avutil/bprint: add av_vbprintf()

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

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;

libavutil/bprint.h

@@ -21,6 +21,8 @@
 #ifndef AVUTIL_BPRINT_H
 #define AVUTIL_BPRINT_H
 
+#include <stdarg.h>
+
 #include "attributes.h"
 #include "avstring.h"
 
@@ -121,6 +123,11 @@ void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size);
  */
 void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);
 
+/**
+ * Append a formatted string to a print buffer.
+ */
+void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg);
+
 /**
  * Append char c n times to a print buffer.
  */

libavutil/version.h

@@ -75,7 +75,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  52
-#define LIBAVUTIL_VERSION_MINOR  41
+#define LIBAVUTIL_VERSION_MINOR  42
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \