UCHARP get_line_beg(UCHARP p, UCHARP beg) {
  while(p > beg) {
    if ((*--p) == '\n') return p+1;
  }
  return beg;
}

void print_line(UCHARP beg, UCHARP end) {
  fwrite(beg, sizeof(char), (end - beg + 1), stdout);
}

void grep(char *regexp, int fd, char *name) {
  caddr_t file_mmap;
  UCHARP buf, end, beg;
  off_t size;
  struct stat sb;

  if (fstat(fd, &sb)) {
    fprintf(stderr, "can't fstat %s\n", name);
    exit(0);
  }

  size = sb.st_size;
  file_mmap = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, (off_t)0);

  if (file_mmap == (caddr_t)-1) {
    fprintf(stderr, "can't mmap %s\n", name);
    exit(0);
  }

  beg = buf = (UCHARP) file_mmap;
  end = beg + size - 1;

  matcher(beg, beg, end);

  munmap(file_mmap, size);
  return;
}

int main(int argc, char* argv[]) {
  int i, fd;

  if (argc < 2) {
    fprintf(stderr, "usage: grep regexp [file ...]");
    exit(0);
  }
  if (argc == 2) {
    return 0;
  } else {
    for (i = 2; i < argc; i++) {
      fd = open(argv[i], O_RDONLY, 0666);
      if (fd == 0) {
        fprintf(stderr, "can't open %s:", argv[i]);
        continue;
      }
      grep(argv[1], fd, argc > 3 ? argv[i] : NULL);
      close(fd);
    }
  }

  return 0;
}