1 // Copyright 2011 The Chromium Authors
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/posix/file_descriptor_shuffle.h"
6
7 #include <unistd.h>
8 #include <stddef.h>
9 #include <ostream>
10
11 #include "base/check.h"
12 #include "base/logging.h"
13 #include "base/posix/eintr_wrapper.h"
14
15 namespace base {
16
PerformInjectiveMultimapDestructive(InjectiveMultimap * m,InjectionDelegate * delegate)17 bool PerformInjectiveMultimapDestructive(InjectiveMultimap* m,
18 InjectionDelegate* delegate) {
19 // DANGER: this function must not allocate or lock.
20 // Cannot use STL iterators here, since debug iterators use locks.
21
22 for (size_t i_index = 0; i_index < m->size(); ++i_index) {
23 InjectiveMultimap::value_type* i = &(*m)[i_index];
24 int temp_fd = -1;
25
26 // We DCHECK the injectiveness of the mapping.
27 for (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) {
28 InjectiveMultimap::value_type* j = &(*m)[j_index];
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 (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) {
36 InjectiveMultimap::value_type* j = &(*m)[j_index];
37 if (!is_identity && i->dest == j->source) {
38 if (temp_fd == -1 && !delegate->Duplicate(&temp_fd, i->dest)) {
39 return false;
40 }
41
42 j->source = temp_fd;
43 j->close = true;
44 }
45
46 if (i->close && i->source == j->dest)
47 i->close = false;
48
49 if (i->close && i->source == j->source) {
50 i->close = false;
51 j->close = true;
52 }
53 }
54
55 if (!is_identity) {
56 if (!delegate->Move(i->source, i->dest))
57 return false;
58 }
59
60 if (!is_identity && i->close)
61 delegate->Close(i->source);
62 }
63
64 return true;
65 }
66
PerformInjectiveMultimap(const InjectiveMultimap & m_in,InjectionDelegate * delegate)67 bool PerformInjectiveMultimap(const InjectiveMultimap& m_in,
68 InjectionDelegate* delegate) {
69 InjectiveMultimap m(m_in);
70 return PerformInjectiveMultimapDestructive(&m, delegate);
71 }
72
Duplicate(int * result,int fd)73 bool FileDescriptorTableInjection::Duplicate(int* result, int fd) {
74 *result = HANDLE_EINTR(dup(fd));
75 return *result >= 0;
76 }
77
Move(int src,int dest)78 bool FileDescriptorTableInjection::Move(int src, int dest) {
79 return HANDLE_EINTR(dup2(src, dest)) != -1;
80 }
81
Close(int fd)82 void FileDescriptorTableInjection::Close(int fd) {
83 int ret = IGNORE_EINTR(close(fd));
84 DPCHECK(ret == 0);
85 }
86
87 } // namespace base
88