sequencer (rebase -i): implement the 'edit' command

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

sequencer.c

@@ -15,6 +15,7 @@
 #include "merge-recursive.h"
 #include "refs.h"
 #include "argv-array.h"
+#include "log-tree.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -35,6 +36,20 @@ static GIT_PATH_FUNC(git_path_rebase_dir, "rebase-merge")
  * file and written to the tail of 'done'.
  */
 static GIT_PATH_FUNC(git_path_rebase_todo, "rebase-merge/git-rebase-todo")
+/*
+ * When an "edit" rebase command is being processed, the SHA1 of the
+ * commit to be edited is recorded in this file.  When "git rebase
+ * --continue" is executed, if there are any staged changes then they
+ * will be amended to the HEAD commit, but only provided the HEAD
+ * commit is still the commit to be edited.  When any other rebase
+ * command is processed, this file is deleted.
+ */
+static GIT_PATH_FUNC(git_path_rebase_amend, "rebase-merge/amend")
+/*
+ * When we stop at a given patch via the "edit" command, this file contains
+ * the long commit name of the corresponding patch.
+ */
+static GIT_PATH_FUNC(stopped_sha, "rebase-merge/stopped-sha")
 
 #define IS_REBASE_I() (opts->action == REPLAY_INTERACTIVE_REBASE)
 
@@ -488,12 +503,14 @@ static int allow_empty(struct replay_opts *opts, struct commit *commit)
 enum todo_command {
 	TODO_PICK,
 	TODO_REVERT,
+	TODO_EDIT,
 	TODO_NOOP
 };
 
 static const char *todo_command_strings[] = {
 	"pick",
 	"revert",
+	"edit",
 	"noop"
 };
 
@@ -1065,10 +1082,67 @@ static int save_opts(struct replay_opts *opts)
 	return res;
 }
 
-static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
+static int make_patch(struct commit *commit, struct replay_opts *opts)
 {
+	struct strbuf buf = STRBUF_INIT;
+	struct rev_info log_tree_opt;
+	const char *commit_buffer = get_commit_buffer(commit, NULL), *subject;
 	int res;
 
+	write_file(stopped_sha(), "%s\n", short_commit_name(commit));
+
+	strbuf_addf(&buf, "%s/patch", get_dir(opts));
+	freopen(buf.buf, "w", stdout);
+	memset(&log_tree_opt, 0, sizeof(log_tree_opt));
+	init_revisions(&log_tree_opt, NULL);
+	log_tree_opt.abbrev = 0;
+	log_tree_opt.diff = 1;
+	log_tree_opt.diffopt.output_format = DIFF_FORMAT_PATCH;
+	log_tree_opt.disable_stdin = 1;
+	log_tree_opt.no_commit_id = 1;
+	res = log_tree_commit(&log_tree_opt, commit);
+	strbuf_reset(&buf);
+
+	strbuf_addf(&buf, "%s/message", get_dir(opts));
+	if (!file_exists(buf.buf)) {
+		find_commit_subject(commit_buffer, &subject);
+		write_file(buf.buf, "%s\n", subject);
+		unuse_commit_buffer(commit, commit_buffer);
+	}
+	strbuf_release(&buf);
+
+	return res;
+}
+
+static int error_with_patch(struct commit *commit,
+		struct replay_opts *opts, int exit_code)
+{
+	unsigned char head[20];
+
+	if (get_sha1("HEAD", head))
+		return error("Cannot read HEAD");
+
+	if (make_patch(commit, opts))
+		return -1;
+
+	write_file(git_path_rebase_amend(),
+		"%s\n", sha1_to_hex(head));
+
+	fprintf(stderr, "You can amend the commit now, with\n"
+		"\n"
+		"  git commit --amend\n" /* TODO:  $gpg_sign_opt_quoted */
+		"\n"
+		"Once you are satisfied with your changes, run\n"
+		"\n"
+		"  git rebase --continue\n");
+
+	return exit_code;
+}
+
+static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
+{
+	int res = 0;
+
 	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 	if (opts->allow_ff)
 		assert(!(opts->signoff || opts->no_commit ||
@@ -1080,9 +1154,18 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
 		struct todo_item *item = todo_list->items + todo_list->current;
 		if (save_todo(todo_list, opts))
 			return -1;
-		if (item->command <= TODO_REVERT)
+		if (item->command <= TODO_EDIT) {
 			res = do_pick_commit(item->command, item->commit,
 					opts);
+			if (item->command == TODO_EDIT) {
+				struct commit *commit = item->commit;
+				if (!res)
+					warning("Stopped at %s... %.*s",
+						short_commit_name(commit),
+						item->arg_len, item->arg);
+				return error_with_patch(commit, opts, res);
+			}
+		}
 		else if (item->command != TODO_NOOP)
 			return error("Unknown command %d", item->command);
 
@@ -1091,6 +1174,12 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
 			return res;
 	}
 
+	if (IS_REBASE_I()) {
+		/* Stopped in the middle, as planned? */
+		if (todo_list->current < todo_list->nr)
+			return 0;
+	}
+
 	/*
 	 * Sequence of picks finished successfully; cleanup by
 	 * removing the .git/sequencer directory