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Merge "Restore errno in signal handlers."

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Christopher Ferris 2017-03-13 20:50:19 +00:00 committed by Gerrit Code Review
commit f161e00289
1 changed files with 20 additions and 0 deletions
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20
libbacktrace/BacktraceCurrent.cpp
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@ -95,11 +95,31 @@ bool BacktraceCurrent::DiscardFrame(const backtrace_frame_data_t& frame) {
static pthread_mutex_t g_sigaction_mutex = PTHREAD_MUTEX_INITIALIZER;
// Since errno is stored per thread, changing it in the signal handler
// modifies the value on the thread in which the signal handler executes.
// If a signal occurs between a call and an errno check, it's possible
// to get the errno set here. Always save and restore it just in case
// code would modify it.
class ErrnoRestorer {
public:
ErrnoRestorer() : saved_errno_(errno) {}
~ErrnoRestorer() {
errno = saved_errno_;
}
private:
int saved_errno_;
};
static void SignalLogOnly(int, siginfo_t*, void*) {
ErrnoRestorer restore;
BACK_LOGE("pid %d, tid %d: Received a spurious signal %d\n", getpid(), gettid(), THREAD_SIGNAL);
}
static void SignalHandler(int, siginfo_t*, void* sigcontext) {
ErrnoRestorer restore;
ThreadEntry* entry = ThreadEntry::Get(getpid(), gettid(), false);
if (!entry) {
BACK_LOGE("pid %d, tid %d entry not found", getpid(), gettid());