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>

1 files changed, 82 insertions, 0 deletions

diff --git a/mailinfo.c b/mailinfo.c
index e19abe3cb..b4118a027 100644
--- a/mailinfo.c
+++ b/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);