chromium/base/posix/global_descriptors.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_POSIX_GLOBAL_DESCRIPTORS_H_
#define BASE_POSIX_GLOBAL_DESCRIPTORS_H_

#include <stdint.h>

#include <vector>
#include <utility>

#include "base/base_export.h"
#include "base/files/memory_mapped_file.h"
#include "base/files/scoped_file.h"
#include "base/memory/singleton.h"

namespace base {

// It's common practice to install file descriptors into well known slot
// numbers before execing a child; stdin, stdout and stderr are ubiqutous
// examples.
//
// However, when using a zygote model, this becomes troublesome. Since the
// descriptors which need to be in these slots generally aren't known, any code
// could open a resource and take one of the reserved descriptors. Simply
// overwriting the slot isn't a viable solution.
//
// We could try to fill the reserved slots as soon as possible, but this is a
// fragile solution since global constructors etc are able to open files.
//
// Instead, we retreat from the idea of installing descriptors in specific
// slots and add a layer of indirection in the form of this singleton object.
// It maps from an abstract key to a descriptor. If independent modules each
// need to define keys, then values should be chosen randomly so as not to
// collide.
//
// Note that this class is deprecated and passing file descriptor should ideally
// be done through the command line and using FileDescriptorStore.
// See https://crbugs.com/detail?id=692619
class BASE_EXPORT GlobalDescriptors { … };

}  // namespace base

#endif  // BASE_POSIX_GLOBAL_DESCRIPTORS_H_