Use posix version of stack_trace on iOS

base/debug/stack_trace_posix.cc

Index: base/debug/stack_trace_posix.cc
diff --git a/base/debug/stack_trace_posix.cc b/base/debug/stack_trace_posix.cc
index ed1a91889b142f432f67fe34c40d38991992117e..fa68a06f895a6266b1f12c7bffa7df8322426baf 100644
--- a/base/debug/stack_trace_posix.cc
+++ b/base/debug/stack_trace_posix.cc
@@ -179,7 +179,6 @@ void PrintToStderr(const char* output) {
   ignore_result(HANDLE_EINTR(write(STDERR_FILENO, output, strlen(output))));
 }
 
-#if !defined(OS_IOS)
 void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
   // NOTE: This code MUST be async-signal safe.
   // NO malloc or stdio is allowed here.
@@ -195,6 +194,8 @@ void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
   char buf[1024] = { 0 };
   internal::itoa_r(signal, buf, sizeof(buf), 10, 0);
   PrintToStderr(buf);
+#if !defined(OS_IOS)
+  // NOTE: on iOS, info and void_context are incorrect. Ignore them.

[Mark Mentovai, 2014/01/15 19:14:06]

If you’ve got a reference (link?) to point to here, it’d be helpful. Also, if
you can determine whether it’s just broken for ARM and OK in the simulator, you
can refine the #ifdef.

   if (signal == SIGBUS) {
     if (info->si_code == BUS_ADRALN)
       PrintToStderr(" BUS_ADRALN ");
@@ -254,6 +255,7 @@ void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
                      buf, sizeof(buf), 16, 12);
     PrintToStderr(buf);
   }
+  #endif  // !defined(OS_IOS)
   PrintToStderr("\n");
 
   debug::StackTrace().Print();
@@ -329,7 +331,7 @@ void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
   }
   PrintToStderr("\n");
 #endif
-#elif defined(OS_MACOSX)
+#elif defined(OS_MACOSX) && !defined(OS_IOS)

[Mark Mentovai, 2014/01/15 19:14:06]

You probably don’t need !defined(OS_IOS) here, because everything inside this is
limited to ARCH_CPU_X86_FAMILY && ARCH_CPU_32_BITS. You could change the next
line to “port to x86_64 and ARM (for iOS).”

Unless this won’t work at all in the simulator.

   // TODO(shess): Port to 64-bit.
 #if ARCH_CPU_X86_FAMILY && ARCH_CPU_32_BITS
   ucontext_t* context = reinterpret_cast<ucontext_t*>(void_context);
@@ -369,10 +371,9 @@ void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {
                context->uc_mcontext->__ss.__gs));
   write(STDERR_FILENO, buf, std::min(len, sizeof(buf) - 1));
 #endif  // ARCH_CPU_32_BITS
-#endif  // defined(OS_MACOSX)
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
   _exit(1);
 }
-#endif  // !defined(OS_IOS)
 
 class PrintBacktraceOutputHandler : public BacktraceOutputHandler {
  public:
@@ -403,7 +404,6 @@ class StreamBacktraceOutputHandler : public BacktraceOutputHandler {
   DISALLOW_COPY_AND_ASSIGN(StreamBacktraceOutputHandler);
 };
 
-#if !defined(OS_IOS)
 void WarmUpBacktrace() {
   // Warm up stack trace infrastructure. It turns out that on the first
   // call glibc initializes some internal data structures using pthread_once,
@@ -436,11 +436,9 @@ void WarmUpBacktrace() {
   // #22 <signal handler called>
   StackTrace stack_trace;
 }
-#endif  // !defined(OS_IOS)
 
 }  // namespace
 
-#if !defined(OS_IOS)
 bool EnableInProcessStackDumping() {
   // When running in an application, our code typically expects SIGPIPE
   // to be ignored.  Therefore, when testing that same code, it should run
@@ -469,7 +467,6 @@ bool EnableInProcessStackDumping() {
 
   return success;
 }
-#endif  // !defined(OS_IOS)
 
 StackTrace::StackTrace() {
   // NOTE: This code MUST be async-signal safe (it's used by in-process