1 files changed, 154 insertions, 19 deletions

diff --git a/builtin/replace.c b/builtin/replace.c
index 1fcd06db25..8020db8500 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -13,19 +13,21 @@
 #include "refs.h"
 #include "parse-options.h"
 #include "run-command.h"
+#include "tag.h"
 
 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>]]"),
 	NULL
 };
 
 enum replace_format {
-      REPLACE_FORMAT_SHORT,
-      REPLACE_FORMAT_MEDIUM,
-      REPLACE_FORMAT_LONG
+	REPLACE_FORMAT_SHORT,
+	REPLACE_FORMAT_MEDIUM,
+	REPLACE_FORMAT_LONG
 };
 
 struct show_data {
@@ -190,27 +192,32 @@ static int replace_object(const char *object_ref, const char *replace_ref, int f
 }
 
 /*
- * Write the contents of the object named by "sha1" to the file "filename",
- * pretty-printed for human editing based on its type.
+ * Write the contents of the object named by "sha1" to the file "filename".
+ * If "raw" is true, then the object's raw contents are printed according to
+ * "type". Otherwise, we pretty-print the contents for human editing.
  */
-static void export_object(const unsigned char *sha1, const char *filename)
+static void export_object(const unsigned char *sha1, enum object_type type,
+			  int raw, const char *filename)
 {
-	const char *argv[] = { "--no-replace-objects", "cat-file", "-p", NULL, NULL };
-	struct child_process cmd = { argv };
+	struct child_process cmd = CHILD_PROCESS_INIT;
 	int fd;
 
 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 	if (fd < 0)
 		die_errno("unable to open %s for writing", filename);
 
-	argv[3] = sha1_to_hex(sha1);
+	argv_array_push(&cmd.args, "--no-replace-objects");
+	argv_array_push(&cmd.args, "cat-file");
+	if (raw)
+		argv_array_push(&cmd.args, typename(type));
+	else
+		argv_array_push(&cmd.args, "-p");
+	argv_array_push(&cmd.args, sha1_to_hex(sha1));
 	cmd.git_cmd = 1;
 	cmd.out = fd;
 
 	if (run_command(&cmd))
 		die("cat-file reported failure");
-
-	close(fd);
 }
 
 /*
@@ -219,7 +226,7 @@ static void export_object(const unsigned char *sha1, const char *filename)
  * The sha1 of the written object is returned via sha1.
  */
 static void import_object(unsigned char *sha1, enum object_type type,
-			  const char *filename)
+			  int raw, const char *filename)
 {
 	int fd;
 
@@ -227,9 +234,9 @@ static void import_object(unsigned char *sha1, enum object_type type,
 	if (fd < 0)
 		die_errno("unable to open %s for reading", filename);
 
-	if (type == OBJ_TREE) {
+	if (!raw && type == OBJ_TREE) {
 		const char *argv[] = { "mktree", NULL };
-		struct child_process cmd = { argv };
+		struct child_process cmd = CHILD_PROCESS_INIT;
 		struct strbuf result = STRBUF_INIT;
 
 		cmd.argv = argv;
@@ -267,7 +274,7 @@ static void import_object(unsigned char *sha1, enum object_type type,
 	 */
 }
 
-static int edit_and_replace(const char *object_ref, int force)
+static int edit_and_replace(const char *object_ref, int force, int raw)
 {
 	char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 	enum object_type type;
@@ -283,10 +290,10 @@ static int edit_and_replace(const char *object_ref, int force)
 
 	check_ref_valid(old, prev, ref, sizeof(ref), force);
 
-	export_object(old, tmpfile);
+	export_object(old, type, raw, tmpfile);
 	if (launch_editor(tmpfile, NULL, NULL) < 0)
 		die("editing object file failed");
-	import_object(new, type, tmpfile);
+	import_object(new, type, raw, tmpfile);
 
 	free(tmpfile);
 
@@ -296,22 +303,137 @@ 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);
+
+	strbuf_release(&new_parents);
+}
+
+struct check_mergetag_data {
+	int argc;
+	const char **argv;
+};
+
+static void check_one_mergetag(struct commit *commit,
+			       struct commit_extra_header *extra,
+			       void *data)
+{
+	struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
+	const char *ref = mergetag_data->argv[0];
+	unsigned char tag_sha1[20];
+	struct tag *tag;
+	int i;
+
+	hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_sha1);
+	tag = lookup_tag(tag_sha1);
+	if (!tag)
+		die(_("bad mergetag in commit '%s'"), ref);
+	if (parse_tag_buffer(tag, extra->value, extra->len))
+		die(_("malformed mergetag in commit '%s'"), ref);
+
+	/* iterate over new parents */
+	for (i = 1; i < mergetag_data->argc; i++) {
+		unsigned char sha1[20];
+		if (get_sha1(mergetag_data->argv[i], sha1) < 0)
+			die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
+		if (!hashcmp(tag->tagged->sha1, sha1))
+			return; /* found */
+	}
+
+	die(_("original commit '%s' contains mergetag '%s' that is discarded; "
+	      "use --edit instead of --graft"), ref, sha1_to_hex(tag_sha1));
+}
+
+static void check_mergetags(struct commit *commit, int argc, const char **argv)
+{
+	struct check_mergetag_data mergetag_data;
+
+	mergetag_data.argc = argc;
+	mergetag_data.argv = argv;
+	for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
+}
+
+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 (remove_signature(&buf)) {
+		warning(_("the original commit '%s' has a gpg signature."), old_ref);
+		warning(_("the signature will be removed in the replacement commit!"));
+	}
+
+	check_mergetags(commit, argc, argv);
+
+	if (write_sha1_file(buf.buf, buf.len, commit_type, new))
+		die(_("could not write replacement commit for: '%s'"), old_ref);
+
+	strbuf_release(&buf);
+
+	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;
+	int raw = 0;
 	const char *format = NULL;
 	enum {
 		MODE_UNSPECIFIED = 0,
 		MODE_LIST,
 		MODE_DELETE,
 		MODE_EDIT,
+		MODE_GRAFT,
 		MODE_REPLACE
 	} cmdmode = MODE_UNSPECIFIED;
 	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_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 		OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 		OPT_END()
 	};
@@ -327,10 +449,17 @@ 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);
 
+	if (raw && cmdmode != MODE_EDIT)
+		usage_msg_opt("--raw only makes sense with --edit",
+			      git_replace_usage, options);
+
 	switch (cmdmode) {
 	case MODE_DELETE:
 		if (argc < 1)
@@ -348,7 +477,13 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
 		if (argc != 1)
 			usage_msg_opt("-e needs exactly one argument",
 				      git_replace_usage, options);
-		return edit_and_replace(argv[0], force);
+		return edit_and_replace(argv[0], force, raw);
+
+	case MODE_GRAFT:
+		if (argc < 1)
+			usage_msg_opt("-g needs at least one argument",
+				      git_replace_usage, options);
+		return create_graft(argc, argv, force);
 
 	case MODE_LIST:
 		if (argc > 1)