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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/posix/file_descriptor_shuffle.h" | |
| 6 | |
| 7 #include <unistd.h> | |
| 8 #include <stddef.h> | |
| 9 #include <ostream> | |
| 10 | |
| 11 #include "base/posix/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 must not allocate or lock. | |
| 23 // Cannot use STL iterators here, since debug iterators use locks. | |
| 24 | |
| 25 for (size_t i_index = 0; i_index < m->size(); ++i_index) { | |
| 26 InjectiveMultimap::value_type* i = &(*m)[i_index]; | |
| 27 int temp_fd = -1; | |
| 28 | |
| 29 // We DCHECK the injectiveness of the mapping. | |
| 30 for (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) { | |
| 31 InjectiveMultimap::value_type* j = &(*m)[j_index]; | |
| 32 DCHECK(i->dest != j->dest) << "Both fd " << i->source | |
| 33 << " and " << j->source << " map to " << i->dest; | |
| 34 } | |
| 35 | |
| 36 const bool is_identity = i->source == i->dest; | |
| 37 | |
| 38 for (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) { | |
| 39 InjectiveMultimap::value_type* j = &(*m)[j_index]; | |
| 40 if (!is_identity && i->dest == j->source) { | |
| 41 if (temp_fd == -1) { | |
| 42 if (!delegate->Duplicate(&temp_fd, i->dest)) | |
| 43 return false; | |
| 44 if (next_extra_fd < kMaxExtraFDs) { | |
| 45 extra_fds[next_extra_fd++] = temp_fd; | |
| 46 } else { | |
| 47 RAW_LOG(ERROR, "PerformInjectiveMultimapDestructive overflowed " | |
| 48 "extra_fds. Leaking file descriptors!"); | |
| 49 } | |
| 50 } | |
| 51 | |
| 52 j->source = temp_fd; | |
| 53 j->close = false; | |
| 54 } | |
| 55 | |
| 56 if (i->close && i->source == j->dest) | |
| 57 i->close = false; | |
| 58 | |
| 59 if (i->close && i->source == j->source) { | |
| 60 i->close = false; | |
| 61 j->close = true; | |
| 62 } | |
| 63 } | |
| 64 | |
| 65 if (!is_identity) { | |
| 66 if (!delegate->Move(i->source, i->dest)) | |
| 67 return false; | |
| 68 } | |
| 69 | |
| 70 if (!is_identity && i->close) | |
| 71 delegate->Close(i->source); | |
| 72 } | |
| 73 | |
| 74 for (unsigned i = 0; i < next_extra_fd; i++) | |
| 75 delegate->Close(extra_fds[i]); | |
| 76 | |
| 77 return true; | |
| 78 } | |
| 79 | |
| 80 bool PerformInjectiveMultimap(const InjectiveMultimap& m_in, | |
| 81 InjectionDelegate* delegate) { | |
| 82 InjectiveMultimap m(m_in); | |
| 83 return PerformInjectiveMultimapDestructive(&m, delegate); | |
| 84 } | |
| 85 | |
| 86 bool FileDescriptorTableInjection::Duplicate(int* result, int fd) { | |
| 87 *result = HANDLE_EINTR(dup(fd)); | |
| 88 return *result >= 0; | |
| 89 } | |
| 90 | |
| 91 bool FileDescriptorTableInjection::Move(int src, int dest) { | |
| 92 return HANDLE_EINTR(dup2(src, dest)) != -1; | |
| 93 } | |
| 94 | |
| 95 void FileDescriptorTableInjection::Close(int fd) { | |
| 96 int ret = IGNORE_EINTR(close(fd)); | |
| 97 DPCHECK(ret == 0); | |
| 98 } | |
| 99 | |
| 100 } // namespace base | |
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