[BRLTTY] screen driver in brlapi

[Tage Johansson]

The code works now!

The problem was that I have to reinitialize the pollfd-struct for every 
call to poll.

How ever, I have still one question.

Revents is allways set to 10. Wich means that both the POLLPRI and 
POLLERR flags are set.

Why is the POLLERR flag set? Is there still a problem with my code?


Thae code follows:

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/poll.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>

int main () {
     int vcsa = open("/dev/vcsa", O_RDONLY);
     if (vcsa == -1) {
         printf("OpenError: %s\n", strerror(errno));
         exit(EXIT_FAILURE);
     }
     uint8_t header[4];
     for(int i = 0; i < 30; i++) {
         struct pollfd fd = {
             .fd = vcsa,
             .events = POLLPRI
         };
         if (pread(vcsa, header, sizeof(header), 0) == -1) {
             printf("PreadError: %s\n", strerror(errno));
             exit(EXIT_FAILURE);
         }
         int ret = poll(&fd, 1, -1);
         if(ret == -1) {
             printf("PollError: %s\n", strerror(errno));
             exit(EXIT_FAILURE);
         }
         else if (ret == 0) {
             printf("PollError: poll timed out unexpectedly.\n");
             exit(EXIT_FAILURE);
         }
         else if (ret != 1) {
             printf("PollError: bad return value from poll %d\n", ret);
             exit(EXIT_FAILURE);
         }
         printf("%d header: %d, %d, %d, %d\n", fd.revents, header[0], 
header[1], header[2], header[3]);
     }
     printf("\nPOLLPRI = %d POLLERR = %d\n", POLLPRI, POLLERR);
     exit(EXIT_SUCCESS);
}

Thanks in advance,

Tage