Make signalfd wrapper more robust
I realized afterwards it's only used in tests, but whatever.
Change-Id: I23f654a0119faefec6a3888dc7d7c8ba38cf1b4f
diff --git a/aos/ipc_lib/signalfd.cc b/aos/ipc_lib/signalfd.cc
index af95598..363bf4a 100644
--- a/aos/ipc_lib/signalfd.cc
+++ b/aos/ipc_lib/signalfd.cc
@@ -12,21 +12,35 @@
SignalFd::SignalFd(::std::initializer_list<unsigned int> signals) {
// Build up the mask with the provided signals.
- sigemptyset(&mask_);
+ CHECK_EQ(0, sigemptyset(&blocked_mask_));
for (int signal : signals) {
- sigaddset(&mask_, signal);
+ CHECK_EQ(0, sigaddset(&blocked_mask_, signal));
}
// Then build a signalfd. Make it nonblocking so it works well with an epoll
// loop, and have it close on exec.
- PCHECK((fd_ = signalfd(-1, &mask_, SFD_NONBLOCK | SFD_CLOEXEC)) != 0);
+ PCHECK((fd_ = signalfd(-1, &blocked_mask_, SFD_NONBLOCK | SFD_CLOEXEC)) != 0);
// Now that we have a consumer of the signal, block the signals so the
- // signalfd gets them.
- pthread_sigmask(SIG_BLOCK, &mask_, nullptr);
+ // signalfd gets them. Record which ones we actually blocked, so we can
+ // unblock just those later.
+ sigset_t old_mask;
+ CHECK_EQ(0, pthread_sigmask(SIG_BLOCK, &blocked_mask_, &old_mask));
+ for (int signal : signals) {
+ if (sigismember(&old_mask, signal)) {
+ CHECK_EQ(0, sigdelset(&blocked_mask_, signal));
+ }
+ }
}
SignalFd::~SignalFd() {
- // Unwind the constructor. Unblock the signals and close the fd.
- pthread_sigmask(SIG_UNBLOCK, &mask_, nullptr);
+ // Unwind the constructor. Unblock the signals and close the fd. Verify nobody
+ // else unblocked the signals we're supposed to unblock in the meantime.
+ sigset_t old_mask;
+ CHECK_EQ(0, pthread_sigmask(SIG_UNBLOCK, &blocked_mask_, &old_mask));
+ sigset_t unblocked_mask;
+ CHECK_EQ(0, sigandset(&unblocked_mask, &blocked_mask_, &old_mask));
+ if (memcmp(&unblocked_mask, &blocked_mask_, sizeof(unblocked_mask)) != 0) {
+ LOG(FATAL) << "Some other code unblocked one or more of our signals";
+ }
PCHECK(close(fd_) == 0);
}
@@ -39,6 +53,8 @@
// by setting the signal number to 0.
if (ret != static_cast<int>(sizeof(signalfd_siginfo))) {
result.ssi_signo = 0;
+ } else {
+ CHECK_NE(0u, result.ssi_signo);
}
return result;
}