Add new function strbuf_add_xml_quoted()

Substantially the same code is present in http-push.c and imap-send.c,
so make a library function out of it.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/strbuf.c b/strbuf.c
index 0510f76..41828f0 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -428,6 +428,32 @@ void strbuf_add_lines(struct strbuf *out, const char *prefix,
 	strbuf_complete_line(out);
 }
 
+void strbuf_addstr_xml_quoted(struct strbuf *buf, const char *s)
+{
+	while (*s) {
+		size_t len = strcspn(s, "\"<>&");
+		strbuf_add(buf, s, len);
+		s += len;
+		switch (*s) {
+		case '"':
+			strbuf_addstr(buf, "&quot;");
+			break;
+		case '<':
+			strbuf_addstr(buf, "&lt;");
+			break;
+		case '>':
+			strbuf_addstr(buf, "&gt;");
+			break;
+		case '&':
+			strbuf_addstr(buf, "&amp;");
+			break;
+		case 0:
+			return;
+		}
+		s++;
+	}
+}
+
 static int is_rfc3986_reserved(char ch)
 {
 	switch (ch) {