mojo/system/raw_shared_buffer.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "mojo/system/raw_shared_buffer.h"
   6
   7 #include "base/logging.h"
   8
   9 namespace mojo {
  10 namespace system {
  11
  12 // static
  13 RawSharedBuffer* RawSharedBuffer::Create(size_t num_bytes) {
  14   DCHECK_GT(num_bytes, 0u);
  15
  16   RawSharedBuffer* rv = new RawSharedBuffer(num_bytes);
  17   // No need to take the lock since we haven't given the object to anyone yet.
  18   if (!rv->InitNoLock())
  19     return NULL;
  20
  21   return rv;
  22 }
  23
  24 scoped_ptr<RawSharedBufferMapping> RawSharedBuffer::Map(size_t offset,
  25                                                         size_t length) {
  26   if (!IsValidMap(offset, length))
  27     return scoped_ptr<RawSharedBufferMapping>();
  28
  29   return MapNoCheck(offset, length);
  30 }
  31
  32 bool RawSharedBuffer::IsValidMap(size_t offset, size_t length) {
  33   if (offset > num_bytes_ || length == 0)
  34     return false;
  35
  36   // Note: This is an overflow-safe check of |offset + length > num_bytes_|
  37   // (that |num_bytes >= offset| is verified above).
  38   if (length > num_bytes_ - offset)
  39     return false;
  40
  41   return true;
  42 }
  43
  44 scoped_ptr<RawSharedBufferMapping> RawSharedBuffer::MapNoCheck(size_t offset,
  45                                                                size_t length) {
  46   DCHECK(IsValidMap(offset, length));
  47
  48   base::AutoLock locker(lock_);
  49   return MapImplNoLock(offset, length);
  50 }
  51
  52 RawSharedBuffer::RawSharedBuffer(size_t num_bytes) : num_bytes_(num_bytes) {
  53 }
  54
  55 RawSharedBuffer::~RawSharedBuffer() {
  56 }
  57
  58 }  // namespace system
  59 }  // namespace mojo