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Digg  tempnam
Create file with unique file name
(PHP 4, PHP 5)
Example 670. tempnam() example<?phpCode Examples / Notes » tempnamchris
Use the following to create a temporary directory... // Creates a directory with a unique name // at the specified with the specified prefix. // Returns directory name on success, false otherwise function tmpdir($path, $prefix) { // Use PHP's tmpfile function to create a temporary // directory name. Delete the file and keep the name. $tempname = tempnam($path,$prefix); if (!$tempname) return false; if (!unlink($tempname)) return false; // Create the temporary directory and returns its name. if (mkdir($tempname)) return $tempname; return false; } ron korving
This function creates a temporary directory. The previous example given could bug if between the unlink() and mkdir() some process creates the same directory or file. This implementation is faster too. <?php function tempdir($dir, $prefix='', $mode=0700) { if (substr($dir, -1) != '/') $dir .= '/'; do { $path = $dir.$prefix.mt_rand(0, 9999999); } while (!mkdir($path, $mode)); return $path; } ?> komashooter
This Example makes a File called "user.txt" in the dir www.XXXXX.XX/restricted/ <?php $tmpfname = tempnam($_ENV["DOCUMENT_ROOT"]."/restricted", "FOO"); $handle = fopen($tmpfname, "w"); fwrite($handle, "writing to tempfile"); fclose($handle); // do here something //echo($_ENV["DOCUMENT_ROOT"]); copy($tmpfname,'user.txt'); ?> 23-jul-2003 06:56
The tempnam() function will not let you specify a postfix to the filename created. Here is a function that will create a new filename with pre and post fix'es. Not returns false if it can't create in the dir specified where tempnam() creates in the systems temp dir. function newtempnam($dir, $prefix, $postfix){ /* Creates a new non-existant file with the specified post and pre fixes */ if ($dir[strlen($dir) - 1] == '/') { $trailing_slash = ""; } else { $trailing_slash = "/"; } /*The PHP function is_dir returns true on files that have no extension. The filetype function will tell you correctly what the file is */ if (!is_dir(realpath($dir)) || filetype(realpath($dir)) != "dir") { // The specified dir is not actualy a dir return false; } if (!is_writable($dir)){ // The directory will not let us create a file there return false; } do{ $seed = substr(md5(microtime().posix_getpid()), 0, 8); $filename = $dir . $trailing_slash . $prefix . $seed . $postfix; } while (file_exists($filename)); $fp = fopen($filename, "w"); fclose($fp); return $filename; } phpdoc
The "newtempnam" recipe provided below (posted by "tempnam" on " 23-Jul-2003 08:56") has at least one race condition. The while loop checks to make sure that the file in question doesn't exist, and then goes and creates the file. In between the existence test and the fopen() call there is an opportunity for an attacker to create the file in question. This is a classic race-condition, and while it seems difficult to exploit there are a number of well-known attacks against this kind of sloppy file creation. The atomic primitives necessary to implement secure file creation are not available at the language level in PHP. This further underscores the need for PHP-language developers to rely on the language's security primitives (including tempnam() and tempfile()) instead of rolling their own. andi
tempname ignores the current umask and always creates the file with permission 0600.
kulpp
tempnam should not be used with SAFE MODE as of 4.3.4 see http://bugs.php.net/bug.php?id=27133 soletan
tempnam and SAFE MODE don't generally exclude each other - that link below just shows frustrating trials to find some meaning in SAFE MODE. However, SAFE MODE is good and I'd appreciate to find it used in more of contemporarily hyped projects like typo3 or similar, since many people don't seem to care about security that much, but get enraged by tens and hundreds of Spam-Mails a day. Okay, that post from Feb-2004 and the "bug report" is unconditionally true for multi-hosted PHP environments where several users may have their individual scripts placed on same server machine. Just take a visit to one of your local webspace-providers, that give space for 5 € or less a month. But the truth get conditional if you gain access to the server all by yourself and may set it up to have your script's and the web server's GID being same so you can "fall back" to GID-based SAFE MODE and use tempnam as desired. This is true for several local work, intranet-related projects in your company etc. Just take a look at how SAFE MODE _really_ works and why it's rockingly important to use it. You should do when you're developing a company tool for public access at least. Never forget to take a moment to think about Unix-filesystem and access rights as well ... even if you're locally running Windows to have some great IDE or similar (like me :). PHP is available on both systems, but that's not succeeding to define your work as "portable". 17-feb-2005 02:13
Regarding Typo3 and Safe mode "Generally, everything in TYPO3 can work under safe_mode and open_basedir as long as the script permissions are correct. Notice, this is not something TYPO3 can do better or worse; for a working TYPO3 system there must be access to writing files and directories in the filesystem and this is done by plain PHP functions."
guillaume paramelle
On a windows server (php 5.1.2), tempnam() may not use the dir parameter, and create the file in $_ENV['TMP']. I also had problem because the directory was relative. Everything was solved using : tempnam(realpath("../_cache/"), "prefix") ; php
Note that tempnam returns the full path to the temporary file, not just the filename.
flat
It seems that in between 5.2.2 and 5.2.4 tempnam() changed how it handles a relative path: In 5.2.2: $file=tempnam('tmpdownload', 'Ergebnis_'.date(Y.m.d).'_').'.pdf'; echo $file; tmpdownload/Ergebnis_20071004_xTfKzz.pdf In 5.2.4: $file=tempnam('tmpdownload', 'Ergebnis_'.date(Y.m.d).'_').'.pdf'; echo $file; /var/www/html/tmpdownload/Ergebnis_20071004_Xbn6PY.pdf This broke quite a lot of our webpages as we try to display those pdfs (and other files) via the webbrowser and the resulting URI is of course invalid and gets the user a 404 page. nick smith
It is worth noting that if the 'dir' that you supply doesn't exist, then it is silently ignored and the system /tmp directory used. At least under Linux, PHP v4.1.2. I had a script that appeared to work fine with safe mode switched off, but I didn't realise that my 'dir' parameter had a typo (so the files were going in /tmp), and once safe mode was switched on I started getting errors because the rest of the script couldn't read files from the system /tmp folder. seb
In addition to a note previously posted, on Windows NT Server 4.0, I noticed that tempnam() only uses the first THREE characters of the specified prefix.
sebastian kun
If you go to the linux man page for the C function tempnam(3), you will see at the end "Never use this function. Use mkstemp(3) instead." But php's tempnam() function doesn't actually use tmpnam(3), so there's no problem (under Linux, it will use mkstemp(3) if it's available).
jason pell
I want to guarantee that the file will be created in the specified directory or else the function should return FALSE, I have a simple function that works, but I am unsure if its a potential security issue. function dir_tempnam($dir, $prefix) { $real_dir_path = realpath($dir); if (substr($real_dir_path, -1) != '/') $real_dir_path .= '/'; $tempfile = tempnam($real_dir_path, $prefix); $name = basename($tempfile); if(is_file($real_dir_path.$name)) return $name; else { @unlink($name); return FALSE; } } This function returns just the name of the temporary file in the specified directory, or FALSE. Obviously it could return the entire $tempfile, but in my case, I actually want the basename value seperate. dmhouse
Guillaume Paramelle's comments below are worth underlining: tempnam() will not accept a relative path for its first directory. If you pass it one, it will (on Windows XP at least) create the temporary file in the system temp directory. The easiest way to convert a relative path to an absolute path is to prepend getcwd(): <?php $file = tempnam('files/temp', 'tmp'); // Wrong! $file = tempnam(getcwd() . 'files/tmp', 'tmp') // Right. ?> bishop
Creating a temporary file with a specific extension is a common requirement on dynamic websites. Largely this need arises from Microsoft browsers that identify a downloaded file's mimetype based on the file's extension. No single PHP function creates a temporary filename with a specific extension, and, as has been shown, there are race conditions involved unless you use the PHP atomic primitives. I use only primitives below and exploit OS dependent behaviour to securely create a file with a specific postfix, prefix, and directory. Enjoy. <?php function secure_tmpname($postfix = '.tmp', $prefix = 'tmp', $dir = null) { // validate arguments if (! (isset($postfix) && is_string($postfix))) { return false; } if (! (isset($prefix) && is_string($prefix))) { return false; } if (! isset($dir)) { $dir = getcwd(); } // find a temporary name $tries = 1; do { // get a known, unique temporary file name $sysFileName = tempnam($dir, $prefix); if ($sysFileName === false) { return false; } // tack on the extension $newFileName = $sysFileName . $postfix; if ($sysFileName == $newFileName) { return $sysFileName; } // move or point the created temporary file to the new filename // NOTE: these fail if the new file name exist $newFileCreated = (isWindows() ? @rename($sysFileName, $newFileName) : @link($sysFileName, $newFileName)); if ($newFileCreated) { return $newFileName; } unlink ($sysFileName); $tries++; } while ($tries <= 5); return false; } ?> The isWindows function is mostly left as an exercise for the reader. A starting point is below: <?php function isWindows() { return (DIRECTORY_SEPARATOR == '\\' ? true : false); } ?> Like tempnam(), this function requires you to cleanup your own files later. Under UNIX (where you can rename onto an extant file and so I used link), you will have to remove both the link and the link's target. Cleanup is left entirely to the reader. tux arroba cenobioracing punto com
Beware that on Windows NT and other windows, if you have, for example, a variable $work_dir with a path to some dir on your document root(or any other dir). Note the following: <?php $work_dir = 'C:/some/path/to/document_root/dir'; file_exists($working_dir); // Returns true is_writable($working_dir); // Returns true $tempfile = tempnam($working_dir,'img'); //$temfile now contains a system wide temp directory file, like 'C:/WINNT.SBS/img444.tmp' instead of the directory we pass it //Thats because we need to give I_USR (IIS user) user write permission to $working_dir although according to the aforementioned functions seemed it already had it... //If you want to use just the system wide temp directory return by default by tempnam you will also need to give it write permission to I_USR user to be able to write to that file... ?> lreilly
Be careful with you forward and back slashes. Innocent looking code like this... $uploaddir = "C:/Program Files/Apache Group/Apache2/htdocs/sasdap/uploads/"; $tempFile = tempnam ($uploaddir, "TMPANAL"); $fp = fopen($tmpfname, "w"); fwrite($fp, $iqdata); //fclose($fp); ... may show something odd when echoing $tempFile"; i.e. /Program Files/Apache Group/Apache2/htdocs/sasdap/uploads/\TMP3D.tmp Must... remember... to... use... backslashes... - Lee P. Reilly anakin dot skyw
>Under UNIX (where you can rename onto an extant file and so I used link), you will have to remove both the link and the link's target. Couldn't you do <?php if ($newFileCreated) { unlink ($sysFileName); return $newFileName; } ?> and get the same semantics as the windows version? |
Change Language
basename chgrp chmod chown clearstatcache copy delete dirname disk_free_space disk_total_space diskfreespace fclose feof fflush fgetc fgetcsv fgets fgetss file_exists file_get_contents file_put_contents file fileatime filectime filegroup fileinode filemtime fileowner fileperms filesize filetype flock fnmatch fopen fpassthru fputcsv fputs fread fscanf fseek fstat ftell ftruncate fwrite glob is_dir is_executable is_file is_link is_readable is_uploaded_file is_writable is_writeable lchgrp lchown link linkinfo lstat mkdir move_uploaded_file parse_ini_file pathinfo pclose popen readfile readlink realpath rename rewind rmdir set_file_buffer stat symlink tempnam tmpfile touch umask unlink |
