#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h> 

#define MAXLINESIZE 1024

/* Print lines of a file in reverse order. 
   Adapted from Rochkind, Advanced Unix Programming, p. 109 
*/
int main(int argc, char * argv[])
{
     char  c, line[MAXLINESIZE];
     int   i, fd;
     off_t file_size, loc;

     if (argc !=2) {
	  fprintf(stderr, "Usage: %s file\n", argv[0]);
	  exit(1);
     }

     fd = open(argv[1], O_RDONLY);
     if (fd == -1) {
	  perror(argv[0]);
	  exit(1);
     }

     file_size = lseek(fd, 0L, SEEK_END);
     if (file_size == -1) {
	  perror(argv[0]);
	  exit(1);
     }

     i = sizeof(line) - 1;
     line[i] = '\0';

     for (loc = file_size-1; loc >= 0; --loc)
	  switch (pread(fd, &c, 1, loc)) {
	  case 1:
	       if (c == '\n') {
		    printf("%s", &line[i]);
		    i = sizeof(line) - 1;
	       }
	       if (i <= 0 ) {
		    fprintf(stderr, "%s:  line too big\n", argv[0]);
		    exit(E2BIG);
	       }
	       line[--i] = c;
	       break;
	  case -1:
	       perror(argv[0]);
	       exit(1);
	       break;
	  default:  /* will never happen */
	       exit(1);
	  }
     printf("%s", &line[i]);  /* one more line to do */

     if (close(fd) == -1) {
	  perror("argv[0]");
	  exit(1);
     }

     return 0;
  
}