strbuf: add strbuf_reencode helper

This is a convenience wrapper around `reencode_string_len`
and `strbuf_attach`.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/strbuf.c b/strbuf.c
index ee96dcfb81..fc7290f57a 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "refs.h"
+#include "utf8.h"
 
 int starts_with(const char *str, const char *prefix)
 {
@@ -106,6 +107,22 @@ void strbuf_ltrim(struct strbuf *sb)
 	sb->buf[sb->len] = '\0';
 }
 
+int strbuf_reencode(struct strbuf *sb, const char *from, const char *to)
+{
+	char *out;
+	int len;
+
+	if (same_encoding(from, to))
+		return 0;
+
+	out = reencode_string_len(sb->buf, sb->len, to, from, &len);
+	if (!out)
+		return -1;
+
+	strbuf_attach(sb, out, len, len);
+	return 0;
+}
+
 struct strbuf **strbuf_split_buf(const char *str, size_t slen,
 				 int terminator, int max)
 {