Function luaO_chunkid

3rd/lua-5.4.3/src/lobject.c:557–591

#define addstr(a,b,l)	( memcpy(a,b,(l) * sizeof(char)), a += (l) )

void luaO_chunkid (char *out, const char *source, size_t srclen) {
  size_t bufflen = LUA_IDSIZE;  /* free space in buffer */
  if (*source == '=') {  /* 'literal' source */
    if (srclen <= bufflen)  /* small enough? */
      memcpy(out, source + 1, srclen * sizeof(char));
    else {  /* truncate it */
      addstr(out, source + 1, bufflen - 1);
      *out = '\0';
    }
  }
  else if (*source == '@') {  /* file name */
    if (srclen <= bufflen)  /* small enough? */
      memcpy(out, source + 1, srclen * sizeof(char));
    else {  /* add '...' before rest of name */
      addstr(out, RETS, LL(RETS));
      bufflen -= LL(RETS);
      memcpy(out, source + 1 + srclen - bufflen, bufflen * sizeof(char));
    }
  }
  else {  /* string; format as [string "source"] */
    const char *nl = strchr(source, '\n');  /* find first new line (if any) */
    addstr(out, PRE, LL(PRE));  /* add prefix */
    bufflen -= LL(PRE RETS POS) + 1;  /* save space for prefix+suffix+'\0' */
    if (srclen < bufflen && nl == NULL) {  /* small one-line source? */
      addstr(out, source, srclen);  /* keep it */
    }
    else {
      if (nl != NULL) srclen = nl - source;  /* stop at first newline */
      if (srclen > bufflen) srclen = bufflen;
      addstr(out, source, srclen);
      addstr(out, RETS, LL(RETS));
    }
    memcpy(out, POS, (LL(POS) + 1) * sizeof(char));
  }
}