Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : // Copyright (c) 2009 The Chromium Authors. All rights reserved.
       4             : // Use of this source code is governed by a BSD-style license that can be
       5             : // found in the LICENSE file.
       6             : 
       7             : #include "base/file_descriptor_shuffle.h"
       8             : 
       9             : #include <errno.h>
      10             : #include <unistd.h>
      11             : 
      12             : #include "base/eintr_wrapper.h"
      13             : #include "base/logging.h"
      14             : 
      15             : namespace base {
      16             : 
      17           0 : bool PerformInjectiveMultimapDestructive(
      18             :     InjectiveMultimap* m, InjectionDelegate* delegate) {
      19             :   static const size_t kMaxExtraFDs = 16;
      20             :   int extra_fds[kMaxExtraFDs];
      21           0 :   unsigned next_extra_fd = 0;
      22             : 
      23             :   // DANGER: this function may not allocate.
      24             : 
      25           0 :   for (InjectiveMultimap::iterator i = m->begin(); i != m->end(); ++i) {
      26           0 :     int temp_fd = -1;
      27             : 
      28             :     // We DCHECK the injectiveness of the mapping.
      29           0 :     for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {
      30           0 :       DCHECK(i->dest != j->dest) << "Both fd " << i->source
      31           0 :           << " and " << j->source << " map to " << i->dest;
      32             :     }
      33             : 
      34           0 :     const bool is_identity = i->source == i->dest;
      35             : 
      36           0 :     for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {
      37           0 :       if (!is_identity && i->dest == j->source) {
      38           0 :         if (temp_fd == -1) {
      39           0 :           if (!delegate->Duplicate(&temp_fd, i->dest))
      40           0 :             return false;
      41           0 :           if (next_extra_fd < kMaxExtraFDs) {
      42           0 :             extra_fds[next_extra_fd++] = temp_fd;
      43             :           } else {
      44           0 :               DLOG(ERROR) << "PerformInjectiveMultimapDestructive overflowed "
      45           0 :                           << "extra_fds. Leaking file descriptors!";
      46             :           }
      47             :         }
      48             : 
      49           0 :         j->source = temp_fd;
      50           0 :         j->close = false;
      51             :       }
      52             : 
      53           0 :       if (i->close && i->source == j->dest)
      54           0 :         i->close = false;
      55             : 
      56           0 :       if (i->close && i->source == j->source) {
      57           0 :         i->close = false;
      58           0 :         j->close = true;
      59             :       }
      60             :     }
      61             : 
      62           0 :     if (!is_identity) {
      63           0 :       if (!delegate->Move(i->source, i->dest))
      64           0 :         return false;
      65             :     }
      66             : 
      67           0 :     if (!is_identity && i->close)
      68           0 :       delegate->Close(i->source);
      69             :   }
      70             : 
      71           0 :   for (unsigned i = 0; i < next_extra_fd; i++)
      72           0 :     delegate->Close(extra_fds[i]);
      73             : 
      74           0 :   return true;
      75             : }
      76             : 
      77           0 : bool PerformInjectiveMultimap(const InjectiveMultimap& m_in,
      78             :                               InjectionDelegate* delegate) {
      79           0 :     InjectiveMultimap m(m_in);
      80           0 :     return PerformInjectiveMultimapDestructive(&m, delegate);
      81             : }
      82             : 
      83           0 : bool FileDescriptorTableInjection::Duplicate(int* result, int fd) {
      84           0 :   *result = HANDLE_EINTR(dup(fd));
      85           0 :   return *result >= 0;
      86             : }
      87             : 
      88           0 : bool FileDescriptorTableInjection::Move(int src, int dest) {
      89           0 :   return HANDLE_EINTR(dup2(src, dest)) != -1;
      90             : }
      91             : 
      92           0 : void FileDescriptorTableInjection::Close(int fd) {
      93           0 :   HANDLE_EINTR(close(fd));
      94           0 : }
      95             : 
      96             : }  // namespace base