Fix #848, crash at HTTP fast buffer grow 2.0.239

@@ -336,6 +336,7 @@ Remark:
 
 ## History
 
+* v2.0, 2017-04-18, Fix [#848][bug #848], crash at HTTP fast buffer grow 2.0.239
 * v2.0, 2017-04-15, Fix [#844][bug #844], support Haivision encoder. 2.0.238
 * v2.0, 2017-04-15, Merge [#846][bug #846], fix fd leak for FLV stream caster. 2.0.237
 * v2.0, 2017-04-15, Merge [#841][bug #841], avoid the duplicated sps/pps in ts. 2.0.236
@@ -1287,6 +1288,7 @@ Winlin
 [bug #841]: https://github.com/ossrs/srs/issues/841
 [bug #846]: https://github.com/ossrs/srs/issues/846
 [bug #844]: https://github.com/ossrs/srs/issues/844
+[bug #848]: https://github.com/ossrs/srs/issues/848
 [bug #xxxxxxxxxx]: https://github.com/ossrs/srs/issues/xxxxxxxxxx
 
 [exo #828]: https://github.com/google/ExoPlayer/pull/828

@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // current release version
 #define VERSION_MAJOR       2
 #define VERSION_MINOR       0
-#define VERSION_REVISION    238
+#define VERSION_REVISION    239
 
 // generated by configure, only macros.
 #include <srs_auto_headers.hpp>

@@ -160,9 +160,10 @@ int SrsFastBuffer::grow(ISrsBufferReader* reader, int required_size)
             // reset when buffer is empty.
             p = end = buffer;
             srs_verbose("all consumed, reset fast buffer");
-        } else {
+        } else if (nb_exists_bytes < nb_buffer && p > buffer) {
             // move the left bytes to start of buffer.
-            srs_assert(nb_exists_bytes < nb_buffer);
+            // @remark Only move memory when space is enough, or failed at next check.
+            // @see https://github.com/ossrs/srs/issues/848
             buffer = (char*)memmove(buffer, p, nb_exists_bytes);
             p = buffer;
             end = p + nb_exists_bytes;