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Date: Tue, 12 Jul 2005 00:36:22 -0400
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Subject: Interesting zend_executor_globals Find...
From: jrhernandez05@gmail.com (Jessie Hernandez)

Today I've been debugging a segfault with my namespace patch until I found
that the problem was simply the placement of a variable in a struct. I
still don't see the logic behind it, but I got the segfault both in Windows
2000 and Linux (FC3). The steps to reproduce this segfault are very simple
(using PHP 5.1.0b2):

1) In zend_globals.h, modify the struct _zend_executor_globals and add a
simple HashTable pointer after class_table or zend_constants. It should 
look like this:

        ...
        HashTable *class_table;         /* class table */
        HashTable *my_hash;
        HashTable *zend_constants;      /* constants table */

2) Compile PHP. Now any script you execute will produce a segmentation
fault.

3) Move your hash table to the end of the struct, right before the
"reserved" array:

        HashTable *my_hash;
        void *reserved[ZEND_MAX_RESERVED_RESOURCES];

4) make clean (or simply delete all the *.o and *.lo files under Zend/) and
compile PHP again. All executed scripts work as usual, and no segfault is
produced.


Does anyone know why this happens?


Regards,

Jessie Hernandez