The Tor Browser: ipc/chromium/src/base/file_descriptor

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 // Copyright (c) 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.

     5 #include "base/file_descriptor_shuffle.h"

     7 #include <errno.h>

     8 #include <unistd.h>

    10 #include "base/eintr_wrapper.h"

    11 #include "base/logging.h"

    13 namespace base {

    15 bool PerformInjectiveMultimapDestructive(

    16     InjectiveMultimap* m, InjectionDelegate* delegate) {

    17   static const size_t kMaxExtraFDs = 16;

    18   int extra_fds[kMaxExtraFDs];

    19   unsigned next_extra_fd = 0;

    21   // DANGER: this function may not allocate.

    23   for (InjectiveMultimap::iterator i = m->begin(); i != m->end(); ++i) {

    24     int temp_fd = -1;

    26     // We DCHECK the injectiveness of the mapping.

    27     for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {

    28       DCHECK(i->dest != j->dest) << "Both fd " << i->source

    29           << " and " << j->source << " map to " << i->dest;

    30     }

    32     const bool is_identity = i->source == i->dest;

    34     for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {

    35       if (!is_identity && i->dest == j->source) {

    36         if (temp_fd == -1) {

    37           if (!delegate->Duplicate(&temp_fd, i->dest))

    38             return false;

    39           if (next_extra_fd < kMaxExtraFDs) {

    40             extra_fds[next_extra_fd++] = temp_fd;

    41           } else {

    42               DLOG(ERROR) << "PerformInjectiveMultimapDestructive overflowed "

    43                           << "extra_fds. Leaking file descriptors!";

    44           }

    45         }

    47         j->source = temp_fd;

    48         j->close = false;

    49       }

    51       if (i->close && i->source == j->dest)

    52         i->close = false;

    54       if (i->close && i->source == j->source) {

    55         i->close = false;

    56         j->close = true;

    57       }

    58     }

    60     if (!is_identity) {

    61       if (!delegate->Move(i->source, i->dest))

    62         return false;

    63     }

    65     if (!is_identity && i->close)

    66       delegate->Close(i->source);

    67   }

    69   for (unsigned i = 0; i < next_extra_fd; i++)

    70     delegate->Close(extra_fds[i]);

    72   return true;

    73 }

    75 bool PerformInjectiveMultimap(const InjectiveMultimap& m_in,

    76                               InjectionDelegate* delegate) {

    77     InjectiveMultimap m(m_in);

    78     return PerformInjectiveMultimapDestructive(&m, delegate);

    79 }

    81 bool FileDescriptorTableInjection::Duplicate(int* result, int fd) {

    82   *result = HANDLE_EINTR(dup(fd));

    83   return *result >= 0;

    84 }

    86 bool FileDescriptorTableInjection::Move(int src, int dest) {

    87   return HANDLE_EINTR(dup2(src, dest)) != -1;

    88 }

    90 void FileDescriptorTableInjection::Close(int fd) {

    91   HANDLE_EINTR(close(fd));

    92 }

    94 }  // namespace base

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