Move overflow check up

Author: tbeu

include/msgpack/v1/vrefbuffer.hpp

@@ -58,6 +58,10 @@ class vrefbuffer {
         :m_ref_size(std::max(ref_size, detail::packer_max_buffer_size + 1)),
          m_chunk_size(chunk_size)
     {
+        if((sizeof(chunk) + chunk_size) < chunk_size) {
+            throw std::bad_alloc();
+        }
+
         size_t nfirst = (sizeof(iovec) < 72/2) ?
             72 / sizeof(iovec) : 8;
 
@@ -71,11 +75,6 @@ class vrefbuffer {
         m_end   = array + nfirst;
         m_array = array;
 
-        if((sizeof(chunk) + chunk_size) < chunk_size){
-            ::free(array);
-            throw std::bad_alloc();
-        }
-
         chunk* c = static_cast<chunk*>(::malloc(sizeof(chunk) + chunk_size));
         if(!c) {
             ::free(array);

src/vrefbuffer.c

@@ -30,6 +30,10 @@ bool msgpack_vrefbuffer_init(msgpack_vrefbuffer* vbuf,
         ref_size > MSGPACK_PACKER_MAX_BUFFER_SIZE + 1 ?
         ref_size : MSGPACK_PACKER_MAX_BUFFER_SIZE + 1 ;
 
+    if((sizeof(msgpack_vrefbuffer_chunk) + chunk_size) < chunk_size) {
+        return false;
+    }
+
     nfirst = (sizeof(struct iovec) < 72/2) ?
             72 / sizeof(struct iovec) : 8;
 
@@ -43,11 +47,6 @@ bool msgpack_vrefbuffer_init(msgpack_vrefbuffer* vbuf,
     vbuf->end   = array + nfirst;
     vbuf->array = array;
 
-    if((sizeof(msgpack_vrefbuffer_chunk) + chunk_size) < chunk_size){
-        free(array);
-        return false;
-    }
-
     chunk = (msgpack_vrefbuffer_chunk*)malloc(
             sizeof(msgpack_vrefbuffer_chunk) + chunk_size);
     if(chunk == NULL) {