Add safe FX_Alloc2D() macro

core/include/fxcrt/fx_memory.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef _FX_MEMORY_H_
 #define _FX_MEMORY_H_
 
 #include "fx_system.h"
@@ skipping 23 matching lines @@
 
 inline void* FX_AllocOrDie(size_t num_members, size_t member_size) {
     // TODO(tsepez): See if we can avoid the implicit memset(0).
     if (void* result = calloc(num_members, member_size)) {
         return result;
     }
     FX_OutOfMemoryTerminate();  // Never returns.
     return nullptr;  // Suppress compiler warning.
 }
 
+inline void* FX_AllocOrDie2D(size_t w, size_t h, size_t member_size) {
+    if (w < std::numeric_limits<size_t>::max() / h) {
+        return FX_AllocOrDie(w * h, member_size);
+    }
+    FX_OutOfMemoryTerminate();  // Never returns.
+    return nullptr;  // Suppress compiler warning.
+}
+
 inline void* FX_ReallocOrDie(void* ptr, size_t num_members, size_t member_size) {
     if (void* result = FX_SafeRealloc(ptr, num_members, member_size)) {
         return result;
     }
     FX_OutOfMemoryTerminate();  // Never returns.
     return nullptr;  // Suppress compiler warning.
 }
 
 // Never returns NULL.
 #define FX_Alloc(type, size) (type*)FX_AllocOrDie(size, sizeof(type))
+#define FX_Alloc2D(type, w, h) (type*)FX_AllocOrDie2D(w, h, sizeof(type))
 #define FX_Realloc(type, ptr, size) \
     (type*)FX_ReallocOrDie(ptr, size, sizeof(type))
 
 // May return NULL.
 #define FX_TryAlloc(type, size) (type*)calloc(size, sizeof(type))
 #define FX_TryRealloc(type, ptr, size) \
     (type*)FX_SafeRealloc(ptr, size, sizeof(type))
 
 #define FX_Free(ptr) free(ptr)
 
@@ skipping 37 matching lines @@
 
     void        FreeAll();
 private:
 
     size_t      m_TrunkSize;
 
     void*       m_pFirstTrunk;
 };
 #endif  // __cplusplust
 #endif  // _FX_MEMORY_H_