note 78554 added to function.posix-setuid

When you do a posix_setuid from root to some other users you will not have access to files owned by root according to their permissions. For instance if you change owner of the process and still need to open a file for read or write with 600 permission owned by root you will receive a permission denied. There are some ways to do this (i.e. a unix socket or tcp daemon etc), but probably the most easiest way is: Open the file before changing ownership of process, save the file pointer in a global variable and use it after changing ownership. For example assume /root/test_file is a file owned by root:root and have a permission of 600 and you are running this script under root. This code will not work: <?php // Change ownership of process to nobody posix_setgid(99); posix_setuid(99); $fd = fopen('/root/test_file','a'); fwrite($fd,"some test strings"); fclose(); ?> But this one will work: <?php $fd = fopen('/root/test_file','a'); // Change ownership of process to nobody posix_setgid(99); posix_setuid(99); fwrite($fd,"some test strings"); fclose(); ?> Hope this helps some one. [Tested on CentOS 5 - Linux 2.6.x - PHP 5.2.x] ---- Server IP: 66.207.199.35 Probable Submitter: 70.68.54.184 ---- Manual Page -- http://www.php.net/manual/en/function.posix-setuid.php Edit -- https://master.php.net/note/edit/78554 Del: integrated -- https://master.php.net/note/delete/78554/integrated Del: useless -- https://master.php.net/note/delete/78554/useless Del: bad code -- https://master.php.net/note/delete/78554/bad+code Del: spam -- https://master.php.net/note/delete/78554/spam Del: non-english -- https://master.php.net/note/delete/78554/non-english Del: in docs -- https://master.php.net/note/delete/78554/in+docs Del: other reasons-- https://master.php.net/note/delete/78554 Reject -- https://master.php.net/note/reject/78554 Search -- https://master.php.net/manage/user-notes.php