nodejs/node · error

error parsing lgwin value [%s]\n

Error message

error parsing lgwin value [%s]\n

What it means

`ParseInt` (brotli.c:228) parses `-w`'s argument with bounds `[0, BROTLI_MAX_WINDOW_BITS]`. It rejects non-digits, leading zeros, >5 digits, and out-of-range values. A failure prints `error parsing lgwin value [<arg>]` and returns COMMAND_INVALID.

Source

Thrown at deps/brotli/c/tools/brotli.c:472

          if (quality_set) {
            fprintf(stderr, "quality already set\n");
            return COMMAND_INVALID;
          }
          quality_set = ParseInt(argv[i], BROTLI_MIN_QUALITY,
                                 BROTLI_MAX_QUALITY, &params->quality);
          if (!quality_set) {
            fprintf(stderr, "error parsing quality value [%s]\n", argv[i]);
            return COMMAND_INVALID;
          }
        } else if (c == 'w') {
          if (lgwin_set) {
            fprintf(stderr, "lgwin parameter already set\n");
            return COMMAND_INVALID;
          }
          lgwin_set = ParseInt(argv[i], 0,
                               BROTLI_MAX_WINDOW_BITS, &params->lgwin);
          if (!lgwin_set) {
            fprintf(stderr, "error parsing lgwin value [%s]\n", argv[i]);
            return COMMAND_INVALID;
          }
          if (params->lgwin != 0 && params->lgwin < BROTLI_MIN_WINDOW_BITS) {
            fprintf(stderr,
                    "lgwin parameter (%d) smaller than the minimum (%d)\n",
                    params->lgwin, BROTLI_MIN_WINDOW_BITS);
            return COMMAND_INVALID;
          }
        } else if (c == 'C') {
          if (comment_set) {
            fprintf(stderr, "comment already set\n");
            return COMMAND_INVALID;
          }
          params->comment_len = MAX_COMMENT_LEN;
          if (!ParseBase64(argv[i], params->comment, &params->comment_len)) {
            fprintf(stderr, "invalid base64-encoded comment\n");
            return COMMAND_INVALID;
          }

View on GitHub (pinned to 1b2de5e052)

Solutions

  1. Pass an integer in [0, BROTLI_MAX_WINDOW_BITS] with no leading zeros (e.g. `-w 22`).
  2. Use `0` for the auto/default window; pick a value in [BROTLI_MIN_WINDOW_BITS, BROTLI_MAX_WINDOW_BITS] otherwise.
  3. Validate the variable: `[[ "$W" =~ ^[0-9]{1,5}$ ]] || exit 1`.

Example fix

# before
brotli -w 030 in
# after
brotli -w 22 in
Defensive patterns

Strategy: validation

Validate before calling

# bash: validate -w value (0..BROTLI_MAX_WINDOW_BITS, no leading zero)
MAXW=24  # BROTLI_MAX_WINDOW_BITS; some builds allow larger with --large-window
argv=("$@")
for ((i=0;i<${#argv[@]};i++)); do
  if [ "${argv[$i]}" = -w ]; then
    v=${argv[$((i+1))]:-}
    if ! [[ "$v" =~ ^(0|[1-9][0-9]{0,4})$ ]] || [ "$v" -gt "$MAXW" ]; then
      echo "invalid lgwin '$v'" >&2; exit 2
    fi
  fi
done
brotli "$@"

Try / catch

# bash
if ! brotli "$@"; then rc=$?; echo "brotli exit $rc; verify -w value" >&2; exit "$rc"; fi

Prevention

When it happens

Trigger: `brotli -w abc in` (non-digit), `brotli -w 030 in` (leading zero), `brotli -w 999999 in` (>5 digits), `brotli -w 999 in` (above BROTLI_MAX_WINDOW_BITS).

Common situations: Passing a float (`-w 22.5`); negative values from misconfigured env; confusing lgwin with quality magnitude.

Related errors

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/d139307f35106705. Report an issue: GitHub.