Handle malloc() fail in PoolAllocator

Fix #682

include/rapidjson/allocators.h

@@ -179,7 +179,8 @@ public:
 
         size = RAPIDJSON_ALIGN(size);
         if (chunkHead_ == 0 || chunkHead_->size + size > chunkHead_->capacity)
-            AddChunk(chunk_capacity_ > size ? chunk_capacity_ : size);
+            if (!AddChunk(chunk_capacity_ > size ? chunk_capacity_ : size))
+                return NULL;
 
         void *buffer = reinterpret_cast<char *>(chunkHead_) + RAPIDJSON_ALIGN(sizeof(ChunkHeader)) + chunkHead_->size;
         chunkHead_->size += size;
@@ -211,11 +212,13 @@ public:
         }
 
         // Realloc process: allocate and copy memory, do not free original buffer.
-        void* newBuffer = Malloc(newSize);
-        RAPIDJSON_ASSERT(newBuffer != 0);   // Do not handle out-of-memory explicitly.
-        if (originalSize)
-            std::memcpy(newBuffer, originalPtr, originalSize);
-        return newBuffer;
+        if (void* newBuffer = Malloc(newSize)) {
+            if (originalSize)
+                std::memcpy(newBuffer, originalPtr, originalSize);
+            return newBuffer;
+        }
+        else
+            return NULL;
     }
 
     //! Frees a memory block (concept Allocator)
@@ -229,15 +232,20 @@ private:
 
     //! Creates a new chunk.
     /*! \param capacity Capacity of the chunk in bytes.
+        \return true if success.
     */
-    void AddChunk(size_t capacity) {
+    bool AddChunk(size_t capacity) {
         if (!baseAllocator_)
             ownBaseAllocator_ = baseAllocator_ = RAPIDJSON_NEW(BaseAllocator());
-        ChunkHeader* chunk = reinterpret_cast<ChunkHeader*>(baseAllocator_->Malloc(RAPIDJSON_ALIGN(sizeof(ChunkHeader)) + capacity));
-        chunk->capacity = capacity;
-        chunk->size = 0;
-        chunk->next = chunkHead_;
-        chunkHead_ =  chunk;
+        if (ChunkHeader* chunk = reinterpret_cast<ChunkHeader*>(baseAllocator_->Malloc(RAPIDJSON_ALIGN(sizeof(ChunkHeader)) + capacity))) {
+            chunk->capacity = capacity;
+            chunk->size = 0;
+            chunk->next = chunkHead_;
+            chunkHead_ =  chunk;
+            return true;
+        }
+        else
+            return false;
     }
 
     static const int kDefaultChunkCapacity = 64 * 1024; //!< Default chunk capacity.