/* ----------- count.c -------------*/
# include "count.h"

int count(int pid, int delay) {
   int fd, n, seqno; char buffer[MAXBUF + 1];
   if ( (fd = open(SEQFILE,O_RDWR) ) < 0 ) {
      perror("SEQFILE"); return -1;
   }
   /* rewind before read: */ lseek(fd, 0L, 0); 
   if ( (n = read(fd, buffer, MAXBUF) ) <= 0) {
      perror("read"); return -1;
   }
   buffer[n] = '\0';
   if ( (n = sscanf(buffer, "%d\n", &seqno)) != 1) {
         fprintf(stderr, "sscanf error\n");
         return -1;
   }
   fprintf(stderr, "%d -- Read: %d\n", pid, seqno);
   seqno++;
   sprintf(buffer, "%03d\n", seqno);
   n = strlen(buffer);
   /* wait delay sec: */ sleep(delay);
   /* rewind before write: */ lseek(fd,0L,0);
   if (write(fd, buffer, n) != n) {
      perror("write");
      return -1;
   }
   close(fd); return 0;
}