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| 1 // Copyright 2017 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 #ifndef BASE_FILE_DESCRIPTOR_STORE_H_ |
| 6 #define BASE_FILE_DESCRIPTOR_STORE_H_ |
| 7 |
| 8 #include <map> |
| 9 #include <string> |
| 10 |
| 11 #include "base/files/memory_mapped_file.h" |
| 12 #include "base/files/scoped_file.h" |
| 13 #include "base/macros.h" |
| 14 |
| 15 namespace base { |
| 16 |
| 17 // The file descriptor store is used to associate file descriptors with keys |
| 18 // that must be unique. |
| 19 // It is used to share file descriptors from a process to its child. |
| 20 class BASE_EXPORT FileDescriptorStore { |
| 21 public: |
| 22 struct Descriptor { |
| 23 Descriptor(const std::string& key, base::ScopedFD fd); |
| 24 Descriptor(const std::string& key, |
| 25 base::ScopedFD fd, |
| 26 base::MemoryMappedFile::Region region); |
| 27 Descriptor(Descriptor&& other); |
| 28 ~Descriptor(); |
| 29 |
| 30 Descriptor& operator=(Descriptor&& other) = default; |
| 31 |
| 32 // Globally unique key. |
| 33 std::string key; |
| 34 // Actual FD. |
| 35 base::ScopedFD fd; |
| 36 // Optional region, defaults to kWholeFile. |
| 37 base::MemoryMappedFile::Region region; |
| 38 }; |
| 39 using Mapping = std::map<std::string, Descriptor>; |
| 40 |
| 41 // Returns the singleton instance of FileDescriptorStore. |
| 42 static FileDescriptorStore& GetInstance(); |
| 43 |
| 44 // Gets a descriptor given a key and also populates |region|. |
| 45 // It is a fatal error if the key is not known. |
| 46 base::ScopedFD TakeFD(const std::string& key, |
| 47 base::MemoryMappedFile::Region* region); |
| 48 |
| 49 // Gets a descriptor given a key. Returns an empty ScopedFD on error. |
| 50 base::ScopedFD MaybeTakeFD(const std::string& key, |
| 51 base::MemoryMappedFile::Region* region); |
| 52 |
| 53 // Sets the descriptor for the given |key|. This sets the region associated |
| 54 // with |key| to kWholeFile. |
| 55 void Set(const std::string& key, base::ScopedFD fd); |
| 56 |
| 57 // Sets the descriptor and |region| for the given |key|. |
| 58 void Set(const std::string& key, |
| 59 base::ScopedFD fd, |
| 60 base::MemoryMappedFile::Region region); |
| 61 |
| 62 private: |
| 63 FileDescriptorStore(); |
| 64 ~FileDescriptorStore(); |
| 65 |
| 66 Mapping descriptors_; |
| 67 |
| 68 DISALLOW_COPY_AND_ASSIGN(FileDescriptorStore); |
| 69 }; |
| 70 |
| 71 } // namespace base |
| 72 |
| 73 #endif // BASE_FILE_DESCRIPTOR_STORE_H_ |
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