PHP 4.0 Bug #9136 Updated: simple script with infinite function calls causes seg fault

ID: 9136 Updated by: waldschrott Reported By: nathan@synop.com Old-Status: Closed Status: Feedback Old-Bug Type: Reproduceable crash Bug Type: Feature/Change Request Assigned To: waldschrott Comments: maybe we should move this to feature request for safe mode? it would be fine to give the server owner the possibility to autokill scripts which would kill the server in a few microseconds, shouldn't it be implementable without loosing performance, check the level the stack is filled up against a values in php.ini maybe... Previous Comments: --------------------------------------------------------------------------- [2001-02-06 17:31:02] waldschrott@php.net and guess this "bug" was present in any version before, what do you expect to happen here? you will never leave these function calls (as you know I guess), as far as your stack is full it is full remember php has to remember each and every function call it did... a() b() a() b() .... if you really need exactly this construct, I would suggest you to use a static variable to count the total function calls and find the critical values a specific system segfaults (with your original code), then you stick a for(;;) around it and implement a check (eg. in a()) against the static variable to leave the recursion if a value with enough distance to the critical value is reached, then you should be able to begin the recursion again any recursion can be displayed as a loop, do not use recursion if you want to recurse infinitely --------------------------------------------------------------------------- [2001-02-06 17:22:36] derick@php.net PHP doesn't handle infinite recursion, and as earlier was discussed on the php-dev list, it wont be implemented to guard for this, because of the high performance impact. --------------------------------------------------------------------------- [2001-02-06 17:18:03] nathan@synop.com ------------------- <% function a () { b(); } function b () { a(); } a(); %> <h1>done</h1> --------------------- The simple script above causes a seg fault. If you need more info on configuration etc please mail me. We made this simple example from a more compilcated instance. This bug was also present in 4.0.3pl1, we upgraded to try and stop the seg fault... thanks! --------------------------------------------------------------------------- ATTENTION! Do NOT reply to this email! To reply, use the web interface found at http://bugs.php.net/?id=9136&edit=2