NAME
CGI::Capture - Meticulously thorough capture and replaying of CGI calls
SYNOPSIS
# Capture the current CGI to a file, and replay it once created
use CGI::Capture 'fileupload.dat';
# Create an object and capture the state
my $Capture = CGI::Capture->new->capture;
# Store it in a file and load it back in
$Capture->store('somefile.dat');
my $second = CGI::Capture->apply('somefile.dat');
# Apply the CGI call to the current environment
$second->apply;
DESCRIPTION
CGI does a terribly bad job of saving CGI calls. "CGI::Capture" tries to
resolve this and save a CGI call in as much painstaking detail as it
possibly can.
Because of this, "CGI::Capture" should work with server logins, cookies,
file uploads, strange execution environments, special environment
variables, the works.
It does this by capturing a large amount of the perl environment BEFORE
CGI.pm itself gets a chance to look at it, and then restores it in the
same way.
So in essence, it grabs all of "STDIN", %ENV, @INC, and anything else it
can think of. The things it can't replicate, it records anyway so that
later in the debugger it can ensure that the execution environment is as
close as possible to what it captured (and bitch at you about anything
you are doing wrong).
This is a huge help when resolving problems such as when a bug won't
appear because you aren't debugging the script as the web user and in
the same directory.
Using CGI::Capture
The brain-dead way is to use it as a pragma.
Add the following to your web application BEFORE you load in CGI itself.
use CGI::Capture 'cookiebug.dat';
If the file "cookiebug.dat" does not exist, CGI::Capture will take a
snapshot of all the bits of the environment that matter to a CGI call,
and freeze it to the file.
If the file DOES exist however, CGI::Capture will load in the file and
replace the current CGI call with the stored one.
Security
The actual captured CGI files are Storable CGI::Capture objects. If you
want to use CGI::Capture in an environment where you have CODE
refereneces in your @INC path (such as with PAR files), you will need to
disable security for Storable by setting $CGI::Capture::DEPARSE to true,
which will enable B::Deparse and Eval support for stored objects.
Hand-Crafting CGI Captures
In its default usage, CGI::Capture takes an all or nothing approach,
requiring you to capture absolutely every element of a CGI call.
Sometimes you want to be a little more targetted, and for these
situations an alternative methodology is provided.
The "as_yaml" and "from_yaml" methods allow you to store and retrieve a
CGI capture using YAML::Tiny instead of Storable.
Once you have stored the CGI capture as a YAML file, you can hand-edit
the capture file, removing any keys you will not want to be restored,
keeping only the useful parts.
For example, to create a test file upload or CGI request involving
cookies, you could discard everything except for the STDIN section of
the capture file, which will then allow you to reuse the capture on
other hosts, operating systems, and so on.
METHODS
In most cases, the above is all you probably need. However, if you want
to get more fine-grained control, you can create and manipulate
CGI::Capture object directly.
new
The "new" only creates a new, empty, capture object.
Because capturing is destructive to some values (STDIN for example) the
capture method will capture and then immediately reapply the object, so
that the current call can continue.
Returns a CGI::Capture object. Never dies or returns an error, and so
can be safely method-chained.
store $filename
This method behaves slightly differently in object and static context.
In object context ( $object->store($filename) ) it stores the captured
data to a file via Storable.
In static context ( CGI::Capture->store($filename) ) automatically
creates a new capture object, captures the CGI call, and then stores it,
all in one hit.
Returns as for Storable::store or dies if there is a problem storing the
file. Also dies if it finds a CODE reference in @INC and you have not
enabled $CGI::Capture::Deparse.
retrieve
The "retrieve" method is used identically to the Storable method of the
same name, and wraps it.
Loads in a stored CGI::Capture object from a file.
If the stored object had a CODE ref in it's @INC, you will also need to
enable $CGI::Capture::DEPARSE when loading the file.
Returns a new CGI::Capture object, or dies on failure.
as_yaml
To allow for more portable storage and communication of the CGI
environment, the "as_yaml" method can be used to generate a YAML
document for the request (generated via YAML::Tiny).
Returns a YAML::Tiny object.
from_yaml
To allow for more portable storage and communication of the CGI
environment, the "from_yaml" method can be used to restore a
CGI::Capture object from a YAML::Tiny object.
Returns a new CGI::Capture object, or croaks if passed an invalid param.
as_yaml_string
To allow for more portable storage and communication of the CGI
environment, the "as_yaml_string" method can be used to generate a YAML
document for the request (generated via YAML::Tiny).
Returns a YAML document as a string.
from_yaml_string
To allow for more portable storage and communication of the CGI
environment, the "from_yaml_string" method can be used to restore a
CGI::Capture object from a string containing a YAML document.
Returns a new CGI::Capture object, or croaks if the YAML document is
invalid.
capture
Again, "capture" can be used either as an object or static methods
When called as an object method ( $object->capture ) it captures the
current CGI call environment into the object, replacing the existing one
if needed.
When called as a static method ( CGI::Capture->capture ) it acts as a
constructor, creating an object and capturing the CGI call into it
before returning it.
In both cases, returns the CGI::Capture object. This method will not die
or return an error and can be safely method-chained.
apply [ $filename ]
Again, "apply" works different when called as an object of static
method.
If called as an object method ( $object->apply ) it will take the CGI
call the object contains, and apply it to the current environment.
Because this works at the environment level, it needs to be done BEFORE
CGI.pm attempts to create the CGI object.
The "apply" method will also check certain values against the current
environment. In short, if it can't alter the environment, it won't run
unless YOU alter the environment and try again.
These include the real and effective user and group, the OS name, the
perl version, and whether Tainting is on or off.
The effect is to really make sure you are replaying the call in your
console debugger exactly as it was from the browser, and you arn't
accidentally using a different user, a different perl, or are making
some other overlooked and hard to debug mistake.
In the future, by request, I may add some options to selectively disable
some of the tests. But unless someone asks, I'm leaving all of them on.
In the static context, ( CGI::Capture->apply($file) ) it takes a
filename argument, immediately retrieves the CGI call from the object
and immediately applies it to the current environment.
In both context, returns true on success or dies on error, or it your
testing environment does not match.
SUPPORT
All bugs should be filed via the bug tracker at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=CGI-Capture>
For other issues, or commercial enhancement or support, contact the
author.
AUTHORS
Adam Kennedy <adamk@cpan.org>
SEE ALSO
<http://ali.as/>, CGI
COPYRIGHT
Copyright 2004 - 2010 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.