usage.c + gc: add and use a die_message_errno()

Change the "error: " output when we exit with 128 due to gc.log errors
to use a "fatal: " prefix instead. To do this add a
die_message_errno() a sibling function to the die_errno() added in a
preceding commit.

Before this we'd expect report_last_gc_error() to return -1 from
error_errno() in this case. It already treated a status of 0 and 1
specially. Let's just document that anything that's not 0 or 1 should
be returned.

We could also retain the "ret < 0" behavior here without hardcoding
128 by returning -128, and having the caller do a "return -ret", but I
think this makes more sense, and preserves the path from
die_message*()'s return value to the "return" without hardcoding
"128".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/builtin/gc.c b/builtin/gc.c
index 900ccfb8d4..8e60ef1eab 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -470,7 +470,8 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 /*
  * 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 occurred while reading gc.log
+ * message and returns with a non-[01] status code if an error occurred
+ * while reading gc.log
  */
 static int report_last_gc_error(void)
 {
@@ -484,7 +485,7 @@ static int report_last_gc_error(void)
 		if (errno == ENOENT)
 			goto done;
 
-		ret = error_errno(_("cannot stat '%s'"), gc_log_path);
+		ret = die_message_errno(_("cannot stat '%s'"), gc_log_path);
 		goto done;
 	}
 
@@ -493,7 +494,7 @@ static int report_last_gc_error(void)
 
 	len = strbuf_read_file(&sb, gc_log_path, 0);
 	if (len < 0)
-		ret = error_errno(_("cannot read '%s'"), gc_log_path);
+		ret = die_message_errno(_("cannot read '%s'"), gc_log_path);
 	else if (len > 0) {
 		/*
 		 * A previous gc failed.  Report the error, and don't
@@ -612,12 +613,12 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		if (detach_auto) {
 			int ret = report_last_gc_error();
 
-			if (ret < 0)
-				/* an I/O error occurred, already reported */
-				return 128;
 			if (ret == 1)
 				/* Last gc --auto failed. Skip this one. */
 				return 0;
+			else if (ret)
+				/* an I/O error occurred, already reported */
+				return ret;
 
 			if (lock_repo_for_gc(force, &pid))
 				return 0;