mailinfo: unescape quoted-pair in header fields

rfc2822 has provisions for quoted strings in structured header fields,
but also allows for escaping these with so-called quoted-pairs.

The only thing git currently does is removing exterior quotes, but
quotes within are left alone.

Remove exterior quotes and remove escape characters so that they don't
show up in the author field.

Signed-off-by: Kevin Daudt <me@ikke.info>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

mailinfo.c

@@ -54,6 +54,86 @@ static void parse_bogus_from(struct mailinfo *mi, const struct strbuf *line)
 	get_sane_name(&mi->name, &mi->name, &mi->email);
 }
 
+static const char *unquote_comment(struct strbuf *outbuf, const char *in)
+{
+	int c;
+	int take_next_litterally = 0;
+
+	strbuf_addch(outbuf, '(');
+
+	while ((c = *in++) != 0) {
+		if (take_next_litterally == 1) {
+			take_next_litterally = 0;
+		} else {
+			switch (c) {
+			case '\\':
+				take_next_litterally = 1;
+				continue;
+			case '(':
+				in = unquote_comment(outbuf, in);
+				continue;
+			case ')':
+				strbuf_addch(outbuf, ')');
+				return in;
+			}
+		}
+
+		strbuf_addch(outbuf, c);
+	}
+
+	return in;
+}
+
+static const char *unquote_quoted_string(struct strbuf *outbuf, const char *in)
+{
+	int c;
+	int take_next_litterally = 0;
+
+	while ((c = *in++) != 0) {
+		if (take_next_litterally == 1) {
+			take_next_litterally = 0;
+		} else {
+			switch (c) {
+			case '\\':
+				take_next_litterally = 1;
+				continue;
+			case '"':
+				return in;
+			}
+		}
+
+		strbuf_addch(outbuf, c);
+	}
+
+	return in;
+}
+
+static void unquote_quoted_pair(struct strbuf *line)
+{
+	struct strbuf outbuf;
+	const char *in = line->buf;
+	int c;
+
+	strbuf_init(&outbuf, line->len);
+
+	while ((c = *in++) != 0) {
+		switch (c) {
+		case '"':
+			in = unquote_quoted_string(&outbuf, in);
+			continue;
+		case '(':
+			in = unquote_comment(&outbuf, in);
+			continue;
+		}
+
+		strbuf_addch(&outbuf, c);
+	}
+
+	strbuf_swap(&outbuf, line);
+	strbuf_release(&outbuf);
+
+}
+
 static void handle_from(struct mailinfo *mi, const struct strbuf *from)
 {
 	char *at;
@@ -63,6 +143,8 @@ static void handle_from(struct mailinfo *mi, const struct strbuf *from)
 	strbuf_init(&f, from->len);
 	strbuf_addbuf(&f, from);
 
+	unquote_quoted_pair(&f);
+
 	at = strchr(f.buf, '@');
 	if (!at) {
 		parse_bogus_from(mi, from);

t/t5100-mailinfo.sh

@@ -144,4 +144,18 @@ test_expect_success 'mailinfo unescapes with --mboxrd' '
 	test_cmp expect mboxrd/msg
 '
 
+test_expect_success 'mailinfo handles rfc2822 quoted-string' '
+	mkdir quoted-string &&
+	git mailinfo /dev/null /dev/null <"$DATA/quoted-string.in" \
+		>quoted-string/info &&
+	test_cmp "$DATA/quoted-string.expect" quoted-string/info
+'
+
+test_expect_success 'mailinfo handles rfc2822 comment' '
+	mkdir comment &&
+	git mailinfo /dev/null /dev/null <"$DATA/comment.in" \
+		>comment/info &&
+	test_cmp "$DATA/comment.expect" comment/info
+'
+
 test_done

t/t5100/comment.expect

@@ -0,0 +1,5 @@
+Author: A U Thor (this is (really) a comment (honestly))
+Email: somebody@example.com
+Subject: testing comments
+Date: Sun, 25 May 2008 00:38:18 -0700
+

t/t5100/comment.in

@@ -0,0 +1,9 @@
+From 1234567890123456789012345678901234567890 Mon Sep 17 00:00:00 2001
+From: "A U Thor" <somebody@example.com> (this is \(really\) a comment (honestly))
+Date: Sun, 25 May 2008 00:38:18 -0700
+Subject: [PATCH] testing comments
+
+
+
+---
+patch

t/t5100/quoted-string.expect

@@ -0,0 +1,5 @@
+Author: Author "The Author" Name
+Email: somebody@example.com
+Subject: testing quoted-pair
+Date: Sun, 25 May 2008 00:38:18 -0700
+

t/t5100/quoted-string.in

@@ -0,0 +1,9 @@
+From 1234567890123456789012345678901234567890 Mon Sep 17 00:00:00 2001
+From: "Author \"The Author\" Name" <somebody@example.com>
+Date: Sun, 25 May 2008 00:38:18 -0700
+Subject: [PATCH] testing quoted-pair
+
+
+
+---
+patch