builtin: add git-check-mailmap command

Introduce command check-mailmap, similar to check-attr and check-ignore,
which allows direct testing of .mailmap configuration.

As plumbing accessible to scripts and other porcelain, check-mailmap
publishes the stable, well-tested .mailmap functionality employed by
built-in Git commands.  Consequently, script authors need not
re-implement .mailmap functionality manually, thus avoiding potential
quirks and behavioral differences.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/builtin/check-mailmap.c b/builtin/check-mailmap.c
new file mode 100644
index 0000000000..8f4d809bd8
--- /dev/null
+++ b/builtin/check-mailmap.c
@@ -0,0 +1,66 @@
+#include "builtin.h"
+#include "mailmap.h"
+#include "parse-options.h"
+#include "string-list.h"
+
+static int use_stdin;
+static const char * const check_mailmap_usage[] = {
+N_("git check-mailmap [options] <contact>..."),
+NULL
+};
+
+static const struct option check_mailmap_options[] = {
+	OPT_BOOL(0, "stdin", &use_stdin, N_("also read contacts from stdin")),
+	OPT_END()
+};
+
+static void check_mailmap(struct string_list *mailmap, const char *contact)
+{
+	const char *name, *mail;
+	size_t namelen, maillen;
+	struct ident_split ident;
+
+	if (split_ident_line(&ident, contact, strlen(contact)))
+		die(_("unable to parse contact: %s"), contact);
+
+	name = ident.name_begin;
+	namelen = ident.name_end - ident.name_begin;
+	mail = ident.mail_begin;
+	maillen = ident.mail_end - ident.mail_begin;
+
+	map_user(mailmap, &mail, &maillen, &name, &namelen);
+
+	if (namelen)
+		printf("%.*s ", (int)namelen, name);
+	printf("<%.*s>\n", (int)maillen, mail);
+}
+
+int cmd_check_mailmap(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	struct string_list mailmap = STRING_LIST_INIT_NODUP;
+
+	git_config(git_default_config, NULL);
+	argc = parse_options(argc, argv, prefix, check_mailmap_options,
+			     check_mailmap_usage, 0);
+	if (argc == 0 && !use_stdin)
+		die(_("no contacts specified"));
+
+	read_mailmap(&mailmap, NULL);
+
+	for (i = 0; i < argc; ++i)
+		check_mailmap(&mailmap, argv[i]);
+	maybe_flush_or_die(stdout, "stdout");
+
+	if (use_stdin) {
+		struct strbuf buf = STRBUF_INIT;
+		while (strbuf_getline(&buf, stdin, '\n') != EOF) {
+			check_mailmap(&mailmap, buf.buf);
+			maybe_flush_or_die(stdout, "stdout");
+		}
+		strbuf_release(&buf);
+	}
+
+	clear_mailmap(&mailmap);
+	return 0;
+}