Advertise a minimum alignment for SharedMemory::Map().

base/shared_memory_nacl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/shared_memory.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
@@ skipping 72 matching lines @@
 }
 
 bool SharedMemory::Map(uint32 bytes) {
   if (mapped_file_ == -1)
     return false;
 
   memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
                  MAP_SHARED, mapped_file_, 0);
 
   bool mmap_succeeded = memory_ != MAP_FAILED && memory_ != NULL;
-  if (mmap_succeeded)
+  if (mmap_succeeded) {
     mapped_size_ = bytes;
-  else
+    DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
+        (SharedMemory::kMapMinimumAlignment - 1));
+  } else {
     memory_ = NULL;
+  }
 
   return mmap_succeeded;
 }
 
 bool SharedMemory::Unmap() {
   if (memory_ == NULL)
     return false;
 
   if (munmap(memory_, mapped_size_) < 0)
     DPLOG(ERROR) << "munmap";
@@ skipping 24 matching lines @@
   NOTIMPLEMENTED();
 }
 
 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
                                         SharedMemoryHandle *new_handle,
                                         bool close_self) {
   return false;
 }
 
 }  // namespace base