1 files changed, 260 insertions, 0 deletions
diff --git a/gpg-interface.c b/gpg-interface.c
new file mode 100644
index 0000000000..3dc2fe397e
--- /dev/null
+++ b/gpg-interface.c
@@ -0,0 +1,260 @@
+#include "cache.h"
+#include "run-command.h"
+#include "strbuf.h"
+#include "gpg-interface.h"
+#include "sigchain.h"
+
+static char *configured_signing_key;
+static const char *gpg_program = "gpg";
+
+#define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
+#define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
+
+void signature_check_clear(struct signature_check *sigc)
+{
+	free(sigc->payload);
+	free(sigc->gpg_output);
+	free(sigc->gpg_status);
+	free(sigc->signer);
+	free(sigc->key);
+	sigc->payload = NULL;
+	sigc->gpg_output = NULL;
+	sigc->gpg_status = NULL;
+	sigc->signer = NULL;
+	sigc->key = NULL;
+}
+
+static struct {
+	char result;
+	const char *check;
+} sigcheck_gpg_status[] = {
+	{ 'G', "\n[GNUPG:] GOODSIG " },
+	{ 'B', "\n[GNUPG:] BADSIG " },
+	{ 'U', "\n[GNUPG:] TRUST_NEVER" },
+	{ 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
+};
+
+void parse_gpg_output(struct signature_check *sigc)
+{
+	const char *buf = sigc->gpg_status;
+	int i;
+
+	/* Iterate over all search strings */
+	for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
+		const char *found, *next;
+
+		if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
+			found = strstr(buf, sigcheck_gpg_status[i].check);
+			if (!found)
+				continue;
+			found += strlen(sigcheck_gpg_status[i].check);
+		}
+		sigc->result = sigcheck_gpg_status[i].result;
+		/* The trust messages are not followed by key/signer information */
+		if (sigc->result != 'U') {
+			sigc->key = xmemdupz(found, 16);
+			found += 17;
+			next = strchrnul(found, '\n');
+			sigc->signer = xmemdupz(found, next - found);
+		}
+	}
+}
+
+int check_signature(const char *payload, size_t plen, const char *signature,
+	size_t slen, struct signature_check *sigc)
+{
+	struct strbuf gpg_output = STRBUF_INIT;
+	struct strbuf gpg_status = STRBUF_INIT;
+	int status;
+
+	sigc->result = 'N';
+
+	status = verify_signed_buffer(payload, plen, signature, slen,
+				      &gpg_output, &gpg_status);
+	if (status && !gpg_output.len)
+		goto out;
+	sigc->payload = xmemdupz(payload, plen);
+	sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
+	sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
+	parse_gpg_output(sigc);
+
+ out:
+	strbuf_release(&gpg_status);
+	strbuf_release(&gpg_output);
+
+	return sigc->result != 'G' && sigc->result != 'U';
+}
+
+void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
+{
+	const char *output = flags & GPG_VERIFY_RAW ?
+		sigc->gpg_status : sigc->gpg_output;
+
+	if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
+		fputs(sigc->payload, stdout);
+
+	if (output)
+		fputs(output, stderr);
+}
+
+/*
+ * Look at GPG signed content (e.g. a signed tag object), whose
+ * payload is followed by a detached signature on it.  Return the
+ * offset where the embedded detached signature begins, or the end of
+ * the data when there is no such signature.
+ */
+size_t parse_signature(const char *buf, unsigned long size)
+{
+	char *eol;
+	size_t len = 0;
+	while (len < size && !starts_with(buf + len, PGP_SIGNATURE) &&
+			!starts_with(buf + len, PGP_MESSAGE)) {
+		eol = memchr(buf + len, '\n', size - len);
+		len += eol ? eol - (buf + len) + 1 : size - len;
+	}
+	return len;
+}
+
+void set_signing_key(const char *key)
+{
+	free(configured_signing_key);
+	configured_signing_key = xstrdup(key);
+}
+
+int git_gpg_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "user.signingkey")) {
+		set_signing_key(value);
+	}
+	if (!strcmp(var, "gpg.program")) {
+		if (!value)
+			return config_error_nonbool(var);
+		gpg_program = xstrdup(value);
+	}
+	return 0;
+}
+
+const char *get_signing_key(void)
+{
+	if (configured_signing_key)
+		return configured_signing_key;
+	return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
+}
+
+/*
+ * Create a detached signature for the contents of "buffer" and append
+ * it after "signature"; "buffer" and "signature" can be the same
+ * strbuf instance, which would cause the detached signature appended
+ * at the end.
+ */
+int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
+{
+	struct child_process gpg = CHILD_PROCESS_INIT;
+	const char *args[4];
+	ssize_t len;
+	size_t i, j, bottom;
+
+	gpg.argv = args;
+	gpg.in = -1;
+	gpg.out = -1;
+	args[0] = gpg_program;
+	args[1] = "-bsau";
+	args[2] = signing_key;
+	args[3] = NULL;
+
+	if (start_command(&gpg))
+		return error(_("could not run gpg."));
+
+	/*
+	 * When the username signingkey is bad, program could be terminated
+	 * because gpg exits without reading and then write gets SIGPIPE.
+	 */
+	sigchain_push(SIGPIPE, SIG_IGN);
+
+	if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
+		close(gpg.in);
+		close(gpg.out);
+		finish_command(&gpg);
+		return error(_("gpg did not accept the data"));
+	}
+	close(gpg.in);
+
+	bottom = signature->len;
+	len = strbuf_read(signature, gpg.out, 1024);
+	close(gpg.out);
+
+	sigchain_pop(SIGPIPE);
+
+	if (finish_command(&gpg) || !len || len < 0)
+		return error(_("gpg failed to sign the data"));
+
+	/* Strip CR from the line endings, in case we are on Windows. */
+	for (i = j = bottom; i < signature->len; i++)
+		if (signature->buf[i] != '\r') {
+			if (i != j)
+				signature->buf[j] = signature->buf[i];
+			j++;
+		}
+	strbuf_setlen(signature, j);
+
+	return 0;
+}
+
+/*
+ * Run "gpg" to see if the payload matches the detached signature.
+ * gpg_output, when set, receives the diagnostic output from GPG.
+ * gpg_status, when set, receives the status output from GPG.
+ */
+int verify_signed_buffer(const char *payload, size_t payload_size,
+			 const char *signature, size_t signature_size,
+			 struct strbuf *gpg_output, struct strbuf *gpg_status)
+{
+	struct child_process gpg = CHILD_PROCESS_INIT;
+	const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
+	char path[PATH_MAX];
+	int fd, ret;
+	struct strbuf buf = STRBUF_INIT;
+	struct strbuf *pbuf = &buf;
+
+	args_gpg[0] = gpg_program;
+	fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
+	if (fd < 0)
+		return error(_("could not create temporary file '%s': %s"),
+			     path, strerror(errno));
+	if (write_in_full(fd, signature, signature_size) < 0)
+		return error(_("failed writing detached signature to '%s': %s"),
+			     path, strerror(errno));
+	close(fd);
+
+	gpg.argv = args_gpg;
+	gpg.in = -1;
+	gpg.out = -1;
+	if (gpg_output)
+		gpg.err = -1;
+	args_gpg[3] = path;
+	if (start_command(&gpg)) {
+		unlink(path);
+		return error(_("could not run gpg."));
+	}
+
+	write_in_full(gpg.in, payload, payload_size);
+	close(gpg.in);
+
+	if (gpg_output) {
+		strbuf_read(gpg_output, gpg.err, 0);
+		close(gpg.err);
+	}
+	if (gpg_status)
+		pbuf = gpg_status;
+	strbuf_read(pbuf, gpg.out, 0);
+	close(gpg.out);
+
+	ret = finish_command(&gpg);
+
+	unlink_or_warn(path);
+
+	ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
+	strbuf_release(&buf); /* no matter it was used or not */
+
+	return ret;
+}