b_date = *(author_date_slab_at(author_date, b));

  /* newer commits with larger date first */
  if (a_date < b_date)
    return 1;
  else if (a_date > b_date)
    return -1;
  return 0;
}

int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_,
              void *unused UNUSED)
{
  const struct commit *a = a_, *b = b_;
  const timestamp_t generation_a = commit_graph_generation(a),
        generation_b = commit_graph_generation(b);

  /* newer commits first */
  if (generation_a < generation_b)
    return 1;
  else if (generation_a > generation_b)
    return -1;

  /* use date as a heuristic when generations are equal */
  if (a->date < b->date)
    return 1;
  else if (a->date > b->date)
    return -1;
  return 0;
}

int compare_commits_by_commit_date(const void *a_, const void *b_,
           void *unused UNUSED)
{
  const struct commit *a = a_, *b = b_;
  /* newer commits with larger date first */
  if (a->date < b->date)
    return 1;
  else if (a->date > b->date)
    return -1;
  return 0;
}

/*
 * Performs an in-place topological sort on the list supplied.
 */
void sort_in_topological_order(struct commit_list **list, enum rev_sort_order sort_order)
{
  struct commit_list *next, *orig = *list;
  struct commit_list **pptr;
  struct indegree_slab indegree;
  struct prio_queue queue;
  struct commit *commit;
  struct author_date_slab author_date;

  if (!orig)
    return;
  *list = NULL;

  init_indegree_slab(&indegree);
  memset(&queue, '\0', sizeof(queue));

  switch (sort_order) {
  default: /* REV_SORT_IN_GRAPH_ORDER */
    queue.compare = NULL;
    break;
  case REV_SORT_BY_COMMIT_DATE:
    queue.compare = compare_commits_by_commit_date;
    break;
  case REV_SORT_BY_AUTHOR_DATE:
    init_author_date_slab(&author_date);
    queue.compare = compare_commits_by_author_date;
    queue.cb_data = &author_date;
    break;
  }

  /* Mark them and clear the indegree */
  for (next = orig; next; next = next->next) {
    struct commit *commit = next->item;
    *(indegree_slab_at(&indegree, commit)) = 1;
    /* also record the author dates, if needed */
    if (sort_order == REV_SORT_BY_AUTHOR_DATE)
      record_author_date(&author_date, commit);
  }

  /* update the indegree */
  for (next = orig; next; next = next->next) {
    struct commit_list *parents = next->item->parents;
    while (parents) {
      struct commit *parent = parents->item;
      int *pi = indegree_slab_at(&indegree, parent);

      if (*pi)
        (*pi)++;
      parents = parents->next;
    }
  }

  /*
   * find the tips
   *
   * tips are nodes not reachable from any other node in the list
   *
   * the tips serve as a starting set for the work queue.
   */
  for (next = orig; next; next = next->next) {
    struct commit *commit = next->item;

    if (*(indegree_slab_at(&indegree, commit)) == 1)
      prio_queue_put(&queue, commit);
  }

  /*
   * This is unfortunate; the initial tips need to be shown
   * in the order given from the revision traversal machinery.
   */
  if (sort_order == REV_SORT_IN_GRAPH_ORDER)
    prio_queue_reverse(&queue);

  /* We no longer need the commit list */
  free_commit_list(orig);

  pptr = list;
  *list = NULL;
  while ((commit = prio_queue_get(&queue)) != NULL) {
    struct commit_list *parents;

    for (parents = commit->parents; parents ; parents = parents->next) {
      struct commit *parent = parents->item;
      int *pi = indegree_slab_at(&indegree, parent);

      if (!*pi)
        continue;

      /*
       * parents are only enqueued for emission
       * when all their children have been emitted thereby
       * guaranteeing topological order.
       */
      if (--(*pi) == 1)
        prio_queue_put(&queue, parent);
    }
    /*
     * all children of commit have already been
     * emitted. we can emit it now.
     */
    *(indegree_slab_at(&indegree, commit)) = 0;

    pptr = &commit_list_insert(commit, pptr)->next;
  }

  clear_indegree_slab(&indegree);
  clear_prio_queue(&queue);
  if (sort_order == REV_SORT_BY_AUTHOR_DATE)
    clear_author_date_slab(&author_date);
}

struct rev_collect {
  struct commit **commit;
  int nr;
  int alloc;
  unsigned int initial : 1;
};

static void add_one_commit(struct object_id *oid, struct rev_collect *revs)
{
  struct commit *commit;

  if (is_null_oid(oid))
    return;

  commit = lookup_commit(the_repository, oid);
  if (!commit ||
      (commit->object.flags & TMP_MARK) ||
      repo_parse_commit(the_repository, commit))
    return;

  ALLOC_GROW(revs->commit, revs->nr + 1, revs->alloc);
  revs->commit[revs->nr++] = commit;
  commit->object.flags |= TMP_MARK;
}

static int collect_one_reflog_ent(const char *refname UNUSED,
          struct object_id *ooid, struct object_id *noid,
          const char *ident UNUSED,
          timestamp_t timestamp UNUSED, int tz UNUSED,
          const char *message UNUSED, void *cbdata)
{
  struct rev_collect *revs = cbdata;

  if (revs->initial) {
    revs->initial = 0;
    add_one_commit(ooid, revs);
  }
  add_one_commit(noid, revs);
  return 0;
}

struct commit *get_fork_point(const char *refname, struct commit *commit)
{
  struct object_id oid;
  struct rev_collect revs;
  struct commit_list *bases = NULL;
  int i;
  struct commit *ret = NULL;
  char *full_refname;

  switch (repo_dwim_ref(the_repository, refname, strlen(refname), &oid,
            &full_refname, 0)) {
  case 0:
    die("No such ref: '%s'", refname);
  case 1:
    break; /* good */
  default:
    die("Ambiguous refname: '%s'", refname);
  }

  memset(&revs, 0, sizeof(revs));
  revs.initial = 1;
  refs_for_each_reflog_ent(get_main_ref_store(the_repository),
         full_refname, collect_one_reflog_ent, &revs);

  if (!revs.nr)
    add_one_commit(&oid, &revs);

  for (i = 0; i < revs.nr; i++)
    revs.commit[i]->object.flags &= ~TMP_MARK;

  if (repo_get_merge_bases_many(the_repository, commit, revs.nr,
              revs.commit, &bases) < 0)
    exit(128);

  /*
   * There should be one and only one merge base, when we found
   * a common ancestor among reflog entries.
   */
  if (!bases || bases->next)
    goto cleanup_return;

  /* And the found one must be one of the reflog entries */
  for (i = 0; i < revs.nr; i++)
    if (&bases->item->object == &revs.commit[i]->object)
      break; /* found */
  if (revs.nr <= i)
    goto cleanup_return;

  ret = bases->item;

cleanup_return:
  free(revs.commit);
  free_commit_list(bases);
  free(full_refname);
  return ret;
}

/*
 * Indexed by hash algorithm identifier.
 */
static const char *gpg_sig_headers[] = {
  NULL,
  "gpgsig",
  "gpgsig-sha256",
};

int add_header_signature(struct strbuf *buf, struct strbuf *sig, const struct git_hash_algo *algo)
{
  int inspos, copypos;
  const char *eoh;
  const char *gpg_sig_header = gpg_sig_headers[hash_algo_by_ptr(algo)];
  int gpg_sig_header_len = strlen(gpg_sig_header);

  /* find the end of the header */
  eoh = strstr(buf->buf, "\n\n");
  if (!eoh)
    inspos = buf->len;
  else
    inspos = eoh - buf->buf + 1;

  for (copypos = 0; sig->buf[copypos]; ) {
    const char *bol = sig->buf + copypos;
    const char *eol = strchrnul(bol, '\n');
    int len = (eol - bol) + !!*eol;

    if (!copypos) {
      strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
      inspos += gpg_sig_header_len;
    }
    strbuf_insertstr(buf, inspos++, " ");
    strbuf_insert(buf, inspos, bol, len);
    inspos += len;
    copypos += len;
  }
  return 0;
}

static int sign_commit_to_strbuf(struct strbuf *sig, struct strbuf *buf, const char *keyid)
{
  char *keyid_to_free = NULL;
  int ret = 0;
  if (!keyid || !*keyid)
    keyid = keyid_to_free = get_signing_key();
  if (sign_buffer(buf, sig, keyid))
    ret = -1;
  free(keyid_to_free);
  return ret;
}

int parse_signed_commit(const struct commit *commit,
      struct strbuf *payload, struct strbuf *signature,
      const struct git_hash_algo *algop)
{
  unsigned long size;
  const char *buffer = repo_get_commit_buffer(the_repository, commit,
                &size);
  int ret = parse_buffer_signed_by_header(buffer, size, payload, signature, algop);

  repo_unuse_commit_buffer(the_repository, commit, buffer);
  return ret;
}

int parse_buffer_signed_by_header(const char *buffer,
          unsigned long size,
          struct strbuf *payload,
          struct strbuf *signature,
          const struct git_hash_algo *algop)
{
  int in_signature = 0, saw_signature = 0, other_signature = 0;
  const char *line, *tail, *p;
  const char *gpg_sig_header = gpg_sig_headers[hash_algo_by_ptr(algop)];

  line = buffer;
  tail = buffer + size;
  while (line < tail) {
    const char *sig = NULL;
    const char *next = memchr(line, '\n', tail - line);

    next = next ? next + 1 : tail;
    if (in_signature && line[0] == ' ')
      sig = line + 1;
    else if (skip_prefix(line, gpg_sig_header, &p) &&
       *p == ' ') {
      sig = line + strlen(gpg_sig_header) + 1;
      other_signature = 0;
    }
    else if (starts_with(line, "gpgsig"))
      other_signature = 1;
    else if (other_signature && line[0] != ' ')
      other_signature = 0;
    if (sig) {
      strbuf_add(signature, sig, next - sig);
      saw_signature = 1;
      in_signature = 1;
    } else {
      if (*line == '\n')
        /* dump the whole remainder of the buffer */
        next = tail;
      if (!other_signature)
        strbuf_add(payload, line, next - line);
      in_signature = 0;
    }
    line = next;
  }
  return saw_signature;
}

int remove_signature(struct strbuf *buf)
{
  const char *line = buf->buf;
  const char *tail = buf->buf + buf->len;
  int in_signature = 0;
  struct sigbuf {
    const char *start;
    const char *end;
  } sigs[2], *sigp = &sigs[0];
  int i;
  const char *orig_buf = buf->buf;

  memset(sigs, 0, sizeof(sigs));

  while (line < tail) {
    const char *next = memchr(line, '\n', tail - line);
    next = next ? next + 1 : tail;

    if (in_signature && line[0] == ' ')
      sigp->end = next;
    else if (starts_with(line, "gpgsig")) {
      int i;
      for (i = 1; i < GIT_HASH_NALGOS; i++) {
        const char *p;
        if (skip_prefix(line, gpg_sig_headers[i], &p) &&
            *p == ' ') {
          sigp->start = line;
          sigp->end = next;
          in_signature = 1;
        }
      }
    } else {
      if (*line == '\n')
        /* dump the whole remainder of the buffer */
        next = tail;
      if (in_signature && sigp - sigs != ARRAY_SIZE(sigs))
        sigp++;
      in_signature = 0;
    }
    line = next;
  }

  for (i = ARRAY_SIZE(sigs) - 1; i >= 0; i--)
    if (sigs[i].start)
      strbuf_remove(buf, sigs[i].start - orig_buf, sigs[i].end - sigs[i].start);

  return sigs[0].start != NULL;
}

static void handle_signed_tag(const struct commit *parent, struct commit_extra_header ***tail)
{
  struct merge_remote_desc *desc;
  struct commit_extra_header *mergetag;
  char *buf;
  unsigned long size;
  enum object_type type;
  struct strbuf payload = STRBUF_INIT;
  struct strbuf signature = STRBUF_INIT;

  desc = merge_remote_util(parent);
  if (!desc || !desc->obj)
    return;
  buf = odb_read_object(the_repository->objects, &desc->obj->oid,
            &type, &size);
  if (!buf || type != OBJ_TAG)
    goto free_return;
  if (!parse_signature(buf, size, &payload, &signature))
    goto free_return;
  /*
   * We could verify this signature and either omit the tag when
   * it does not validate, but the integrator may not have the
   * public key of the signer of the tag being merged, while a
   * later auditor may have it while auditing, so let's not run
   * verify-signed-buffer here for now...
   *
   * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
   *  warn("warning: signed tag unverified.");
   */
  CALLOC_ARRAY(mergetag, 1);
  mergetag->key = xstrdup("mergetag");
  mergetag->value = buf;
  mergetag->len = size;

  **tail = mergetag;
  *tail = &mergetag->next;
  strbuf_release(&payload);
  strbuf_release(&signature);
  return;

free_return:
  free(buf);
}

int verify_commit_buffer(const char *buffer, size_t size,
       struct signature_check *sigc)
{
  struct strbuf payload = STRBUF_INIT;
  struct strbuf signature = STRBUF_INIT;
  int ret = 1;

  sigc->result = 'N';

  if (parse_buffer_signed_by_header(buffer, size, &payload,
            &signature, the_hash_algo) <= 0)
    goto out;

  sigc->payload_type = SIGNATURE_PAYLOAD_COMMIT;
  sigc->payload = strbuf_detach(&payload, &sigc->payload_len);
  ret = check_signature(sigc, signature.buf, signature.len);

 out:
  strbuf_release(&payload);
  strbuf_release(&signature);

  return ret;
}

int check_commit_signature(const struct commit *commit, struct signature_check *sigc)
{
  unsigned long size;
  const char *buffer = repo_get_commit_buffer(the_repository, commit, &size);
  int ret = verify_commit_buffer(buffer, size, sigc);

  repo_unuse_commit_buffer(the_repository, commit, buffer);

  return ret;
}

void verify_merge_signature(struct commit *commit, int verbosity,
          int check_trust)
{
  char hex[GIT_MAX_HEXSZ + 1];
  struct signature_check signature_check;
  int ret;
  memset(&signature_check, 0, sizeof(signature_check));

  ret = check_commit_signature(commit, &signature_check);

  repo_find_unique_abbrev_r(the_repository, hex, &commit->object.oid,
          DEFAULT_ABBREV);
  switch (signature_check.result) {
  case 'G':
    if (ret || (check_trust && signature_check.trust_level < TRUST_MARGINAL))
      die(_("Commit %s has an untrusted GPG signature, "
            "allegedly by %s."), hex, signature_check.signer);
    break;
  case 'B':
    die(_("Commit %s has a bad GPG signature "
          "allegedly by %s."), hex, signature_check.signer);
  default: /* 'N' */
    die(_("Commit %s does not have a GPG signature."), hex);
  }
  if (verbosity >= 0 && signature_check.result == 'G')
    printf(_("Commit %s has a good GPG signature by %s\n"),
           hex, signature_check.signer);

  signature_check_clear(&signature_check);
}

void append_merge_tag_headers(const struct commit_list *parents,
            struct commit_extra_header ***tail)
{
  while (parents) {
    const struct commit *parent = parents->item;
    handle_signed_tag(parent, tail);
    parents = parents->next;
  }
}

static int convert_commit_extra_headers(const struct commit_extra_header *orig,
          struct commit_extra_header **result)
{
  const struct git_hash_algo *compat = the_repository->compat_hash_algo;
  const struct git_hash_algo *algo = the_repository->hash_algo;
  struct commit_extra_header *extra = NULL, **tail = &extra;
  struct strbuf out = STRBUF_INIT;
  while (orig) {
    struct commit_extra_header *new;
    CALLOC_ARRAY(new, 1);
    if (!strcmp(orig->key, "mergetag")) {
      if (convert_object_file(the_repository, &out, algo, compat,
            orig->value, orig->len,
            OBJ_TAG, 1)) {
        free(new);
        free_commit_extra_headers(extra);
        return -1;
      }
      new->key = xstrdup("mergetag");
      new->value = strbuf_detach(&out, &new->len);
    } else {
      new->key = xstrdup(orig->key);
      new->len = orig->len;
      new->value = xmemdupz(orig->value, orig->len);
    }
    *tail = new;
    tail = &new->next;
    orig = orig->next;
  }
  *result = extra;
  return 0;
}

static void add_extra_header(struct strbuf *buffer,
           const struct commit_extra_header *extra)
{
  strbuf_addstr(buffer, extra->key);
  if (extra->len)
    strbuf_add_lines(buffer, " ", extra->value, extra->len);
  else
    strbuf_addch(buffer, '\n');
}

struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
                  const char **exclude)
{
  struct commit_extra_header *extra = NULL;
  unsigned long size;
  const char *buffer = repo_get_commit_buffer(the_repository, commit,
                &size);
  extra = read_commit_extra_header_lines(buffer, size, exclude);
  repo_unuse_commit_buffer(the_repository, commit, buffer);
  return extra;
}

int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
{
  struct commit_extra_header *extra, *to_free;
  int res = 0;

  to_free = read_commit_extra_headers(commit, NULL);
  for (extra = to_free; !res && extra; extra = extra->next) {
    if (strcmp(extra->key, "mergetag"))
      continue; /* not a merge tag */
    res = fn(commit, extra, data);
  }
  free_commit_extra_headers(to_free);
  return res;
}

static inline int standard_header_field(const char *field, size_t len)
{
  return ((len == 4 && !memcmp(field, "tree", 4)) ||
    (len == 6 && !memcmp(field, "parent", 6)) ||
    (len == 6 && !memcmp(field, "author", 6)) ||
    (len == 9 && !memcmp(field, "committer", 9)) ||
    (len == 8 && !memcmp(field, "encoding", 8)));
}

static int excluded_header_field(const char *field, size_t len, const char **exclude)
{
  if (!exclude)
    return 0;

  while (*exclude) {
    size_t xlen = strlen(*exclude);
    if (len == xlen && !memcmp(field, *exclude, xlen))
      return 1;
    exclude++;
  }
  return 0;
}

static struct commit_extra_header *read_commit_extra_header_lines(
  const char *buffer, size_t size,
  const char **exclude)
{
  struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
  const char *line, *next, *eof, *eob;
  struct strbuf buf = STRBUF_INIT;

  for (line = buffer, eob = line + size;
       line < eob && *line != '\n';
       line = next) {
    next = memchr(line, '\n', eob - line);
    next = next ? next + 1 : eob;
    if (*line == ' ') {
      /* continuation */
      if (it)
        strbuf_add(&buf, line + 1, next - (line + 1));
      continue;
    }
    if (it)
      it->value = strbuf_detach(&buf, &it->len);
    strbuf_reset(&buf);
    it = NULL;

    eof = memchr(line, ' ', next - line);
    if (!eof)
      eof = next;
    else if (standard_header_field(line, eof - line) ||
       excluded_header_field(line, eof - line, exclude))
      continue;

    CALLOC_ARRAY(it, 1);
    it->key = xmemdupz(line, eof-line);
    *tail = it;
    tail = &it->next;
    if (eof + 1 < next)
      strbuf_add(&buf, eof + 1, next - (eof + 1));
  }
  if (it)
    it->value = strbuf_detach(&buf, &it->len);
  return extra;
}

void free_commit_extra_headers(struct commit_extra_header *extra)
{
  while (extra) {
    struct commit_extra_header *next = extra->next;
    free(extra->key);
    free(extra->value);
    free(extra);
    extra = next;
  }
}

int commit_tree(const char *msg, size_t msg_len, const struct object_id *tree,
    const struct commit_list *parents, struct object_id *ret,
    const char *author, const char *sign_commit)
{
  struct commit_extra_header *extra = NULL, **tail = &extra;
  int result;

  append_merge_tag_headers(parents, &tail);
  result = commit_tree_extended(msg, msg_len, tree, parents, ret, author,
              NULL, sign_commit, extra);
  free_commit_extra_headers(extra);
  return result;
}

static int find_invalid_utf8(const char *buf, int len)
{
  int offset = 0;
  static const unsigned int max_codepoint[] = {
    0x7f, 0x7ff, 0xffff, 0x10ffff
  };

  while (len) {
    unsigned char c = *buf++;
    int bytes, bad_offset;
    unsigned int codepoint;
    unsigned int min_val, max_val;

    len--;
    offset++;

    /* Simple US-ASCII? No worries. */
    if (c < 0x80)
      continue;

    bad_offset = offset-1;

    /*
     * Count how many more high bits set: that's how
     * many more bytes this sequence should have.
     */
    bytes = 0;
    while (c & 0x40) {
      c <<= 1;
      bytes++;
    }

    /*
     * Must be between 1 and 3 more bytes.  Longer sequences result in
     * codepoints beyond U+10FFFF, which are guaranteed never to exist.
     */
    if (bytes < 1 || 3 < bytes)
      return bad_offset;

    /* Do we *have* that many bytes? */
    if (len < bytes)
      return bad_offset;

    /*
     * Place the encoded bits at the bottom of the value and compute the
     * valid range.
     */
    codepoint = (c & 0x7f) >> bytes;
    min_val = max_codepoint[bytes-1] + 1;
    max_val = max_codepoint[bytes];

    offset += bytes;
    len -= bytes;

    /* And verify that they are good continuation bytes */
    do {
      codepoint <<= 6;
      codepoint |= *buf & 0x3f;
      if ((*buf++ & 0xc0) != 0x80)
        return bad_offset;
    } while (--bytes);

    /* Reject codepoints that are out of range for the sequence length. */
    if (codepoint < min_val || codepoint > max_val)
      return bad_offset;
    /* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
    if ((codepoint & 0x1ff800) == 0xd800)
      return bad_offset;
    /* U+xxFFFE and U+xxFFFF are guaranteed non-characters. */
    if ((codepoint & 0xfffe) == 0xfffe)
      return bad_offset;
    /* So are anything in the range U+FDD0..U+FDEF. */
    if (codepoint >= 0xfdd0 && codepoint <= 0xfdef)
      return bad_offset;
  }
  return -1;
}

/*
 * This verifies that the buffer is in proper utf8 format.
 *
 * If it isn't, it assumes any non-utf8 characters are Latin1,
 * and does the conversion.
 */
static int verify_utf8(struct strbuf *buf)
{
  int ok = 1;
  long pos = 0;

  for (;;) {
    int bad;
    unsigned char c;
    unsigned char replace[2];

    bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
    if (bad < 0)
      return ok;
    pos += bad;
    ok = 0;
    c = buf->buf[pos];
    strbuf_remove(buf, pos, 1);

    /* We know 'c' must be in the range 128-255 */
    replace[0] = 0xc0 + (c >> 6);
    replace[1] = 0x80 + (c & 0x3f);
    strbuf_insert(buf, pos, replace, 2);
    pos += 2;
  }
}

static const char commit_utf8_warn[] =
N_("Warning: commit message did not conform to UTF-8.\n"
   "You may want to amend it after fixing the message, or set the config\n"
   "variable i18n.commitEncoding to the encoding your project uses.\n");

static void write_commit_tree(struct strbuf *buffer, const char *msg, size_t msg_len,
            const struct object_id *tree,
            const struct object_id *parents, size_t parents_len,
            const char *author, const char *committer,
            const struct commit_extra_header *extra)
{
  int encoding_is_utf8;
  size_t i;

  /* Not having i18n.commitencoding is the same as having utf-8 */
  encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);

  strbuf_grow(buffer, 8192); /* should avoid reallocs for the headers */
  strbuf_addf(buffer, "tree %s\n", oid_to_hex(tree));

  /*
   * NOTE! This ordering means that the same exact tree merged with a
   * different order of parents will be a _different_ changeset even
   * if everything else stays the same.
   */
  for (i = 0; i < parents_len; i++)
    strbuf_addf(buffer, "parent %s\n", oid_to_hex(&parents[i]));

  /* Person/date information */
  if (!author)
    author = git_author_info(IDENT_STRICT);
  strbuf_addf(buffer, "author %s\n", author);
  if (!committer)
    committer = git_committer_info(IDENT_STRICT);
  strbuf_addf(buffer, "committer %s\n", committer);
  if (!encoding_is_utf8)
    strbuf_addf(buffer, "encoding %s\n", git_commit_encoding);

  while (extra) {
    add_extra_header(buffer, extra);
    extra = extra->next;
  }
  strbuf_addch(buffer, '\n');

  /* And add the comment */
  strbuf_add(buffer, msg, msg_len);
}

int commit_tree_extended(const char *msg, size_t msg_len,
       const struct object_id *tree,
       const struct commit_list *parents, struct object_id *ret,
       const char *author, const char *committer,
       const char *sign_commit,
       const struct commit_extra_header *extra)
{
  struct repository *r = the_repository;
  int result = 0;
  int encoding_is_utf8;
  struct strbuf buffer = STRBUF_INIT, compat_buffer = STRBUF_INIT;
  struct strbuf sig = STRBUF_INIT, compat_sig = STRBUF_INIT;
  struct object_id *parent_buf = NULL, *compat_oid = NULL;
  struct object_id compat_oid_buf;
  size_t i, nparents;

  /* Not having i18n.commitencoding is the same as having utf-8 */
  encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);

  odb_assert_oid_type(the_repository->objects, tree, OBJ_TREE);

  if (memchr(msg, '\0', msg_len))
    return error("a NUL byte in commit log message not allowed.");

  nparents = commit_list_count(parents);
  CALLOC_ARRAY(parent_buf, nparents);
  i = 0;
  for (const struct commit_list *p = parents; p; p = p->next)
    oidcpy(&parent_buf[i++], &p->item->object.oid);

  write_commit_tree(&buffer, msg, msg_len, tree, parent_buf, nparents, author, committer, extra);
  if (sign_commit && sign_commit_to_strbuf(&sig, &buffer, sign_commit)) {
    result = -1;
    goto out;
  }
  if (r->compat_hash_algo) {
    struct commit_extra_header *compat_extra = NULL;
    struct object_id mapped_tree;
    struct object_id *mapped_parents;

    CALLOC_ARRAY(mapped_parents, nparents);

    if (repo_oid_to_algop(r, tree, r->compat_hash_algo, &mapped_tree)) {
      result = -1;
      free(mapped_parents);
      goto out;
    }
    for (i = 0; i < nparents; i++)
      if (repo_oid_to_algop(r, &parent_buf[i], r->compat_hash_algo, &mapped_parents[i])) {
        result = -1;
        free(mapped_parents);
        goto out;
      }
    if (convert_commit_extra_headers(extra, &compat_extra)) {
      result = -1;
      free(mapped_parents);
      goto out;
    }
    write_commit_tree(&compat_buffer, msg, msg_len, &mapped_tree,
          mapped_parents, nparents, author, committer, compat_extra);
    free_commit_extra_headers(compat_extra);
    free(mapped_parents);

    if (sign_commit && sign_commit_to_strbuf(&compat_sig, &compat_buffer, sign_commit)) {
      result = -1;
      goto out;
    }
  }

  if (sign_commit) {
    struct sig_pairs {
      struct strbuf *sig;
      const struct git_hash_algo *algo;
    } bufs [2] = {
      { &compat_sig, r->compat_hash_algo },
      { &sig, r->hash_algo },
    };

    /*
     * We write algorithms in the order they were implemented in
     * Git to produce a stable hash when multiple algorithms are
     * used.
     */
    if (r->compat_hash_algo && hash_algo_by_ptr(bufs[0].algo) > hash_algo_by_ptr(bufs[1].algo))
      SWAP(bufs[0], bufs[1]);

    /*
     * We traverse each algorithm in order, and apply the signature
     * to each buffer.
     */
    for (size_t i = 0; i < ARRAY_SIZE(bufs); i++) {
      if (!bufs[i].algo)
        continue;
      add_header_signature(&buffer, bufs[i].sig, bufs[i].algo);
      if (r->compat_hash_algo)
        add_header_signature(&compat_buffer, bufs[i].sig, bufs[i].algo);
    }
  }

  /* And check the encoding. */
  if (encoding_is_utf8 && (!verify_utf8(&buffer) || !verify_utf8(&compat_buffer)))
    fprintf(stderr, _(commit_utf8_warn));

  if (r->compat_hash_algo) {
    hash_object_file(r->compat_hash_algo, compat_buffer.buf, compat_buffer.len,
      OBJ_COMMIT, &compat_oid_buf);
    compat_oid = &compat_oid_buf;
  }

  result = odb_write_object_ext(the_repository->objects, buffer.buf, buffer.len,
              OBJ_COMMIT, ret, compat_oid, 0);
out:
  free(parent_buf);
  strbuf_release(&buffer);
  strbuf_release(&compat_buffer);
  strbuf_release(&sig);
  strbuf_release(&compat_sig);
  return result;
}

define_commit_slab(merge_desc_slab, struct merge_remote_desc *);
static struct merge_desc_slab merge_desc_slab = COMMIT_SLAB_INIT(1, merge_desc_slab);

struct merge_remote_desc *merge_remote_util(const struct commit *commit)
{
  return *merge_desc_slab_at(&merge_desc_slab, commit);
}

void set_merge_remote_desc(struct commit *commit,
         const char *name, struct object *obj)
{
  struct merge_remote_desc *desc;
  FLEX_ALLOC_STR(desc, name, name);
  desc->obj = obj;
  *merge_desc_slab_at(&merge_desc_slab, commit) = desc;
}

struct commit *get_merge_parent(const char *name)
{
  struct object *obj;
  struct commit *commit;
  struct object_id oid;
  if (repo_get_oid(the_repository, name, &oid))
    return NULL;
  obj = parse_object(the_repository, &oid);
  commit = (struct commit *)repo_peel_to_type(the_repository, name, 0,
                obj, OBJ_COMMIT);
  if (commit && !merge_remote_util(commit))
    set_merge_remote_desc(commit, name, obj);
  return commit;
}

/*
 * Append a commit to the end of the commit_list.
 *
 * next starts by pointing to the variable that holds the head of an
 * empty commit_list, and is updated to point to the "next" field of
 * the last item on the list as new commits are appended.
 *
 * Usage example:
 *
 *     struct commit_list *list;
 *     struct commit_list **next = &list;
 *
 *     next = commit_list_append(c1, next);
 *     next = commit_list_append(c2, next);
 *     assert(commit_list_count(list) == 2);
 *     return list;
 */
struct commit_list **commit_list_append(struct commit *commit,
          struct commit_list **next)
{
  struct commit_list *new_commit = xmalloc(sizeof(struct commit_list));
  new_commit->item = commit;
  *next = new_commit;
  new_commit->next = NULL;
  return &new_commit->next;
}

const char *find_commit_header(const char *msg, const char *key, size_t *out_len)
{
  int key_len = strlen(key);
  const char *line = msg;

  while (line) {
    const char *eol = strchrnul(line, '\n');

    if (line == eol)
      return NULL;

    if (eol - line > key_len &&
        !strncmp(line, key, key_len) &&
        line[key_len] == ' ') {
      *out_len = eol - line - key_len - 1;
      return line + key_len + 1;
    }
    line = *eol ? eol + 1 : NULL;
  }
  return NULL;
}

/*
 * Inspect the given string and determine the true "end" of the log message, in
 * order to find where to put a new Signed-off-by trailer.  Ignored are
 * trailing comment lines and blank lines.  To support "git commit -s
 * --amend" on an existing commit, we also ignore "Conflicts:".  To
 * support "git commit -v", we truncate at cut lines.
 *
 * Returns the number of bytes from the tail to ignore, to be fed as
 * the second parameter to append_signoff().
 */
size_t ignored_log_message_bytes(const char *buf, size_t len)
{
  size_t boc = 0;
  size_t bol = 0;
  int in_old_conflicts_block = 0;
  size_t cutoff = wt_status_locate_end(buf, len);

  while (bol < cutoff) {
    const char *next_line = memchr(buf + bol, '\n', len - bol);

    if (!next_line)
      next_line = buf + len;
    else
      next_line++;

    if (starts_with_mem(buf + bol, cutoff - bol, comment_line_str) ||
        buf[bol] == '\n') {
      /* is this the first of the run of comments? */
      if (!boc)
        boc = bol;
      /* otherwise, it is just continuing */
    } else if (starts_with(buf + bol, "Conflicts:\n")) {
      in_old_conflicts_block = 1;
      if (!boc)
        boc = bol;
    } else if (in_old_conflicts_block && buf[bol] == '\t') {
      ; /* a pathname in the conflicts block */
    } else if (boc) {
      /* the previous was not trailing comment */
      boc = 0;
      in_old_conflicts_block = 0;
    }
    bol = next_line - buf;
  }
  return boc ? len - boc : len - cutoff;
}

int run_commit_hook(int editor_is_used, const char *index_file,
        int *invoked_hook, const char *name, ...)
{
  struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
  va_list args;
  const char *arg;

  strvec_pushf(&opt.env, "GIT_INDEX_FILE=%s", index_file);

  /*
   * Let the hook know that no editor will be launched.
   */
  if (!editor_is_used)
    strvec_push(&opt.env, "GIT_EDITOR=:");

  va_start(args, name);
  while ((arg = va_arg(args, const char *)))
    strvec_push(&opt.args, arg);
  va_end(args);

  opt.invoked_hook = invoked_hook;
  return run_hooks_opt(the_repository, name, &opt);
}

Coverage Report

Created: 2025-12-31 07:01