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Message-ID: <4e89b426050203173642c9c28b@mail.gmail.com>
Date: Thu, 3 Feb 2005 20:36:58 -0500
Reply-To: Wez Furlong <kingwez@gmail.com>
To: Derrell.Lipman@unwireduniverse.com
Cc: internals <internals@lists.php.net>
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References: <acqlti66.fsf@random.internal>
Subject: Re: [PHP-DEV] how to make nasty code less nasty (obtaining sqlite db handle)
From: kingwez@gmail.com (Wez Furlong)

There is no official way to do this kind of thing between arbitrary extensions.
When extensions that are written to share this information, they
typically export an XXX_API function that you can link against to
fetch the data.

What you've done works, so that's fine, although there is a risk of
crashing if someone passes the wrong type of resource in.  If you're
thinking of distributing your extension, we could add a more official
API for you to use, although that doesn't exist in older versions of
the extension, etc. etc.

Some time back, I proposed a framework (and even a patch IIRC) that
allowed this kind of thing at run-time; despite "we the extension
developers" liking the idea, there was some negative feedback from
andi/zeev so it never went further.  Search the php-dev archives for
my name and "interfaces" for more on that if you're interesting in
this seeing light in PHP 5.2.

--Wez.

On Thu, 03 Feb 2005 17:03:45 -0500, Derrell.Lipman@unwireduniverse.com
<Derrell.Lipman@unwireduniverse.com> wrote:
> I've written an extension which needs to accept a Resource which is an SQLite
> database handle, and call a C function which will be using that db handle to
> issue queries.  What I've done works, but is kinda nasty because there doesn't
> appear to be a clean way to obtain that database handle nor, from what I can
> tell, determine the resource type to expect.  Is there a nicer way of doing
> this?
> 
> PHP_FUNCTION(my_PHP_function)
> {
>     int             id;
>     int             dataLen;
>     int             resourceType;
>     char *          pData;
>     zval *          zdb;
>     void *          hDB;
>     void **         phDB;
> 
>     /* Ensure we got the correct number of parameters */
>     if (ZEND_NUM_ARGS() != 2)
>     {
>         WRONG_PARAM_COUNT;
>     }
> 
>     /* Retrieve the parameters */
>     if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC,
>                               "rs",
>                               &zdb, &pData, &dataLen) == FAILURE)
>     {
>         return;
>     }
> 
>     /*
>      * Voodoo to retrieve the sqlite database handle from the resource.
>      * How do I validate that resourceType is reasonable?
>      */
>     id = zdb->value.lval;
>     if ((phDB = zend_list_find(id, &resourceType)) == NULL)
>     {
>         return;
>     }
> 
>     /*
>      * This is nasty too.  We "know" that the first field in the private
>      * structure is the database handle.  Just extract it.
>      */
>     hDB = *phDB;
> 
>     RETURN_STRING(my_C_function(hDB, pData), TRUE);
> }
> 
> Thanks,
> 
> Derrell
> 
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