Building and Debugging PHPMapScript on Linux

Stephen Woodbridge wrote:

 > I have finally gotten around to trying to debug the
 > PHP3/Mapscript? problem I was having. You said I should
 > build PHP/Mapscript? as a static php CGI executable so I
 > can run it in gdb.

Actually, I meant compile PHP as a CGI executable instead of as an Apache DSO. And then you still compile PHP MapScript the same way, as a php_mapscript.so file that will be loaded by PHP at runtime.

Once you're all setup, you can debug a PHP script that crashes using the 'php' CGI executable in gdb with:

  $ gdb ./php
  ...
  (gdb) run /path/to/test.php
  ...

Here is the fun part: If you need to setup a breakpoint inside php_mapscript.so then you have to:

• First set a breakpoint in php_dl()
• start the program, when it reaches php_dl(), type "finish" to let php_dl() finish its execution
• debugger will stop again at the end of php_dl(), after php_mapscript.so is loaded... then you can set breakpoints anywhere in php_mapscript.so and enjoy gdb! :)
• Make sure you disable all breakpoints before re-running the program or gdb will keep complaining about them

There may be ways to automate this in gdb but I never looked into that any further... I welcome suggestions.

 > All the documentation only talks about building it as a DSO module for
 > apache. Can you send me a link or have someone add it to Wiki? I think
 > this would be a great help to aid others that might want to work with
 > PHP3 and Mapscript.
 > 

The answer to this question has been moved to a separate PHPMapScriptCGI page.

 > Also have you guys posted documentation on how to build Mapscript for
 > PHP4 and !MapServer 3.5? on Wiki?
 > 

Nothing special to say there... MapServer's configure takes care of it all on most platforms... here are some detailed steps (hopefully I didn't forget anything):

1- Compile and install PHP as a CGI as described above

2- Run configure in your mapserver dir. with the --with-php switch:

./configure --with-php=/path/to/php-src-that-you-just-compiled ...

3- run 'make', that will automagically build mapserv, etc. ... and php_mapscript.so in mapserver/mapscript/php3

4- Edit your php.ini and make sure extensions_dir is set to point to a valid location (e.g. /usr/local/lib/php4)

5- Copy php_mapscript.so to your extensions_dir

6- Make sure all libs used in your MapServer build are included in your runtime library path. See the PHP MapScript install FAQ about this common problem: ​http://www.mapserver.org/installation/php.html#faq-common-problems

7- You're ready to use dl("php_mapscript.so"); to load and use PHP MapScript in your PHP apps.

See also the PHPMapScript-install-HOWTO for more info: ​http://www.mapserver.org/installation/php.html