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encoding.ts
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/*---------------------------------------------------------------------------------------------
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
import { Readable, ReadableStream, newWriteableStream, listenStream } from 'vs/base/common/stream';
import { VSBuffer, VSBufferReadable, VSBufferReadableStream } from 'vs/base/common/buffer';
import { IDisposable } from 'vs/base/common/lifecycle';
export const UTF8 = 'utf8';
export const UTF8_with_bom = 'utf8bom';
export const UTF16be = 'utf16be';
export const UTF16le = 'utf16le';
export type UTF_ENCODING = typeof UTF8 | typeof UTF8_with_bom | typeof UTF16be | typeof UTF16le;
export function isUTFEncoding(encoding: string): encoding is UTF_ENCODING {
return [UTF8, UTF8_with_bom, UTF16be, UTF16le].some(utfEncoding => utfEncoding === encoding);
}
export const UTF16be_BOM = [0xFE, 0xFF];
export const UTF16le_BOM = [0xFF, 0xFE];
export const UTF8_BOM = [0xEF, 0xBB, 0xBF];
const ZERO_BYTE_DETECTION_BUFFER_MAX_LEN = 512; // number of bytes to look at to decide about a file being binary or not
const NO_ENCODING_GUESS_MIN_BYTES = 512; // when not auto guessing the encoding, small number of bytes are enough
const AUTO_ENCODING_GUESS_MIN_BYTES = 512 * 8; // with auto guessing we want a lot more content to be read for guessing
const AUTO_ENCODING_GUESS_MAX_BYTES = 512 * 128; // set an upper limit for the number of bytes we pass on to jschardet
export interface IDecodeStreamOptions {
acceptTextOnly: boolean;
guessEncoding: boolean;
minBytesRequiredForDetection?: number;
overwriteEncoding(detectedEncoding: string | null): Promise<string>;
}
export interface IDecodeStreamResult {
stream: ReadableStream<string>;
detected: IDetectedEncodingResult;
}
export const enum DecodeStreamErrorKind {
/**
* Error indicating that the stream is binary even
* though `acceptTextOnly` was specified.
*/
STREAM_IS_BINARY = 1
}
export class DecodeStreamError extends Error {
constructor(
message: string,
readonly decodeStreamErrorKind: DecodeStreamErrorKind
) {
super(message);
}
}
export interface IDecoderStream {
write(buffer: Uint8Array): string;
end(): string | undefined;
}
class DecoderStream implements IDecoderStream {
/**
* This stream will only load iconv-lite lazily if the encoding
* is not UTF-8. This ensures that for most common cases we do
* not pay the price of loading the module from disk.
*
* We still need to be careful when converting UTF-8 to a string
* though because we read the file in chunks of Buffer and thus
* need to decode it via TextDecoder helper that is available
* in browser and node.js environments.
*/
static async create(encoding: string): Promise<DecoderStream> {
let decoder: IDecoderStream | undefined = undefined;
if (encoding !== UTF8) {
const iconv = await import('@vscode/iconv-lite-umd');
decoder = iconv.getDecoder(toNodeEncoding(encoding));
} else {
const utf8TextDecoder = new TextDecoder();
decoder = {
write(buffer: Uint8Array): string {
return utf8TextDecoder.decode(buffer, {
// Signal to TextDecoder that potentially more data is coming
// and that we are calling `decode` in the end to consume any
// remainders
stream: true
});
},
end(): string | undefined {
return utf8TextDecoder.decode();
}
};
}
return new DecoderStream(decoder);
}
private constructor(private iconvLiteDecoder: IDecoderStream) { }
write(buffer: Uint8Array): string {
return this.iconvLiteDecoder.write(buffer);
}
end(): string | undefined {
return this.iconvLiteDecoder.end();
}
}
export function toDecodeStream(source: VSBufferReadableStream, options: IDecodeStreamOptions): Promise<IDecodeStreamResult> {
const minBytesRequiredForDetection = options.minBytesRequiredForDetection ?? options.guessEncoding ? AUTO_ENCODING_GUESS_MIN_BYTES : NO_ENCODING_GUESS_MIN_BYTES;
return new Promise<IDecodeStreamResult>((resolve, reject) => {
const target = newWriteableStream<string>(strings => strings.join(''));
const bufferedChunks: VSBuffer[] = [];
let bytesBuffered = 0;
let decoder: IDecoderStream | undefined = undefined;
let sourceListener: IDisposable | undefined = undefined;
const createDecoder = async () => {
try {
// detect encoding from buffer
const detected = await detectEncodingFromBuffer({
buffer: VSBuffer.concat(bufferedChunks),
bytesRead: bytesBuffered
}, options.guessEncoding);
// throw early if the source seems binary and
// we are instructed to only accept text
if (detected.seemsBinary && options.acceptTextOnly) {
throw new DecodeStreamError('Stream is binary but only text is accepted for decoding', DecodeStreamErrorKind.STREAM_IS_BINARY);
}
// ensure to respect overwrite of encoding
detected.encoding = await options.overwriteEncoding(detected.encoding);
// decode and write buffered content
decoder = await DecoderStream.create(detected.encoding);
const decoded = decoder.write(VSBuffer.concat(bufferedChunks).buffer);
target.write(decoded);
bufferedChunks.length = 0;
bytesBuffered = 0;
// signal to the outside our detected encoding and final decoder stream
resolve({
stream: target,
detected
});
} catch (error) {
// Stop handling anything from the source and target
sourceListener?.dispose();
target.destroy();
reject(error);
}
};
sourceListener = listenStream(source, {
onData: async chunk => {
// if the decoder is ready, we just write directly
if (decoder) {
target.write(decoder.write(chunk.buffer));
}
// otherwise we need to buffer the data until the stream is ready
else {
bufferedChunks.push(chunk);
bytesBuffered += chunk.byteLength;
// buffered enough data for encoding detection, create stream
if (bytesBuffered >= minBytesRequiredForDetection) {
// pause stream here until the decoder is ready
source.pause();
await createDecoder();
// resume stream now that decoder is ready but
// outside of this stack to reduce recursion
setTimeout(() => source.resume());
}
}
},
onError: error => target.error(error), // simply forward to target
onEnd: async () => {
// we were still waiting for data to do the encoding
// detection. thus, wrap up starting the stream even
// without all the data to get things going
if (!decoder) {
await createDecoder();
}
// end the target with the remainders of the decoder
target.end(decoder?.end());
}
});
});
}
export async function toEncodeReadable(readable: Readable<string>, encoding: string, options?: { addBOM?: boolean }): Promise<VSBufferReadable> {
const iconv = await import('@vscode/iconv-lite-umd');
const encoder = iconv.getEncoder(toNodeEncoding(encoding), options);
let bytesWritten = false;
let done = false;
return {
read() {
if (done) {
return null;
}
const chunk = readable.read();
if (typeof chunk !== 'string') {
done = true;
// If we are instructed to add a BOM but we detect that no
// bytes have been written, we must ensure to return the BOM
// ourselves so that we comply with the contract.
if (!bytesWritten && options?.addBOM) {
switch (encoding) {
case UTF8:
case UTF8_with_bom:
return VSBuffer.wrap(Uint8Array.from(UTF8_BOM));
case UTF16be:
return VSBuffer.wrap(Uint8Array.from(UTF16be_BOM));
case UTF16le:
return VSBuffer.wrap(Uint8Array.from(UTF16le_BOM));
}
}
const leftovers = encoder.end();
if (leftovers && leftovers.length > 0) {
bytesWritten = true;
return VSBuffer.wrap(leftovers);
}
return null;
}
bytesWritten = true;
return VSBuffer.wrap(encoder.write(chunk));
}
};
}
export async function encodingExists(encoding: string): Promise<boolean> {
const iconv = await import('@vscode/iconv-lite-umd');
return iconv.encodingExists(toNodeEncoding(encoding));
}
export function toNodeEncoding(enc: string | null): string {
if (enc === UTF8_with_bom || enc === null) {
return UTF8; // iconv does not distinguish UTF 8 with or without BOM, so we need to help it
}
return enc;
}
export function detectEncodingByBOMFromBuffer(buffer: VSBuffer | null, bytesRead: number): typeof UTF8_with_bom | typeof UTF16le | typeof UTF16be | null {
if (!buffer || bytesRead < UTF16be_BOM.length) {
return null;
}
const b0 = buffer.readUInt8(0);
const b1 = buffer.readUInt8(1);
// UTF-16 BE
if (b0 === UTF16be_BOM[0] && b1 === UTF16be_BOM[1]) {
return UTF16be;
}
// UTF-16 LE
if (b0 === UTF16le_BOM[0] && b1 === UTF16le_BOM[1]) {
return UTF16le;
}
if (bytesRead < UTF8_BOM.length) {
return null;
}
const b2 = buffer.readUInt8(2);
// UTF-8
if (b0 === UTF8_BOM[0] && b1 === UTF8_BOM[1] && b2 === UTF8_BOM[2]) {
return UTF8_with_bom;
}
return null;
}
// we explicitly ignore a specific set of encodings from auto guessing
// - ASCII: we never want this encoding (most UTF-8 files would happily detect as
// ASCII files and then you could not type non-ASCII characters anymore)
// - UTF-16: we have our own detection logic for UTF-16
// - UTF-32: we do not support this encoding in VSCode
const IGNORE_ENCODINGS = ['ascii', 'utf-16', 'utf-32'];
/**
* Guesses the encoding from buffer.
*/
async function guessEncodingByBuffer(buffer: VSBuffer): Promise<string | null> {
const jschardet = await import('jschardet');
// ensure to limit buffer for guessing due to https://github.com/aadsm/jschardet/issues/53
const limitedBuffer = buffer.slice(0, AUTO_ENCODING_GUESS_MAX_BYTES);
// before guessing jschardet calls toString('binary') on input if it is a Buffer,
// since we are using it inside browser environment as well we do conversion ourselves
// https://github.com/aadsm/jschardet/blob/v2.1.1/src/index.js#L36-L40
const binaryString = encodeLatin1(limitedBuffer.buffer);
const guessed = jschardet.detect(binaryString);
if (!guessed || !guessed.encoding) {
return null;
}
const enc = guessed.encoding.toLowerCase();
if (0 <= IGNORE_ENCODINGS.indexOf(enc)) {
return null; // see comment above why we ignore some encodings
}
return toIconvLiteEncoding(guessed.encoding);
}
const JSCHARDET_TO_ICONV_ENCODINGS: { [name: string]: string } = {
'ibm866': 'cp866',
'big5': 'cp950'
};
function toIconvLiteEncoding(encodingName: string): string {
const normalizedEncodingName = encodingName.replace(/[^a-zA-Z0-9]/g, '').toLowerCase();
const mapped = JSCHARDET_TO_ICONV_ENCODINGS[normalizedEncodingName];
return mapped || normalizedEncodingName;
}
function encodeLatin1(buffer: Uint8Array): string {
let result = '';
for (let i = 0; i < buffer.length; i++) {
result += String.fromCharCode(buffer[i]);
}
return result;
}
/**
* The encodings that are allowed in a settings file don't match the canonical encoding labels specified by WHATWG.
* See https://encoding.spec.whatwg.org/#names-and-labels
* Iconv-lite strips all non-alphanumeric characters, but ripgrep doesn't. For backcompat, allow these labels.
*/
export function toCanonicalName(enc: string): string {
switch (enc) {
case 'shiftjis':
return 'shift-jis';
case 'utf16le':
return 'utf-16le';
case 'utf16be':
return 'utf-16be';
case 'big5hkscs':
return 'big5-hkscs';
case 'eucjp':
return 'euc-jp';
case 'euckr':
return 'euc-kr';
case 'koi8r':
return 'koi8-r';
case 'koi8u':
return 'koi8-u';
case 'macroman':
return 'x-mac-roman';
case 'utf8bom':
return 'utf8';
default: {
const m = enc.match(/windows(\d+)/);
if (m) {
return 'windows-' + m[1];
}
return enc;
}
}
}
export interface IDetectedEncodingResult {
encoding: string | null;
seemsBinary: boolean;
}
export interface IReadResult {
buffer: VSBuffer | null;
bytesRead: number;
}
export function detectEncodingFromBuffer(readResult: IReadResult, autoGuessEncoding?: false): IDetectedEncodingResult;
export function detectEncodingFromBuffer(readResult: IReadResult, autoGuessEncoding?: boolean): Promise<IDetectedEncodingResult>;
export function detectEncodingFromBuffer({ buffer, bytesRead }: IReadResult, autoGuessEncoding?: boolean): Promise<IDetectedEncodingResult> | IDetectedEncodingResult {
// Always first check for BOM to find out about encoding
let encoding = detectEncodingByBOMFromBuffer(buffer, bytesRead);
// Detect 0 bytes to see if file is binary or UTF-16 LE/BE
// unless we already know that this file has a UTF-16 encoding
let seemsBinary = false;
if (encoding !== UTF16be && encoding !== UTF16le && buffer) {
let couldBeUTF16LE = true; // e.g. 0xAA 0x00
let couldBeUTF16BE = true; // e.g. 0x00 0xAA
let containsZeroByte = false;
// This is a simplified guess to detect UTF-16 BE or LE by just checking if
// the first 512 bytes have the 0-byte at a specific location. For UTF-16 LE
// this would be the odd byte index and for UTF-16 BE the even one.
// Note: this can produce false positives (a binary file that uses a 2-byte
// encoding of the same format as UTF-16) and false negatives (a UTF-16 file
// that is using 4 bytes to encode a character).
for (let i = 0; i < bytesRead && i < ZERO_BYTE_DETECTION_BUFFER_MAX_LEN; i++) {
const isEndian = (i % 2 === 1); // assume 2-byte sequences typical for UTF-16
const isZeroByte = (buffer.readUInt8(i) === 0);
if (isZeroByte) {
containsZeroByte = true;
}
// UTF-16 LE: expect e.g. 0xAA 0x00
if (couldBeUTF16LE && (isEndian && !isZeroByte || !isEndian && isZeroByte)) {
couldBeUTF16LE = false;
}
// UTF-16 BE: expect e.g. 0x00 0xAA
if (couldBeUTF16BE && (isEndian && isZeroByte || !isEndian && !isZeroByte)) {
couldBeUTF16BE = false;
}
// Return if this is neither UTF16-LE nor UTF16-BE and thus treat as binary
if (isZeroByte && !couldBeUTF16LE && !couldBeUTF16BE) {
break;
}
}
// Handle case of 0-byte included
if (containsZeroByte) {
if (couldBeUTF16LE) {
encoding = UTF16le;
} else if (couldBeUTF16BE) {
encoding = UTF16be;
} else {
seemsBinary = true;
}
}
}
// Auto guess encoding if configured
if (autoGuessEncoding && !seemsBinary && !encoding && buffer) {
return guessEncodingByBuffer(buffer.slice(0, bytesRead)).then(guessedEncoding => {
return {
seemsBinary: false,
encoding: guessedEncoding
};
});
}
return { seemsBinary, encoding };
}
export const SUPPORTED_ENCODINGS: { [encoding: string]: { labelLong: string; labelShort: string; order: number; encodeOnly?: boolean; alias?: string } } = {
utf8: {
labelLong: 'UTF-8',
labelShort: 'UTF-8',
order: 1,
alias: 'utf8bom'
},
utf8bom: {
labelLong: 'UTF-8 with BOM',
labelShort: 'UTF-8 with BOM',
encodeOnly: true,
order: 2,
alias: 'utf8'
},
utf16le: {
labelLong: 'UTF-16 LE',
labelShort: 'UTF-16 LE',
order: 3
},
utf16be: {
labelLong: 'UTF-16 BE',
labelShort: 'UTF-16 BE',
order: 4
},
windows1252: {
labelLong: 'Western (Windows 1252)',
labelShort: 'Windows 1252',
order: 5
},
iso88591: {
labelLong: 'Western (ISO 8859-1)',
labelShort: 'ISO 8859-1',
order: 6
},
iso88593: {
labelLong: 'Western (ISO 8859-3)',
labelShort: 'ISO 8859-3',
order: 7
},
iso885915: {
labelLong: 'Western (ISO 8859-15)',
labelShort: 'ISO 8859-15',
order: 8
},
macroman: {
labelLong: 'Western (Mac Roman)',
labelShort: 'Mac Roman',
order: 9
},
cp437: {
labelLong: 'DOS (CP 437)',
labelShort: 'CP437',
order: 10
},
windows1256: {
labelLong: 'Arabic (Windows 1256)',
labelShort: 'Windows 1256',
order: 11
},
iso88596: {
labelLong: 'Arabic (ISO 8859-6)',
labelShort: 'ISO 8859-6',
order: 12
},
windows1257: {
labelLong: 'Baltic (Windows 1257)',
labelShort: 'Windows 1257',
order: 13
},
iso88594: {
labelLong: 'Baltic (ISO 8859-4)',
labelShort: 'ISO 8859-4',
order: 14
},
iso885914: {
labelLong: 'Celtic (ISO 8859-14)',
labelShort: 'ISO 8859-14',
order: 15
},
windows1250: {
labelLong: 'Central European (Windows 1250)',
labelShort: 'Windows 1250',
order: 16
},
iso88592: {
labelLong: 'Central European (ISO 8859-2)',
labelShort: 'ISO 8859-2',
order: 17
},
cp852: {
labelLong: 'Central European (CP 852)',
labelShort: 'CP 852',
order: 18
},
windows1251: {
labelLong: 'Cyrillic (Windows 1251)',
labelShort: 'Windows 1251',
order: 19
},
cp866: {
labelLong: 'Cyrillic (CP 866)',
labelShort: 'CP 866',
order: 20
},
iso88595: {
labelLong: 'Cyrillic (ISO 8859-5)',
labelShort: 'ISO 8859-5',
order: 21
},
koi8r: {
labelLong: 'Cyrillic (KOI8-R)',
labelShort: 'KOI8-R',
order: 22
},
koi8u: {
labelLong: 'Cyrillic (KOI8-U)',
labelShort: 'KOI8-U',
order: 23
},
iso885913: {
labelLong: 'Estonian (ISO 8859-13)',
labelShort: 'ISO 8859-13',
order: 24
},
windows1253: {
labelLong: 'Greek (Windows 1253)',
labelShort: 'Windows 1253',
order: 25
},
iso88597: {
labelLong: 'Greek (ISO 8859-7)',
labelShort: 'ISO 8859-7',
order: 26
},
windows1255: {
labelLong: 'Hebrew (Windows 1255)',
labelShort: 'Windows 1255',
order: 27
},
iso88598: {
labelLong: 'Hebrew (ISO 8859-8)',
labelShort: 'ISO 8859-8',
order: 28
},
iso885910: {
labelLong: 'Nordic (ISO 8859-10)',
labelShort: 'ISO 8859-10',
order: 29
},
iso885916: {
labelLong: 'Romanian (ISO 8859-16)',
labelShort: 'ISO 8859-16',
order: 30
},
windows1254: {
labelLong: 'Turkish (Windows 1254)',
labelShort: 'Windows 1254',
order: 31
},
iso88599: {
labelLong: 'Turkish (ISO 8859-9)',
labelShort: 'ISO 8859-9',
order: 32
},
windows1258: {
labelLong: 'Vietnamese (Windows 1258)',
labelShort: 'Windows 1258',
order: 33
},
gbk: {
labelLong: 'Simplified Chinese (GBK)',
labelShort: 'GBK',
order: 34
},
gb18030: {
labelLong: 'Simplified Chinese (GB18030)',
labelShort: 'GB18030',
order: 35
},
cp950: {
labelLong: 'Traditional Chinese (Big5)',
labelShort: 'Big5',
order: 36
},
big5hkscs: {
labelLong: 'Traditional Chinese (Big5-HKSCS)',
labelShort: 'Big5-HKSCS',
order: 37
},
shiftjis: {
labelLong: 'Japanese (Shift JIS)',
labelShort: 'Shift JIS',
order: 38
},
eucjp: {
labelLong: 'Japanese (EUC-JP)',
labelShort: 'EUC-JP',
order: 39
},
euckr: {
labelLong: 'Korean (EUC-KR)',
labelShort: 'EUC-KR',
order: 40
},
windows874: {
labelLong: 'Thai (Windows 874)',
labelShort: 'Windows 874',
order: 41
},
iso885911: {
labelLong: 'Latin/Thai (ISO 8859-11)',
labelShort: 'ISO 8859-11',
order: 42
},
koi8ru: {
labelLong: 'Cyrillic (KOI8-RU)',
labelShort: 'KOI8-RU',
order: 43
},
koi8t: {
labelLong: 'Tajik (KOI8-T)',
labelShort: 'KOI8-T',
order: 44
},
gb2312: {
labelLong: 'Simplified Chinese (GB 2312)',
labelShort: 'GB 2312',
order: 45
},
cp865: {
labelLong: 'Nordic DOS (CP 865)',
labelShort: 'CP 865',
order: 46
},
cp850: {
labelLong: 'Western European DOS (CP 850)',
labelShort: 'CP 850',
order: 47
}
};