lavu/bprint: add av_bprint_reset().

libavutil/avutil.h

@@ -153,7 +153,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 50
+#define LIBAVUTIL_VERSION_MINOR 51
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

libavutil/bprint.c

@@ -119,6 +119,14 @@ void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
     av_bprint_grow(buf, n);
 }
 
+void av_bprint_clear(AVBPrint *buf)
+{
+    if (buf->len) {
+        *buf->str = 0;
+        buf->len  = 0;
+    }
+}
+
 int av_bprint_finalize(AVBPrint *buf, char **ret_str)
 {
     unsigned real_size = FFMIN(buf->len + 1, buf->size);

libavutil/bprint.h

@@ -109,6 +109,11 @@ void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);
  */
 void av_bprint_chars(AVBPrint *buf, char c, unsigned n);
 
+/**
+ * Reset the string to "" but keep internal allocated data.
+ */
+void av_bprint_clear(AVBPrint *buf);
+
 /**
  * Test if the print buffer is complete (not truncated).
  *