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Nova deViator
Asked: 2011-03-28 09:25:48 +0800 CST

how to calculate exact php upload limits

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maximum size of uploads in php depend on number of settings. here they are, as put into apache virtual hosts file:

php_admin_flag file_uploads on

php_admin_value memory_limit 560M
php_admin_value post_max_size 530M
php_admin_value upload_max_filesize 500M

php_admin_value max_execution_time 0
php_admin_value max_input_time 0

please ignore the values above, but they enable me to allow uploads of around 150-200M. memory_limit, post_max_size and upload_max_filesize have some specific ratios between each other. i believe that 

upload_max_filesize < post_max_size < memory_limit

however, i dont' know how to calculate exact sizes. for example what must be values of these settings in order to allow exactly 100M file upload? from what i gathered online, there is number of factors that determine these ratios, but i couldn't find any references what are these factors.

i'm using linux system.

php apache-2.2 upload maximum

1 Answers

  1. The memory limit is independent of the POST size you upload files. The uploaded files will be parsed directly by PHP and put in a temp folder.

    The upload_max_filesize must be 100M and your post_max_size must be 100M + the overhead of the multipart encoding. The overhead is low as it is binary encoded with a boundary. Even with 101MB it will work.

    Now, it may still crash your script if you then do $file = file_get_contents('path/to/uploaded/file.ext'); because in this case the memory_limit will kick in.

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