[PATCH 2/3] add strbuf_adddup()

["René Scharfe" <rene.scharfe@lsrfire.ath.cx>]

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>
---
 strbuf.c |    7 +++++++
 strbuf.h |    1 +
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/strbuf.c b/strbuf.c
index 536b432..dbd8c4b 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;
diff --git a/strbuf.h b/strbuf.h
index 21d8944..1391912 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -101,6 +101,7 @@ static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
 static inline void strbuf_addbuf(struct strbuf *sb, struct strbuf *sb2) {
 	strbuf_add(sb, sb2->buf, sb2->len);
 }
+extern void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len);
 
 typedef void (*expand_fn_t) (struct strbuf *sb, const char *placeholder, void *context);
 extern void strbuf_expand(struct strbuf *sb, const char *format, const char **placeholders, expand_fn_t fn, void *context);
-- 
1.5.3.5.1651.g30bf