-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi again!

Just took some more time to investigate on my problems with PHP-Gtk
2.0.0 and 2.0.1. Let me explain the overall situation first:

I work as a programmer for a research institute, currently on a project
involving PHP-Gtk. Unfortunately so far it looks like it will not be
open-sourced. The problems started occuring while I was trying to go
from the beta version to the 2.0.0 release and were not fixed by 2.0.1.
The application makes use of the ODBC extension and displays some data
in several GtkTreeViews using stock GtkTreeStore and GtkListStore as
well as custom derived model classes.

When running my application with PHP-Gtk starting at 2.0.0, I get an
error message during startup saying that
'the instruction at "0x1008bd58" points to memory at "0x0000005d". The
operation "read" could not be executed on that memory. Click OK to exit
the program, Cancel to debug.' (Translated from the German error message.)

I tried to narrow it down to where in the PHP source the error occurs
using simple echo statements. It's been a while since then and I was
assigned to a different project meanwhile, then continued development
with the PHP-Gtk beta version. So I'm not quite sure about the details I
found out back then. IIRC, the error occured between calls to the
append() and set() methods on a regular GtkListStore object. I fetched
some data from the database into an associative array, then accessed the
array when passing parameters to set(). Copying the value to another
variable, then passing that to set() worked around the segfault but
produced garbage in the list row (and another segfault at a later query
I think).

Curiously, calling var_dump($database_result_row) also gave me garbage.
That is, before the call to append() it contained the correct database
values, but between append() and set(), the array content magically
changed. So I guess that there is some kind of buffer overflow in the
append() code or somewhere around it.

Now I have just successfully reproduced the segfault on my laptop at
home. It occurs in a different place, but also between a database query
and the list store append(). The query result array is still intact.
However, a few lines above, a similar construct returns NULL values or
random integer values for the database row and causes the segfault to
appear a few lines earlier. But only when var_dump()ing that earlier result.

As you can see, the behaviour varies wildly between different machines
and produces unpredictable behaviour when changing single lines of code.
With the PHP-Gtk2 beta, I haven't had a single segfault so I think this
is a regression. Unfortunately, it could be in a different module or
even related to some other PHP extension, and just by accident always
happens to show up between those calls.

I'm afraid I cannot give you much more useful information right now. I'm
not very experienced in Windows debugging and have no clue about the
Zend internals. Also, I'm not sure whether I can provide the source code
for others to reproduce the error as I haven't succeded in writing a
simpler test case yet. But I'm offering to spend some time trying to
nail it down and report back my results.

So can someone please give me a quick introduction about PHP-Gtk
debugging on a Windows XP system and the required Zend internals to find
memory handling errors in some extension?

Hope this won't get too complicated and time-consuming as my boss will
probably not support it and tell me to stick with the beta if it works.

Regards,
Andre
- --
Greetings...
From: Andre Colomb <acolomb@schickhardt.org>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iEYEARECAAYFAkjn50oACgkQZ6c/lG/u2qxvfgCgoYD5Y7CtoBQ/w0O0R4CYAWjX
EJgAnA6NasjNQItFPTg3jSQHz2PCeDH7
=Qt64
-----END PGP SIGNATURE-----