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Reply-To: bishop@php.net
Date: Fri, 8 Sep 2023 15:54:34 -0400
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To: Vinicius Dias <carlosv775@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] FFI in PHAR files
From: bishop@php.net (Bishop Bettini)

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On Fri, Sep 8, 2023 at 2:33=E2=80=AFPM Vinicius Dias <carlosv775@gmail.com>=
 wrote:

> I was playing around with some libraries using FFI and I wanted to
> share a .phar with the result, but to my surprise, it didn't work.
>
> Apparently we are not able to load shared libraries using FFI from
> within .phar files.
> Is that the expected behavior or is it a bug in the FFI extension?
>
> I have setup a dummy repo so the error could be easily reproduced:
> https://github.com/CViniciusSDias/ffi-phar-problem
>
> I am sorry if this is not the list to send this type of problem. I
> will gladly move the thread to the right one if someone points it out.
>  https://www.php.net/unsub.php


Erstwhile PHAR extension maintainer here. What an interesting question! The
short answer is no, FFI does not support loading dynamic libraries
contained within a PHAR archive.

The longer answer is that FFI was not written to be able to support VFS
locations, including the phar:// scheme. In this case, PHP starts and
invokes the code. The code invokes FFI[1] with a phar:// path, which then
tries to perform a dlopen()[2], which fails because dlopen has no idea how
to resolve PHAR paths: dlopen() expects a path that the OS can resolve[3].

I suppose it'd be possible to improve FFI to call the PHP VFS layer to
resolve a path, which would handle the phar:// scheme and other schemes.
But, I would be worried about potential other downstream impacts - esp.
security implications - as this is a novel (to me at least) scenario.

bishop

[1]:
https://github.com/php/php-src/blob/50ca24251d97dbf78b0c1165dac7c1a19ff1c87=
a/ext/ffi/ffi.c#L2968C3-L2968C3
[2]:
https://github.com/php/php-src/blob/50ca24251d97dbf78b0c1165dac7c1a19ff1c87=
a/Zend/zend_portability.h#L156
[3]:https://man7.org/linux/man-pages/man3/dlopen.3.html

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