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https://github.com/denoland/deno.git
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ebbc897b69
Fixes #22158. Basically reimplements the whole `StringDecoder` with a much more direct translation (read like one-to-one) of node's current logic. The old implementation was closer to node's super old impl and it was too hard to keep the code structure while matching the behavior of their new logic. This adds support for UTF-16LE, ascii, and latin1. This also enables the node_compat test, which now passes without modification.
412 lines
12 KiB
TypeScript
412 lines
12 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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// Copyright Joyent, Inc. and other Node contributors.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to permit
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// persons to whom the Software is furnished to do so, subject to the
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// following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
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// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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// USE OR OTHER DEALINGS IN THE SOFTWARE.
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// TODO(petamoriken): enable prefer-primordials for node polyfills
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// deno-lint-ignore-file prefer-primordials
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// Logic and comments translated pretty much one-to-one from node's impl
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// (https://github.com/nodejs/node/blob/ba06c5c509956dc413f91b755c1c93798bb700d4/src/string_decoder.cc)
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import { Buffer, constants } from "node:buffer";
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import { normalizeEncoding as castEncoding } from "ext:deno_node/_utils.ts";
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import {
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ERR_INVALID_ARG_TYPE,
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ERR_INVALID_THIS,
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ERR_UNKNOWN_ENCODING,
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NodeError,
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} from "ext:deno_node/internal/errors.ts";
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import { primordials } from "ext:core/mod.js";
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const {
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ArrayBufferIsView,
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ObjectDefineProperties,
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} = primordials;
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const { MAX_STRING_LENGTH } = constants;
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// to cast from string to `BufferEncoding`, which doesn't seem nameable from here
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// deno-lint-ignore no-explicit-any
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type Any = any;
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function normalizeEncoding(enc?: string): string {
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const encoding = castEncoding(enc ?? null);
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if (!encoding) {
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if (typeof enc !== "string" || enc.toLowerCase() !== "raw") {
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throw new ERR_UNKNOWN_ENCODING(
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enc as Any,
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);
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}
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}
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return String(encoding);
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}
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/**
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* Check is `ArrayBuffer` and not `TypedArray`. Typescript allowed `TypedArray` to be passed as `ArrayBuffer` and does not do a deep check
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*/
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function isBufferType(buf: Buffer) {
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return buf instanceof Buffer && buf.BYTES_PER_ELEMENT;
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}
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function normalizeBuffer(buf: Buffer) {
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if (!ArrayBufferIsView(buf)) {
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throw new ERR_INVALID_ARG_TYPE(
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"buf",
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["Buffer", "TypedArray", "DataView"],
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buf,
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);
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}
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if (isBufferType(buf)) {
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return buf;
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} else {
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return Buffer.from(
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buf.buffer,
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);
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}
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}
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function bufferToString(
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buf: Buffer,
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encoding?: string,
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start?: number,
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end?: number,
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): string {
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const len = (end ?? buf.length) - (start ?? 0);
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if (len > MAX_STRING_LENGTH) {
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throw new NodeError("ERR_STRING_TOO_LONG", "string exceeds maximum length");
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}
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return buf.toString(encoding as Any, start, end);
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}
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// the heart of the logic, decodes a buffer, storing
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// incomplete characters in a buffer if applicable
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function decode(this: StringDecoder, buf: Buffer) {
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const enc = this.enc;
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let bufIdx = 0;
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let bufEnd = buf.length;
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let prepend = "";
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let rest = "";
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if (
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enc === Encoding.Utf8 || enc === Encoding.Utf16 || enc === Encoding.Base64
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) {
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// check if we need to finish an incomplete char from the last chunk
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// written. If we do, we copy the bytes into our `lastChar` buffer
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// and prepend the completed char to the result of decoding the rest of the buffer
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if (this[kMissingBytes] > 0) {
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if (enc === Encoding.Utf8) {
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// Edge case for incomplete character at a chunk boundary
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// (see https://github.com/nodejs/node/blob/73025c4dec042e344eeea7912ed39f7b7c4a3991/src/string_decoder.cc#L74)
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for (
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let i = 0;
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i < buf.length - bufIdx && i < this[kMissingBytes];
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i++
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) {
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if ((buf[i] & 0xC0) !== 0x80) {
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// We expected a continuation byte, but got something else.
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// Stop trying to decode the incomplete char, and assume
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// the byte we got starts a new char.
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this[kMissingBytes] = 0;
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buf.copy(this.lastChar, this[kBufferedBytes], bufIdx, bufIdx + i);
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this[kBufferedBytes] += i;
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bufIdx += i;
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break;
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}
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}
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}
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const bytesToCopy = Math.min(buf.length - bufIdx, this[kMissingBytes]);
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buf.copy(
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this.lastChar,
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this[kBufferedBytes],
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bufIdx,
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bufIdx + bytesToCopy,
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);
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bufIdx += bytesToCopy;
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this[kBufferedBytes] += bytesToCopy;
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this[kMissingBytes] -= bytesToCopy;
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if (this[kMissingBytes] === 0) {
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// we have all the bytes, complete the char
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prepend = bufferToString(
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this.lastChar,
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this.encoding,
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0,
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this[kBufferedBytes],
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);
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// reset the char buffer
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this[kBufferedBytes] = 0;
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}
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}
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if (buf.length - bufIdx === 0) {
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// we advanced the bufIdx, so we may have completed the
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// incomplete char
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rest = prepend.length > 0 ? prepend : "";
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prepend = "";
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} else {
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// no characters left to finish
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// check if the end of the buffer has an incomplete
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// character, if so we write it into our `lastChar` buffer and
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// truncate buf
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if (enc === Encoding.Utf8 && (buf[buf.length - 1] & 0x80)) {
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for (let i = buf.length - 1;; i--) {
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this[kBufferedBytes] += 1;
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if ((buf[i] & 0xC0) === 0x80) {
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// Doesn't start a character (i.e. it's a trailing byte)
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if (this[kBufferedBytes] >= 4 || i === 0) {
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// invalid utf8, we'll just pass it to the underlying decoder
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this[kBufferedBytes] = 0;
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break;
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}
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} else {
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// First byte of a UTF-8 char, check
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// to see how long it should be
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if ((buf[i] & 0xE0) === 0xC0) {
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this[kMissingBytes] = 2;
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} else if ((buf[i] & 0xF0) === 0xE0) {
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this[kMissingBytes] = 3;
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} else if ((buf[i] & 0xF8) === 0xF0) {
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this[kMissingBytes] = 4;
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} else {
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// invalid
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this[kBufferedBytes] = 0;
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break;
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}
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if (this[kBufferedBytes] >= this[kMissingBytes]) {
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// We have enough trailing bytes to complete
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// the char
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this[kMissingBytes] = 0;
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this[kBufferedBytes] = 0;
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}
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this[kMissingBytes] -= this[kBufferedBytes];
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break;
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}
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}
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} else if (enc === Encoding.Utf16) {
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if ((buf.length - bufIdx) % 2 === 1) {
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// Have half of a code unit
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this[kBufferedBytes] = 1;
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this[kMissingBytes] = 1;
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} else if ((buf[buf.length - 1] & 0xFC) === 0xD8) {
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// 2 bytes out of a 4 byte UTF-16 char
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this[kBufferedBytes] = 2;
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this[kMissingBytes] = 2;
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}
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} else if (enc === Encoding.Base64) {
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this[kBufferedBytes] = (buf.length - bufIdx) % 3;
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if (this[kBufferedBytes] > 0) {
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this[kMissingBytes] = 3 - this[kBufferedBytes];
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}
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}
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if (this[kBufferedBytes] > 0) {
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// Copy the bytes that make up the incomplete char
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// from the end of the buffer into our `lastChar` buffer
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buf.copy(
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this.lastChar,
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0,
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buf.length - this[kBufferedBytes],
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);
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bufEnd -= this[kBufferedBytes];
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}
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rest = bufferToString(buf, this.encoding, bufIdx, bufEnd);
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}
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if (prepend.length === 0) {
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return rest;
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} else {
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return prepend + rest;
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}
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} else {
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return bufferToString(buf, this.encoding, bufIdx, bufEnd);
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}
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}
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function flush(this: StringDecoder) {
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const enc = this.enc;
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if (enc === Encoding.Utf16 && this[kBufferedBytes] % 2 === 1) {
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// ignore trailing byte if it isn't a complete code unit (2 bytes)
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this[kBufferedBytes] -= 1;
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this[kMissingBytes] -= 1;
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}
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if (this[kBufferedBytes] === 0) {
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return "";
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}
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const ret = bufferToString(
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this.lastChar,
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this.encoding,
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0,
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this[kBufferedBytes],
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);
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this[kBufferedBytes] = 0;
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this[kMissingBytes] = 0;
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return ret;
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}
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enum Encoding {
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Utf8,
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Base64,
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Utf16,
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Ascii,
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Latin1,
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Hex,
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}
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const kBufferedBytes = Symbol("bufferedBytes");
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const kMissingBytes = Symbol("missingBytes");
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type StringDecoder = {
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encoding: string;
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end: (buf: Buffer) => string;
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write: (buf: Buffer) => string;
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lastChar: Buffer;
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lastNeed: number;
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lastTotal: number;
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text: (buf: Buffer, idx: number) => string;
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enc: Encoding;
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decode: (buf: Buffer) => string;
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[kBufferedBytes]: number;
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[kMissingBytes]: number;
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flush: () => string;
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};
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/*
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* StringDecoder provides an interface for efficiently splitting a series of
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* buffers into a series of JS strings without breaking apart multi-byte
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* characters.
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*/
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export function StringDecoder(this: Partial<StringDecoder>, encoding?: string) {
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const normalizedEncoding = normalizeEncoding(encoding);
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let enc: Encoding = Encoding.Utf8;
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let bufLen = 0;
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switch (normalizedEncoding) {
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case "utf8":
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enc = Encoding.Utf8;
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bufLen = 4;
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break;
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case "base64":
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enc = Encoding.Base64;
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bufLen = 3;
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break;
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case "utf16le":
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enc = Encoding.Utf16;
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bufLen = 4;
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break;
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case "hex":
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enc = Encoding.Hex;
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bufLen = 0;
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break;
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case "latin1":
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enc = Encoding.Latin1;
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bufLen = 0;
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break;
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case "ascii":
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enc = Encoding.Ascii;
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bufLen = 0;
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break;
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}
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this.encoding = normalizedEncoding;
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this.lastChar = Buffer.allocUnsafe(bufLen);
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this.enc = enc;
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this[kBufferedBytes] = 0;
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this[kMissingBytes] = 0;
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this.flush = flush;
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this.decode = decode;
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}
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/**
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* Returns a decoded string, omitting any incomplete multi-bytes
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* characters at the end of the Buffer, or TypedArray, or DataView
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*/
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StringDecoder.prototype.write = function write(buf: Buffer): string {
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if (typeof buf === "string") {
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return buf;
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}
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const normalizedBuf = normalizeBuffer(buf);
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if (this[kBufferedBytes] === undefined) {
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throw new ERR_INVALID_THIS("StringDecoder");
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}
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return this.decode(normalizedBuf);
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};
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/**
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* Returns any remaining input stored in the internal buffer as a string.
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* After end() is called, the stringDecoder object can be reused for new
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* input.
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*/
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StringDecoder.prototype.end = function end(buf: Buffer): string {
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let ret = "";
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if (buf !== undefined) {
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ret = this.write(buf);
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}
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if (this[kBufferedBytes] > 0) {
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ret += this.flush();
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}
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return ret;
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};
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// Below is undocumented but accessible stuff from node's old impl
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// (node's tests assert on these, so we need to support them)
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StringDecoder.prototype.text = function text(
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buf: Buffer,
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offset: number,
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): string {
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this[kBufferedBytes] = 0;
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this[kMissingBytes] = 0;
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return this.write(buf.subarray(offset));
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};
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ObjectDefineProperties(StringDecoder.prototype, {
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lastNeed: {
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configurable: true,
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enumerable: true,
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get(this: StringDecoder): number {
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return this[kMissingBytes];
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},
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},
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lastTotal: {
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configurable: true,
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enumerable: true,
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get(this: StringDecoder): number {
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return this[kBufferedBytes] + this[kMissingBytes];
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},
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},
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});
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export default { StringDecoder };
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