1 files changed, 140 insertions, 0 deletions
diff --git a/gpg-interface.c b/gpg-interface.c
new file mode 100644
index 0000000000..09ab64aa24
--- /dev/null
+++ b/gpg-interface.c
@@ -0,0 +1,140 @@
+#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";
+
+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_ERROR_ON_NO_NAME|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;
+	const char *args[4];
+	ssize_t len;
+	size_t i, j, bottom;
+
+	memset(&gpg, 0, sizeof(gpg));
+	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.
+ */
+int verify_signed_buffer(const char *payload, size_t payload_size,
+			 const char *signature, size_t signature_size,
+			 struct strbuf *gpg_output)
+{
+	struct child_process gpg;
+	const char *args_gpg[] = {NULL, "--verify", "FILE", "-", NULL};
+	char path[PATH_MAX];
+	int fd, ret;
+
+	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);
+
+	memset(&gpg, 0, sizeof(gpg));
+	gpg.argv = args_gpg;
+	gpg.in = -1;
+	if (gpg_output)
+		gpg.err = -1;
+	args_gpg[2] = 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);
+	ret = finish_command(&gpg);
+
+	unlink_or_warn(path);
+
+	return ret;
+}