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Cleanup: hide undefined behavior from the compiler better.

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Submitting this on behalf of Paul Pluzhnikov.

R=mark@chromium.org

Review URL: https://breakpad.appspot.com/6674002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1342 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
ivanpe@chromium.org 2014-07-01 17:50:05 +00:00
parent ada265ebbd
commit bf0e00374f
1 changed files with 18 additions and 4 deletions
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22
src/client/linux/handler/exception_handler_unittest.cc
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@ -193,6 +193,20 @@ static bool DoneCallback(const MinidumpDescriptor& descriptor,
#ifndef ADDRESS_SANITIZER
// This is a replacement for "*reinterpret_cast<volatile int*>(NULL) = 0;"
// It is needed because GCC is allowed to assume that the program will
// not execute any undefined behavior (UB) operation. Further, when GCC
// observes that UB statement is reached, it can assume that all statements
// leading to the UB one are never executed either, and can completely
// optimize them out. In the case of ExceptionHandlerTest::ExternalDumper,
// GCC-4.9 optimized out the entire set up of ExceptionHandler, causing
// test failure.
volatile int *p_null; // external linkage, so GCC can't tell that it
// remains NULL. Volatile just for a good measure.
static void DoNullPointerDereference() {
*p_null = 1;
}
void ChildCrash(bool use_fd) {
AutoTempDir temp_dir;
int fds[2] = {0};
@ -219,7 +233,7 @@ void ChildCrash(bool use_fd) {
true, -1));
}
// Crash with the exception handler in scope.
*reinterpret_cast<volatile int*>(NULL) = 0;
DoNullPointerDereference();
}
}
if (!use_fd)
@ -295,7 +309,7 @@ static void CrashWithCallbacks(ExceptionHandler::FilterCallback filter,
ExceptionHandler handler(
MinidumpDescriptor(path), filter, done, NULL, true, -1);
// Crash with the exception handler in scope.
*reinterpret_cast<volatile int*>(NULL) = 0;
DoNullPointerDereference();
}
TEST(ExceptionHandlerTest, RedeliveryOnFilterCallbackFalse) {
@ -386,7 +400,7 @@ TEST(ExceptionHandlerTest, RedeliveryOnBadSignalHandlerFlag) {
reinterpret_cast<void*>(SIG_ERR));
// Crash with the exception handler in scope.
*reinterpret_cast<volatile int*>(NULL) = 0;
DoNullPointerDereference();
}
// SIGKILL means Breakpad's signal handler didn't crash.
ASSERT_NO_FATAL_FAILURE(WaitForProcessToTerminate(child, SIGKILL));
@ -922,7 +936,7 @@ TEST(ExceptionHandlerTest, ExternalDumper) {
ExceptionHandler handler(MinidumpDescriptor("/tmp1"), NULL, NULL,
reinterpret_cast<void*>(fds[1]), true, -1);
handler.set_crash_handler(CrashHandler);
*reinterpret_cast<volatile int*>(NULL) = 0;
DoNullPointerDereference();
}
close(fds[1]);
struct msghdr msg = {0};