[Bug 1548442] Re: php7.0: segmentation fault running twig test suite

[Neal Gompa]

After working with Remi Collet to track down the issue, we've identified
the problem to be with PCRE support, specifically with PCRE JIT. We
reached this suspicion after Remi was able to run the tests successfully
with his PHP7 SCL for Fedora 23 just fine with the JIT enabled, but it
broke on CentOS 7.2 and Ubuntu Xenial.

I tested on Ubuntu Xenial php7.0-7.0.3-9 (from xenial-proposed) and
CentOS 7.2 php70-php-7.0.3-1.el7.remi SCL (from Remi's repository).

On both systems, I did the following:

0. Installed the required php7 packages.
** Ubuntu Xenial: php7.0-{cli,json,xml,mbstring}
** CentOS 7.2 php70 scl: php70-php-{cli,json,xml,mbstring}

1. Downloaded Twig 1.24.0 tarball from GitHub
(https://github.com/twigphp/Twig/archive/v1.24.0/Twig-1.24.0.tar.gz)

2. Untarred it and changed into the new Twig-1.24.0 directory.

3. Downloaded composer.phar ( https://getcomposer.org/composer.phar ) and phpunit.phar ( https://phar.phpunit.de/phpunit.phar )
4. Run composer to set up the Twig sources.
** Ubuntu Xenial: php7.0 composer.phar install
** CentOS 7.2 php70 scl: php70 composer.phar install

5. Run phpunit on the Twig sources.
** Ubuntu Xenial: php7.0 phpunit.phar -v
** CentOS 7.2 php70 scl: php70 phpunit.phar -v

With the default configuration, these both fail with a segmentation
fault.

However, if I add "pcre.jit=0" to php.ini (/etc/php/7.0/cli/php.ini on
Ubuntu Xenial, /etc/opt/remi/php70/php.ini for CentOS 7.2 php70 scl) and
re-run the tests, they pass completely.


There are two solutions here:
1) Identify what Fedora's pcre package has that fixes it vs the Debian/Ubuntu package (Fedora sources available here: http://pkgs.fedoraproject.org/cgit/rpms/pcre.git/tree/?h=f23), as both are using pcre 8.38, though I don't know why the soversion differs...
2) Add "pcre.jit=0" to the php configuration.

I don't consider solution 2 to be valid unless we're okay with disabling
PCRE JIT across the board.

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Title:
  php7.0: segmentation fault running twig test suite

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