Merge branch 'jn/gc-auto' into pu

"gc --auto" ended up calling exit(-1) upon error, which has been
corrected to use exit(1).  Also the error reporting behaviour when
daemonized has been updated to exit with zero status when stopping
due to a previously discovered error (which implies there is no
point running gc to improve the situation); we used to exit with
failure in such a case.

Under discussion.
cf. <[email protected]>

* jn/gc-auto:
  gc: do not return error for prior errors in daemonized mode
  gc: exit with status 128 on failure
  gc: improve handling of errors reading gc.log

Author: gitster

Documentation/config.txt

@@ -1697,7 +1697,8 @@ will be repacked. After this the number of packs should go below
 gc.autoPackLimit and gc.bigPackThreshold should be respected again.
 
 gc.logExpiry::
-	If the file gc.log exists, then `git gc --auto` won't run
+	If the file gc.log exists, then `git gc --auto` will print
+	its content and exit with status zero instead of running
 	unless that file is more than 'gc.logExpiry' old.  Default is
 	"1.day".  See `gc.pruneExpire` for more ways to specify its
 	value.

builtin/gc.c

@@ -442,50 +442,64 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 	return NULL;
 }
 
+/*
+ * Returns 0 if there was no previous error and gc can proceed, 1 if
+ * gc should not proceed due to an error in the last run. Prints a
+ * message and returns -1 if an error occured while reading gc.log
+ */
 static int report_last_gc_error(void)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int ret = 0;
+	ssize_t len;
 	struct stat st;
 	char *gc_log_path = git_pathdup("gc.log");
 
 	if (stat(gc_log_path, &st)) {
 		if (errno == ENOENT)
 			goto done;
 
-		ret = error_errno(_("Can't stat %s"), gc_log_path);
+		ret = error_errno(_("cannot stat '%s'"), gc_log_path);
 		goto done;
 	}
 
 	if (st.st_mtime < gc_log_expire_time)
 		goto done;
 
-	ret = strbuf_read_file(&sb, gc_log_path, 0);
-	if (ret > 0)
-		ret = error(_("The last gc run reported the following. "
+	len = strbuf_read_file(&sb, gc_log_path, 0);
+	if (len < 0)
+		ret = error_errno(_("cannot read '%s'"), gc_log_path);
+	else if (len > 0) {
+		/*
+		 * A previous gc failed.  Report the error, and don't
+		 * bother with an automatic gc run since it is likely
+		 * to fail in the same way.
+		 */
+		warning(_("The last gc run reported the following. "
 			       "Please correct the root cause\n"
 			       "and remove %s.\n"
 			       "Automatic cleanup will not be performed "
 			       "until the file is removed.\n\n"
 			       "%s"),
 			    gc_log_path, sb.buf);
+		ret = 1;
+	}
 	strbuf_release(&sb);
 done:
 	free(gc_log_path);
 	return ret;
 }
 
-static int gc_before_repack(void)
+static void gc_before_repack(void)
 {
 	if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
-		return error(FAILED_RUN, pack_refs_cmd.argv[0]);
+		die(FAILED_RUN, pack_refs_cmd.argv[0]);
 
 	if (prune_reflogs && run_command_v_opt(reflog.argv, RUN_GIT_CMD))
-		return error(FAILED_RUN, reflog.argv[0]);
+		die(FAILED_RUN, reflog.argv[0]);
 
 	pack_refs = 0;
 	prune_reflogs = 0;
-	return 0;
 }
 
 int cmd_gc(int argc, const char **argv, const char *prefix)
@@ -566,13 +580,17 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
 		}
 		if (detach_auto) {
-			if (report_last_gc_error())
-				return -1;
+			int ret = report_last_gc_error();
+			if (ret < 0)
+				/* an I/O error occured, already reported */
+				exit(128);
+			if (ret == 1)
+				/* Last gc --auto failed. Skip this one. */
+				return 0;
 
 			if (lock_repo_for_gc(force, &pid))
 				return 0;
-			if (gc_before_repack())
-				return -1;
+			gc_before_repack(); /* dies on failure */
 			delete_tempfile(&pidfile);
 
 			/*
@@ -612,13 +630,12 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		atexit(process_log_file_at_exit);
 	}
 
-	if (gc_before_repack())
-		return -1;
+	gc_before_repack();
 
 	if (!repository_format_precious_objects) {
 		close_all_packs(the_repository->objects);
 		if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
-			return error(FAILED_RUN, repack.argv[0]);
+			die(FAILED_RUN, repack.argv[0]);
 
 		if (prune_expire) {
 			argv_array_push(&prune, prune_expire);
@@ -628,18 +645,18 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 				argv_array_push(&prune,
 						"--exclude-promisor-objects");
 			if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
-				return error(FAILED_RUN, prune.argv[0]);
+				die(FAILED_RUN, prune.argv[0]);
 		}
 	}
 
 	if (prune_worktrees_expire) {
 		argv_array_push(&prune_worktrees, prune_worktrees_expire);
 		if (run_command_v_opt(prune_worktrees.argv, RUN_GIT_CMD))
-			return error(FAILED_RUN, prune_worktrees.argv[0]);
+			die(FAILED_RUN, prune_worktrees.argv[0]);
 	}
 
 	if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
-		return error(FAILED_RUN, rerere.argv[0]);
+		die(FAILED_RUN, rerere.argv[0]);
 
 	report_garbage = report_pack_garbage;
 	reprepare_packed_git(the_repository);

t/t6500-gc.sh

@@ -116,11 +116,11 @@ test_expect_success 'background auto gc does not run if gc.log is present and re
 	test_config gc.autopacklimit 1 &&
 	test_config gc.autodetach true &&
 	echo fleem >.git/gc.log &&
-	test_must_fail git gc --auto 2>err &&
-	test_i18ngrep "^error:" err &&
+	git gc --auto 2>err &&
+	test_i18ngrep "^warning:" err &&
 	test_config gc.logexpiry 5.days &&
 	test-tool chmtime =-345600 .git/gc.log &&
-	test_must_fail git gc --auto &&
+	git gc --auto &&
 	test_config gc.logexpiry 2.days &&
 	run_and_wait_for_auto_gc &&
 	ls .git/objects/pack/pack-*.pack >packs &&