/* Excerpted from 'The Practice of Programming' */
/* by Brian W. Kernighan and Rob Pike */

int grep(char * regexp, FILE *f, char *name) {
  int n, nmatch;
  char buf[LINEBUFSIZE];
  nmatch = 0;
  while (fgets(buf, sizeof buf, f) != NULL) {
    n = strlen(buf);
    if (n > 0 && buf[n-1] == '\n')
      buf[n-1] = '\0';
    if (match(regexp, buf)) {
      nmatch++;
      if (name != NULL)
        printf("%s:", name);
      printf("%s\n", buf);
    }
  }
  return nmatch;
}

int grepmain(int argc, char* argv[]) {
  int i, nmatch;
  FILE *f;

  if (argc < 2) {
    fprintf(stderr, "usage: grep regexp [file ...]");
    exit(0);
  }
  nmatch = 0;
  if (argc == 2) {
    if (grep(argv[1], stdin, NULL))
      nmatch;
  } else {
    for (i = 2; i < argc; i++) {
      f = fopen(argv[i], "r");
      if (f == NULL) {
        fprintf(stderr, "can't open %s:", argv[i]);
        continue;
      }
      if (READBUFSIZE > 0)
        setvbuf(f, readbuf, _IOFBF, READBUFSIZE);
      if (grep(argv[1], f, argc > 3 ? argv[i] : NULL) > 0)
        nmatch++;
      fclose(f);
    }
  }

  return nmatch;
}