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296 lines
9.2 KiB
296 lines
9.2 KiB
// 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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'use strict';
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/*<replacement>*/
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var Buffer = require('safe-buffer').Buffer;
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/*</replacement>*/
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var isEncoding = Buffer.isEncoding || function (encoding) {
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encoding = '' + encoding;
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switch (encoding && encoding.toLowerCase()) {
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case 'hex':case 'utf8':case 'utf-8':case 'ascii':case 'binary':case 'base64':case 'ucs2':case 'ucs-2':case 'utf16le':case 'utf-16le':case 'raw':
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return true;
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default:
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return false;
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}
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};
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function _normalizeEncoding(enc) {
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if (!enc) return 'utf8';
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var retried;
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while (true) {
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switch (enc) {
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case 'utf8':
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case 'utf-8':
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return 'utf8';
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case 'ucs2':
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case 'ucs-2':
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case 'utf16le':
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case 'utf-16le':
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return 'utf16le';
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case 'latin1':
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case 'binary':
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return 'latin1';
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case 'base64':
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case 'ascii':
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case 'hex':
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return enc;
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default:
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if (retried) return; // undefined
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enc = ('' + enc).toLowerCase();
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retried = true;
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}
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}
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};
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// Do not cache `Buffer.isEncoding` when checking encoding names as some
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// modules monkey-patch it to support additional encodings
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function normalizeEncoding(enc) {
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var nenc = _normalizeEncoding(enc);
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if (typeof nenc !== 'string' && (Buffer.isEncoding === isEncoding || !isEncoding(enc))) throw new Error('Unknown encoding: ' + enc);
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return nenc || enc;
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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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exports.StringDecoder = StringDecoder;
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function StringDecoder(encoding) {
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this.encoding = normalizeEncoding(encoding);
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var nb;
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switch (this.encoding) {
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case 'utf16le':
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this.text = utf16Text;
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this.end = utf16End;
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nb = 4;
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break;
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case 'utf8':
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this.fillLast = utf8FillLast;
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nb = 4;
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break;
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case 'base64':
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this.text = base64Text;
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this.end = base64End;
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nb = 3;
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break;
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default:
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this.write = simpleWrite;
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this.end = simpleEnd;
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return;
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}
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this.lastNeed = 0;
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this.lastTotal = 0;
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this.lastChar = Buffer.allocUnsafe(nb);
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}
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StringDecoder.prototype.write = function (buf) {
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if (buf.length === 0) return '';
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var r;
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var i;
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if (this.lastNeed) {
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r = this.fillLast(buf);
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if (r === undefined) return '';
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i = this.lastNeed;
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this.lastNeed = 0;
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} else {
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i = 0;
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}
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if (i < buf.length) return r ? r + this.text(buf, i) : this.text(buf, i);
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return r || '';
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};
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StringDecoder.prototype.end = utf8End;
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// Returns only complete characters in a Buffer
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StringDecoder.prototype.text = utf8Text;
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// Attempts to complete a partial non-UTF-8 character using bytes from a Buffer
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StringDecoder.prototype.fillLast = function (buf) {
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if (this.lastNeed <= buf.length) {
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buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, this.lastNeed);
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return this.lastChar.toString(this.encoding, 0, this.lastTotal);
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}
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buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, buf.length);
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this.lastNeed -= buf.length;
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};
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// Checks the type of a UTF-8 byte, whether it's ASCII, a leading byte, or a
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// continuation byte. If an invalid byte is detected, -2 is returned.
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function utf8CheckByte(byte) {
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if (byte <= 0x7F) return 0;else if (byte >> 5 === 0x06) return 2;else if (byte >> 4 === 0x0E) return 3;else if (byte >> 3 === 0x1E) return 4;
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return byte >> 6 === 0x02 ? -1 : -2;
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}
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// Checks at most 3 bytes at the end of a Buffer in order to detect an
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// incomplete multi-byte UTF-8 character. The total number of bytes (2, 3, or 4)
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// needed to complete the UTF-8 character (if applicable) are returned.
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function utf8CheckIncomplete(self, buf, i) {
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var j = buf.length - 1;
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if (j < i) return 0;
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var nb = utf8CheckByte(buf[j]);
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if (nb >= 0) {
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if (nb > 0) self.lastNeed = nb - 1;
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return nb;
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}
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if (--j < i || nb === -2) return 0;
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nb = utf8CheckByte(buf[j]);
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if (nb >= 0) {
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if (nb > 0) self.lastNeed = nb - 2;
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return nb;
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}
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if (--j < i || nb === -2) return 0;
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nb = utf8CheckByte(buf[j]);
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if (nb >= 0) {
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if (nb > 0) {
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if (nb === 2) nb = 0;else self.lastNeed = nb - 3;
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}
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return nb;
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}
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return 0;
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}
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// Validates as many continuation bytes for a multi-byte UTF-8 character as
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// needed or are available. If we see a non-continuation byte where we expect
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// one, we "replace" the validated continuation bytes we've seen so far with
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// a single UTF-8 replacement character ('\ufffd'), to match v8's UTF-8 decoding
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// behavior. The continuation byte check is included three times in the case
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// where all of the continuation bytes for a character exist in the same buffer.
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// It is also done this way as a slight performance increase instead of using a
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// loop.
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function utf8CheckExtraBytes(self, buf, p) {
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if ((buf[0] & 0xC0) !== 0x80) {
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self.lastNeed = 0;
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return '\ufffd';
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}
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if (self.lastNeed > 1 && buf.length > 1) {
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if ((buf[1] & 0xC0) !== 0x80) {
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self.lastNeed = 1;
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return '\ufffd';
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}
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if (self.lastNeed > 2 && buf.length > 2) {
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if ((buf[2] & 0xC0) !== 0x80) {
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self.lastNeed = 2;
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return '\ufffd';
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}
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}
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}
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}
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// Attempts to complete a multi-byte UTF-8 character using bytes from a Buffer.
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function utf8FillLast(buf) {
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var p = this.lastTotal - this.lastNeed;
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var r = utf8CheckExtraBytes(this, buf, p);
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if (r !== undefined) return r;
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if (this.lastNeed <= buf.length) {
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buf.copy(this.lastChar, p, 0, this.lastNeed);
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return this.lastChar.toString(this.encoding, 0, this.lastTotal);
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}
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buf.copy(this.lastChar, p, 0, buf.length);
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this.lastNeed -= buf.length;
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}
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// Returns all complete UTF-8 characters in a Buffer. If the Buffer ended on a
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// partial character, the character's bytes are buffered until the required
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// number of bytes are available.
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function utf8Text(buf, i) {
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var total = utf8CheckIncomplete(this, buf, i);
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if (!this.lastNeed) return buf.toString('utf8', i);
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this.lastTotal = total;
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var end = buf.length - (total - this.lastNeed);
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buf.copy(this.lastChar, 0, end);
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return buf.toString('utf8', i, end);
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}
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// For UTF-8, a replacement character is added when ending on a partial
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// character.
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function utf8End(buf) {
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var r = buf && buf.length ? this.write(buf) : '';
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if (this.lastNeed) return r + '\ufffd';
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return r;
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}
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// UTF-16LE typically needs two bytes per character, but even if we have an even
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// number of bytes available, we need to check if we end on a leading/high
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// surrogate. In that case, we need to wait for the next two bytes in order to
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// decode the last character properly.
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function utf16Text(buf, i) {
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if ((buf.length - i) % 2 === 0) {
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var r = buf.toString('utf16le', i);
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if (r) {
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var c = r.charCodeAt(r.length - 1);
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if (c >= 0xD800 && c <= 0xDBFF) {
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this.lastNeed = 2;
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this.lastTotal = 4;
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this.lastChar[0] = buf[buf.length - 2];
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this.lastChar[1] = buf[buf.length - 1];
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return r.slice(0, -1);
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}
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}
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return r;
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}
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this.lastNeed = 1;
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this.lastTotal = 2;
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this.lastChar[0] = buf[buf.length - 1];
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return buf.toString('utf16le', i, buf.length - 1);
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}
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// For UTF-16LE we do not explicitly append special replacement characters if we
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// end on a partial character, we simply let v8 handle that.
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function utf16End(buf) {
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var r = buf && buf.length ? this.write(buf) : '';
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if (this.lastNeed) {
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var end = this.lastTotal - this.lastNeed;
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return r + this.lastChar.toString('utf16le', 0, end);
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}
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return r;
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}
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function base64Text(buf, i) {
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var n = (buf.length - i) % 3;
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if (n === 0) return buf.toString('base64', i);
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this.lastNeed = 3 - n;
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this.lastTotal = 3;
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if (n === 1) {
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this.lastChar[0] = buf[buf.length - 1];
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} else {
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this.lastChar[0] = buf[buf.length - 2];
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this.lastChar[1] = buf[buf.length - 1];
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}
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return buf.toString('base64', i, buf.length - n);
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}
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function base64End(buf) {
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var r = buf && buf.length ? this.write(buf) : '';
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if (this.lastNeed) return r + this.lastChar.toString('base64', 0, 3 - this.lastNeed);
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return r;
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}
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// Pass bytes on through for single-byte encodings (e.g. ascii, latin1, hex)
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function simpleWrite(buf) {
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return buf.toString(this.encoding);
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}
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function simpleEnd(buf) {
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return buf && buf.length ? this.write(buf) : '';
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}
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