将php中stat()得到的文件权限转成Linux形式

php的stat函数可以返回文件的各种属性，详情见：http://php.net/manual/zh/function.stat.php

其中mode字段表示文件的权限，一个int型的数值。下边的函数是将这个int型数值转换成Linux形式的格式，比如 33206 -> -rw-rw-rw-

/**
 * [返回-rwxrwxrwx文件权限表达方式]
 * @param  string $filePath [文件路径]
 * @return [string]         []
 */
function getHumanFileStat($filePath = '')
{
    if(!file_exists($filePath) || !is_file($filePath))
        return false;

    clearstatcache();
    $stat = stat($filePath);
    $mode = $stat['mode'];

    //参考libc's fstat()： http://man.he.net/man2/fstat
    //8进制数值对应的文件类型
    $typeMap = array(
        0140000    => 'ssocket',
        0120000    => 'llink',
        0100000    => '-file',
        0060000    => 'bblock',
        0040000    => 'ddirectory',
        0020000    => 'cchar',
        0010000    => 'pfifo',
    );

    //各个位的权限对应的8进制数值
    $bitValueMap = array(
        'mask'         => 0170000,
        'ubit'         => 0004000,
        'gbit'        => 0002000,
        'stickybit'    => 0001000,
        'ur'        => 0400,
        'uw'        => 0200,
        'ux'        => 0100,
        'gr'        => 0040,
        'gw'        => 0020,
        'gx'        => 0010,
        'or'        => 0004,
        'ow'        => 0002,
        'ox'        => 0001,
    );

    $str = '';
    //filetype，first character
    $str .= array_key_exists($mode & $bitValueMap['mask'], $typeMap) ? substr($typeMap[$mode & $bitValueMap['mask']], 0, 1) : 'u';

    //user Permission
    $str .= $mode & $bitValueMap['ur'] ? 'r' : '-';
    $str .= $mode & $bitValueMap['uw'] ? 'w' : '-';
    $str .= $mode & $bitValueMap['ux'] ? ($mode & $bitValueMap['ubit'] ? 's' : 'x') : ($mode & $bitValueMap['ubit'] ? 'S' : '-');

    //group Permission
    $str .= $mode & $bitValueMap['gr'] ? 'r' : '-';
    $str .= $mode & $bitValueMap['gw'] ? 'w' : '-';
    $str .= $mode & $bitValueMap['gx'] ? ($mode & $bitValueMap['gbit'] ? 's' : 'x') : ($mode & $bitValueMap['gbit'] ? 'S' : '-');

    //other Permission
    $str .= $mode & $bitValueMap['or'] ? 'r' : '-';
    $str .= $mode & $bitValueMap['ow'] ? 'w' : '-';
    $str .= $mode & $bitValueMap['ox'] ? ($mode & $bitValueMap['stickybit'] ? 't' : 'x') : ($mode & $bitValueMap['stickybit'] ? 'T' : '-');

    clearstatcache();
    return $str;
}

参考文献：

http://php.net/manual/zh/function.stat.php

http://technosophos.com/2012/02/15/php-mode-strings-stat-and-stream-wrappers.html

http://man.he.net/man2/fstat