parseHumanSize #c #atoi

parseHumanSize.c

uintmax_t parseHumanSize (const char* s) {
  char *endp = (char *)s;
  int sh;
  errno = 0;

  uintmax_t x = strtoumax(s, &endp, 10);
  if (errno || endp == s) {
    errno = EINVAL;
    goto ERROR;
  }

  switch (*endp) {
  case 'k':
  case 'K':
    sh = 10;
    break;
  case 'M':
  case 'm':
    sh = 20;
    break;
  case 'g':
  case 'G':
    sh = 30;
    break;
  case 0:
    sh = 0;
    break;
  default:
    goto ERROR;
  }
  if (sh && endp[1]) {
    errno = EINVAL;
    goto ERROR;
  }

  if (x > SIZE_MAX>>sh) {
    errno = ERANGE;
    goto ERROR;
  }

  x <<= sh; 

  return x;
ERROR:
  return 0;
}