Prototype implementation of zygotes

base/file_descriptor_shuffle.cc

 // Copyright (c) 2009 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/file_descriptor_shuffle.h"
 
 #include <errno.h>
 #include <unistd.h>
 
 #include "base/eintr_wrapper.h"
 #include "base/logging.h"
 
 namespace base {
 
 bool PerformInjectiveMultimap(const InjectiveMultimap& m_in,
                               InjectionDelegate* delegate) {
   InjectiveMultimap m(m_in);
   std::vector<int> extra_fds;
 
   for (InjectiveMultimap::iterator i = m.begin(); i != m.end(); ++i) {
     int temp_fd = -1;
 
     // We DCHECK the injectiveness of the mapping.
-    for (InjectiveMultimap::iterator j = i + 1; j != m.end(); ++j)
-      DCHECK(i->dest != j->dest);
+    for (InjectiveMultimap::iterator j = i + 1; j != m.end(); ++j) {
+      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) {
       if (!is_identity && i->dest == j->source) {
         if (temp_fd == -1) {
           if (!delegate->Duplicate(&temp_fd, i->dest))
             return false;
           extra_fds.push_back(temp_fd);
         }
@@ skipping 35 matching lines @@
 
 bool FileDescriptorTableInjection::Move(int src, int dest) {
   return HANDLE_EINTR(dup2(src, dest)) != -1;
 }
 
 void FileDescriptorTableInjection::Close(int fd) {
   HANDLE_EINTR(close(fd));
 }
 
 }  // namespace base