Add write and read/write support to FileStream (renamed from FileInputStream)...

net/disk_cache/os_file_posix.cc

-// Copyright (c) 2006-2008 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 "net/disk_cache/os_file.h"
-
-#include <fcntl.h>
-#include <errno.h>
-
-#include "base/logging.h"
-#include "base/string_util.h"
-
-namespace disk_cache {
-
-OSFile CreateOSFile(const std::wstring& name, int flags, bool* created) {
-  int open_flags = 0;
-  if (flags & OS_FILE_CREATE)
-    open_flags = O_CREAT | O_EXCL;
-
-  if (flags & OS_FILE_CREATE_ALWAYS) {
-    DCHECK(!open_flags);
-    open_flags = O_CREAT | O_TRUNC;
-  }
-
-  if (!open_flags && !(flags & OS_FILE_OPEN) &&
-      !(flags & OS_FILE_OPEN_ALWAYS)) {
-    NOTREACHED();
-    errno = ENOTSUP;
-    return INVALID_HANDLE_VALUE;
-  }
-
-  if (flags & OS_FILE_WRITE && flags & OS_FILE_READ) {
-    open_flags |= O_RDWR;
-  } else if (flags & OS_FILE_WRITE) {
-    open_flags |= O_WRONLY;
-  } else if (!(flags & OS_FILE_READ)) {
-    NOTREACHED();
-  }
-
-  DCHECK(O_RDONLY == 0);
-
-  int descriptor = open(WideToUTF8(name).c_str(), open_flags,
-                        S_IRUSR | S_IWUSR);
-
-  if (flags & OS_FILE_OPEN_ALWAYS) {
-    if (descriptor > 0) {
-      if (created)
-        *created = false;
-    } else {
-      open_flags |= O_CREAT;
-      descriptor = open(WideToUTF8(name).c_str(), open_flags,
-                        S_IRUSR | S_IWUSR);
-      if (created && descriptor > 0)
-        *created = true;
-    }
-  }
-
-  return descriptor;
-}
-
-}  // namespace disk_cache