[PATCH v4 20/27] fetch.c: clear errno before calling functions that might set it

[Ronnie Sahlberg <sahlberg@google.com>]

In s_update_ref there are two calls that when they fail we return an error
based on the errno value. In particular we want to return a specific error
if ENOTDIR happened. Both these functions do have failure modes where they
may return an error without updating errno, in which case a previous and
unrelated ENOTDIT may cause us to return the wrong error. Clear errno before
calling any functions if we check errno afterwards.

Also skip initializing a static variable to 0. Statics live in .bss and
are all automatically initialized to 0.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/fetch.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 55f457c..a93c893 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -44,7 +44,7 @@ static struct transport *gtransport;
 static struct transport *gsecondary;
 static const char *submodule_prefix = "";
 static const char *recurse_submodules_default;
-static int shown_url = 0;
+static int shown_url;
 
 static int option_parse_recurse_submodules(const struct option *opt,
 				   const char *arg, int unset)
@@ -382,6 +382,8 @@ static int s_update_ref(const char *action,
 	if (!rla)
 		rla = default_rla.buf;
 	snprintf(msg, sizeof(msg), "%s: %s", rla, action);
+
+	errno = 0;
 	lock = lock_any_ref_for_update(ref->name,
 				       check_old ? ref->old_sha1 : NULL,
 				       0, NULL);
-- 
1.9.1.528.g98b8868.dirty