[PHP-DEV] Re: [PHP-QA] Re: [PHP-DEV] Re: [PHP-QA] RC6 ISAPI problems From: Andi Gutmans (andi <email protected>)
Date: 12/18/00

By the wya, do you have an easy way of reproducing this?

Andi

At 10:56 18/12/00 +0000, Phil Driscoll wrote:
>When I run the debug version of RC6 as an isapi module on NT4 SP6, I cannot
>even get a simple phpinfo() page to display.
>Now that I have the thing running in my VC++ debugger in what seems to be a
>reliable way, I can see where things hang up. (Note that the non debug
>version definitely gets past this point - as I suspect there is less (or no)
>heap integrity checking.)
>
>The problem seems to be due to a corrupt heap which comes to light in
>virtual_cwd as it tries to free(cwd) immediately before the final return in
>the function. The debugger reports that 'a user breakpoint has been
>encountered', and when I continue from there, the code just goes round in
>circles.
>
>I can't work out whether the cwd passed to free is a dodgy pointer or the
>heap itself is corrupted somehow. cwd certainly contains the null terminated
>string 'C:\WINNT\system32' which should have been allocated by the strdup at
>the return from virtual_getcwd_ex.
>
>The nearest I know how to get to a stack backtrace is to manually copy out
>the Context fields from the debug window:
>
>Loads of stuff before php gets called, then:
>DLLMain
>php_isapi_startup
>php_module_startup
>php_config_ini_startup
>php_init_config
>php_fopen_with_path
>php_fopen_and_set_opened_path
>expand_filepath
>virtual_get_cwd
>
>then we are into the C runtime with
>free
>_free_dbg
>_free_dbg_lk
>_CrtlsValidHeapPointer
>
>then into the Kernel (no debug symbols here - just memory locations
>KERNEL32! (memory location)
>NTDLL! (memory location)
>NTDLL! (memory location)
>
>So, does anyone have any suggestions as to where I should go from here?
>
>Cheers
>--
>Phil Driscoll
>Dial Solutions
>+44 (0)113 294 5112
>http://www.dialsolutions.com
>http://www.dtonline.org 

---
Andi Gutmans <andi <email protected>>
http://www.zend.com/

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