Add lock to prevent race on SysTimeFromTimeStruct

base/time/time_posix.cc

 // Copyright (c) 2012 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/time/time.h"
 
 #include <stdint.h>
 #include <sys/time.h>
 #include <time.h>
 #if defined(OS_ANDROID) && !defined(__LP64__)
 #include <time64.h>
 #endif
 #include <unistd.h>
 
 #include <limits>
 #include <ostream>
 
 #include "base/basictypes.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/port.h"
+#include "base/synchronization/lock.h"
 #include "build/build_config.h"
 
 #if defined(OS_ANDROID)
 #include "base/os_compat_android.h"
 #elif defined(OS_NACL)
 #include "base/os_compat_nacl.h"
 #endif
 
 namespace {
 
+// This prevents a crash on traversing the environment global and looking up
+// the 'TZ' variable in libc.

[willchan no longer on Chromium, 2014/08/06 20:43:24]

Please update this to reference the bug so people can understand what's going
on.

[bengr, 2014/08/07 18:28:30]

Done.

+base::LazyInstance<base::Lock>::Leaky
+    g_sys_time_to_time_struct_lock = LAZY_INSTANCE_INITIALIZER;
+
 #if !defined(OS_MACOSX)
 // Define a system-specific SysTime that wraps either to a time_t or
 // a time64_t depending on the host system, and associated convertion.
 // See crbug.com/162007
 #if defined(OS_ANDROID) && !defined(__LP64__)
 typedef time64_t SysTime;
 
 SysTime SysTimeFromTimeStruct(struct tm* timestruct, bool is_local) {
+  base::AutoLock locked(g_sys_time_to_time_struct_lock.Get());
   if (is_local)
     return mktime64(timestruct);
   else
     return timegm64(timestruct);
 }
 
 void SysTimeToTimeStruct(SysTime t, struct tm* timestruct, bool is_local) {
+  base::AutoLock locked(g_sys_time_to_time_struct_lock.Get());
   if (is_local)
     localtime64_r(&t, timestruct);
   else
     gmtime64_r(&t, timestruct);
 }
 
 #else  // OS_ANDROID && !__LP64__
 typedef time_t SysTime;
 
 SysTime SysTimeFromTimeStruct(struct tm* timestruct, bool is_local) {
+  base::AutoLock locked(g_sys_time_to_time_struct_lock.Get());
   if (is_local)
     return mktime(timestruct);
   else
     return timegm(timestruct);
 }
 
 void SysTimeToTimeStruct(SysTime t, struct tm* timestruct, bool is_local) {
+  base::AutoLock locked(g_sys_time_to_time_struct_lock.Get());
   if (is_local)
     localtime_r(&t, timestruct);
   else
     gmtime_r(&t, timestruct);
 }
 #endif  // OS_ANDROID
 
 // Helper function to get results from clock_gettime() as TimeTicks object.
 // Minimum requirement is MONOTONIC_CLOCK to be supported on the system.
 // FreeBSD 6 has CLOCK_MONOTONIC but defines _POSIX_MONOTONIC_CLOCK to -1.
@@ skipping 304 matching lines @@
     result.tv_usec = static_cast<suseconds_t>(Time::kMicrosecondsPerSecond) - 1;
     return result;
   }
   int64 us = us_ - kTimeTToMicrosecondsOffset;
   result.tv_sec = us / Time::kMicrosecondsPerSecond;
   result.tv_usec = us % Time::kMicrosecondsPerSecond;
   return result;
 }
 
 }  // namespace base