[PATCH v3 2/2] mailinfo: unescape quoted-pair in header fields

[Kevin Daudt <me@ikke.info>]

rfc2822 has provisions for quoted strings and comments 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>
---
 Changes since v2:

 - handle comments inside comments recursively
 - renamed the main function to unquote_quoted_pairs because it also
   handles quoted pairs in comments


 mailinfo.c                   | 82 ++++++++++++++++++++++++++++++++++++++++++++
 t/t5100-mailinfo.sh          | 14 ++++++++
 t/t5100/comment.expect       |  5 +++
 t/t5100/comment.in           |  9 +++++
 t/t5100/quoted-string.expect |  5 +++
 t/t5100/quoted-string.in     |  9 +++++
 6 files changed, 124 insertions(+)
 create mode 100644 t/t5100/comment.expect
 create mode 100644 t/t5100/comment.in
 create mode 100644 t/t5100/quoted-string.expect
 create mode 100644 t/t5100/quoted-string.in

diff --git a/mailinfo.c b/mailinfo.c
index e19abe3..b4118a0 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);
diff --git a/t/t5100-mailinfo.sh b/t/t5100-mailinfo.sh
index c4ed0f4..3e983c0 100755
--- a/t/t5100-mailinfo.sh
+++ b/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
diff --git a/t/t5100/comment.expect b/t/t5100/comment.expect
new file mode 100644
index 0000000..7228177
--- /dev/null
+++ b/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
+
diff --git a/t/t5100/comment.in b/t/t5100/comment.in
new file mode 100644
index 0000000..c53a192
--- /dev/null
+++ b/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
diff --git a/t/t5100/quoted-string.expect b/t/t5100/quoted-string.expect
new file mode 100644
index 0000000..cab1bce
--- /dev/null
+++ b/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
+
diff --git a/t/t5100/quoted-string.in b/t/t5100/quoted-string.in
new file mode 100644
index 0000000..e2e627a
--- /dev/null
+++ b/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
-- 
2.10.0.89.ge802c3a.dirty