add slide_write to switch_buffer

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@15297 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/include/switch_buffer.h

@@ -137,6 +137,8 @@ SWITCH_DECLARE(switch_size_t) switch_buffer_toss(_In_ switch_buffer_t *buffer, _
  */
 SWITCH_DECLARE(void) switch_buffer_zero(_In_ switch_buffer_t *buffer);
 
+SWITCH_DECLARE(switch_size_t) switch_buffer_slide_write(switch_buffer_t *buffer, const void *data, switch_size_t datalen);
+
 /*! \brief Destroy the buffer
  * \param buffer buffer to destroy
  * \note only neccessary on dynamic buffers (noop on pooled ones)

src/switch_buffer.c

@@ -280,6 +280,18 @@ SWITCH_DECLARE(switch_size_t) switch_buffer_zwrite(switch_buffer_t *buffer, cons
 	return w;
 }
 
+SWITCH_DECLARE(switch_size_t) switch_buffer_slide_write(switch_buffer_t *buffer, const void *data, switch_size_t datalen)
+{
+	switch_size_t w;
+
+	if (!(w = switch_buffer_write(buffer, data, datalen))) {
+		switch_buffer_toss(buffer, datalen);
+		return switch_buffer_write(buffer, data, datalen);
+	}
+
+	return w;
+}
+
 SWITCH_DECLARE(void) switch_buffer_destroy(switch_buffer_t **buffer)
 {
 	if (buffer && *buffer) {