File permissions

Question

I have a PHP script running which makes symlinks.

To confirm which user it is:

file_put_contents("testFile", "test");
$user = fileowner("testFile");
unlink("testFile");
echo "running as user '" . $user . "'";
var_dump( exec('whoami'));

running like this ...

$ php script.php

runs correct all symlinks are made and output is:

running as user '999'string(5) "admin"

Running through a shell script:

#!/bin/sh
php /path/to/script.php

gives the following output and doesn't work:

PHP Warning: symlink(): Permission denied in /path/to/script.php on line 8 running as user '999'string(5) "admin"

I'm not sure what the difference between the two is, as the users they are running as are identical.

Any suggestions on how to make them both have the correct permissions for symlinking?

---

cat /proc/version

gives:

Linux version 2.6.39 (root@cross-builder) (gcc version 4.6.3 (x86 32-bit toolchain - ASUSTOR Inc.) ) #1 SMP PREEMPT Thu Oct 31 21:27:37 CST 2013

That's the only output I can generate for any sort of release information.

---

All of the code:

$files = scandir('/volume1/dir1');
$base = "/volume1/";
foreach($files as $file) {
        $f_letter = $file{0};
        $new_path = $base . "ByLetter/" . strtoupper($f_letter) . "/" . $file;
        if(ctype_alpha ($f_letter) && !is_link($new_path)) {
                var_dump($base. "TV/" . $file);
                var_dump($new_path);
                symlink ($base . "TV/" . $file , $new_path);
        }


}

gives the same output for the var dumps both methods.

Answer 1

Try using an absolute path. The code unlink("testFile"); looks for a file at present working directory. The pwd changes according to the current working directory. So use unlink("/path/to/testFile");

Answer 2

I took the code you posted, thought it was the beginning of a useful function, tweaked it, and couldn't get it to fail (probably because my user has write access to both paths). I made sure to add lots of checks to let you know if something is going wrong. Let me know if you still get the same issue. Make sure to remember that if you execute the script through the CLI, the script has the permissions as you, however if executed through a webserver, it has the permissions of the webserver user (e.g. www-data)

<?php

/**
 * Creates an index of the files in the specified directory, by creating symlinks to them, which
 * are separated into folders having the first letter.
 * WARNING - this will only index files that start with alphabetical characters.
 * @param $directory_to_index - the directory we wish to index.
 * @param $index_location - where to stick the index.
 * @return void
 */
function create_file_index($directory_to_index, $index_location)
{
    # Don't let the user place the index in the same folder being indexed, otherwise the directory
    # cannot be re-indexed later, otherwise we will be indexing the index.
    if ($directory_to_index == $index_location)
    {
        throw new Exception('Cannot place index in same folder being indexed!');
    }

    # delete the old index if one already exists.
    if (file_exists($index_location))
    {
        deleteNonEmptyDir($index_location);
    }

    if (!mkdir($index_location))
    {
        throw new Exception('Failed to create index directory, check write permissions');
    }

    $files = scandir($directory_to_index);

    foreach ($files as $filename) 
    {
        $first_letter = $filename[0];
        $placement_dir = $index_location . "/" . strtoupper($first_letter);

        if (ctype_alpha($first_letter))
        {
            # create the placement directory if it doesn't exist already
            mkdir($placement_dir);

            $new_path = $placement_dir . "/" . $filename;

            if (!is_link($new_path)) 
            {
                symlink($directory_to_index . '/' . $filename, $new_path);
            }
        }
    }
}

/**
 * Deletes a directory even if it is not already empty. This resolves the issue with
 * trying to use unlink on a non-empty dir.
 * @param String $dir - the path to the directory you wish to delete
 * @return void - changes your filesystem
 */
function deleteNonEmptyDir($dir) 
{
    if (is_dir($dir)) 
    {
        $objects = scandir($dir);

        foreach ($objects as $object) 
        {
            if ($object != "." && $object != "..") 
            {
                if (filetype($dir . "/" . $object) == "dir")
                {
                    deleteNonEmptyDir($dir . "/" . $object); 
                }
                else
                {
                    unlink($dir . "/" . $object);
                }
            }
        }

        reset($objects);
        rmdir($dir);
    }
}

create_file_index('/volume1/dir1', '/volume1/dir1/ByLetter');

Answer 3

The PHP function fileowner returns a numeric uid and not a username. The uid 999 probably corresponds to your admin user; you can check this with the command id:

id admin

The output should begin with the uid of that account.