The Tor Browser / file comparison
comparison: ipc/chromium/src/base/file_descriptor_shuffle.h
ipc/chromium/src/base/file_descriptor_shuffle.h
- changeset 0
- 6474c204b198
equal
deleted
inserted
replaced
| -1:000000000000 | 0:f3b29fcb3e2a |
|---|---|
| 1 // Copyright (c) 2009 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_SHUFFLE_H_ | |
| 6 #define BASE_FILE_DESCRIPTOR_SHUFFLE_H_ | |
| 7 | |
| 8 // This code exists to perform the shuffling of file descriptors which is | |
| 9 // commonly needed when forking subprocesses. The naive approve is very simple, | |
| 10 // just call dup2 to setup the desired descriptors, but wrong. It's tough to | |
| 11 // handle the edge cases (like mapping 0 -> 1, 1 -> 0) correctly. | |
| 12 // | |
| 13 // In order to unittest this code, it's broken into the abstract action (an | |
| 14 // injective multimap) and the concrete code for dealing with file descriptors. | |
| 15 // Users should use the code like this: | |
| 16 // base::InjectiveMultimap file_descriptor_map; | |
| 17 // file_descriptor_map.push_back(base::InjectionArc(devnull, 0, true)); | |
| 18 // file_descriptor_map.push_back(base::InjectionArc(devnull, 2, true)); | |
| 19 // file_descriptor_map.push_back(base::InjectionArc(pipe[1], 1, true)); | |
| 20 // base::ShuffleFileDescriptors(file_descriptor_map); | |
| 21 // | |
| 22 // and trust the the Right Thing will get done. | |
| 23 | |
| 24 #include <vector> | |
| 25 | |
| 26 namespace base { | |
| 27 | |
| 28 // A Delegate which performs the actions required to perform an injective | |
| 29 // multimapping in place. | |
| 30 class InjectionDelegate { | |
| 31 public: | |
| 32 // Duplicate |fd|, an element of the domain, and write a fresh element of the | |
| 33 // domain into |result|. Returns true iff successful. | |
| 34 virtual bool Duplicate(int* result, int fd) = 0; | |
| 35 // Destructively move |src| to |dest|, overwriting |dest|. Returns true iff | |
| 36 // successful. | |
| 37 virtual bool Move(int src, int dest) = 0; | |
| 38 // Delete an element of the domain. | |
| 39 virtual void Close(int fd) = 0; | |
| 40 }; | |
| 41 | |
| 42 // An implementation of the InjectionDelegate interface using the file | |
| 43 // descriptor table of the current process as the domain. | |
| 44 class FileDescriptorTableInjection : public InjectionDelegate { | |
| 45 bool Duplicate(int* result, int fd); | |
| 46 bool Move(int src, int dest); | |
| 47 void Close(int fd); | |
| 48 }; | |
| 49 | |
| 50 // A single arc of the directed graph which describes an injective multimapping. | |
| 51 struct InjectionArc { | |
| 52 InjectionArc(int in_source, int in_dest, bool in_close) | |
| 53 : source(in_source), | |
| 54 dest(in_dest), | |
| 55 close(in_close) { | |
| 56 } | |
| 57 | |
| 58 int source; | |
| 59 int dest; | |
| 60 bool close; // if true, delete the source element after performing the | |
| 61 // mapping. | |
| 62 }; | |
| 63 | |
| 64 typedef std::vector<InjectionArc> InjectiveMultimap; | |
| 65 | |
| 66 bool PerformInjectiveMultimap(const InjectiveMultimap& map, | |
| 67 InjectionDelegate* delegate); | |
| 68 bool PerformInjectiveMultimapDestructive(InjectiveMultimap* map, | |
| 69 InjectionDelegate* delegate); | |
| 70 | |
| 71 // This function will not call malloc but will mutate |map| | |
| 72 static inline bool ShuffleFileDescriptors(InjectiveMultimap *map) { | |
| 73 FileDescriptorTableInjection delegate; | |
| 74 return PerformInjectiveMultimapDestructive(map, &delegate); | |
| 75 } | |
| 76 | |
| 77 } // namespace base | |
| 78 | |
| 79 #endif // !BASE_FILE_DESCRIPTOR_SHUFFLE_H_ |
