Question

In a multi threaded application all threads block all signals and a single thread does the signal handling in a loop with sigwait. Now should we consider EINTR after using system calls like read and write in other threads?

while (true)
{
    num = read(fd, buf, size);
    if (num == -1 && errno == EINTR)
        continue;
    else if (num > 0)
        /* handle the buf and read more */
}

Answer 1

EINTR is only returned if the system call was interrupted by a signal handler. If all signals are blocked in the signal mask of the thread that’s making the system call, then this can’t happen.