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comparison: ipc/chromium/src/chrome/common/file_descriptor_set_posix.h
ipc/chromium/src/chrome/common/file_descriptor_set_posix.h
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| 1 // Copyright (c) 2006-2009 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 CHROME_COMMON_FILE_DESCRIPTOR_SET_POSIX_H_ | |
| 6 #define CHROME_COMMON_FILE_DESCRIPTOR_SET_POSIX_H_ | |
| 7 | |
| 8 #include <vector> | |
| 9 | |
| 10 #include "base/basictypes.h" | |
| 11 #include "base/file_descriptor_posix.h" | |
| 12 #include "base/ref_counted.h" | |
| 13 | |
| 14 // ----------------------------------------------------------------------------- | |
| 15 // A FileDescriptorSet is an ordered set of POSIX file descriptors. These are | |
| 16 // associated with IPC messages so that descriptors can be transmitted over a | |
| 17 // UNIX domain socket. | |
| 18 // ----------------------------------------------------------------------------- | |
| 19 class FileDescriptorSet : public base::RefCountedThreadSafe<FileDescriptorSet> { | |
| 20 public: | |
| 21 FileDescriptorSet(); | |
| 22 ~FileDescriptorSet(); | |
| 23 | |
| 24 // This is the maximum number of descriptors per message. We need to know this | |
| 25 // because the control message kernel interface has to be given a buffer which | |
| 26 // is large enough to store all the descriptor numbers. Otherwise the kernel | |
| 27 // tells us that it truncated the control data and the extra descriptors are | |
| 28 // lost. | |
| 29 // | |
| 30 // In debugging mode, it's a fatal error to try and add more than this number | |
| 31 // of descriptors to a FileDescriptorSet. | |
| 32 enum { | |
| 33 MAX_DESCRIPTORS_PER_MESSAGE = 4 | |
| 34 }; | |
| 35 | |
| 36 // --------------------------------------------------------------------------- | |
| 37 // Interfaces for building during message serialisation... | |
| 38 | |
| 39 // Add a descriptor to the end of the set. Returns false iff the set is full. | |
| 40 bool Add(int fd); | |
| 41 // Add a descriptor to the end of the set and automatically close it after | |
| 42 // transmission. Returns false iff the set is full. | |
| 43 bool AddAndAutoClose(int fd); | |
| 44 | |
| 45 // --------------------------------------------------------------------------- | |
| 46 | |
| 47 | |
| 48 // --------------------------------------------------------------------------- | |
| 49 // Interfaces for accessing during message deserialisation... | |
| 50 | |
| 51 // Return the number of descriptors | |
| 52 unsigned size() const { return descriptors_.size(); } | |
| 53 // Return true if no unconsumed descriptors remain | |
| 54 bool empty() const { return descriptors_.empty(); } | |
| 55 // Fetch the nth descriptor from the beginning of the set. Code using this | |
| 56 // /must/ access the descriptors in order, except that it may wrap from the | |
| 57 // end to index 0 again. | |
| 58 // | |
| 59 // This interface is designed for the deserialising code as it doesn't | |
| 60 // support close flags. | |
| 61 // returns: file descriptor, or -1 on error | |
| 62 int GetDescriptorAt(unsigned n) const; | |
| 63 | |
| 64 // --------------------------------------------------------------------------- | |
| 65 | |
| 66 | |
| 67 // --------------------------------------------------------------------------- | |
| 68 // Interfaces for transmission... | |
| 69 | |
| 70 // Fill an array with file descriptors without 'consuming' them. CommitAll | |
| 71 // must be called after these descriptors have been transmitted. | |
| 72 // buffer: (output) a buffer of, at least, size() integers. | |
| 73 void GetDescriptors(int* buffer) const; | |
| 74 // This must be called after transmitting the descriptors returned by | |
| 75 // GetDescriptors. It marks all the descriptors as consumed and closes those | |
| 76 // which are auto-close. | |
| 77 void CommitAll(); | |
| 78 | |
| 79 // --------------------------------------------------------------------------- | |
| 80 | |
| 81 | |
| 82 // --------------------------------------------------------------------------- | |
| 83 // Interfaces for receiving... | |
| 84 | |
| 85 // Set the contents of the set from the given buffer. This set must be empty | |
| 86 // before calling. The auto-close flag is set on all the descriptors so that | |
| 87 // unconsumed descriptors are closed on destruction. | |
| 88 void SetDescriptors(const int* buffer, unsigned count); | |
| 89 | |
| 90 // --------------------------------------------------------------------------- | |
| 91 | |
| 92 private: | |
| 93 // A vector of descriptors and close flags. If this message is sent, then | |
| 94 // these descriptors are sent as control data. After sending, any descriptors | |
| 95 // with a true flag are closed. If this message has been received, then these | |
| 96 // are the descriptors which were received and all close flags are true. | |
| 97 std::vector<base::FileDescriptor> descriptors_; | |
| 98 | |
| 99 // This contains the index of the next descriptor which should be consumed. | |
| 100 // It's used in a couple of ways. Firstly, at destruction we can check that | |
| 101 // all the descriptors have been read (with GetNthDescriptor). Secondly, we | |
| 102 // can check that they are read in order. | |
| 103 mutable unsigned consumed_descriptor_highwater_; | |
| 104 | |
| 105 DISALLOW_COPY_AND_ASSIGN(FileDescriptorSet); | |
| 106 }; | |
| 107 | |
| 108 #endif // CHROME_COMMON_FILE_DESCRIPTOR_SET_POSIX_H_ |
