Common Pitfalls

The MAX_FILE_SIZE item cannot specify a file size greater than the file size that has been set in the upload_max_filesize ini-setting. The default is 2 Megabytes.

If a memory limit is enabled, a larger memory_limit may be needed. Make sure you set memory_limit large enough.

If max_execution_time is set too small, script execution may be exceeded by the value. Make sure you set max_execution_time large enough.

Note: max_execution_time only affects the execution time of the script itself. Any time spent on activity that happens outside the execution of the script such as system calls using system(), the sleep() function, database queries, time taken by the file upload process, etc. is not included when determining the maximum time that the script has been running.

Warning

max_input_time sets the maximum time, in seconds, the script is allowed to receive input; this includes file uploads. For large or multiple files, or users on slower connections, the default of 60 seconds may be exceeded.

If post_max_size is set too small, large files cannot be uploaded. Make sure you set post_max_size large enough.

Not validating which file you operate on may mean that users can access sensitive information in other directories.

Please note that the CERN httpd seems to strip off everything starting at the first whitespace in the content-type mime header it gets from the client. As long as this is the case, CERN httpd will not support the file upload feature.

Due to the large amount of directory listing styles we cannot guarantee that files with exotic names (like containing spaces) are handled properly.

A developer may not mix normal input fields and file upload fields in the same form variable (by using an input name like foo[]).

User Contributed Notes
Common Pitfalls

amalcon _a_t_ eudoramail _d_o_t_ com
11-Aug-2004 04:35


Note that, when you want to upload VERY large files (or you want to set the limiters VERY high for test purposes), all of the upload file size limiters are stored in signed 32-bit ints.  This means that setting a limit higher than about 2.1 GB will result in PHP seeing a large negative number.  I have not found any way around this.

morganaj at coleggwent dot ac dot uk
21-Oct-2003 11:53


Here is another that may make your upload fall over.  If you are using Squid or similar proxy server make sure that this is not limiting the size of the HTTP headers. This took me weeks to figure out!

tomcashman at unitekgroup dot com
09-Jun-2003 08:59


For apache, also check the LimitRequestBody directive.

If you're running a Red Hat install, this might be set in /etc/httpd/conf.d/php.conf.

By default, mine was set to 512 KB.

sebastian at drozdz dot ch
28-Apr-2003 05:59


It's important that the variable 'open_basedir' in php.ini isn't  set to a directory that doesn't not includes tempupload directory

admin at creationfarm dot com
04-Feb-2003 10:16


The macintosh OS (not sure about OSx) uses a dual forked file system, unlike the rest of the world ;-). Every macintosh file has a data fork and a resource fork. When a dual forked file hits a single forked file system, something has to go, and it is the resource fork. This was recognized as a problem (bad idea to begin with) and apple started recomending that developers avoid sticking vital file info in the resource fork portion of a file, but some files are still very sensitive to this. The main ones to watch out for are macintosh font files and executables, once the resource fork is gone from a mac font or an executable it is useless. To protect the files they should be stuffed or zipped prior to upload to protect the resource fork. 



Most mac ftp clients (like fetch) allow files to be uploaded in Macbinhex, which will also protect the resource fork when transfering files via ftp. I have not seen this equivilent in any mac browser (but I haven't done too much digging either).



FYI, apple does have an old utility called ResEdit that lets you manipulate the resource fork portion of a file.