isgzipBuffer

Test if a value is a gzip buffer.

Usage

var isgzipBuffer = require( '@stdlib/assert/is-gzip-buffer' );

isgzipBuffer( value )

Tests if a value is a gzip buffer.

var Uint8Array = require( '@stdlib/array/uint8' );

var buf = new Uint8Array( 20 );
buf[ 0 ] = 31;  // 0x1f => magic number
buf[ 1 ] = 139; // 0x8b
buf[ 2 ] = 8;   // 0x08 => compression method

var bool = isgzipBuffer( buf );
// returns true

bool = isgzipBuffer( [] );
// returns false

Notes

A gzip buffer is defined as either a Node.js Buffer or Uint8Array which contains a 10-byte header, a body containing the compressed payload, and an 8-byte footer containing a CRC-32 checksum and the length of the original uncompressed data, modulo 2^32.
This function only examines the 10-byte header to ensure the header includes the expected magic number and compression method. The function does not perform an integrity check.

Examples

var Float32Array = require( '@stdlib/array/float32' );
var Float64Array = require( '@stdlib/array/float64' );
var Int8Array = require( '@stdlib/array/int8' );
var Int16Array = require( '@stdlib/array/int16' );
var Int32Array = require( '@stdlib/array/int32' );
var Uint8Array = require( '@stdlib/array/uint8' );
var Uint8ClampedArray = require( '@stdlib/array/uint8c' );
var Uint16Array = require( '@stdlib/array/uint16' );
var Uint32Array = require( '@stdlib/array/uint32' );
var isgzipBuffer = require( '@stdlib/assert/is-gzip-buffer' );

var buf = new Uint8Array( 20 );
buf[ 0 ] = 31;  // 0x1f => magic number
buf[ 1 ] = 139; // 0x8b
buf[ 2 ] = 8;   // 0x08 => compression method

var bool = isgzipBuffer( buf );
// returns true

bool = isgzipBuffer( new Float32Array( 20 ) );
// returns false

bool = isgzipBuffer( new Int8Array( 20 ) );
// returns false

bool = isgzipBuffer( new Uint8Array( 20 ) );
// returns false

bool = isgzipBuffer( new Uint8ClampedArray( 20 ) );
// returns false

bool = isgzipBuffer( new Int16Array( 20 ) );
// returns false

bool = isgzipBuffer( new Uint16Array( 20 ) );
// returns false

bool = isgzipBuffer( new Int32Array( 20 ) );
// returns false

bool = isgzipBuffer( new Uint32Array( 20 ) );
// returns false

bool = isgzipBuffer( new Float64Array( 20 ) );
// returns false

bool = isgzipBuffer( new Array( 20 ) );
// returns false

bool = isgzipBuffer( {} );
// returns false

bool = isgzipBuffer( null );
// returns false