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<title>Common Pitfalls</title>
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<h2 class="title">Common Pitfalls</h2>
<p class="simpara">
The <em>MAX_FILE_SIZE</em> item cannot specify a file size
greater than the file size that has been set in the <a href="ini.core.html#ini.upload-max-filesize" class="link">upload_max_filesize</a> in
the <var class="filename">php.ini</var> file. The default is 2 megabytes.
</p>
<p class="simpara">
If a memory limit is enabled, a larger <a href="ini.core.html#ini.memory-limit" class="link">memory_limit</a> may be needed. Make
sure you set <a href="ini.core.html#ini.memory-limit" class="link">memory_limit</a>
large enough.
</p>
<p class="simpara">
If <a href="info.configuration.html#ini.max-execution-time" class="link">max_execution_time</a>
is set too small, script execution may be exceeded by the value. Make
sure you set <em>max_execution_time</em> large enough.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<span class="simpara">
<a href="info.configuration.html#ini.max-execution-time" class="link">max_execution_time</a> 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 <span class="function"><a href="function.system.html" class="function">system()</a></span>, the
<span class="function"><a href="function.sleep.html" class="function">sleep()</a></span> 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.
</span>
</p></blockquote>
<div class="warning"><strong class="warning">Warning</strong>
<p class="simpara">
<a href="info.configuration.html#ini.max-input-time" class="link">max_input_time</a> 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 <em>60 seconds</em> may be exceeded.
</p>
</div>
<p class="simpara">
If <a href="ini.core.html#ini.post-max-size" class="link">post_max_size</a> is set too
small, large files cannot be uploaded. Make sure you set
<em>post_max_size</em> large enough.
</p>
<p class="simpara">
Since PHP 5.2.12, the
<a href="ini.core.html#ini.max-file-uploads" class="link">max_file_uploads</a> configuration
setting controls the maximum number of files that can uploaded in one
request. If more files are uploaded than the limit, then
<var class="varname"><var class="varname"><a href="reserved.variables.files.html" class="classname">$_FILES</a></var></var> will stop processing files once the limit is
reached. For example, if
<a href="ini.core.html#ini.max-file-uploads" class="link">max_file_uploads</a> is set to
<em>10</em>, then <var class="varname"><var class="varname"><a href="reserved.variables.files.html" class="classname">$_FILES</a></var></var> will never contain
more than 10 items.
</p>
<p class="simpara">
Not validating which file you operate on may mean that users can access
sensitive information in other directories.
</p>
<p class="simpara">
Please note that the <span class="productname">CERN httpd</span> 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, <span class="productname">CERN httpd</span>
will not support the file upload feature.
</p>
<p class="simpara">
Due to the large amount of directory listing styles we cannot guarantee
that files with exotic names (like containing spaces) are handled properly.
</p>
<p class="simpara">
A developer may not mix normal <em>input</em> fields and file upload fields in the same
form variable (by using an <em>input</em> name like <em>foo[]</em>).
</p>
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