77 lines
1.8 KiB
JavaScript
77 lines
1.8 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2020 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var isUint8Array = require( './../../is-uint8array' );
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var isBuffer = require( './../../is-buffer' );
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// MAIN //
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/**
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* Tests if a value is a gzip buffer (or Uint8Array).
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*
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* @param {*} value - value to test
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* @returns {boolean} boolean indicating whether a value is a gzip buffer
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*
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* @example
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* var Uint8Array = require( '@stdlib/array/uint8' );
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*
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* var buf = new Uint8Array( 20 );
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* buf[ 0 ] = 31; // 0x1f => magic number
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* buf[ 1 ] = 139; // 0x8b
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* buf[ 2 ] = 8; // 0x08 => compression method
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*
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* var bool = isgzipBuffer( buf );
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* // returns true
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*
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* @example
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* var Uint8Array = require( '@stdlib/array/uint8' );
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*
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* var bool = isgzipBuffer( new Uint8Array( 20 ) );
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* // returns false
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*
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* @example
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* var bool = isgzipBuffer( [] );
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* // returns false
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*/
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function isgzipBuffer( value ) {
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if ( !isUint8Array( value ) && !isBuffer( value ) ) {
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return false;
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}
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if ( value.length < 19 ) { // 10-byte header + 8-byte footer + payload
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return false;
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}
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return (
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// Check for expected magic number:
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value[ 0 ] === 0x1F &&
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value[ 1 ] === 0x8B &&
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// Check for expected compression method:
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value[ 2 ] === 0x08
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);
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}
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// EXPORTS //
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module.exports = isgzipBuffer;
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