Commit 4228e8bc authored by Christian Couder's avatar Christian Couder Committed by Junio C Hamano

replace: add --graft option

The usage string for this option is:

git replace [-f] --graft <commit> [<parent>...]

First we create a new commit that is the same as <commit>
except that its parents are [<parents>...]

Then we create a replace ref that replace <commit> with
the commit we just created.

With this new option, it should be straightforward to
convert grafts to replace refs.
Signed-off-by: Christian Couder's avatarChristian Couder <>
Signed-off-by: default avatarJunio C Hamano <>
parent 1c2828c1
......@@ -17,6 +17,7 @@
static const char * const git_replace_usage[] = {
N_("git replace [-f] <object> <replacement>"),
N_("git replace [-f] --edit <object>"),
N_("git replace [-f] --graft <commit> [<parent>...]"),
N_("git replace -d <object>..."),
N_("git replace [--format=<format>] [-l [<pattern>]]"),
......@@ -294,6 +295,66 @@ static int edit_and_replace(const char *object_ref, int force)
return replace_object_sha1(object_ref, old, "replacement", new, force);
static void replace_parents(struct strbuf *buf, int argc, const char **argv)
struct strbuf new_parents = STRBUF_INIT;
const char *parent_start, *parent_end;
int i;
/* find existing parents */
parent_start = buf->buf;
parent_start += 46; /* "tree " + "hex sha1" + "\n" */
parent_end = parent_start;
while (starts_with(parent_end, "parent "))
parent_end += 48; /* "parent " + "hex sha1" + "\n" */
/* prepare new parents */
for (i = 0; i < argc; i++) {
unsigned char sha1[20];
if (get_sha1(argv[i], sha1) < 0)
die(_("Not a valid object name: '%s'"), argv[i]);
lookup_commit_or_die(sha1, argv[i]);
strbuf_addf(&new_parents, "parent %s\n", sha1_to_hex(sha1));
/* replace existing parents with new ones */
strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
new_parents.buf, new_parents.len);
static int create_graft(int argc, const char **argv, int force)
unsigned char old[20], new[20];
const char *old_ref = argv[0];
struct commit *commit;
struct strbuf buf = STRBUF_INIT;
const char *buffer;
unsigned long size;
if (get_sha1(old_ref, old) < 0)
die(_("Not a valid object name: '%s'"), old_ref);
commit = lookup_commit_or_die(old, old_ref);
buffer = get_commit_buffer(commit, &size);
strbuf_add(&buf, buffer, size);
unuse_commit_buffer(commit, buffer);
replace_parents(&buf, argc - 1, &argv[1]);
if (write_sha1_file(buf.buf, buf.len, commit_type, new))
die(_("could not write replacement commit for: '%s'"), old_ref);
if (!hashcmp(old, new))
return error("new commit is the same as the old one: '%s'", sha1_to_hex(old));
return replace_object_sha1(old_ref, old, "replacement", new, force);
int cmd_replace(int argc, const char **argv, const char *prefix)
int force = 0;
......@@ -303,12 +364,14 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
struct option options[] = {
OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
......@@ -325,7 +388,10 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
usage_msg_opt("--format cannot be used when not listing",
git_replace_usage, options);
if (force && cmdmode != MODE_REPLACE && cmdmode != MODE_EDIT)
if (force &&
cmdmode != MODE_REPLACE &&
cmdmode != MODE_EDIT &&
cmdmode != MODE_GRAFT)
usage_msg_opt("-f only makes sense when writing a replacement",
git_replace_usage, options);
......@@ -348,6 +414,12 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
git_replace_usage, options);
return edit_and_replace(argv[0], force);
if (argc < 1)
usage_msg_opt("-g needs at least one argument",
git_replace_usage, options);
return create_graft(argc, argv, force);
if (argc > 1)
usage_msg_opt("only one pattern can be given with -l",
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