function Archive_Tar::_tarRecToSize

Convert Tar record size to actual size

Parameters

string $tar_size:

Return value

size of tar record in bytes

File

modules/system/system.tar.inc, line 1835

Class

Archive_Tar

Code

private function _tarRecToSize($tar_size) {
    
    /*
     * First byte of size has a special meaning if bit 7 is set.
     *
     * Bit 7 indicates base-256 encoding if set.
     * Bit 6 is the sign bit.
     * Bits 5:0 are most significant value bits.
     */
    $ch = ord($tar_size[0]);
    if ($ch & 0x80) {
        // Full 12-bytes record is required.
        $rec_str = $tar_size . "\x00";
        $size = $ch & 0x40 ? -1 : 0;
        $size = $size << 6 | $ch & 0x3f;
        for ($num_ch = 1; $num_ch < 12; ++$num_ch) {
            $size = $size * 256 + ord($rec_str[$num_ch]);
        }
        return $size;
    }
    else {
        return OctDec(trim($tar_size));
    }
}