Making a temporary dir for unpacking a zipfile into

Question

I have a script that checks a zipfile containing a number of matching PDF+textfiles. I want to unpack, or somehow read the textfiles from the zipfile, and just pick out some

Answer 1

I wanted to add a refinement to @Mario Mueller's answer, as his is subject to possible race conditions, however I believe the following should not be:

function tempdir(int $mode = 0700): string {
    do { $tmp = sys_get_temp_dir() . '/' . mt_rand(); }
    while (!@mkdir($tmp, $mode));
    return $tmp;
}

This works because mkdir returns false if $tmp already exists, causing the loop to repeat and try another name.

Note also that I've added handling for $mode, with a default that ensures the directory is accessible to the current user only, as mkdir's default is 0777 otherwise.

It is strongly advised that you use a shutdown function to ensure the directory is removed when no longer needed, even if your script exits by unexpected means*. To facilitate this, the full function that I use does this automatically unless the $auto_delete argument is set to false.

// Deletes a non-empty directory
function destroydir(string $dir): bool { 
    if (!is_dir($dir)) { return false; }

    $files = array_diff(scandir($dir), ['.', '..']);
    foreach ($files as $file) {
        if (is_dir("$dir/$file")) { destroydir("$dir/$file"); }
        else { unlink("$dir/$file"); }
    }
    return rmdir($dir); 
}

function tempdir(int $mode = 0700, bool $auto_delete = true): string {
    do { $tmp = sys_get_temp_dir() . '/' . mt_rand(); }
    while (!@mkdir($tmp, $mode));

    if ($auto_delete) {
        register_shutdown_function(function() use ($tmp) { destroydir($tmp); });
    }
    return $tmp;
}

This means that by default any temporary directory created by tempdir() will have permissions of 0700 and will be automatically deleted (along with its contents) when your script ends.

NOTE: *This may not be the case if the script is killed, for this you might need to look into registering a signal handler as well.

Answer 2

Another possibility is to use the temporal file as a kind of semaphore to guarantee the unicity of the directory name. Then, create a directory whose name is based on the file name.

define ('TMP_DIR', '/tmp'); // sys_get_temp_dir() PHP 5 >= 5.2.1
define ('TMP_DIR_PREFIX', 'tmpdir_');
define ('TMP_DIR_SUFFIX', '.d');

/* ************************************************************************** */

function createTmpDir() {
  $tmpFile = tempnam(TMP_DIR, TMP_DIR_PREFIX);
  $tmpDir = $tmpFile.TMP_DIR_SUFFIX;
  mkdir($tmpDir);
  return $tmpDir;
}

function rmTmpDir($tmpDir) {
  $offsetSuffix = -1 * strlen(TMP_DIR_SUFFIX);
  assert(strcmp(substr($tmpDir, $offsetSuffix), TMP_DIR_SUFFIX) === 0);
  $tmpFile = substr($tmpDir, 0, $offsetSuffix);

  // Removes non-empty directory
  $command = "rm -rf $tmpDir/";
  exec($command);
  // rmdir($tmpDir);

  unlink($tmpFile);
}

/* ************************************************************************** */

Answer 3

There are a lot of overkill answers to this question. One simple answer would be:

$tempdir = tempnam(sys_get_temp_dir()) . 'dir';
mkdir($tempdir);

1. Obtain a temporary file name.
2. Create the directory (append a suffix to temp file, to avoid file name collision.)
3. Done.

Answer 4

So I first found a post by Ron Korving on PHP.net, which I then modified to make a bit safer (from endless loops, invalid characters, and unwritable parent dirs) and use a bit more entropy.

<?php
/**
 * Creates a random unique temporary directory, with specified parameters,
 * that does not already exist (like tempnam(), but for dirs).
 *
 * Created dir will begin with the specified prefix, followed by random
 * numbers.
 *
 * @link https://php.net/manual/en/function.tempnam.php
 *
 * @param string|null $dir Base directory under which to create temp dir.
 *     If null, the default system temp dir (sys_get_temp_dir()) will be
 *     used.
 * @param string $prefix String with which to prefix created dirs.
 * @param int $mode Octal file permission mask for the newly-created dir.
 *     Should begin with a 0.
 * @param int $maxAttempts Maximum attempts before giving up (to prevent
 *     endless loops).
 * @return string|bool Full path to newly-created dir, or false on failure.
 */
function tempdir($dir = null, $prefix = 'tmp_', $mode = 0700, $maxAttempts = 1000)
{
    /* Use the system temp dir by default. */
    if (is_null($dir))
    {
        $dir = sys_get_temp_dir();
    }

    /* Trim trailing slashes from $dir. */
    $dir = rtrim($dir, DIRECTORY_SEPARATOR);

    /* If we don't have permission to create a directory, fail, otherwise we will
     * be stuck in an endless loop.
     */
    if (!is_dir($dir) || !is_writable($dir))
    {
        return false;
    }

    /* Make sure characters in prefix are safe. */
    if (strpbrk($prefix, '\\/:*?"<>|') !== false)
    {
        return false;
    }

    /* Attempt to create a random directory until it works. Abort if we reach
     * $maxAttempts. Something screwy could be happening with the filesystem
     * and our loop could otherwise become endless.
     */
    $attempts = 0;
    do
    {
        $path = sprintf('%s%s%s%s', $dir, DIRECTORY_SEPARATOR, $prefix, mt_rand(100000, mt_getrandmax()));
    } while (
        !mkdir($path, $mode) &&
        $attempts++ < $maxAttempts
    );

    return $path;
}
?>

So, let's try it out:

<?php
echo "\n";
$dir1 = tempdir();
echo $dir1, "\n";
var_dump(is_dir($dir1), is_writable($dir1));
var_dump(rmdir($dir1));

echo "\n";
$dir2 = tempdir('/tmp', 'stack_');
echo $dir2, "\n";
var_dump(is_dir($dir2), is_writable($dir2));
var_dump(rmdir($dir2));

echo "\n";
$dir3 = tempdir(null, 'stack_');
echo $dir3, "\n";
var_dump(is_dir($dir3), is_writable($dir3));
var_dump(rmdir($dir3));
?>

Result:

/var/folders/v4/647wm24x2ysdjwx6z_f07_kw0000gp/T/tmp_900342820
bool(true)
bool(true)
bool(true)

/tmp/stack_1102047767
bool(true)
bool(true)
bool(true)

/var/folders/v4/647wm24x2ysdjwx6z_f07_kw0000gp/T/stack_638989419
bool(true)
bool(true)
bool(true)

Answer 5

The "mkdir" function raises a warning if the directory already exists, so you can catch this using "@mkdir" and avoid any race condition:

function tempDir($parent = null)
{
    // Prechecks
    if ($parent === null) {
        $parent = sys_get_temp_dir();
    }
    $parent = rtrim($parent, '/');
    if (!is_dir($parent) || !is_writeable($parent)) {
        throw new Exception(sprintf('Parent directory is not writable: %s', $parent));
    }

    // Create directory
    do  { 
        $directory = $parent . '/' . mt_rand();
        $success = @mkdir($directory);
    }
    while (!$success);

    return $directory; 
}

Answer 6

quite easy (I took partly it from the PHP manual):

<?php

function tempdir() {
    $tempfile=tempnam(sys_get_temp_dir(),'');
    // you might want to reconsider this line when using this snippet.
    // it "could" clash with an existing directory and this line will
    // try to delete the existing one. Handle with caution.
    if (file_exists($tempfile)) { unlink($tempfile); }
    mkdir($tempfile);
    if (is_dir($tempfile)) { return $tempfile; }
}

/*example*/

echo tempdir();
// returns: /tmp/8e9MLi

See: https://www.php.net/manual/en/function.tempnam.php

Please look at Will's solution below.

=> My answer should not be the accepted answer anymore.