Quite often when you are working with legacy code you will come across a mess of globals. Every single method will make use of the same global instance of the database class for example. So where do you begin to work with this massive impediment?

Logging is a great way to see what methods and classes are being used by you application and where. To achieve this you would normally need to add a logging call to each and every method in the code base. Clearly this would be incredibly tedious and time consuming.

This is where a proxy object can be implemented to save time and centralise the logging functions. The basic idea of a proxy object is that it will be instantiated in place of the actual class and the proxy will delegate any calls through to the original class. For the purposes of this example the original class will be called Database and the proxy object will be called LazyLoadingProxy.

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I needed to add a new port forward to a router, but I did not have access to the web interface through a graphical browser. Attempts to get in using Lynx stalled as it seems the router will not serve up the frames in the interface independently of each other and it kept issuing 404 errors.

Either way I had to use the telnet interface using the following command (replace 192.168.1.1 23 with the IP address of your router):

telnet 192.168.1.1 23

This is fine except that Draytek have absolutely no documentation available for the commands. So to discover the correct command I had to go through all the available options (and sub options and sub sub options) as it was not immediately clear to me which option port forwarding was hiding under. To give you an idea here is a list of the top level options (run the `?` command to get this view):

> ?
% Valid commands are:
adsl         bpa          csm          webf         ddns         ddos
urlf         kw           exit         fe           internet     ip
ipf          log          mngt         port         portmaptime  prn
quit         show         srv          sys          tsmail       upnp
vigbrg       vlan         vpn          wan          wol          qos

The option we are interested in is `srv` which has a number of sub options but we are only interested in `nat`. Now we have yet more options but lets just stick with `portmap`.

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Introduction

When working in a team it is very useful to have a central web server with multiple environments and a configuration as close to the live server as possible. This can be a bit of a nightmare though if you need to setup a new VirtualHost container in Apache every time a new project is brought on or when a developer wants to work on a version of the site in their own environment.

The good news is that this can all be handled automatically and new sites can be setup by simply adding a new directory to the file system. There are at least two ways of getting this going; the first of which is the mod_vhost_alias module for Apache and the second is enabled via mod_rewrite. I prefer to use the second method as it is more flexible and it allows you tap into the ability of mod_rewrite to introduce environment variables and redirect requests (this is particularly useful for robots.txt - you’ll see).

The Apache2 Manual does have a very good page dedicated to overcoming this problem, but I will be sharing with you all the settings I am using which you will need to stop Google et. al. from crawling your sites served from the staging environment for example.

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Installing via the pecl command can be a pain on Redhat. First off all you will need to install the php-devel package:

yum install php-devel

Then you will need ensure that the PEAR/PECL installer is at the latest version so as root run:

pear update-channel pear.php.net
pear upgrade pear

You may need to force pear to upgrade itself by using:

pear upgrade —force pear

I had to use the —force option because my version of PEAR was so old that the installer thought my version of Tar_Archive might not have been up to muster. It was however.

With all this in place you are ready to attempt to install your chosen extension:

pecl install ssdeep

If you get something like the following back:

/usr/bin/phpize: /tmp/ssdeep/build/shtool: /bin/sh: bad interpreter: Permission

Then it is likely that your temporary directory is mounted in a safer noexec state, which means that you cannot execute scripts within the /tmp directory. To test this you can put a simple bash script into your /tmp directory and chmod it with +x. I used the following bash script:

#!/bin/bash
echo “SIMON” 

If you do not get SIMON back when you execute the file, but an error like “/bin/sh: bad interpreter: Permission” then the directory is set to noexec.

There are a few ways to overcome this with the easiest being to:

1. Remount the directory as exec:

   mount -o remount,exec /tmp

2. Install your pecl extension

   pecl install ssdeep

3. Remount the directory as noexec again for safety

   mount -o remount,noexec /tmp

There are a variety of other ways to get this working documented in the Media Temple wiki pages if the above technique does not work for you.

Whilst developing a PHP extension recently I spent quite a bit of time researching exactly how to create an extension, the best practices and the DocBook format of the PHP manual for documenting the extension.

By the time I finished writing the extension I had found some very good resources both on the web and in print.

Online Articles or Websites:

• The Internals section of the PHP manual
• Wez Furlong’s Extending PHP slides
• Marcus Börger and Johannes Schlüter: PHP Extension Writing slides
• O’Reilly Programming PHP Chapter 14: Extending PHP
• Sara Golemon’s Zend DevZone articles with parts I, II and III:
  • Extension Writing Part I: Introduction to PHP and Zend
  • Extension Writing Part II: Parameters, Arrays, and ZVALs
  • Extension Writing Part III: Resources
• Paul Osman’s Wrapping C++ Classes in a PHP Extension article on Zend DevZone
• Kristina Chodorow’s PHP Extensions Made Eldrich on her blog

Printed Books:

• Sara Golemon’s Extending and Embedding PHP
• Advanced PHP Programming by George Schlossnagle

Information on Documenting PHP and PECL Extensions:

• PHP Wiki: Documentation Introduction
• PHP Wiki: Editing Documentation
• PHP Documentation Team: How to pages
• PHP Wiki: Documenting PECL Extensions

Also worth a mention is the ability of the new PEAR2 Pyrus installer to generate a skeleton for you to build your PECL extension upon - see the generate-ext section of the manual.

Pyrus can also be used to package your extension up for release using the pickle command.

For more help there is a PECL mailing list and IRC channel (#php.pecl on efnet), both of which are in the support section of the PECL website.

Whilst not strictly for PHP extensions the Autotools: a practitioner’s guide to Autoconf, Automake and Libtool book by John Calcote on the Free Software Magazine is very useful reading for an understanding of the build process involved in extension writing.

There is also the GNU Manual for Autoconf and GNU Autoconf, Automake, and Libtool by Gary V. Vaughan et al.