vips_foreign_load_gif_is_a_buffer( const void *buf, size_t len )
{
	const guchar *str = (const guchar *) buf;

	if( len >= 4 &&
		str[0] == 'G' && 
		str[1] == 'I' &&
		str[2] == 'F' &&
		str[3] == '8' )
		return( 1 );

	return( 0 );
}

Unknown