Merge branch 'hn/bisect-auto-reset' into seen

The 'git bisect' command has been taught a '--auto-reset[=<where>]'
option that tells the command to automatically run 'git bisect reset'
to jump back to the original state or to the found culprit.

* hn/bisect-auto-reset:
  bisect: add --auto-reset to leave when done
  bisect: let bisect_reset() optionally check out quietly
  bisect: read run output from the open descriptor

Author: gitster

Documentation/git-bisect.adoc

@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [synopsis]
 git bisect start [--term-(bad|new)=<term-new> --term-(good|old)=<term-old>]
-		 [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<pathspec>...]
+		 [--no-checkout] [--first-parent] [--auto-reset[=<where>]] [<bad> [<good>...]] [--] [<pathspec>...]
 git bisect (bad|new|<term-new>) [<rev>]
 git bisect (good|old|<term-old>) [<rev>...]
 git bisect terms [--term-(good|old) | --term-(bad|new)]
@@ -20,7 +20,7 @@ git bisect reset [<commit>]
 git bisect (visualize|view)
 git bisect replay <logfile>
 git bisect log
-git bisect run <cmd> [<arg>...]
+git bisect run [--auto-reset[=<where>]] <cmd> [<arg>...]
 git bisect help
 
 DESCRIPTION
@@ -385,6 +385,16 @@ ignored.
 This option is particularly useful in avoiding false positives when a merged
 branch contained broken or non-buildable commits, but the merge itself was OK.
 
+`--auto-reset[=<where>]`::
+	Once the first bad commit is found, report it and clean up the
+	bisection state. `<where>` may be `original` to return to the commit
+	checked out before `git bisect start`, or `found` to leave the first
+	bad commit checked out. If `<where>` is omitted, it defaults to
+	`original`.
++
+This option may be given to `git bisect start` or to `git bisect run`. It
+cannot be used for a bisection started with `--no-checkout`.
+
 EXAMPLES
 --------
 

bisect.c

@@ -488,6 +488,7 @@ static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
 static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
 static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
+static GIT_PATH_FUNC(git_path_bisect_auto_reset, "BISECT_AUTO_RESET")
 
 static void read_bisect_paths(struct strvec *array)
 {
@@ -1213,6 +1214,7 @@ int bisect_clean_state(void)
 	unlink_or_warn(git_path_bisect_run());
 	unlink_or_warn(git_path_bisect_terms());
 	unlink_or_warn(git_path_bisect_first_parent());
+	unlink_or_warn(git_path_bisect_auto_reset());
 	/*
 	 * Cleanup BISECT_START last to support the --no-checkout option
 	 * introduced in the commit 4796e823a.

builtin/bisect.c

@@ -24,11 +24,12 @@ static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
 static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
 static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
+static GIT_PATH_FUNC(git_path_bisect_auto_reset, "BISECT_AUTO_RESET")
 static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
 
 #define BUILTIN_GIT_BISECT_START_USAGE \
 	N_("git bisect start [--term-(bad|new)=<term-new> --term-(good|old)=<term-old>]\n" \
-	   "                 [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<pathspec>...]")
+	   "                 [--no-checkout] [--first-parent] [--auto-reset[=<where>]] [<bad> [<good>...]] [--] [<pathspec>...]")
 #define BUILTIN_GIT_BISECT_BAD_USAGE \
 	N_("git bisect (bad|new|<term-new>) [<rev>]")
 #define BUILTIN_GIT_BISECT_GOOD_USAGE \
@@ -48,7 +49,7 @@ static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
 #define BUILTIN_GIT_BISECT_LOG_USAGE \
 	"git bisect log"
 #define BUILTIN_GIT_BISECT_RUN_USAGE \
-	N_("git bisect run <cmd> [<arg>...]")
+	N_("git bisect run [--auto-reset[=<where>]] <cmd> [<arg>...]")
 #define BUILTIN_GIT_BISECT_HELP_USAGE \
 	"git bisect help"
 
@@ -68,6 +69,12 @@ static const char * const git_bisect_usage[] = {
 	NULL
 };
 
+enum auto_reset_mode {
+	AUTO_RESET_NONE,
+	AUTO_RESET_ORIGINAL,
+	AUTO_RESET_FOUND,
+};
+
 struct add_bisect_ref_data {
 	struct rev_info *revs;
 	unsigned int object_flags;
@@ -178,17 +185,13 @@ static int append_to_file(const char *path, const char *format, ...)
 	return res;
 }
 
-static int print_file_to_stdout(const char *path)
+static int print_fd_to_stdout(int fd)
 {
-	int fd = open(path, O_RDONLY);
-	int ret = 0;
-
-	if (fd < 0)
-		return error_errno(_("cannot open file '%s' for reading"), path);
+	if (lseek(fd, 0, SEEK_SET) < 0)
+		return error_errno(_("failed to rewind BISECT_RUN output"));
 	if (copy_fd(fd, 1) < 0)
-		ret = error_errno(_("failed to read '%s'"), path);
-	close(fd);
-	return ret;
+		return error_errno(_("failed to read BISECT_RUN output"));
+	return 0;
 }
 
 static int check_term_format(const char *term, const char *orig_term)
@@ -234,7 +237,7 @@ static int write_terms(const char *bad, const char *good)
 	return res;
 }
 
-static int bisect_reset(const char *commit)
+static int bisect_reset(const char *commit, int quiet)
 {
 	struct strbuf branch = STRBUF_INIT;
 
@@ -255,8 +258,10 @@ static int bisect_reset(const char *commit)
 		struct child_process cmd = CHILD_PROCESS_INIT;
 
 		cmd.git_cmd = 1;
-		strvec_pushl(&cmd.args, "checkout", "--ignore-other-worktrees",
-				branch.buf, "--", NULL);
+		strvec_pushl(&cmd.args, "checkout", "--ignore-other-worktrees", NULL);
+		if (quiet)
+			strvec_push(&cmd.args, "--quiet");
+		strvec_pushl(&cmd.args, branch.buf, "--", NULL);
 		if (run_command(&cmd)) {
 			error(_("could not check out original"
 				" HEAD '%s'. Try 'git bisect"
@@ -270,6 +275,59 @@ static int bisect_reset(const char *commit)
 	return bisect_clean_state();
 }
 
+static int parse_auto_reset(const char *value, enum auto_reset_mode *mode)
+{
+	if (!strcmp(value, "original"))
+		*mode = AUTO_RESET_ORIGINAL;
+	else if (!strcmp(value, "found"))
+		*mode = AUTO_RESET_FOUND;
+	else
+		return error(_("invalid value for '--auto-reset': '%s'"), value);
+
+	return 0;
+}
+
+static const char *auto_reset_mode_name(enum auto_reset_mode mode)
+{
+	switch (mode) {
+	case AUTO_RESET_ORIGINAL:
+		return "original";
+	case AUTO_RESET_FOUND:
+		return "found";
+	case AUTO_RESET_NONE:
+		BUG("no name for unset auto-reset mode");
+	}
+	BUG("unknown auto-reset mode %d", mode);
+}
+
+static int bisect_auto_reset(struct bisect_terms *terms)
+{
+	struct strbuf value = STRBUF_INIT;
+	enum auto_reset_mode mode;
+	char *commit = NULL;
+	int res;
+
+	if (strbuf_read_file(&value, git_path_bisect_auto_reset(), 0) < 0) {
+		res = error_errno(_("could not read '%s'"),
+				  git_path_bisect_auto_reset());
+		goto cleanup;
+	}
+	strbuf_trim(&value);
+	if (parse_auto_reset(value.buf, &mode)) {
+		res = -1;
+		goto cleanup;
+	}
+
+	if (mode == AUTO_RESET_FOUND)
+		commit = xstrfmt("refs/bisect/%s", terms->term_bad);
+	res = bisect_reset(commit, 1);
+
+cleanup:
+	free(commit);
+	strbuf_release(&value);
+	return res;
+}
+
 static void log_commit(FILE *fp,
 		       const char *fmt, const char *state,
 		       struct commit *commit)
@@ -701,6 +759,8 @@ static enum bisect_error bisect_next(struct bisect_terms *terms, const char *pre
 
 	if (res == BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND) {
 		res = bisect_successful(terms);
+		if (!res && !is_empty_or_missing_file(git_path_bisect_auto_reset()))
+			res = bisect_auto_reset(terms);
 		return res ? res : BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
 	} else if (res == BISECT_ONLY_SKIPPED_LEFT) {
 		res = bisect_skipped_commits(terms);
@@ -724,6 +784,7 @@ static enum bisect_error bisect_start(struct bisect_terms *terms, int argc,
 {
 	int no_checkout = 0;
 	int first_parent_only = 0;
+	enum auto_reset_mode auto_reset = AUTO_RESET_NONE;
 	int i, has_double_dash = 0, must_write_terms = 0, bad_seen = 0;
 	int flags, pathspec_pos;
 	enum bisect_error res = BISECT_OK;
@@ -756,6 +817,13 @@ static enum bisect_error bisect_start(struct bisect_terms *terms, int argc,
 			no_checkout = 1;
 		} else if (!strcmp(arg, "--first-parent")) {
 			first_parent_only = 1;
+		} else if (!strcmp(arg, "--auto-reset")) {
+			auto_reset = AUTO_RESET_ORIGINAL;
+		} else if (skip_prefix(arg, "--auto-reset=", &arg)) {
+			if (parse_auto_reset(arg, &auto_reset)) {
+				res = BISECT_FAILED;
+				goto finish;
+			}
 		} else if (!strcmp(arg, "--term-good") ||
 			 !strcmp(arg, "--term-old")) {
 			i++;
@@ -793,6 +861,10 @@ static enum bisect_error bisect_start(struct bisect_terms *terms, int argc,
 			break;
 		}
 	}
+	if (auto_reset != AUTO_RESET_NONE && no_checkout) {
+		res = error(_("'--auto-reset' cannot be used with '--no-checkout'"));
+		goto finish;
+	}
 	pathspec_pos = i;
 
 	/*
@@ -872,6 +944,10 @@ static enum bisect_error bisect_start(struct bisect_terms *terms, int argc,
 	if (first_parent_only)
 		write_file(git_path_bisect_first_parent(), "\n");
 
+	if (auto_reset != AUTO_RESET_NONE)
+		write_file(git_path_bisect_auto_reset(), "%s\n",
+			   auto_reset_mode_name(auto_reset));
+
 	if (no_checkout) {
 		if (repo_get_oid(the_repository, start_head.buf, &oid) < 0) {
 			res = error(_("invalid ref: '%s'"), start_head.buf);
@@ -1104,7 +1180,7 @@ static enum bisect_error bisect_replay(struct bisect_terms *terms, const char *f
 	if (is_empty_or_missing_file(filename))
 		return error(_("cannot read file '%s' for replaying"), filename);
 
-	if (bisect_reset(NULL))
+	if (bisect_reset(NULL, 0))
 		return BISECT_FAILED;
 
 	fp = fopen(filename, "r");
@@ -1252,13 +1328,31 @@ static int bisect_run(struct bisect_terms *terms, int argc, const char **argv)
 {
 	int res = BISECT_OK;
 	struct strbuf command = STRBUF_INIT;
+	enum auto_reset_mode auto_reset = AUTO_RESET_NONE;
+	const char *auto_reset_arg;
 	const char *new_state;
 	int temporary_stdout_fd, saved_stdout;
 	int is_first_run = 1;
 
 	if (bisect_next_check(terms, NULL))
 		return BISECT_FAILED;
 
+	if (argc && !strcmp(argv[0], "--auto-reset"))
+		auto_reset = AUTO_RESET_ORIGINAL;
+	else if (argc && skip_prefix(argv[0], "--auto-reset=", &auto_reset_arg)) {
+		if (parse_auto_reset(auto_reset_arg, &auto_reset))
+			return BISECT_FAILED;
+	}
+
+	if (auto_reset != AUTO_RESET_NONE) {
+		if (refs_ref_exists(get_main_ref_store(the_repository), "BISECT_HEAD"))
+			return error(_("'--auto-reset' cannot be used with '--no-checkout'"));
+		write_file(git_path_bisect_auto_reset(), "%s\n",
+			   auto_reset_mode_name(auto_reset));
+		argc--;
+		argv++;
+	}
+
 	if (!argc) {
 		error(_("bisect run failed: no command provided."));
 		return BISECT_FAILED;
@@ -1306,7 +1400,7 @@ static int bisect_run(struct bisect_terms *terms, int argc, const char **argv)
 		else
 			new_state = terms->term_bad;
 
-		temporary_stdout_fd = open(git_path_bisect_run(), O_CREAT | O_WRONLY | O_TRUNC, 0666);
+		temporary_stdout_fd = open(git_path_bisect_run(), O_CREAT | O_RDWR | O_TRUNC, 0666);
 
 		if (temporary_stdout_fd < 0) {
 			res = error_errno(_("cannot open file '%s' for writing"), git_path_bisect_run());
@@ -1327,9 +1421,9 @@ static int bisect_run(struct bisect_terms *terms, int argc, const char **argv)
 		fflush(stdout);
 		dup2(saved_stdout, 1);
 		close(saved_stdout);
-		close(temporary_stdout_fd);
 
-		print_file_to_stdout(git_path_bisect_run());
+		print_fd_to_stdout(temporary_stdout_fd);
+		close(temporary_stdout_fd);
 
 		if (res == BISECT_ONLY_SKIPPED_LEFT)
 			error(_("bisect run cannot continue any more"));
@@ -1358,7 +1452,7 @@ static int cmd_bisect__reset(int argc, const char **argv, const char *prefix UNU
 	if (argc > 1)
 		return error(_("'%s' requires either no argument or a commit"),
 			     "git bisect reset");
-	return bisect_reset(argc ? argv[0] : NULL);
+	return bisect_reset(argc ? argv[0] : NULL, 0);
 }
 
 static int cmd_bisect__terms(int argc, const char **argv, const char *prefix UNUSED,