avutil/bprint: add av_vbprintf()

Reviewed-by: Nicolas George <nicolas.george@normalesup.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 23 insertions, 0 deletions

diff --git a/libavutil/bprint.c b/libavutil/bprint.c
index fd7611aaed..e7799563ec 100644
--- a/libavutil/bprint.c
+++ b/libavutil/bprint.c
@@ -113,6 +113,29 @@ void av_bprintf(AVBPrint *buf, const char *fmt, ...)
     av_bprint_grow(buf, extra_len);
 }
 
+void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg)
+{
+    unsigned room;
+    char *dst;
+    int extra_len;
+    va_list vl;
+
+    while (1) {
+        room = av_bprint_room(buf);
+        dst = room ? buf->str + buf->len : NULL;
+        va_copy(vl, vl_arg);
+        extra_len = vsnprintf(dst, room, fmt, vl);
+        va_end(vl);
+        if (extra_len <= 0)
+            return;
+        if (extra_len < room)
+            break;
+        if (av_bprint_alloc(buf, extra_len))
+            break;
+    }
+    av_bprint_grow(buf, extra_len);
+}
+
 void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
 {
     unsigned room, real_n;