Re: [PATCH v6 3/9] ssh signing: retrieve a default key from ssh-agent
From: Junio C Hamano <hidden>
Date: 2021-07-28 21:29:05
"Fabian Stelzer via GitGitGadget" [off-list ref] writes:
From: Fabian Stelzer <redacted> if user.signingkey is not set and a ssh signature is requested we call ssh-add -L and use the first key we get Signed-off-by: Fabian Stelzer <redacted> --- gpg-interface.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-)
I would have expected that this also would become a method call into *use_format object (instead of dispatching on use_format->name), but let's not go overboard. I think this is good enough for now.
quoted hunk
diff --git a/gpg-interface.c b/gpg-interface.c index c131977b347..3afacb48900 100644 --- a/gpg-interface.c +++ b/gpg-interface.c@@ -470,11 +470,35 @@ 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); + } + + strbuf_release(&key_stdout); + return ""; +} + const char *get_signing_key(void) { if (configured_signing_key) return configured_signing_key; - return git_committer_info(IDENT_STRICT|IDENT_NO_DATE); + if (!strcmp(use_format->name, "ssh")) { + return get_default_ssh_signing_key(); + } else { + return git_committer_info(IDENT_STRICT | IDENT_NO_DATE); + } } int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)