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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_ | |
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