posix LaunchProcess: Don't use STL iterators after fork.

base/posix/file_descriptor_shuffle.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/posix/file_descriptor_shuffle.h"
 
 #include <unistd.h>
 #include <stddef.h>
 #include <ostream>
 
 #include "base/posix/eintr_wrapper.h"
 #include "base/logging.h"
 
 namespace base {
 
 bool PerformInjectiveMultimapDestructive(
     InjectiveMultimap* m, InjectionDelegate* delegate) {
   static const size_t kMaxExtraFDs = 16;
   int extra_fds[kMaxExtraFDs];
   unsigned next_extra_fd = 0;
 
-  // DANGER: this function may not allocate.
+  // DANGER: this function must not allocate or lock.
+  // Cannot use STL iterators here, since debug iterators use locks.
 
-  for (InjectiveMultimap::iterator i = m->begin(); i != m->end(); ++i) {
+  for (size_t i_index = 0; i_index < m->size(); ++i_index) {
+    InjectiveMultimap::value_type* i = &(*m)[i_index];
     int temp_fd = -1;
 
     // We DCHECK the injectiveness of the mapping.
-    for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {
+    for (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) {
+      InjectiveMultimap::value_type* j = &(*m)[j_index];
       DCHECK(i->dest != j->dest) << "Both fd " << i->source
           << " and " << j->source << " map to " << i->dest;
     }
 
     const bool is_identity = i->source == i->dest;
 
-    for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {
+    for (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) {
+      InjectiveMultimap::value_type* j = &(*m)[j_index];
       if (!is_identity && i->dest == j->source) {
         if (temp_fd == -1) {
           if (!delegate->Duplicate(&temp_fd, i->dest))
             return false;
           if (next_extra_fd < kMaxExtraFDs) {
             extra_fds[next_extra_fd++] = temp_fd;
           } else {
             RAW_LOG(ERROR, "PerformInjectiveMultimapDestructive overflowed "
                            "extra_fds. Leaking file descriptors!");
           }
@@ skipping 41 matching lines @@
 bool FileDescriptorTableInjection::Move(int src, int dest) {
   return HANDLE_EINTR(dup2(src, dest)) != -1;
 }
 
 void FileDescriptorTableInjection::Close(int fd) {
   int ret = IGNORE_EINTR(close(fd));
   DPCHECK(ret == 0);
 }
 
 }  // namespace base