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    User Contributed Notes 8 notes

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    9
    mbirth at webwriters dot de
    16 years ago
    To find out whether a file is hardlinked to another filename, check the number of links of the stat() output. If it is >1 there is another filename for that file.

    To find out whether two filenames are pointing to the same file, check the inode number of those 2 filenames. If it is equal, the 2 filenames are hardlinked together.
    up
    10
    PaulE
    15 years ago
    A workaround for Windows LNK files:

    <?php

    function _is_link($filename)
    {
    if(    is_link($filename))
    return     true;

    $ext = substr(strrchr($filename, '.'), 1);
    if(    strtolower($ext) == 'lnk')
    {
    return (    _readlink($filename) ? true : false);
    }

    return     false;
    }

    function     _readlink($file)
    {
    if(    file_exists($file))
    {
    if(    is_link($file))
    {
    return     readlink($file);
    }

    // Get file content
    $handle = fopen($file, "rb");
    $buffer = array();

    while(!    feof($handle))
    {
    $buffer[] = fread($handle, 1);
    }

    fclose($handle);

    // Test magic value and GUID
    if(count($buffer) < 20)
    return     false;
    if(    $buffer[0] != 'L')
    return     false;
    if((    ord($buffer[4]) != 0x01) ||
    (    ord($buffer[5]) != 0x14) ||
    (    ord($buffer[6]) != 0x02) ||
    (    ord($buffer[7]) != 0x00) ||
    (    ord($buffer[8]) != 0x00) ||
    (    ord($buffer[9]) != 0x00) ||
    (    ord($buffer[10]) != 0x00) ||
    (    ord($buffer[11]) != 0x00) ||
    (    ord($buffer[12]) != 0xC0) ||
    (    ord($buffer[13]) != 0x00) ||
    (    ord($buffer[14]) != 0x00) ||
    (    ord($buffer[15]) != 0x00) ||
    (    ord($buffer[16]) != 0x00) ||
    (    ord($buffer[17]) != 0x00) ||
    (    ord($buffer[18]) != 0x00) ||
    (    ord($buffer[19]) != 0x46))
    {
    return     false;
    }

    $i = 20;
    if(    count($buffer) < ($i + 4))
    return     false;

    $flags = ord($buffer[$i]);
    $flags = $flags | (ord($buffer[++$i]) << 8);
    $flags = $flags | (ord($buffer[++$i]) << 16);
    $flags = $flags | (ord($buffer[++$i]) << 24);

    $hasShellItemIdList = ($flags & 0x00000001) ? true : false;
    $pointsToFileOrDir = ($flags & 0x00000002) ? true : false;

    if(!    $pointsToFileOrDir)
    return     false;

    if(    $hasShellItemIdList)
    {
    $i = 76;
    if(    count($buffer) < ($i + 2))
    return     false;

    $a = ord($buffer[$i]);
    $a = $a | (ord($buffer[++$i]) << 8);

    }

    $i = 78 + 4 + $a;
    if(    count($buffer) < ($i + 4))
    return     false;

    $b = ord($buffer[$i]);
    $b = $b | (ord($buffer[++$i]) << 8);
    $b = $b | (ord($buffer[++$i]) << 16);
    $b = $b | (ord($buffer[++$i]) << 24);

    $i = 78 + $a + $b;
    if(    count($buffer) < ($i + 4))
    return     false;

    $c = ord($buffer[$i]);
    $c = $c | (ord($buffer[++$i]) << 8);
    $c = $c | (ord($buffer[++$i]) << 16);
    $c = $c | (ord($buffer[++$i]) << 24);

    $i = 78 + $a + $b + $c;
    if(    count($buffer) < ($i +1))
    return     false;

    $linkedTarget = "";
    for(;    $i < count($buffer); ++$i)
    {
    if(!    ord($buffer[$i]))
    break;

    $linkedTarget .= $buffer[$i];
    }

    if(empty(    $linkedTarget))
    return     false;


    return     $linkedTarget;
    }

    return     false;
    }

    if(    _is_link('test.lnk'))
    {
    echo     _readlink('test.lnk');
    }
    ?>
    up
    1
    msaladna at apisnetworks dot com
    7 years ago
    Careful when using is_link() in thread-safe builds with the self-referential directory entry ".". On ZTS builds is_link("/home/symlink/.") will return true whereas it returns false on non-ZTS builds.
    up
    2
    gggeek
    11 years ago
    On windows, take care that is_link returns false for Junctions.
    Ways of telling apart a directory from a junction include doing both a stat() and and lstat() call and checking if there is any difference in the results
    up
    1
    neverpanic->gmail[com]
    18 years ago
    For me (Debian Sarge VPS) is_link returns true even for directories if you don't add a trailing slash to the filename.
    <?php
    if ($dir{strlen($dir)-1} == '/') $dir = substr($dir, 0, -1);
    is_link($dir);
    ?>
    This works for me. It can't detect a symlink somewhere in a complete path, though (i.e. is_link(/www/somedir/file.php) will return false, just as is_link(/www/) would)
    up
    -2
    foobarfarter
    16 years ago
    @radon8472 at hotmail dot com
    The windows .lnk-things are real files, the explorer only treats them like links. Try to open one with Win+R->"notepad X:\Path\Visiblefilename.lnk You will see much 0-Bytes, but the linked path is displayed right on the screen. It should be possible to do the same by php.
    up
    -3
    andudi at gmx dot ch
    22 years ago
    On my SuSE 7.2 is_link does not work on directories, but to find out, if a dir is a link, I use now this:

    $linkdir = $path.$linkdirname;
    if (realpath($linkdir) != realpath($path)."/".$linkdirname):
    //$linkdir is a symbolic linked dir!
    ...

    and this works fine :-)

    Andreas Dick
    up
    -4
    brendy at gmail dot com
    18 years ago
    On Mac OSX, to see if a file is a FInder alias:

    <?PHP
    if( getFinderAlias( $someFile , $target ) ) {
    echo     $target;
    }
    else {
    echo     "File is not an alias";
    }

    function     getFinderAlias( $filename , &$target ) {
    $getAliasTarget = <<< HEREDOC
     -- BEGIN APPLESCRIPT --
    set checkFileStr to "    {$filename}"
    set checkFile to checkFileStr as POSIX file
    try
    tell application "Finder"
    if original item of file checkFile exists then
    set targetFile to (original item of file checkFile) as alias
    set posTargetFile to POSIX path of targetFile as text
    get posTargetFile
    end if
    end tell
    end try
    -- END APPLESCRIPT --
    HEREDOC;
    $runText = "osascript << EOS\n{$getAliasTarget}\nEOS\n";
    $target = trim( shell_exec( $runText ) );
    return (     $target == "" ? false : true );
    }
    ?>
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