gpg-interface: allow sign_buffer() to use default signing key
The `sign_commit_to_strbuf()` helper in "commit.c" provides fallback logic to get the default configured signing key when a key is not provided and handles generating the commit signature accordingly. This signing operation is not really specific to commits as any arbitrary buffer can be signed. Also, in a subsequent commit, this same logic is reused by git-fast-import(1) when signing commits with invalid signatures. Remove the `sign_commit_to_strbuf()` helper from "commit.c" and extend `sign_buffer()` in "gpg-interface.c" to support using the default key as a fallback when the `SIGN_BUFFER_USE_DEFAULT_KEY` flag is provided. Call sites are updated accordingly. Signed-off-by: Justin Tobler <jltobler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Justin Tobler committed
Mar 12, 2026 at 20:39 UTC
86ebf870b909a7f4707aa2601d290bc992d21a53
5 files changed
+29
-21
builtin/tag.c
+2
-2
@@ -167,7 +167,7 @@ static int do_sign(struct strbuf *buffer, struct object_id **compat_oid,
167
char *keyid = get_signing_key();
168
int ret = -1;
169
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- if (sign_buffer(buffer, &sig, keyid))
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+ if (sign_buffer(buffer, &sig, keyid, 0))
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goto out;
172
173
if (compat) {
@@ -176,7 +176,7 @@ static int do_sign(struct strbuf *buffer, struct object_id **compat_oid,
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if (convert_object_file(the_repository ,&compat_buf, algo, compat,
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buffer->buf, buffer->len, OBJ_TAG, 1))
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goto out;
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- if (sign_buffer(&compat_buf, &compat_sig, keyid))
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+ if (sign_buffer(&compat_buf, &compat_sig, keyid, 0))
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goto out;
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add_header_signature(&compat_buf, &sig, algo);
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strbuf_addbuf(&compat_buf, &compat_sig);
commit.c
+5
-14
@@ -1170,18 +1170,6 @@ int add_header_signature(struct strbuf *buf, struct strbuf *sig, const struct gi
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return 0;
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}
1172
1173
-static int sign_commit_to_strbuf(struct strbuf *sig, struct strbuf *buf, const char *keyid)
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-{
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- char *keyid_to_free = NULL;
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- int ret = 0;
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- if (!keyid || !*keyid)
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- keyid = keyid_to_free = get_signing_key();
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- if (sign_buffer(buf, sig, keyid))
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- ret = -1;
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- free(keyid_to_free);
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- return ret;
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-}
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-
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int parse_signed_commit(const struct commit *commit,
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struct strbuf *payload, struct strbuf *signature,
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const struct git_hash_algo *algop)
@@ -1759,7 +1747,8 @@ int commit_tree_extended(const char *msg, size_t msg_len,
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oidcpy(&parent_buf[i++], &p->item->object.oid);
1748
1749
write_commit_tree(&buffer, msg, msg_len, tree, parent_buf, nparents, author, committer, extra);
1762
- if (sign_commit && sign_commit_to_strbuf(&sig, &buffer, sign_commit)) {
1750
+ if (sign_commit && sign_buffer(&buffer, &sig, sign_commit,
1751
+ SIGN_BUFFER_USE_DEFAULT_KEY)) {
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result = -1;
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goto out;
1754
}
@@ -1791,7 +1780,9 @@ int commit_tree_extended(const char *msg, size_t msg_len,
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free_commit_extra_headers(compat_extra);
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free(mapped_parents);
1782
1794
- if (sign_commit && sign_commit_to_strbuf(&compat_sig, &compat_buffer, sign_commit)) {
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+ if (sign_commit && sign_buffer(&compat_buffer, &compat_sig,
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+ sign_commit,
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+ SIGN_BUFFER_USE_DEFAULT_KEY)) {
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result = -1;
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goto out;
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}
gpg-interface.c
+11
-2
@@ -974,11 +974,20 @@ const char *gpg_trust_level_to_str(enum signature_trust_level level)
974
return sigcheck_gpg_trust_level[level].display_key;
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}
976
977
-int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
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+int sign_buffer(struct strbuf *buffer, struct strbuf *signature,
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+ const char *signing_key, enum sign_buffer_flags flags)
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{
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+ char *keyid_to_free = NULL;
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+ int ret = 0;
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+
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gpg_interface_lazy_init();
984
981
- return use_format->sign_buffer(buffer, signature, signing_key);
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+ if ((flags & SIGN_BUFFER_USE_DEFAULT_KEY) && (!signing_key || !*signing_key))
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+ signing_key = keyid_to_free = get_signing_key();
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+
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+ ret = use_format->sign_buffer(buffer, signature, signing_key);
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+ free(keyid_to_free);
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+ return ret;
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}
992
993
/*
gpg-interface.h
+10
-2
@@ -74,6 +74,15 @@ int parse_signature(const char *buf, size_t size, struct strbuf *payload, struct
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*/
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size_t parse_signed_buffer(const char *buf, size_t size);
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+/* Flags for sign_buffer(). */
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+enum sign_buffer_flags {
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+ /*
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+ * Use the default configured signing key as returned by `get_signing_key()`
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+ * when the provided "signing_key" is NULL or empty.
82
+ */
83
+ SIGN_BUFFER_USE_DEFAULT_KEY = (1 << 0),
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+};
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+
86
/*
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* Create a detached signature for the contents of "buffer" and append
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* it after "signature"; "buffer" and "signature" can be the same
@@ -81,8 +90,7 @@ size_t parse_signed_buffer(const char *buf, size_t size);
90
* at the end. Returns 0 on success, non-zero on failure.
91
*/
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int sign_buffer(struct strbuf *buffer, struct strbuf *signature,
84
- const char *signing_key);
85
-
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+ const char *signing_key, enum sign_buffer_flags flags);
94
95
/*
96
* Returns corresponding string in lowercase for a given member of
send-pack.c
+1
-1
@@ -391,7 +391,7 @@ static int generate_push_cert(struct strbuf *req_buf,
391
if (!update_seen)
392
goto free_return;
393
394
- if (sign_buffer(&cert, &cert, signing_key))
394
+ if (sign_buffer(&cert, &cert, signing_key, 0))
395
die(_("failed to sign the push certificate"));
396
397
packet_buf_write(req_buf, "push-cert%c%s", 0, cap_string);