April 6, 2015

620 words 3 mins read

PHP 5.4 and PHPDBG in OS X

PHP 5.4 and PHPDBG in OS X

I got PHPDBG enabled in PHP 5.4 although I’ve never bothered giving it a try. Recently, I decided to play around with it to try to compare it with Xdebug. I tested it with a minimal Drupal installation.



I use homebrew-php to install PHP 5.4. Versions 5.4+ have the flag --with-phpdbg if you wish to include PHPDBG during installation therefore installation is simply via invoking brew install php54 --with-phpdbg.

The version of PHPDBG that comes with the php54 package is v0.3.2. I gave this a try but didn’t much like it as it had a lot of bugs. What worked for me was replacing it with the one that had the latest changes (specifically this). It still had a few bugs in it but it was way better. I had to change the source of homebrew-php to make it work. Here’s a diff of my changes at homebrew-php installation directory:

diff --git a/Abstract/abstract-php-version.rb b/Abstract/abstract-php-version.rb
index 943b259..9b7dee8 100644
--- a/Abstract/abstract-php-version.rb
+++ b/Abstract/abstract-php-version.rb
@@ -1,10 +1,10 @@
 class AbstractPhpVersion < Formula
   module PhpdbgDefs
-    PHPDBG_SRC_TARBAL = 'https://github.com/krakjoe/phpdbg/archive/v0.3.2.tar.gz'
+    PHPDBG_SRC_TARBAL = 'https://github.com/krakjoe/phpdbg/archive/master.tar.gz'
-                        :md5    => '84255abff00fb31e338d03564c3cc4e4',
-                        :sha1   => 'c57174ab235ec69997e1a37e6d2afe3e4edfb749',
-                        :sha256 => 'feab6e29ef9a490aa53332fe014e8026d89d970acc5105f37330b2f31e711bbd',
+                        :md5    => '5a9346fe533fc486e2427cb0517b7159',
+                        :sha1   => '25e53a5ff1c66afd8c34a98404d5242e61b4d55b',
+                        :sha256 => '06eb09e5cb5deac4812a0ed7305e9d640f1ec6b6fbfdc6ea9a24bf7ea9d01929',


I had a minimal installation of Drupal. I simply grabbed Drupal 7 and installed it via drush si --db-url=sqlite://sites/default/files/.ht.sqlite -y.

Set Up

The documentation is a bit difficult to understand considering that I am relatively new to debugging. Unlike Xdebug, you’ll need to mock a webserver to get PHPDBG to work with web applications like Drupal. An example can be found from both the repository and documentation. I used it like this:

$ cd /path/to/drupal
$ phpdbg
prompt> exec index.php
prompt> ev include '/path/to/web-bootstrap.php';

The file needs to be modified for it to work with Drupal. I made the following changes to it:

diff --git a/web-bootstrap-1.php b/web-bootstrap.php
index 7b8c5d3..da9333b 100644
--- a/web-bootstrap-1.php
+++ b/web-bootstrap.php
@@ -11,7 +11,7 @@
 if (!defined('PHPDBG_BOOTSTRAPPED')) 
     /* define these once */
-    define("PHPDBG_BOOTPATH", "/opt/php-zts/htdocs");
+    define("PHPDBG_BOOTPATH", "/path/to/drupal");
     define("PHPDBG_BOOTSTRAP", "index.php");
     define("PHPDBG_BOOTSTRAPPED", sprintf("/%s", PHPDBG_BOOTSTRAP)); 
@@ -49,13 +49,14 @@ $_SERVER = array
   'QUERY_STRING' => '',
+  'REQUEST_URI' => '/node/1',
   'REQUEST_TIME' => time(),
-$_GET = array();
+$_GET = array('q' => 'node/1');
 $_REQUEST = array();
 $_POST = array();
 $_COOKIE = array();

Basic Usages

Set a breakpoint by invoking break func_name and finally invoking run to start debugging. step would step through each line of code. ev can be used to evaluate expressions. An example is inspecting the available variables in the current scope and stack frame.

I did it like this:

prompt> exec index.php
[Execution context not changed]
prompt> ev include '/private/tmp/web-bootstrap.php';
prompt> run
[Breakpoint #0 in node_load() at /path/to/drupal/modules/node/node.module:962, hits: 1]
>00962: function node_load($nid = NULL, $vid = NULL, $reset = FALSE) {
 00963:   $nids = (isset($nid) ? array($nid) : array());
 00964:   $conditions = (isset($vid) ? array('vid' => $vid) : array());
prompt> s
>00963:   $nids = (isset($nid) ? array($nid) : array());
 00964:   $conditions = (isset($vid) ? array('vid' => $vid) : array());
 00965:   $node = node_load_multiple($nids, $conditions, $reset);
>00964:   $conditions = (isset($vid) ? array('vid' => $vid) : array());
 00965:   $node = node_load_multiple($nids, $conditions, $reset);
 00966:   return $node ? reset($node) : FALSE;
prompt> ev $conditions

prompt> ev $nid
prompt> s
>00965:   $node = node_load_multiple($nids, $conditions, $reset);
 00966:   return $node ? reset($node) : FALSE;
 00967: }
prompt> ev $conditions


I haven’t figured out some of the other basic usages such as stepping over a line rather than stepping through it.

More usage instructions/examples on the documentation, tests, and here.