+std::error_code Process::SafelyCloseFileDescriptor(int FD) {
+ // Create a signal set filled with *all* signals.
+ sigset_t FullSet;
+ if (sigfillset(&FullSet) < 0)
+ return std::error_code(errno, std::generic_category());
+ // Atomically swap our current signal mask with a full mask.
+ sigset_t SavedSet;
+ if (int EC = pthread_sigmask(SIG_SETMASK, &FullSet, &SavedSet))
+ return std::error_code(EC, std::generic_category());
+ // Attempt to close the file descriptor.
+ // We need to save the error, if one occurs, because our subsequent call to
+ // pthread_sigmask might tamper with errno.
+ int ErrnoFromClose = 0;
+ if (::close(FD) < 0)
+ ErrnoFromClose = errno;
+ // Restore the signal mask back to what we saved earlier.
+ int EC = pthread_sigmask(SIG_SETMASK, &SavedSet, nullptr);
+ // The error code from close takes precedence over the one from
+ // pthread_sigmask.
+ if (ErrnoFromClose)
+ return std::error_code(ErrnoFromClose, std::generic_category());
+ return std::error_code(EC, std::generic_category());
+}
+