[Mac] Move the reset of signal handlers to be very soon after the fork, befor...

base/process_util_posix.cc

 // Copyright (c) 2010 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 <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/resource.h>
@@ skipping 91 matching lines @@
 
   return status;
 }
 
 void StackDumpSignalHandler(int signal) {
   LOG(ERROR) << "Received signal " << signal;
   StackTrace().PrintBacktrace();
   _exit(1);
 }
 
+void ResetChildSignalHandlersToDefaults() {
+  // The previous signal handlers are likely to be meaningless in the child's
+  // context so we reset them to the defaults for now. http://crbug.com/44953
+  // These signal handlers are setup in browser_main.cc:BrowserMain
+  signal(SIGTERM, SIG_DFL);
+  signal(SIGHUP, SIG_DFL);
+  signal(SIGINT, SIG_DFL);
+}
+
 }  // anonymous namespace
 
 ProcessId GetCurrentProcId() {
   return getpid();
 }
 
 ProcessHandle GetCurrentProcessHandle() {
   return GetCurrentProcId();
 }
 
@@ skipping 194 matching lines @@
 
   // Error handling philosophy: If Mach IPC fails, don't touch |child_task| but
   // return a valid pid. If IPC fails in the child, the parent will have to wait
   // until kTimeoutMs is over. This is not optimal, but I've never seen it
   // happen, and stuff should still mostly work.
   pid_t pid = fork();
   switch (pid) {
     case -1:
       return pid;
     case 0: {  // child
+      // Must reset signal handlers before doing any mach IPC, as the mach IPC
+      // calls can potentially hang forever.
+      ResetChildSignalHandlersToDefaults();
       MachSendMessage child_message(/* id= */0);
       if (!child_message.AddDescriptor(mach_task_self())) {
         LOG(ERROR) << "child AddDescriptor(mach_task_self()) failed.";
         return pid;
       }
 
       MachPortSender child_sender(mach_connection_name.c_str());
       err = child_sender.SendMessage(child_message, kTimeoutMs);
       if (err != KERN_SUCCESS) {
         LOG(ERROR) << "child SendMessage() failed: " << MachErrorCode(err);
@@ skipping 186 matching lines @@
 #endif
   if (pid < 0)
     return false;
 
   if (pid == 0) {
     // Child process
 #if defined(OS_MACOSX)
     RestoreDefaultExceptionHandler();
 #endif
 
-    // The previous signal handlers are likely to be meaningless in the child's
-    // context so we reset them to the defaults for now. http://crbug.com/44953
-    // These signal handlers are setup in browser_main.cc:BrowserMain
-    signal(SIGTERM, SIG_DFL);
-    signal(SIGHUP, SIG_DFL);
-    signal(SIGINT, SIG_DFL);
+    // On mac, the signal handlers are reset in |fork_and_get_task()|.
+#if !defined(OS_MACOSX)
+    ResetChildSignalHandlersToDefaults();
+#endif
 
 #if 0
     // When debugging it can be helpful to check that we really aren't making
     // any hidden calls to malloc.
     void *malloc_thunk =
         reinterpret_cast<void*>(reinterpret_cast<intptr_t>(malloc) & ~4095);
     mprotect(malloc_thunk, 4096, PROT_READ | PROT_WRITE | PROT_EXEC);
     memset(reinterpret_cast<void*>(malloc), 0xff, 8);
 #endif
 
@@ skipping 352 matching lines @@
                       const ProcessFilter* filter) {
   bool exited_cleanly =
       WaitForProcessesToExit(executable_name, wait_milliseconds,
                              filter);
   if (!exited_cleanly)
     KillProcesses(executable_name, exit_code, filter);
   return exited_cleanly;
 }
 
 }  // namespace base