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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 #include "base/file_descriptor_shuffle.h" | |
6 | |
7 #include <unistd.h> | |
8 #include <stddef.h> | |
9 #include <ostream> | |
10 | |
11 #include "base/eintr_wrapper.h" | |
12 #include "base/logging.h" | |
13 | |
14 namespace base { | |
15 | |
16 bool PerformInjectiveMultimapDestructive( | |
17 InjectiveMultimap* m, InjectionDelegate* delegate) { | |
18 static const size_t kMaxExtraFDs = 16; | |
19 int extra_fds[kMaxExtraFDs]; | |
20 unsigned next_extra_fd = 0; | |
21 | |
22 // DANGER: this function may not allocate. | |
23 | |
24 for (InjectiveMultimap::iterator i = m->begin(); i != m->end(); ++i) { | |
25 int temp_fd = -1; | |
26 | |
27 // We DCHECK the injectiveness of the mapping. | |
28 for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) { | |
29 DCHECK(i->dest != j->dest) << "Both fd " << i->source | |
30 << " and " << j->source << " map to " << i->dest; | |
31 } | |
32 | |
33 const bool is_identity = i->source == i->dest; | |
34 | |
35 for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) { | |
36 if (!is_identity && i->dest == j->source) { | |
37 if (temp_fd == -1) { | |
38 if (!delegate->Duplicate(&temp_fd, i->dest)) | |
39 return false; | |
40 if (next_extra_fd < kMaxExtraFDs) { | |
41 extra_fds[next_extra_fd++] = temp_fd; | |
42 } else { | |
43 RAW_LOG(ERROR, "PerformInjectiveMultimapDestructive overflowed " | |
44 "extra_fds. Leaking file descriptors!"); | |
45 } | |
46 } | |
47 | |
48 j->source = temp_fd; | |
49 j->close = false; | |
50 } | |
51 | |
52 if (i->close && i->source == j->dest) | |
53 i->close = false; | |
54 | |
55 if (i->close && i->source == j->source) { | |
56 i->close = false; | |
57 j->close = true; | |
58 } | |
59 } | |
60 | |
61 if (!is_identity) { | |
62 if (!delegate->Move(i->source, i->dest)) | |
63 return false; | |
64 } | |
65 | |
66 if (!is_identity && i->close) | |
67 delegate->Close(i->source); | |
68 } | |
69 | |
70 for (unsigned i = 0; i < next_extra_fd; i++) | |
71 delegate->Close(extra_fds[i]); | |
72 | |
73 return true; | |
74 } | |
75 | |
76 bool PerformInjectiveMultimap(const InjectiveMultimap& m_in, | |
77 InjectionDelegate* delegate) { | |
78 InjectiveMultimap m(m_in); | |
79 return PerformInjectiveMultimapDestructive(&m, delegate); | |
80 } | |
81 | |
82 bool FileDescriptorTableInjection::Duplicate(int* result, int fd) { | |
83 *result = HANDLE_EINTR(dup(fd)); | |
84 return *result >= 0; | |
85 } | |
86 | |
87 bool FileDescriptorTableInjection::Move(int src, int dest) { | |
88 return HANDLE_EINTR(dup2(src, dest)) != -1; | |
89 } | |
90 | |
91 void FileDescriptorTableInjection::Close(int fd) { | |
92 int ret = HANDLE_EINTR(close(fd)); | |
93 DPCHECK(ret == 0); | |
94 } | |
95 | |
96 } // namespace base | |
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