PHP: How do I avoid reading partial files that are pushed to me with FTP?

Question

Files are being pushed to my server via FTP. I process them with PHP code in a Drupal module. O/S is Ubuntu and the FTP server is vsftp.

At regular intervals I will

Answer 1

I guess you've solved your problem years ago but still.

If you use some pattern to find the files you need you can ask the party uploading the file to use different name and rename the file once the upload has completed.

Answer 2

You should check the Hidden Stores in proftp, more info here: http://www.proftpd.org/docs/directives/linked/config_ref_HiddenStores.html

Answer 3

Using the lock_upload_files configuration option of vsftpd leads to locking files with the fcntl() function. This places advisory lock(s) on uploaded file(s) which are in progress. Other programs don't need to consider advisory locks, and mv for example does not. Advisory locks are in general just an advice for programs that care about such locks. You need another command line tool like lockrun which respects advisory locks.

Note: lockrun must be compiled with the WAIT_AND_LOCK(fd) macro to use the lockf() and not the flock() function in order to work with locks that are set by fcntl() under Linux. So when lockrun is compiled with using lockf() then it will cooperate with the locks set by vsftpd.

With such features (lockrun, mv, lock_upload_files) you can build a shell script or similar that moves files one by one, checking if the file is locked beforehand and holding an advisory lock on it as long as the file is moved. If the file is locked by vsftpd then lockrun can skip the call to mv so that running uploads are skipped.

Answer 4

The lsof linux command lists opened files on your system. I suggest executing it with shell_exec() from PHP and parsing the output to see what files are still being used by your FTP server.

Answer 5

Picking up on the previous answer, you could copy the file over and then compare the sizes of the copied file and the original file at a fixed interval.

If the sizes match, the upload is done, delete the copy, work with the file.

If the sizes do not match, copy the file again.

repeat.

Answer 6

If locking doesn't work, I don't know of a solution as clean/simple as you'd like. You could make an educated guess by not processing files whose last modified time (which you can get with filemtime()) is within the past x minutes.

If you want a higher degree of confidence than that, you could check and store each file's size (using filesize()) in a simple database, and every x minutes check new size against its old size. If the size hasn't changed in x minutes, you can assume nothing more is being sent.