Although Drupals 7+ run smoothly on PHP 5.3, Drupal 6 still feels much better with PHP 5.2. Even though D6 core is compatible with PHP 5.3 for quite some time now, a lot of contributes modules still get nasty hiccup when asked to run on the newer version. Therefore developing for both D7 and D6 at the same time becomes much less painful when running both versions of PHP in parallel.

One way of doing it is using mod_php5 Apache module to serve PHP 5.3 applications, while running PHP 5.2 applications using fastcgi module. Under Ubuntu 12.04 this can be achieved by installing PHP 5.3 from the repositories and manually compiling and installing PHP 5.2 afterwards.

Installing PHP 5.3 from repositories is fairly easy process, which you most probably already have under your belt, so let’s just say that it looks more or less like this:

What is much more interesting though, and what this post will focus on, is how to add PHP 5.2 to the whole picture and make both those versions work nicely together.

Download PHP sources

Let’s then start with downloading PHP 5.2 sources from Unsupported Historical Releases list.

I have originally started with version 5.2.10 (as it is the same version that we have on our production servers), but then was stopped short by OpenSSL error during configuration stage:

to which I was not able to find any good fix (relatively easy to apply anyway), so finally ended up with the most recent version from 5.2 branch – 5.2.17, where those errors haven’t occured anymore.

Let’s then download and uncompress PHP sources into ~/Downloads/php-5.2.17 directory:

Configure

Time to configure the package. Example ./configure call could look as follows:

Obviously you need to adapt it to yur specific needs by adding and/or removing relevant options. You can read more about options you want (or don’t want) to include in PHP core configure options documentation.

Configure errors

Now, that probably didn’t work out of the box, did it?

In most cases quite a lot of dependencies will be missing. You can try to take care of them in one shot, if you don’t care too much about installing a little too much compared to what is really needed:

You can also remedy missing dependencies one by one, and install only those packages that are really needed.

Let’s go through some of the possible errors then (you can skip to the next section if your ./configure finished without any errors and displayed nice Thank you for using PHP at the end of its execution):

• configure: error: xml2-config not found. Please check your libxml2 installation.

  This error message suggests you don’t have libxml2 installed. What it really means though is that you don’t have its development version installed!

  Let’s then search what we can find in available packages, what could help us resolve this issue:

  $ apt-cache search libxml2 | grep dev
libcroco3-dev - Cascading Style Sheet (CSS) parsing and manipulation toolkit
libxml++2.6-dev - C++ interface to the GNOME XML library (libxml2)
libxml2-dev - Development files for the GNOME XML library
libgdome2-cpp-smart-dev - C++ bindings for GDome2 DOM implementation
libgdome2-dev - Development files for libgdome2
libgdome2-ocaml-dev - OCaml bindings for GDome2 DOM implementation
libgtkmathview-dev - rendering engine for MathML documents
libsp-gxmlcpp-dev - S+P C++ wrapper for Gnome libxml2/libxslt

  What we are interested in here is libxml2-dev, let’s install it then:

  sudo apt-get install libxml2-dev

  The same procedure applies to all other missing libraries as well, so I will include only final install calls from now on.

• configure: error: Could not find pcre.h in /usr

  sudo apt-get install libpcre3-dev

• configure: error: Please reinstall the BZip2 distribution

  sudo apt-get install libbz2-dev

• configure: error: Please reinstall the libcurl distribution – easy.h should be in /include/curl/

  sudo apt-get install libcurl4-openssl-dev

• configure: error: DBA: Could not find necessary header file(s).
  checking for db4 major version… configure: error: Header contains different version

  sudo apt-get install libdb4.8-dev

• configure: error: libjpeg.(a|so) not found.

  sudo apt-get install libjpeg-dev

• configure: error: libpng.(a|so) not found.

  sudo apt-get install libpng12-dev

• configure: error: libXpm.(a|so) not found.

  sudo apt-get install libxpm-dev

• configure: error: freetype.h not found.

  sudo apt-get install libfreetype6-dev

• You need to install postgresql-server-dev-X.Y for building a server-side extension or libpq-dev for building a client-side application.
  configure: error: Cannot find libpq-fe.h. Please specify correct PostgreSQL installation path

  sudo apt-get install postgresql-server-dev-9.1

  Make sure you check result of apt-cache search especially in case of this error, as there could be later version of PostgreSQL available.

• checking for FreeType 1 support… no – FreeType 2.x is to be used instead
  configure: error: Your t1lib distribution is not installed correctly. Please reinstall it.

  sudo apt-get install libt1-dev

• configure: error: Unable to find gd.h anywhere under /usr

  sudo apt-get install libgd2-xpm-dev

• configure: error: Unable to locate gmp.h

  sudo apt-get install libgmp-dev

• configure: error: Cannot find MySQL header files under /usr.
  Note that the MySQL client library is not bundled anymore!

  sudo apt-get install libmysqlclient-dev

• configure: error: sasl.h not found!

  sudo apt-get install libsasl2-dev

• configure: error: Please reinstall libmhash – I cannot find mhash.h

  sudo apt-get install libmhash-dev

• checking for unixODBC support… configure: error: ODBC header file ‘/usr/include/sqlext.h’ not found!

  sudo apt-get install unixodbc-dev

• configure: error: Directory /usr is not a FreeTDS installation directory

  sudo apt-get install freetds-dev

• configure: error: Cannot find pspell

  sudo apt-get install libpspell-dev

• configure: error: SNMP sanity check failed. Please check config.log for more information.

  sudo apt-get install libsnmp-dev

• configure: error: Cannot find libtidy

  sudo apt-get install libtidy-dev

• configure: error: xslt-config not found. Please reinstall the libxslt >= 1.1.0 distribution

  sudo apt-get install libxslt1-dev

• configure: error: mcrypt.h not found. Please reinstall libmcrypt.

  sudo apt-get install libmcrypt-dev

• configure: error: Cannot find OpenSSL’s libraries

  Add following switch to your ./configure options (optionally updating the path to reflect your system):

  --with-libdir=/lib/x86_64-linux-gnu

• configure: error: You’ve configured extension pdo_sqlite to build statically, but it depends on extension pdo, which you’ve configured to build shared. You either need to build pdo_sqlite shared or build pdo statically for the build to be successful.

  Add following switches to your ./configure options:

    --with-pdo-sqlite=shared
--with-sqlite=shared

Make

Everything configured properly and without errors? Then it is time to compile (and go for a coffee while it is running):

Now sipping your coffee wait for approaching errors…

Make errors

Yes, things can go awry here too. And most probably will.

There are two make errors and one warning you are most probably going to experience:

• ext/openssl/.libs/xp_ssl.o: In function `php_openssl_setup_crypto’:
  ext/openssl/xp_ssl.c:357: undefined reference to `SSLv2_server_method’
  ext/openssl/xp_ssl.c:337: undefined reference to `SSLv2_client_method’

  This is due to PHP bug #54736, which could be easily resolved using patch debian_patches_disable_SSLv2_for_openssl_1_0_0.patch attached to that bug report.

  Download this patch to your ~/Downloads/php-5.2.17 directory, and execute:

  patch -p1 < debian_patches_disable_SSLv2_for_openssl_1_0_0.patch.patch

  You should see friendly success messages like these:

  patching file ext/openssl/xp_ssl.c
Hunk #1 succeeded at 332 (offset 4 lines).
Hunk #2 succeeded at 354 (offset 4 lines).
Hunk #3 succeeded at 583 (offset -50 lines).
Hunk #4 succeeded at 819 (offset -98 lines).

• ext/gmp/gmp.c: In function ‘zif_gmp_random’:
  ext/gmp/gmp.c:1399:69: error: ‘__GMP_BITS_PER_MP_LIMB’ undeclared (first use in this function)
  ext/gmp/gmp.c:1399:69: note: each undeclared identifier is reported only once for each function it appears in

  This time it’s PHP bug #50990. In one of comments there susan dot smith dot dev at gmail dot com suggested solution which works and does its magic:

  I solved replacing the outdated __GMP_BITS_PER_MP_LIMB defined constant with GMP_LIMB_BITS. The latter is present in all previous versions, and MPIR define it too.

  You have to edit file ext/gmp/gmp.c and replace one occurence of __GMP_BITS_PER_MP_LIMB with GMP_LIMB_BITS, in my case it was in line 1399.

• ext/zip/lib/.libs/zip_dirent.o: In function `memset’:
  /usr/include/x86_64-linux-gnu/bits/string3.h:82: warning: memset used with constant zero length parameter; this could be due to transposed parameters

  Finally PHP bug #53568, with a pretty easy fix: edit file ext/zip/lib/zip_dirent.c and in line 478 replace:

  memset(&tm, sizeof(tm), 0);

  with

  memset(&tm, 0, sizeof(tm));

There, no more errors!

Install

The simplest way of installing your new shiny PHP 5.2 now is:

Alternatively, if you plan to repeat the same installation again on other machines, or just want to keep the installation package file for the future, you can run:

which, together with installing new PHP, would also create .deb package file in your current directory.

Whichever way you choose, now you have PHP 5.2 installed in /usr/bin/php52

Apache conf files

The /etc/php52/apache2/ configuration directory for PHP 5.2 should have already been created during the installation process (create it now if it is not the case). Now you need to let PHP 5.2 use the same extensions as your version 5.3 is using:

Copy example php.ini-recommended file provided with PHP installation into its new directory (which will be defined in the next step):

and make required amends to it if need be.

Apache and FastCGI

Next thing to do is to set up Apache to run PHP 5.2 using FastCGI. Start with installing fastcgi module:

Make sure all required modules are enabled and restart Apache:

Create a wrapper script called php52-cgi to run the fastcgi enabled version of PHP and place it under /usr/lib/cgi-bin/, with the following content:

The PHPRC parameter tells PHP 5.2 where to look for a php.ini.
The PHP_FCGI_CHILDREN pre-forks threads with the FastCGI process manager.
The PHP_FCGI_MAX_REQUESTS limits the requests.
Finally the exec executes php. You can read more about this on FastCGI site.

Make sure the file is executable:

Finally create new include file /etc/apache2/php52.conf, which will be used by those virtual hosts that need to run off PHP 5.2. Add the following content to it:

The FilesMatch forces the handler to execute files with the suffix .php. This must be set, because if mod_php with PHP 5.3 is installed, the module interprets the php file and not the cgi script.
The ScriptAlias sets the path to the cgi script.
The AddHandler registers a new handler.
The Action activates the cgi script for the files passed from the handler.

Almost there!

Only one thing left to do now – for all hosts which you want to be running on PHP 5.2 , edit their configuration file and add the following line inside their <VirtualHost> definition:

and reload new configuration:

Final result? For all you Drupallers out there – you successfully managed to change this:

into this:

Well done!