add strbuf_adddup()

Add a new function, strbuf_adddup(), that appends a duplicate of a
part of a struct strbuf to end of the latter.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/strbuf.c b/strbuf.c
index 536b43204e..dbd8c4bcfb 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -106,6 +106,13 @@ void strbuf_add(struct strbuf *sb, const void *data, size_t len)
 	strbuf_setlen(sb, sb->len + len);
 }
 
+void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len)
+{
+	strbuf_grow(sb, len);
+	memcpy(sb->buf + sb->len, sb->buf + pos, len);
+	strbuf_setlen(sb, sb->len + len);
+}
+
 void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
 {
 	int len;