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// Copyright 2017 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_FILE_DESCRIPTOR_STORE_H_
#define BASE_FILE_DESCRIPTOR_STORE_H_
#include <map>
#include <string>
#include "base/base_export.h"
#include "base/files/memory_mapped_file.h"
#include "base/files/scoped_file.h"
namespace base {
// The file descriptor store is used to associate file descriptors with keys
// that must be unique.
// It is used to share file descriptors from a process to its child.
class BASE_EXPORT FileDescriptorStore {
public:
FileDescriptorStore(const FileDescriptorStore&) = delete;
FileDescriptorStore& operator=(const FileDescriptorStore&) = delete;
struct Descriptor {
Descriptor(const std::string& key, base::ScopedFD fd);
Descriptor(const std::string& key,
base::ScopedFD fd,
base::MemoryMappedFile::Region region);
Descriptor(Descriptor&& other);
~Descriptor();
Descriptor& operator=(Descriptor&& other) = default;
// Globally unique key.
std::string key;
// Actual FD.
base::ScopedFD fd;
// Optional region, defaults to kWholeFile.
base::MemoryMappedFile::Region region;
};
using Mapping = std::map<std::string, Descriptor>;
// Returns the singleton instance of FileDescriptorStore.
static FileDescriptorStore& GetInstance();
// Gets a descriptor given a key and also populates |region|.
// It is a fatal error if the key is not known.
base::ScopedFD TakeFD(const std::string& key,
base::MemoryMappedFile::Region* region);
// Gets a descriptor given a key. Returns an empty ScopedFD on error.
base::ScopedFD MaybeTakeFD(const std::string& key,
base::MemoryMappedFile::Region* region);
// Sets the descriptor for the given |key|. This sets the region associated
// with |key| to kWholeFile.
void Set(const std::string& key, base::ScopedFD fd);
// Sets the descriptor and |region| for the given |key|.
void Set(const std::string& key,
base::ScopedFD fd,
base::MemoryMappedFile::Region region);
private:
FileDescriptorStore();
~FileDescriptorStore();
Mapping descriptors_;
};
} // namespace base
#endif // BASE_FILE_DESCRIPTOR_STORE_H_
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