NAME
Perl::Stripper - Yet another PPI-based Perl source code stripper
VERSION
This document describes version 0.10 of Perl::Stripper (from Perl
distribution Perl-Stripper), released on 2017-07-11.
SYNOPSIS
use Perl::Stripper;
my $stripper = Perl::Stripper->new(
#maintain_linum => 1, # the default, keep line numbers unchanged
#strip_ws => 1, # the default, strip extra whitespace
#strip_comment => 1, # the default
#strip_pod => 1, # the default
strip_log => 1, # default is 0, strip Log::Any log statements
);
$stripped = $stripper->strip($perl);
DESCRIPTION
This module is yet another PPI-based Perl source code stripper. Its
focus is on costumization and stripping meaningful information from
source code.
ATTRIBUTES
maintain_linum => BOOL (default: 1)
If set to true, stripper will try to maintain line numbers so they do
not change between the unstripped and the stripped version. This is
useful for debugging.
Respected by other settings.
strip_ws => BOOL (default: 1)
Strip extra whitespace, like indentation, padding, even non-significant
newlines. Under "maintain_linum", will not strip newlines.
Not yet implemented.
strip_comment => BOOL (default: 1) | CODE
If set to true, will strip comments. Under "maintain_linum" will replace
comment lines with blank lines.
Shebang line (e.g. "#!/usr/bin/perl", located at the beginning of
script) will not be stripped.
Can also be set to a coderef. Code will be given the PPI comment token
object and expected to modify the object (e.g. using "set_content()"
method). See PPI::Token::Comment for more details. Some usage ideas:
translate comment, replace comment with gibberish, etc.
strip_log => BOOL (default: 1)
If set to true, will strip log statements. Useful for removing debugging
information. Currently supports Log::Any and Log::ger and only looks for
the following statements:
$log->LEVEL(...);
$log->LEVELf(...);
log_LEVEL(...);
if ($log->is_LEVEL) { ... }
if (log_is_LEVEL()) { ... }
Not all methods are stripped. See "stripped_log_levels".
Can also be set to a coderef. Code will be given the PPI::Statement
object and expected to modify it.
These are currently not stripped:
if (something && $log->is_LEVEL) { ... }
stripped_log_levels => ARRAY_OF_STR (default: ['debug', 'trace'])
Log levels to strip. By default, only "debug" and "trace" are stripped.
Levels "info" and up are considered important for users (instead of for
developers only).
strip_pod => BOOL (default: 1)
If set to true, will strip POD. Under "maintain_linum" will replace POD
with blank lines.
Can also be set to a coderef. Code will be given the PPI POD token
object and expected to modify the object (e.g. using "set_content()"
method). See PPI::Token::Pod for more details.Some usage ideas:
translate POD, convert POD to Markdown, replace POD with gibberish, etc.
METHODS
new(%attrs) => OBJ
Constructor.
$stripper->strip($perl) => STR
Strip Perl source code. Return the stripped source code.
FAQ
What is the use of this module?
This module can be used to remove debugging information (logging
statements, conditional code) from source code.
This module can also be employed as part of source code protection
strategy. In theory you cannot hide source code you deploy to
users/clients, but you can reduce the usefulness of the deployed source
code by removing information such as comments and POD (documentation),
or by mangling subroutine/variable names (removing meaningful original
subroutine/variable names).
For compressing source code (reducing source code size), you can try
Perl::Squish or Perl::Strip.
But isn't hiding/protecting source code immoral/unethical/ungrateful?
Discussing hiding/protecting source code in general is really beyond the
scope of this module's documentation. Please consult elsewhere.
How about obfuscating by encoding Perl code?
For example, changing:
foo();
bar();
into:
$src = base64_decode(...); # optionally multiple rounds
eval $src;
This does not really remove meaningful parts of a source code, so I am
not very interested in this approach. You can send a patch if you want.
How about changing string into hexadecimal characters? How about ...?
Other examples similar in spirit would be adding extra parentheses to
expressions, changing constant numbers into mathematical expressions.
Again, this does not *remove* meaningful parts of a source code
(instead, they just transform stuffs). The effect can be reversed
trivially using Perl::Tidy or B::Deparse. So I am not very interested in
doing this, but you can send a patch if you want.
HOMEPAGE
Please visit the project's homepage at
<
https://metacpan.org/release/Perl-Stripper>.
SOURCE
Source repository is at
<
https://github.com/perlancar/perl-Perl-Stripper>.
BUGS
Please report any bugs or feature requests on the bugtracker website
<
https://rt.cpan.org/Public/Dist/Display.html?Name=Perl-Stripper>
When submitting a bug or request, please include a test-file or a patch
to an existing test-file that illustrates the bug or desired feature.
SEE ALSO
There are at least two approaches when analyzing/modifying/producing
Perl code: B-based and PPI-based. In general, B-based modules are orders
of magnitude faster than PPI-based ones, but each approach has its
strengths and weaknesses.
B::Deparse - strips comments and extra newlines
B::Deobfuscate - like B::Deparse, but can also rename variables. Despite
its name, if applied to a "normal" Perl code, the effect is obfuscation
because it removes the original names (and meaning) of variables.
Perl::Strip - PPI-based, focus on compression.
Perl::Squish - PPI-based, focus on compression.
AUTHOR
perlancar <
[email protected]>
COPYRIGHT AND LICENSE
This software is copyright (c) 2017, 2015, 2014, 2013, 2012 by
[email protected].
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
