[PATCH v2] format-patch --signature-file <file>

@@ -14,6 +14,7 @@ SYNOPSIS
 		   [(--attach|--inline)[=<boundary>] | --no-attach]
 		   [-s | --signoff]
 		   [--signature=<signature> | --no-signature]
+		   [--signature-file=<file>]
 		   [-n | --numbered | -N | --no-numbered]
 		   [--start-number <n>] [--numbered-files]
 		   [--in-reply-to=Message-Id] [--suffix=.<sfx>]

@@ -233,6 +234,12 @@ configuration options in linkgit:git-notes[1] to use this workflow).
 	signature option is omitted the signature defaults to the Git version
 	number.
 
+--signature-file=<file>::
+	Add a signature, by including the contents of a file, to each message
+	produced. Per RFC 3676 the signature is separated from the body by a
+	line with '-- ' on it. If the signature option is omitted the signature
+	defaults to the Git version number.
+
 --suffix=.<sfx>::
 	Instead of using `.patch` as the suffix for generated
 	filenames, use specified suffix.  A common alternative is

@@ -1147,6 +1147,27 @@ static int from_callback(const struct option *opt, const char *arg, int unset)
 	return 0;
 }
 
+static int signature_file_callback(const struct option *opt, const char *arg,
+							int unset)
+{
+	const char **signature = opt->value;
+	static char buf[1024];
+	size_t sz;
+	FILE *fd;
+
+	fd = fopen(arg, "r");
+	if (fd) {
+		sz = sizeof(buf);
+		sz = fread(buf, 1, sz - 1, fd);
+		if (sz) {
+			buf[sz] = '\0';
+			*signature = buf;
+		}
+		fclose(fd);
+	}
+	return 0;
+}
+
 int cmd_format_patch(int argc, const char **argv, const char *prefix)
 {
 	struct commit *commit;

@@ -1230,6 +1251,9 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			    PARSE_OPT_OPTARG, thread_callback },
 		OPT_STRING(0, "signature", &signature, N_("signature"),
 			    N_("add a signature")),
+		{ OPTION_CALLBACK, 0, "signature-file", &signature, N_("signature-file"),
+				N_("add a signature from contents of a file"),
+			    PARSE_OPT_NONEG, signature_file_callback },
 		OPT__QUIET(&quiet, N_("don't print the patch filenames")),
 		OPT_END()
 	};

@@ -762,6 +762,19 @@ test_expect_success 'format-patch --signature="" suppresses signatures' '
 	! grep "^-- \$" output
 '
 
+cat > expect << EOF
+Test User <test.email@kernel.org>
+http://git.kernel.org/cgit/git/git.git
+git.kernel.org/?p=git/git.git;a=summary
+EOF
+
+test_expect_success 'format-patch --signature-file file' '
+	git format-patch --stdout --signature-file expect -1 >output &&
+	check_patch output &&
+	fgrep -x -f output expect >output2 &&
+	diff expect output2
+'
+
 test_expect_success TTY 'format-patch --stdout paginates' '
 	rm -f pager_used &&
 	test_terminal env GIT_PAGER="wc >pager_used" git format-patch --stdout --all &&