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Date: Thu, 12 Apr 2018 22:34:52 +0200
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To: Heinz Wiesinger <HMWiesinger@liwjatan.at>
Cc: internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Request-global hashtable initialization
From: nikita.ppv@gmail.com (Nikita Popov)

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On Thu, Apr 12, 2018 at 9:53 PM, Heinz Wiesinger <HMWiesinger@liwjatan.at>
wrote:

> Hi everyone!
>
> I ventured into writing my first PHP extension and did pretty well so far
> following the existing documentation and example code inside the php
> source.
>
> However, I hit an odd bug in my code that I can't quite explain. I'm
> obviously
> missing something and I hope someone here can point me in the right
> direction
> :)
>
> I'd like to set up a request global hashtable. For now I'm running
> ALLOC_HASHTABLE() and zend_hash_init() inside PHP_GINIT_FUNCTION. I then
> have
> a user function that's supposed to add entries to that hashtable and
> another
> user function that reads entries from the hashtable.
>
> I tested with code passed directly on the command line (using php -r) and
> that
> works just like I would expect it too. The value gets written to the
> hashtable
> and I can read it afterwards from the other function. I also verified it's
> the
> same value that I first stored, so from what I can tell the basic
> functionality is good.
>
> When I take the same testcode and write it into a file, and then run php on
> that file, execution aborts trying to allocate almost 2GB of memory when
> trying to store the value in the hashtable (using zend_hash_update()). I
> can
> see PHP_GINIT_FUNCTION being executed in that case as well so I'd assume
> the
> hashtable is setup just fine. Yet something is different.
>
> What's the difference between " php -r '' " and "php test.php" in that
> regard?
>
> I uploaded my current state of the extension to github in case someone
> would
> like to take a closer look at the code: https://github.com/pprkut/
> autoload-psr
>
> Thanks in advance!
>
> Grs,
> Heinz
>

https://github.com/pprkut/autoload-psr/blob/27cfc53c864116cf0b65b8f7e69464e15b3fdef5/autoload_psr.c#L175
should be using ZVAL_STR_COPY. The hashtable API does not automatically
incref stored values.

I'd suggest running under USE_ZEND_ALLOC=0 valgrind to check for further
memory issues. Differences in the mode of execution are likely just
incidental.

Nikita

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