[PATCH v3 3/9] ssh signing: retrieve a default key from ssh-agent

["Fabian Stelzer via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Fabian Stelzer <fs@xxxxxxxxxxxx>

calls ssh-add -L and uses the first key

Signed-off-by: Fabian Stelzer <fs@xxxxxxxxxxxx>
---
 gpg-interface.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/gpg-interface.c b/gpg-interface.c
index 3c9a48c8e7e..c956ed87475 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -467,6 +467,23 @@ int git_gpg_config(const char *var, const char *value, void *cb)
 	return 0;
 }
 
+/* Returns the first public key from an ssh-agent to use for signing */
+static char *get_default_ssh_signing_key(void) {
+	struct child_process ssh_add = CHILD_PROCESS_INIT;
+	int ret = -1;
+	struct strbuf key_stdout = STRBUF_INIT;
+	struct strbuf **keys;
+
+	strvec_pushl(&ssh_add.args, "ssh-add", "-L", NULL);
+	ret = pipe_command(&ssh_add, NULL, 0, &key_stdout, 0, NULL, 0);
+	if (!ret) {
+		keys = strbuf_split_max(&key_stdout, '\n', 2);
+		if (keys[0])
+			return strbuf_detach(keys[0], NULL);
+	}
+
+	return "";
+}
 const char *get_signing_key(void)
 {
 	if (configured_signing_key)
-- 
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