Adding upstream version 1:2.30.2.upstream/1%2.30.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1654 insertions, 0 deletions

diff --git a/commit.c b/commit.c
new file mode 100644
index 0000000..fe1fa3d
--- /dev/null
+++ b/commit.c
@@ -0,0 +1,1654 @@
+#include "cache.h"
+#include "tag.h"
+#include "commit.h"
+#include "commit-graph.h"
+#include "repository.h"
+#include "object-store.h"
+#include "pkt-line.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 "sha1-lookup.h"
+#include "wt-status.h"
+#include "advice.h"
+#include "refs.h"
+#include "commit-reach.h"
+#include "run-command.h"
+#include "shallow.h"
+
+static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
+
+int save_commit_buffer = 1;
+
+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(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)
+{
+	struct object_id oid;
+	struct commit *commit;
+
+	if (get_oid_committish(name, &oid))
+		return NULL;
+	commit = lookup_commit_reference(the_repository, &oid);
+	if (parse_commit(commit))
+		return NULL;
+	return commit;
+}
+
+static timestamp_t parse_commit_date(const char *buf, const char *tail)
+{
+	const char *dateptr;
+
+	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;
+	while (buf < tail && *buf++ != '>')
+		/* nada */;
+	if (buf >= tail)
+		return 0;
+	dateptr = buf;
+	while (buf < tail && *buf++ != '\n')
+		/* nada */;
+	if (buf >= tail)
+		return 0;
+	/* dateptr < buf && buf[-1] == '\n', so parsing will stop at buf-1 */
+	return parse_timestamp(dateptr, NULL, 10);
+}
+
+static const unsigned char *commit_graft_sha1_access(size_t index, void *table)
+{
+	struct commit_graft **commit_graft_table = table;
+	return commit_graft_table[index]->oid.hash;
+}
+
+int commit_graft_pos(struct repository *r, const unsigned char *sha1)
+{
+	return sha1_pos(sha1, r->parsed_objects->grafts,
+			r->parsed_objects->grafts_nr,
+			commit_graft_sha1_access);
+}
+
+int register_commit_graft(struct repository *r, struct commit_graft *graft,
+			  int ignore_dups)
+{
+	int pos = commit_graft_pos(r, graft->oid.hash);
+
+	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;
+	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 (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 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)
+{
+	char *graft_file;
+
+	if (r->parsed_objects->commit_graft_prepared)
+		return;
+	if (!startup_info->have_repository)
+		return;
+
+	graft_file = 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->hash);
+	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 = repo_read_object_file(r, &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 = get_commit_tree(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;
+
+	if (item->parents) {
+		/*
+		 * 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_replace_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;
+	int ret;
+
+	if (!item)
+		return -1;
+	if (item->object.parsed)
+		return 0;
+	if (use_commit_graph && parse_commit_in_graph(r, item))
+		return 0;
+	buffer = repo_read_object_file(r, &item->object.oid, &type, &size);
+	if (!buffer)
+		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) {
+		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 (parse_commit(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;
+}
+
+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;
+}
+
+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(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;
+}
+
+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 void *a, const void *b)
+{
+	timestamp_t a_date = ((const struct commit_list *)a)->item->date;
+	timestamp_t b_date = ((const struct commit_list *)b)->item->date;
+	if (a_date < b_date)
+		return 1;
+	if (a_date > b_date)
+		return -1;
+	return 0;
+}
+
+static void *commit_list_get_next(const void *a)
+{
+	return ((const struct commit_list *)a)->next;
+}
+
+static void commit_list_set_next(void *a, void *next)
+{
+	((struct commit_list *)a)->next = next;
+}
+
+void commit_list_sort_by_date(struct commit_list **list)
+{
+	*list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
+				commit_list_compare_by_date);
+}
+
+struct commit *pop_most_recent_commit(struct commit_list **list,
+				      unsigned int mark)
+{
+	struct commit *ret = pop_commit(list);
+	struct commit_list *parents = ret->parents;
+
+	while (parents) {
+		struct commit *commit = parents->item;
+		if (!parse_commit(commit) && !(commit->object.flags & mark)) {
+			commit->object.flags |= mark;
+			commit_list_insert_by_date(commit, list);
+		}
+		parents = parents->next;
+	}
+	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))
+			commit_list_insert(parents->item, plist);
+
+		commit = commit->parents->item;
+	}
+}
+
+void clear_commit_marks_many(int nr, struct commit **commit, unsigned int mark)
+{
+	struct commit_list *list = NULL;
+
+	while (nr--) {
+		clear_commit_marks_1(&list, *commit, mark);
+		commit++;
+	}
+	while (list)
+		clear_commit_marks_1(&list, pop_commit(&list), mark);
+}
+
+void clear_commit_marks(struct commit *commit, unsigned int mark)
+{
+	clear_commit_marks_many(1, &commit, 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 = get_commit_buffer(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:
+	unuse_commit_buffer(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)
+{
+	const struct commit *a = a_, *b = b_;
+	const uint32_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)
+{
+	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) ||
+	    parse_commit(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(struct object_id *ooid, struct object_id *noid,
+				  const char *ident, timestamp_t timestamp,
+				  int tz, const char *message, 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;
+	int i;
+	struct commit *ret = NULL;
+	char *full_refname;
+
+	switch (dwim_ref(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;
+	for_each_reflog_ent(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;
+
+	bases = get_merge_bases_many(commit, revs.nr, revs.commit);
+
+	/*
+	 * 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_commit_list(bases);
+	free(full_refname);
+	return ret;
+}
+
+/*
+ * Indexed by hash algorithm identifier.
+ */
+static const char *gpg_sig_headers[] = {
+	NULL,
+	"gpgsig",
+	"gpgsig-sha256",
+};
+
+static int do_sign_commit(struct strbuf *buf, const char *keyid)
+{
+	struct strbuf sig = STRBUF_INIT;
+	int inspos, copypos;
+	const char *eoh;
+	const char *gpg_sig_header = gpg_sig_headers[hash_algo_by_ptr(the_hash_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;
+
+	if (!keyid || !*keyid)
+		keyid = get_signing_key();
+	if (sign_buffer(buf, &sig, keyid)) {
+		strbuf_release(&sig);
+		return -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;
+	}
+	strbuf_release(&sig);
+	return 0;
+}
+
+int parse_signed_commit(const struct commit *commit,
+			struct strbuf *payload, struct strbuf *signature)
+{
+
+	unsigned long size;
+	const char *buffer = get_commit_buffer(commit, &size);
+	int in_signature, saw_signature = -1;
+	const char *line, *tail;
+	const char *gpg_sig_header = gpg_sig_headers[hash_algo_by_ptr(the_hash_algo)];
+	int gpg_sig_header_len = strlen(gpg_sig_header);
+
+	line = buffer;
+	tail = buffer + size;
+	in_signature = 0;
+	saw_signature = 0;
+	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 (starts_with(line, gpg_sig_header) &&
+			 line[gpg_sig_header_len] == ' ')
+			sig = line + gpg_sig_header_len + 1;
+		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;
+			strbuf_add(payload, line, next - line);
+			in_signature = 0;
+		}
+		line = next;
+	}
+	unuse_commit_buffer(commit, buffer);
+	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;
+	const char *sig_start = NULL;
+	const char *sig_end = NULL;
+
+	while (line < tail) {
+		const char *next = memchr(line, '\n', tail - line);
+		next = next ? next + 1 : tail;
+
+		if (in_signature && line[0] == ' ')
+			sig_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 == ' ') {
+					sig_start = line;
+					sig_end = next;
+					in_signature = 1;
+				}
+			}
+		} else {
+			if (*line == '\n')
+				/* dump the whole remainder of the buffer */
+				next = tail;
+			in_signature = 0;
+		}
+		line = next;
+	}
+
+	if (sig_start)
+		strbuf_remove(buf, sig_start - buf->buf, sig_end - sig_start);
+
+	return sig_start != NULL;
+}
+
+static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
+{
+	struct merge_remote_desc *desc;
+	struct commit_extra_header *mergetag;
+	char *buf;
+	unsigned long size, len;
+	enum object_type type;
+
+	desc = merge_remote_util(parent);
+	if (!desc || !desc->obj)
+		return;
+	buf = read_object_file(&desc->obj->oid, &type, &size);
+	if (!buf || type != OBJ_TAG)
+		goto free_return;
+	len = parse_signature(buf, size);
+	if (size == len)
+		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 he is merging, 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.");
+	 */
+	mergetag = xcalloc(1, sizeof(*mergetag));
+	mergetag->key = xstrdup("mergetag");
+	mergetag->value = buf;
+	mergetag->len = size;
+
+	**tail = mergetag;
+	*tail = &mergetag->next;
+	return;
+
+free_return:
+	free(buf);
+}
+
+int check_commit_signature(const struct commit *commit, struct signature_check *sigc)
+{
+	struct strbuf payload = STRBUF_INIT;
+	struct strbuf signature = STRBUF_INIT;
+	int ret = 1;
+
+	sigc->result = 'N';
+
+	if (parse_signed_commit(commit, &payload, &signature) <= 0)
+		goto out;
+	ret = check_signature(payload.buf, payload.len, signature.buf,
+		signature.len, sigc);
+
+ out:
+	strbuf_release(&payload);
+	strbuf_release(&signature);
+
+	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);
+
+	find_unique_abbrev_r(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(struct commit_list *parents,
+			      struct commit_extra_header ***tail)
+{
+	while (parents) {
+		struct commit *parent = parents->item;
+		handle_signed_tag(parent, tail);
+		parents = parents->next;
+	}
+}
+
+static void add_extra_header(struct strbuf *buffer,
+			     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 = get_commit_buffer(commit, &size);
+	extra = read_commit_extra_header_lines(buffer, size, exclude);
+	unuse_commit_buffer(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;
+
+		it = xcalloc(1, sizeof(*it));
+		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,
+		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");
+
+int commit_tree_extended(const char *msg, size_t msg_len,
+			 const struct object_id *tree,
+			 struct commit_list *parents, struct object_id *ret,
+			 const char *author, const char *committer,
+			 const char *sign_commit,
+			 struct commit_extra_header *extra)
+{
+	int result;
+	int encoding_is_utf8;
+	struct strbuf buffer;
+
+	assert_oid_type(tree, OBJ_TREE);
+
+	if (memchr(msg, '\0', msg_len))
+		return error("a NUL byte in commit log message not allowed.");
+
+	/* Not having i18n.commitencoding is the same as having utf-8 */
+	encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
+
+	strbuf_init(&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.
+	 */
+	while (parents) {
+		struct commit *parent = pop_commit(&parents);
+		strbuf_addf(&buffer, "parent %s\n",
+			    oid_to_hex(&parent->object.oid));
+	}
+
+	/* 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);
+
+	/* And check the encoding */
+	if (encoding_is_utf8 && !verify_utf8(&buffer))
+		fprintf(stderr, _(commit_utf8_warn));
+
+	if (sign_commit && do_sign_commit(&buffer, sign_commit)) {
+		result = -1;
+		goto out;
+	}
+
+	result = write_object_file(buffer.buf, buffer.len, commit_type, ret);
+out:
+	strbuf_release(&buffer);
+	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(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 (get_oid(name, &oid))
+		return NULL;
+	obj = parse_object(the_repository, &oid);
+	commit = (struct commit *)peel_to_type(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 ignore_non_trailer(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 (buf[bol] == comment_line_char || 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,
+		    const char *name, ...)
+{
+	struct strvec hook_env = STRVEC_INIT;
+	va_list args;
+	int ret;
+
+	strvec_pushf(&hook_env, "GIT_INDEX_FILE=%s", index_file);
+
+	/*
+	 * Let the hook know that no editor will be launched.
+	 */
+	if (!editor_is_used)
+		strvec_push(&hook_env, "GIT_EDITOR=:");
+
+	va_start(args, name);
+	ret = run_hook_ve(hook_env.v, name, args);
+	va_end(args);
+	strvec_clear(&hook_env);
+
+	return ret;
+}