Merge branch 'mr/bisect-in-c-1' into pu

* mr/bisect-in-c-1:
  bisect: libify `bisect_next_all`
  bisect: libify `handle_bad_merge_base` and its dependents
  bisect: libify `check_good_are_ancestors_of_bad` and its dependents
  bisect: libify `check_merge_bases` and its dependents
  bisect: libify `bisect_checkout`
  bisect: libify `exit_if_skipped_commits` to `error_if_skipped*` and its dependents
  bisect--helper: return error codes from `cmd_bisect__helper()`
  bisect: add enum to represent bisect returning codes
  bisect--helper: introduce new `decide_next()` function
  run-command: make `exists_in_PATH()` non-static
  bisect: use the standard 'if (!var)' way to check for 0
  bisect--helper: change `retval` to `res`
  bisect--helper: convert `vocab_*` char pointers to char arrays

Author: gitster

bisect.c

@@ -572,7 +572,7 @@ static int sqrti(int val)
 {
 	float d, x = val;
 
-	if (val == 0)
+	if (!val)
 		return 0;
 
 	do {
@@ -661,11 +661,11 @@ static void bisect_common(struct rev_info *revs)
 		mark_edges_uninteresting(revs, NULL, 0);
 }
 
-static void exit_if_skipped_commits(struct commit_list *tried,
+static enum bisect_error error_if_skipped_commits(struct commit_list *tried,
 				    const struct object_id *bad)
 {
 	if (!tried)
-		return;
+		return BISECT_OK;
 
 	printf("There are only 'skip'ped commits left to test.\n"
 	       "The first %s commit could be any of:\n", term_bad);
@@ -676,7 +676,8 @@ static void exit_if_skipped_commits(struct commit_list *tried,
 	if (bad)
 		printf("%s\n", oid_to_hex(bad));
 	printf(_("We cannot bisect more!\n"));
-	exit(2);
+
+	return BISECT_ONLY_SKIPPED_LEFT;
 }
 
 static int is_expected_rev(const struct object_id *oid)
@@ -703,9 +704,10 @@ static int is_expected_rev(const struct object_id *oid)
 	return res;
 }
 
-static int bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
+static enum bisect_error bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
 {
 	char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
+	enum bisect_error res = BISECT_OK;
 
 	memcpy(bisect_rev_hex, oid_to_hex(bisect_rev), the_hash_algo->hexsz + 1);
 	update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
@@ -715,14 +717,24 @@ static int bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
 		update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0,
 			   UPDATE_REFS_DIE_ON_ERR);
 	} else {
-		int res;
 		res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
 		if (res)
-			exit(res);
+			/*
+			 * Errors in `run_command()` itself, signaled by res < 0,
+			 * and errors in the child process, signaled by res > 0
+			 * can both be treated as regular BISECT_FAILURE (-1).
+			 */
+			return -abs(res);
 	}
 
 	argv_show_branch[1] = bisect_rev_hex;
-	return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
+	res = run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
+	/*
+	 * Errors in `run_command()` itself, signaled by res < 0,
+	 * and errors in the child process, signaled by res > 0
+	 * can both be treated as regular BISECT_FAILURE (-1).
+	 */
+	return -abs(res);
 }
 
 static struct commit *get_commit_reference(struct repository *r,
@@ -749,7 +761,7 @@ static struct commit **get_bad_and_good_commits(struct repository *r,
 	return rev;
 }
 
-static void handle_bad_merge_base(void)
+static enum bisect_error handle_bad_merge_base(void)
 {
 	if (is_expected_rev(current_bad_oid)) {
 		char *bad_hex = oid_to_hex(current_bad_oid);
@@ -770,14 +782,14 @@ static void handle_bad_merge_base(void)
 				"between %s and [%s].\n"),
 				bad_hex, term_bad, term_good, bad_hex, good_hex);
 		}
-		exit(3);
+		return BISECT_MERGE_BASE_CHECK;
 	}
 
 	fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
 		"git bisect cannot work properly in this case.\n"
 		"Maybe you mistook %s and %s revs?\n"),
 		term_good, term_bad, term_good, term_bad);
-	exit(1);
+	return BISECT_FAILED;
 }
 
 static void handle_skipped_merge_base(const struct object_id *mb)
@@ -799,32 +811,43 @@ static void handle_skipped_merge_base(const struct object_id *mb)
  * "check_merge_bases" checks that merge bases are not "bad" (or "new").
  *
  * - If one is "bad" (or "new"), it means the user assumed something wrong
- * and we must exit with a non 0 error code.
+ * and we must return error with a non 0 error code.
  * - If one is "good" (or "old"), that's good, we have nothing to do.
  * - If one is "skipped", we can't know but we should warn.
  * - If we don't know, we should check it out and ask the user to test.
+ * - If a merge base must be tested, on success return
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11) a special condition
+ * for early success, this will be converted back to 0 in
+ * check_good_are_ancestors_of_bad().
  */
-static void check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
+static enum bisect_error check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
 {
+	enum bisect_error res = BISECT_OK;
 	struct commit_list *result;
 
 	result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
 
 	for (; result; result = result->next) {
 		const struct object_id *mb = &result->item->object.oid;
 		if (oideq(mb, current_bad_oid)) {
-			handle_bad_merge_base();
+			res = handle_bad_merge_base();
+			break;
 		} else if (0 <= oid_array_lookup(&good_revs, mb)) {
 			continue;
 		} else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
 			handle_skipped_merge_base(mb);
 		} else {
 			printf(_("Bisecting: a merge base must be tested\n"));
-			exit(bisect_checkout(mb, no_checkout));
+			res = bisect_checkout(mb, no_checkout);
+			if (!res)
+				/* indicate early success */
+				res = BISECT_INTERNAL_SUCCESS_MERGE_BASE;
+			break;
 		}
 	}
 
 	free_commit_list(result);
+	return res;
 }
 
 static int check_ancestors(struct repository *r, int rev_nr,
@@ -850,43 +873,58 @@ static int check_ancestors(struct repository *r, int rev_nr,
  *
  * If that's not the case, we need to check the merge bases.
  * If a merge base must be tested by the user, its source code will be
- * checked out to be tested by the user and we will exit.
+ * checked out to be tested by the user and we will return.
  */
-static void check_good_are_ancestors_of_bad(struct repository *r,
+
+static enum bisect_error check_good_are_ancestors_of_bad(struct repository *r,
 					    const char *prefix,
 					    int no_checkout)
 {
-	char *filename = git_pathdup("BISECT_ANCESTORS_OK");
+	char *filename;
 	struct stat st;
 	int fd, rev_nr;
+	enum bisect_error res = BISECT_OK;
 	struct commit **rev;
 
 	if (!current_bad_oid)
-		die(_("a %s revision is needed"), term_bad);
+		return error(_("a %s revision is needed"), term_bad);
+
+	filename = git_pathdup("BISECT_ANCESTORS_OK");
 
 	/* Check if file BISECT_ANCESTORS_OK exists. */
 	if (!stat(filename, &st) && S_ISREG(st.st_mode))
 		goto done;
 
 	/* Bisecting with no good rev is ok. */
-	if (good_revs.nr == 0)
+	if (!good_revs.nr)
 		goto done;
 
 	/* Check if all good revs are ancestor of the bad rev. */
+
 	rev = get_bad_and_good_commits(r, &rev_nr);
 	if (check_ancestors(r, rev_nr, rev, prefix))
-		check_merge_bases(rev_nr, rev, no_checkout);
+		res = check_merge_bases(rev_nr, rev, no_checkout);
 	free(rev);
 
-	/* Create file BISECT_ANCESTORS_OK. */
-	fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
-	if (fd < 0)
-		warning_errno(_("could not create file '%s'"),
-			      filename);
-	else
-		close(fd);
+	if (!res) {
+		/* Create file BISECT_ANCESTORS_OK. */
+		fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
+		if (fd < 0)
+			/*
+			 * BISECT_ANCESTORS_OK file is not absolutely necessary,
+			 * the bisection process will continue at the next
+			 * bisection step.
+			 * So, just signal with a warning that something
+			 * might be wrong.
+			 */
+			warning_errno(_("could not create file '%s'"),
+				filename);
+		else
+			close(fd);
+	}
  done:
 	free(filename);
+	return res;
 }
 
 /*
@@ -938,26 +976,29 @@ void read_bisect_terms(const char **read_bad, const char **read_good)
 }
 
 /*
- * We use the convention that exiting with an exit code 10 means that
+ * We use the convention that return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10) means
  * the bisection process finished successfully.
- * In this case the calling shell script should exit 0.
- *
+ * In this case the calling function or command should not turn a
+ * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND return code into an error or a non zero exit code.
  * If no_checkout is non-zero, the bisection process does not
  * checkout the trial commit but instead simply updates BISECT_HEAD.
  */
-int bisect_next_all(struct repository *r, const char *prefix, int no_checkout)
+enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int no_checkout)
 {
 	struct rev_info revs;
 	struct commit_list *tried;
 	int reaches = 0, all = 0, nr, steps;
+	enum bisect_error res = BISECT_OK;
 	struct object_id *bisect_rev;
 	char *steps_msg;
 
 	read_bisect_terms(&term_bad, &term_good);
 	if (read_bisect_refs())
 		die(_("reading bisect refs failed"));
 
-	check_good_are_ancestors_of_bad(r, prefix, no_checkout);
+	res = check_good_are_ancestors_of_bad(r, prefix, no_checkout);
+	if (res)
+		return res;
 
 	bisect_rev_setup(r, &revs, prefix, "%s", "^%s", 1);
 	revs.limited = 1;
@@ -969,33 +1010,45 @@ int bisect_next_all(struct repository *r, const char *prefix, int no_checkout)
 
 	if (!revs.commits) {
 		/*
-		 * We should exit here only if the "bad"
+		 * We should return error here only if the "bad"
 		 * commit is also a "skip" commit.
 		 */
-		exit_if_skipped_commits(tried, NULL);
-
+		res = error_if_skipped_commits(tried, NULL);
+		if (res < 0)
+			return res;
 		printf(_("%s was both %s and %s\n"),
 		       oid_to_hex(current_bad_oid),
 		       term_good,
 		       term_bad);
-		exit(1);
+
+		return BISECT_FAILED;
 	}
 
 	if (!all) {
 		fprintf(stderr, _("No testable commit found.\n"
 			"Maybe you started with bad path parameters?\n"));
-		exit(4);
+
+		return BISECT_NO_TESTABLE_COMMIT;
 	}
 
 	bisect_rev = &revs.commits->item->object.oid;
 
 	if (oideq(bisect_rev, current_bad_oid)) {
-		exit_if_skipped_commits(tried, current_bad_oid);
+		res = error_if_skipped_commits(tried, current_bad_oid);
+		if (res)
+			return res;
 		printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
 			term_bad);
+
 		show_diff_tree(r, prefix, revs.commits->item);
-		/* This means the bisection process succeeded. */
-		exit(10);
+		/*
+		 * This means the bisection process succeeded.
+		 * Using BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10)
+		 * so that the call chain can simply check
+		 * for negative return values for early returns up
+		 * until the cmd_bisect__helper() caller.
+		 */
+		return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
 	}
 
 	nr = all - reaches - 1;

bisect.h

@@ -31,7 +31,34 @@ struct rev_list_info {
 	const char *header_prefix;
 };
 
-int bisect_next_all(struct repository *r,
+/*
+ * enum bisect_error represents the following return codes:
+ * BISECT_OK: success code. Internally, it means that next
+ * commit has been found (and possibly checked out) and it
+ * should be tested.
+ * BISECT_FAILED error code: default error code.
+ * BISECT_ONLY_SKIPPED_LEFT error code: only skipped
+ * commits left to be tested.
+ * BISECT_MERGE_BASE_CHECK error code: merge base check failed.
+ * BISECT_NO_TESTABLE_COMMIT error code: no testable commit found.
+ * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND early success code:
+ * first term_bad commit found.
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE early success
+ * code: found merge base that should be tested.
+ * Early success codes BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND and
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE should be only internal codes.
+ */
+enum bisect_error {
+	BISECT_OK = 0,
+	BISECT_FAILED = -1,
+	BISECT_ONLY_SKIPPED_LEFT = -2,
+	BISECT_MERGE_BASE_CHECK = -3,
+	BISECT_NO_TESTABLE_COMMIT = -4,
+	BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND = -10,
+	BISECT_INTERNAL_SUCCESS_MERGE_BASE = -11
+};
+
+enum bisect_error bisect_next_all(struct repository *r,
 		    const char *prefix,
 		    int no_checkout);