mrdoob/three.js · error

invalid length

Error message

invalid length

What it means

Thrown by slice_slice(length) in the shapefile stream reader when the requested slice length, coerced to a 32-bit integer, is negative. The function is a buffered stream slicer: it reads length bytes from the underlying source, so a negative length is treated as a programming error rather than an empty read.

Source

Thrown at manual/resources/tools/geo-picking/shapefile.js:86

  c.set(a);
  c.set(b, a.length);
  return c;
}

var slice_read = function() {
  var that = this, array = that._array.subarray(that._index);
  return that._source.read().then(function(result) {
    that._array = empty;
    that._index = 0;
    return result.done ? (array.length > 0
        ? {done: false, value: array}
        : {done: true, value: undefined})
        : {done: false, value: concat(array, result.value)};
  });
};

var slice_slice = function(length) {
  if ((length |= 0) < 0) throw new Error("invalid length");
  var that = this, index = this._array.length - this._index;

  // If the request fits within the remaining buffer, resolve it immediately.
  if (this._index + length <= this._array.length) {
    return Promise.resolve(this._array.subarray(this._index, this._index += length));
  }

  // Otherwise, read chunks repeatedly until the request is fulfilled.
  var array = new Uint8Array(length);
  array.set(this._array.subarray(this._index));
  return (function read() {
    return that._source.read().then(function(result) {

      // When done, it’s possible the request wasn’t fully fulfilled!
      // If so, the pre-allocated array is too big and needs slicing.
      if (result.done) {
        that._array = empty;
        that._index = 0;

View on GitHub (pinned to da05705fa3)

Solutions

1. Validate the length is a non-negative finite number before calling .slice(); treat a negative computed length as a corrupt-record signal.
2. If the length derives from header fields, clamp/guard against underflow (e.g. Math.max(0, declared - fixedHeader)).
3. Confirm the input is actually a .shp stream and not truncated; re-export or re-download the shapefile if it is malformed.

Example fix

// before
const recordBody = source.slice( recordLength - headerSize ); // can be negative

// after
const bodyLen = recordLength - headerSize;
if ( bodyLen < 0 ) throw new Error( `corrupt record: length ${recordLength}` );
const recordBody = source.slice( bodyLen );

function safeSlice( source, length ) {
  if ( ! Number.isFinite( length ) || ( length | 0 ) < 0 ) {
    throw new Error( `invalid slice length: ${length}` );
  }
  return source.slice( length );
}

try {
  body = source.slice( computedLen );
} catch ( err ) {
  if ( /invalid length/.test( err.message ) ) {
    throw new Error( `corrupt record: computed length ${computedLen}` );
  }
  throw err;
}

When it happens

Trigger: Calling source.slice(n) with n < 0. Passing an undefined/NaN length that coerces to a negative int32 through '| 0'. A caller that computes a length from header fields (e.g. record length minus header) and underflows when the record is malformed or truncated.

Common situations: A corrupted or truncated .shp file where a record's declared byte length is smaller than the fixed header, producing a negative remaining length in the caller. Feeding a non-shapefile blob to the reader so parsed length fields are garbage.

Related errors

• unsupported shape type: ${type}
• unknown geometry type.
• "transform stack empty!
• transform stack not 0
• no diagram ${name}

AI-assisted analysis of mrdoob/three.js@da05705fa3 (2026-08-12). Data as JSON: /api/errors/f64d7ca0079e1853. Report an issue: GitHub.