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[2004-01-06 17:51 UTC] sniper@php.net
[2004-01-07 14:37 UTC] d-alvarez at gmx dot de
[2004-01-19 18:53 UTC] sniper@php.net
[2004-01-25 00:00 UTC] sniper@php.net
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Last updated: Thu Apr 25 17:01:29 2024 UTC |
Description: ------------ Take any html page that uploads a file using HTTP post. It does not matter what the receiving script does, because this issue is only related to the interpreter. A page as simple as the following suffices to reproduce the problem: <html><body> <form method="post" enctype="multipart/form-data" action="http://www.somesite.org/somescript.php"> <input name="somefile" type=file><input type="submit"> </form> </body> </html> Change the form's action to some script on a php server. I have placed an echo in it, so I can see more easily if the script is run. And, of course, it should use the file posted, so that we can get an error if it does not find it. You can use this: <?php echo "the script has been started"; is_uploaded_file ($somefile); ?> Now use the html page to upload a file sufficiently large enough for the upload to take several seconds to complete. While the data is being submitted, load the script a second time in another instance of your browser, and post the same file again (in parallel to the first post running in the background). I use a file 824 kb in size. Transmitted over ISDN, the two posts take like two minutes of time to complete. The file was a zip archive. Now, while the server is handling the two uploads concurrently, get a listing of the directory it uses to store the temporary files. You can watch the two uploading files growing until both uploads complete. web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 228 -rw------- 1 wwwrun www 114688 2004-01-04 23:09 phpHh9HQ9 -rw------- 1 wwwrun www 110592 2004-01-04 23:09 phpp9QIDj web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 360 -rw------- 1 wwwrun www 180224 2004-01-04 23:10 phpHh9HQ9 -rw------- 1 wwwrun www 180224 2004-01-04 23:10 phpp9QIDj web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 572 -rw------- 1 wwwrun www 299008 2004-01-04 23:10 phpHh9HQ9 -rw------- 1 wwwrun www 278528 2004-01-04 23:10 phpp9QIDj web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 1528 -rw------- 1 wwwrun www 790528 2004-01-04 23:12 phpHh9HQ9 -rw------- 1 wwwrun www 765952 2004-01-04 23:12 phpp9QIDj web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 1664 -rw------- 1 wwwrun www 844067 2004-01-04 23:13 phpHh9HQ9 -rw------- 1 wwwrun www 844067 2004-01-04 23:13 phpp9QIDj Now, with both files being uploaded, two scripts begin to execute, one for each file. Subsequent directory listings will show the temporary files being deleted as the php scripts complete. web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 832 -rw------- 1 wwwrun www 844067 2004-01-04 23:13 phpp9QIDj (first file has been deleted automatically, because script started first has completed processing) web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 0 (second file has been deleted automatically, because script started last has completed processing) This is the situation as it should be. Now place an .htaccess file into a directoy above the directory containing your script. The .htaccess file should usually cause your browser to ask you for some realm and password, and then ask you to commit, e.g. by clicking an OK button. Again, start two posts in parallel, but do not yet commit the authorization dialogue shown to you in response to the .htaccess file. The files are uploaded, probably to some temporary location in memory. While the files get uploaded, get some listings of your temporary directory, as before. Neither the system-global /tmp directory, nor the location used to store temporary php files have any entries, but the line is busy for exactly as much time as during the post when there was no .htaccess file yet. Probably the upload is handled differently by Apache. web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 0 web1@julius64:~/html/wcopy/datenaustausch> ls -l /tmp web1@julius64:~/html/wcopy/datenaustausch> Now confirm the authorization dialogue in your browser. In Internet Explorer, you are shown a single dialogue for both html pages. Maybe the .htaccess file per se is irellevant here. I guess the point is that by committing the dialogue, processing continues synchronously for both posts. Anyway, by committing, you trigger something on the server that causes two scripts to execute at exactly the same time, one for each upload. Quickly after committing, get some directory listings, as before. You'll get something along the lines of: web1@julius64:~/html/wcopy/datenaustausch> ls -l ~/phptmp insgesamt 32 --w------- 1 wwwrun www 32768 2004-01-05 00:02 phpu7oZqm The bottom line is: one file instead of two. You can watch it growing as in the first example, but there is no second temporary file. Furthermore, one of the scripts has been started immediately, without waiting for the upload to complete. If you tried to use the file within the script, it will barf out some error. Ocassionally, even the second script will not complete properly, complaining about the uploaded file being corrupted. Probably this script is also started without waiting for the upload to complete. Reproduce code: --------------- See above. Expected result: ---------------- Two files being uploaded, and two instances of the script being run after the uploads have completed. Actual result: -------------- Only a single file being uploaded, and one instance of the script being run before the upload is completed. Sometimes even the second instance of the script is run while the upload is still in progress.