Revert "Remove FX_Alloc() null checks now that it can't return NULL."

core/src/fxcrt/fx_basic_buffer.cpp

 // 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
 
 #include "../../include/fxcrt/fx_basic.h"
 FX_STRSIZE FX_ftoa(FX_FLOAT f, FX_LPSTR buf);
 CFX_BinaryBuf::CFX_BinaryBuf()
     : m_AllocStep(0)
@@ skipping 70 matching lines @@
     } else {
         alloc_step = m_AllocStep;
     }
     new_size = (new_size + alloc_step - 1) / alloc_step * alloc_step;
     FX_LPBYTE pNewBuffer = m_pBuffer;
     if (pNewBuffer) {
         pNewBuffer = FX_Realloc(FX_BYTE, m_pBuffer, new_size);
     } else {
         pNewBuffer = FX_Alloc(FX_BYTE, new_size);
     }
-    m_pBuffer = pNewBuffer;
-    m_AllocSize = new_size;
+    if (pNewBuffer) {
+        m_pBuffer = pNewBuffer;
+        m_AllocSize = new_size;
+    }
 }
 void CFX_BinaryBuf::CopyData(const void* pStr, FX_STRSIZE size)
 {
     if (size == 0) {
         m_DataSize = 0;
         return;
     }
     if (m_AllocSize < size) {
         ExpandBuf(size - m_DataSize);
     }
@@ skipping 344 matching lines @@
     m_Length = 0;
     return bRet;
 }
 FX_INT32 IFX_BufferArchive::AppendBlock(const void* pBuf, size_t size)
 {
     if (!pBuf || size < 1) {
         return 0;
     }
     if (!m_pBuffer) {
         m_pBuffer = FX_Alloc(FX_BYTE, m_BufSize);
+        if (!m_pBuffer) {
+            return -1;
+        }
     }
     FX_LPBYTE buffer = (FX_LPBYTE)pBuf;
     FX_STRSIZE temp_size = (FX_STRSIZE)size;
     while (temp_size > 0) {
         FX_STRSIZE buf_size = FX_MIN(m_BufSize - m_Length, (FX_STRSIZE)temp_size);
         FXSYS_memcpy32(m_pBuffer + m_Length, buffer, buf_size);
         m_Length += buf_size;
         if (m_Length == m_BufSize) {
             if (!Flush()) {
                 return -1;
@@ skipping 82 matching lines @@
 FX_BOOL CFX_FileBufferArchive::DoWork(const void* pBuf, size_t size)
 {
     if (!m_pFile) {
         return FALSE;
     }
     if (!pBuf || size < 1) {
         return TRUE;
     }
     return m_pFile->WriteBlock(pBuf, size);
 }