Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 1 | // Copyright (c) 2011 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 IPC_FILE_DESCRIPTOR_SET_POSIX_H_ |
| 6 | #define IPC_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/memory/ref_counted.h" |
| 13 | #include "ipc/ipc_export.h" |
| 14 | |
| 15 | // ----------------------------------------------------------------------------- |
| 16 | // A FileDescriptorSet is an ordered set of POSIX file descriptors. These are |
| 17 | // associated with IPC messages so that descriptors can be transmitted over a |
| 18 | // UNIX domain socket. |
| 19 | // ----------------------------------------------------------------------------- |
| 20 | class IPC_EXPORT FileDescriptorSet |
| 21 | : public base::RefCountedThreadSafe<FileDescriptorSet> { |
| 22 | public: |
| 23 | FileDescriptorSet(); |
| 24 | |
| 25 | // This is the maximum number of descriptors per message. We need to know this |
| 26 | // because the control message kernel interface has to be given a buffer which |
| 27 | // is large enough to store all the descriptor numbers. Otherwise the kernel |
| 28 | // tells us that it truncated the control data and the extra descriptors are |
| 29 | // lost. |
| 30 | // |
| 31 | // In debugging mode, it's a fatal error to try and add more than this number |
| 32 | // of descriptors to a FileDescriptorSet. |
Torne (Richard Coles) | 424c4d7 | 2013-08-30 15:14:49 +0100 | [diff] [blame^] | 33 | static const size_t kMaxDescriptorsPerMessage = 7; |
Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 34 | |
| 35 | // --------------------------------------------------------------------------- |
| 36 | // Interfaces for building during message serialisation... |
| 37 | |
| 38 | // Add a descriptor to the end of the set. Returns false iff the set is full. |
| 39 | bool Add(int fd); |
| 40 | // Add a descriptor to the end of the set and automatically close it after |
| 41 | // transmission. Returns false iff the set is full. |
| 42 | bool AddAndAutoClose(int fd); |
| 43 | |
| 44 | // --------------------------------------------------------------------------- |
| 45 | |
| 46 | |
| 47 | // --------------------------------------------------------------------------- |
| 48 | // Interfaces for accessing during message deserialisation... |
| 49 | |
| 50 | // Return the number of descriptors |
| 51 | unsigned size() const { return descriptors_.size(); } |
| 52 | // Return true if no unconsumed descriptors remain |
| 53 | bool empty() const { return descriptors_.empty(); } |
| 54 | // Fetch the nth descriptor from the beginning of the set. Code using this |
| 55 | // /must/ access the descriptors in order, except that it may wrap from the |
| 56 | // end to index 0 again. |
| 57 | // |
| 58 | // This interface is designed for the deserialising code as it doesn't |
| 59 | // support close flags. |
| 60 | // returns: file descriptor, or -1 on error |
| 61 | int GetDescriptorAt(unsigned n) const; |
| 62 | |
| 63 | // --------------------------------------------------------------------------- |
| 64 | |
| 65 | |
| 66 | // --------------------------------------------------------------------------- |
| 67 | // Interfaces for transmission... |
| 68 | |
| 69 | // Fill an array with file descriptors without 'consuming' them. CommitAll |
| 70 | // must be called after these descriptors have been transmitted. |
| 71 | // buffer: (output) a buffer of, at least, size() integers. |
| 72 | void GetDescriptors(int* buffer) const; |
| 73 | // This must be called after transmitting the descriptors returned by |
| 74 | // GetDescriptors. It marks all the descriptors as consumed and closes those |
| 75 | // which are auto-close. |
| 76 | void CommitAll(); |
| 77 | // Returns true if any contained file descriptors appear to be handles to a |
| 78 | // directory. |
| 79 | bool ContainsDirectoryDescriptor() const; |
| 80 | |
| 81 | // --------------------------------------------------------------------------- |
| 82 | |
| 83 | |
| 84 | // --------------------------------------------------------------------------- |
| 85 | // Interfaces for receiving... |
| 86 | |
| 87 | // Set the contents of the set from the given buffer. This set must be empty |
| 88 | // before calling. The auto-close flag is set on all the descriptors so that |
| 89 | // unconsumed descriptors are closed on destruction. |
| 90 | void SetDescriptors(const int* buffer, unsigned count); |
| 91 | |
| 92 | // --------------------------------------------------------------------------- |
| 93 | |
| 94 | private: |
| 95 | friend class base::RefCountedThreadSafe<FileDescriptorSet>; |
| 96 | |
| 97 | ~FileDescriptorSet(); |
| 98 | |
| 99 | // A vector of descriptors and close flags. If this message is sent, then |
| 100 | // these descriptors are sent as control data. After sending, any descriptors |
| 101 | // with a true flag are closed. If this message has been received, then these |
| 102 | // are the descriptors which were received and all close flags are true. |
| 103 | std::vector<base::FileDescriptor> descriptors_; |
| 104 | |
| 105 | // This contains the index of the next descriptor which should be consumed. |
| 106 | // It's used in a couple of ways. Firstly, at destruction we can check that |
| 107 | // all the descriptors have been read (with GetNthDescriptor). Secondly, we |
| 108 | // can check that they are read in order. |
| 109 | mutable unsigned consumed_descriptor_highwater_; |
| 110 | |
| 111 | DISALLOW_COPY_AND_ASSIGN(FileDescriptorSet); |
| 112 | }; |
| 113 | |
| 114 | #endif // IPC_FILE_DESCRIPTOR_SET_POSIX_H_ |