// components should not call this.
static std::error_code FixupStandardFileDescriptors();
+ // This function safely closes a file descriptor. It is not safe to retry
+ // close(2) when it returns with errno equivalent to EINTR; this is because
+ // *nixen cannot agree if the file descriptor is, in fact, closed when this
+ // occurs.
+ //
+ // N.B. Some operating systems, due to thread cancellation, cannot properly
+ // guarantee that it will or will not be closed one way or the other!
+ static std::error_code SafelyCloseFileDescriptor(int FD);
+
/// This function determines if the standard input is connected directly
/// to a user's input (keyboard probably), rather than coming from a file
/// or pipe.
return std::error_code();
}
+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());
+}
+
bool Process::StandardInIsUserInput() {
return FileDescriptorIsDisplayed(STDIN_FILENO);
}
return std::error_code();
}
+std::error_code Process::SafelyCloseFileDescriptor(int FD) {
+ if (::close(FD) < 0)
+ return std::error_code(errno, std::generic_category());
+ return std::error_code();
+}
+
bool Process::StandardInIsUserInput() {
return FileDescriptorIsDisplayed(0);
}
raw_fd_ostream::~raw_fd_ostream() {
if (FD >= 0) {
flush();
- if (ShouldClose)
- while (::close(FD) != 0)
- if (errno != EINTR) {
- error_detected();
- break;
- }
+ if (ShouldClose && sys::Process::SafelyCloseFileDescriptor(FD))
+ error_detected();
}
#ifdef __MINGW32__
assert(ShouldClose);
ShouldClose = false;
flush();
- while (::close(FD) != 0)
- if (errno != EINTR) {
- error_detected();
- break;
- }
+ if (sys::Process::SafelyCloseFileDescriptor(FD))
+ error_detected();
FD = -1;
}