base: Move MemoryMappedFile out of file_util.h and into its own header file.

base/files/memory_mapped_file_posix.cc

+// Copyright 2013 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/files/memory_mapped_file.h"
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/threading/thread_restrictions.h"
+
+namespace base {
+
+MemoryMappedFile::MemoryMappedFile()
+    : file_(kInvalidPlatformFileValue),
+      data_(NULL),
+      length_(0) {
+}
+
+bool MemoryMappedFile::MapFileToMemoryInternal() {
+  ThreadRestrictions::AssertIOAllowed();
+
+  struct stat file_stat;
+  if (fstat(file_, &file_stat) == kInvalidPlatformFileValue) {
+    DLOG(ERROR) << "Couldn't fstat " << file_ << ", errno " << errno;
+    return false;
+  }
+  length_ = file_stat.st_size;
+
+  data_ = static_cast<uint8*>(
+      mmap(NULL, length_, PROT_READ, MAP_SHARED, file_, 0));
+  if (data_ == MAP_FAILED)
+    DLOG(ERROR) << "Couldn't mmap " << file_ << ", errno " << errno;
+
+  return data_ != MAP_FAILED;
+}
+
+void MemoryMappedFile::CloseHandles() {
+  ThreadRestrictions::AssertIOAllowed();
+
+  if (data_ != NULL)
+    munmap(data_, length_);
+  if (file_ != kInvalidPlatformFileValue)
+    ignore_result(HANDLE_EINTR(close(file_)));
+
+  data_ = NULL;
+  length_ = 0;
+  file_ = kInvalidPlatformFileValue;
+}
+
+}  // namespace base