sequencer: extract perform_autostash() from rebase

Lib-ify the autostash code by extracting perform_autostash() from rebase
into sequencer. In a future commit, this will be used to implement
`--autostash` in other builtins.

This patch is best viewed with `--color-moved`.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rebase.c

@@ -1274,55 +1274,6 @@ static int check_exec_cmd(const char *cmd)
 	return 0;
 }
 
-static void create_autostash(struct repository *r, const char *path,
-			     const char *default_reflog_action)
-{
-	struct strbuf buf = STRBUF_INIT;
-	struct lock_file lock_file = LOCK_INIT;
-	int fd;
-
-	fd = repo_hold_locked_index(r, &lock_file, 0);
-	refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL);
-	if (0 <= fd)
-		repo_update_index_if_able(r, &lock_file);
-	rollback_lock_file(&lock_file);
-
-	if (has_unstaged_changes(r, 1) ||
-	    has_uncommitted_changes(r, 1)) {
-		struct child_process stash = CHILD_PROCESS_INIT;
-		struct object_id oid;
-
-		argv_array_pushl(&stash.args,
-				 "stash", "create", "autostash", NULL);
-		stash.git_cmd = 1;
-		stash.no_stdin = 1;
-		strbuf_reset(&buf);
-		if (capture_command(&stash, &buf, GIT_MAX_HEXSZ))
-			die(_("Cannot autostash"));
-		strbuf_trim_trailing_newline(&buf);
-		if (get_oid(buf.buf, &oid))
-			die(_("Unexpected stash response: '%s'"),
-			    buf.buf);
-		strbuf_reset(&buf);
-		strbuf_add_unique_abbrev(&buf, &oid, DEFAULT_ABBREV);
-
-		if (safe_create_leading_directories_const(path))
-			die(_("Could not create directory for '%s'"),
-			    path);
-		write_file(path, "%s", oid_to_hex(&oid));
-		printf(_("Created autostash: %s\n"), buf.buf);
-		if (reset_head(r, NULL, "reset --hard",
-			       NULL, RESET_HEAD_HARD, NULL, NULL,
-			       default_reflog_action) < 0)
-			die(_("could not reset --hard"));
-
-		if (discard_index(r->index) < 0 ||
-			repo_read_index(r) < 0)
-			die(_("could not read index"));
-	}
-	strbuf_release(&buf);
-}
-
 int cmd_rebase(int argc, const char **argv, const char *prefix)
 {
 	struct rebase_options options = REBASE_OPTIONS_INIT;

sequencer.c

@@ -32,6 +32,7 @@
 #include "alias.h"
 #include "commit-reach.h"
 #include "rebase-interactive.h"
+#include "reset.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -3657,6 +3658,55 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 	return -1;
 }
 
+void create_autostash(struct repository *r, const char *path,
+		      const char *default_reflog_action)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct lock_file lock_file = LOCK_INIT;
+	int fd;
+
+	fd = repo_hold_locked_index(r, &lock_file, 0);
+	refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL);
+	if (0 <= fd)
+		repo_update_index_if_able(r, &lock_file);
+	rollback_lock_file(&lock_file);
+
+	if (has_unstaged_changes(r, 1) ||
+	    has_uncommitted_changes(r, 1)) {
+		struct child_process stash = CHILD_PROCESS_INIT;
+		struct object_id oid;
+
+		argv_array_pushl(&stash.args,
+				 "stash", "create", "autostash", NULL);
+		stash.git_cmd = 1;
+		stash.no_stdin = 1;
+		strbuf_reset(&buf);
+		if (capture_command(&stash, &buf, GIT_MAX_HEXSZ))
+			die(_("Cannot autostash"));
+		strbuf_trim_trailing_newline(&buf);
+		if (get_oid(buf.buf, &oid))
+			die(_("Unexpected stash response: '%s'"),
+			    buf.buf);
+		strbuf_reset(&buf);
+		strbuf_add_unique_abbrev(&buf, &oid, DEFAULT_ABBREV);
+
+		if (safe_create_leading_directories_const(path))
+			die(_("Could not create directory for '%s'"),
+			    path);
+		write_file(path, "%s", oid_to_hex(&oid));
+		printf(_("Created autostash: %s\n"), buf.buf);
+		if (reset_head(r, NULL, "reset --hard",
+			       NULL, RESET_HEAD_HARD, NULL, NULL,
+			       default_reflog_action) < 0)
+			die(_("could not reset --hard"));
+
+		if (discard_index(r->index) < 0 ||
+			repo_read_index(r) < 0)
+			die(_("could not read index"));
+	}
+	strbuf_release(&buf);
+}
+
 int apply_autostash(const char *path)
 {
 	struct strbuf stash_oid = STRBUF_INIT;

sequencer.h

@@ -191,6 +191,8 @@ void commit_post_rewrite(struct repository *r,
 			 const struct commit *current_head,
 			 const struct object_id *new_head);
 
+void create_autostash(struct repository *r, const char *path,
+		      const char *default_reflog_action);
 int apply_autostash(const char *path);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)