[PATCH v2 1/2] osxkeychain: lock for exclusive execution

["Koji Nakamaru via GitGitGadget" <gitgitgadget@gmail.com>]

From: Koji Nakamaru <koji.nakamaru@gree.net>

Resolves "failed to store: -25299" when "fetch.parallel 0" is configured
and there are many submodules.

The error code -25299 (errSecDuplicateItem) may be returned by
SecItemUpdate() in add_internet_password() if multiple instances of
git-credential-osxkeychain run in parallel. This patch introduces an
exclusive lock to serialize execution for avoiding this and other
potential issues.

Signed-off-by: Koji Nakamaru <koji.nakamaru@gree.net>
---
 contrib/credential/osxkeychain/git-credential-osxkeychain.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/contrib/credential/osxkeychain/git-credential-osxkeychain.c b/contrib/credential/osxkeychain/git-credential-osxkeychain.c
index 6a40917b1ef..0884db48d0a 100644
--- a/contrib/credential/osxkeychain/git-credential-osxkeychain.c
+++ b/contrib/credential/osxkeychain/git-credential-osxkeychain.c
@@ -414,6 +414,9 @@ int main(int argc, const char **argv)
 	if (!argv[1])
 		die("%s", usage);
 
+	if (open(argv[0], O_RDONLY | O_EXLOCK) == -1)
+		die("failed to lock %s", argv[0]);
+
 	read_credential();
 
 	if (!strcmp(argv[1], "get"))
-- 
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