[RFC PATCH 05/21] usage.c + gc: add and use a die_message_errno()

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change code the "error: " output when we exit with 128 due to gc.log
errors to use a "fatal: " prefix instead. This adds a sibling function
to the die_errno() added in a preceding commit.

Since it returns 128 instead of -1 we'll need to adjust
report_last_gc_error(). Let's adjust it while we're at it to not
conflate the "should skip" and "exit with this non-zero code"
conditions, as the caller is no longer hardcoding "128", but relying
on die_errno() to return a nen-zero exit() status.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/gc.c      | 21 ++++++++++++---------
 git-compat-util.h |  1 +
 usage.c           | 12 ++++++++++++
 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index bcef6a4c8da..a70a935dab3 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -472,19 +472,20 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
  * 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
  */
-static int report_last_gc_error(void)
+static int report_last_gc_error(int *skip)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int ret = 0;
 	ssize_t len;
 	struct stat st;
 	char *gc_log_path = git_pathdup("gc.log");
+	*skip = 0;
 
 	if (stat(gc_log_path, &st)) {
 		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
@@ -507,7 +508,7 @@ static int report_last_gc_error(void)
 			       "until the file is removed.\n\n"
 			       "%s"),
 			    gc_log_path, sb.buf);
-		ret = 1;
+		*skip = 1;
 	}
 	strbuf_release(&sb);
 done:
@@ -610,13 +611,15 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
 		}
 		if (detach_auto) {
-			int ret = report_last_gc_error();
-			if (ret < 0)
-				/* an I/O error occurred, already reported */
-				exit(128);
-			if (ret == 1)
+			int skip;
+			int ret = report_last_gc_error(&skip);
+
+			if (skip)
 				/* Last gc --auto failed. Skip this one. */
 				return 0;
+			if (ret)
+				/* an error occurred, already reported */
+				exit(ret);
 
 			if (lock_repo_for_gc(force, &pid))
 				return 0;
diff --git a/git-compat-util.h b/git-compat-util.h
index dd0170e3dd9..d56f416af8a 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -472,6 +472,7 @@ NORETURN void usagef(const char *err, ...) __attribute__((format (printf, 1, 2))
 NORETURN void die(const char *err, ...) __attribute__((format (printf, 1, 2)));
 NORETURN void die_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 int die_message(const char *err, ...) __attribute__((format (printf, 1, 2)));
+int die_message_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 int error(const char *err, ...) __attribute__((format (printf, 1, 2)));
 int error_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 void warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
diff --git a/usage.c b/usage.c
index 8ee5c6493fb..a39d7aa330b 100644
--- a/usage.c
+++ b/usage.c
@@ -233,6 +233,18 @@ int die_message(const char *err, ...)
 	return 128;
 }
 
+#undef die_message_errno
+int die_message_errno(const char *fmt, ...)
+{
+	char buf[1024];
+	va_list params;
+
+	va_start(params, fmt);
+	die_message_routine(fmt_with_err(buf, sizeof(buf), fmt), params);
+	va_end(params);
+	return -1;
+}
+
 #undef error_errno
 int error_errno(const char *fmt, ...)
 {
-- 
2.34.0.rc2.809.g11e21d44b24