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GseTDDUebungKCLR/database/perl/vendor/lib/PAR/Tutorial.pod
Riley Schneider b732d8d4b5 Initial Commit
2025-12-03 16:38:10 +01:00

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=head1 NAME
PAR::Tutorial - Cross-Platform Packaging and Deployment with PAR
=head1 SYNOPSIS
This is a tutorial on PAR, first appeared at the 7th Perl Conference.
The HTML version of this tutorial is available online as
L<http://search.cpan.org/perldoc?PAR::Tutorial>
=head1 DESCRIPTION
=head2 On Deploying Perl Applications
% sshnuke.pl 10.2.2.2 -rootpw="Z1ON0101"
Perl v5.6.1 required--this is only v5.6.0, stopped at sshnuke.pl line 1.
BEGIN failed--compilation aborted at sshnuke.pl line 1.
=over 4
=item * Q: "Help! I can't run your program!"
=item * A1: Install Perl & C<perl -MCPAN -e'install(...)'>
=over 4
=item * How do we know which modules are needed?
=item * New versions of CPAN modules may break C<sshnuke.pl>
=back
=item * A2: Install Perl & C<tar zxf my_perllib.tgz>
=over 4
=item * Possibly overwriting existing modules; not cross-platform at all
=back
=item * A3: Use the executable generated by C<perlcc sshnuke.pl>
=over 4
=item * Impossible to debug; C<perlcc> usually does not work anyway
=back
=back
=head2 PAR, the Perl Archive Toolkit
=over 4
=item * Do what JAR (Java Archive) does for Perl
=over 4
=item * Aggregates modules, scripts and other files into a Zip file
=item * Easy to generate, update and extract
=item * Version consistency: solves forward-compatibility problems
=item * Developed by community: C<par@perl.org>
=back
=item * PAR files can be packed into self-contained scripts
=over 4
=item * Automatically scans perl script for dependencies
=item * Bundles all necessary 3rd-party modules with it
=item * Requires only core Perl to run on the target machine
=item * PAR also comes with C<pp>, the Perl Packager:
% pp -o sshnuke.exe sshnuke.pl # stand-alone executable!
=back
=back
=head2 Simple Packaging
=over 4
=item * PAR files are just Zip files with modules in it
=item * Any Zip tools can generate them:
% zip foo.par Hello.pm World.pm # pack two modules
% zip -r bar.par lib/ # grab all modules in lib/
=item * To load modules from PAR files:
use PAR;
use lib "foo.par"; # the .par part is optional
use Hello;
=item * This also works:
use PAR "/home/mylibs/*.par"; # put all of them into @INC
use Hello;
=back
=head2 PAR Loaders
=over 4
=item * Use C<par.pl> to run files inside a PAR archive:
% par.pl foo.par # looks for 'main.pl' by default
% par.pl foo.par test.pl # runs script/test.pl in foo.par
=item * Same thing, with the stand-alone C<parl> or C<parl.exe>:
% parl foo.par # no perl or PAR.pm needed!
% parl foo.par test.pl # ditto
=item * The PAR loader can prepend itself to a PAR file:
=over 4
=item * C<-b> bundles non-core modules needed by C<PAR.pm>:
% par.pl -b -O./foo.pl foo.par # self-contained script
=item * C<-B> bundles core modules in addition to C<-b>:
% parl -B -O./foo.exe foo.par # self-contained binary
=back
=back
=head2 Dependency Scanning
=over 4
=item * Recursively scan dependencies with C<scandeps.pl>:
% scandeps.pl sshnuke.pl
# Legend: [C]ore [X]ternal [S]ubmodule [?]NotOnCPAN
'Crypt::SSLeay' => '0', # X #
'Net::HTTP' => '0', # #
'Crypt::SSLeay::X509' => '0', # S # Crypt::SSLeay
'Net::HTTP::Methods' => '0', # S # Net::HTTP
'Compress::Zlib' => '0', # X # Net::HTTP::Methods
=item * Scan an one-liner, list all involved files:
% scandeps.pl -V -e "use Dynaloader;"
...
# auto/DynaLoader/dl_findfile.al [autoload]
# auto/DynaLoader/extralibs.ld [autoload]
# auto/File/Glob/Glob.bs [data]
# auto/File/Glob/Glob.so [shared]
...
=back
=head2 Perl Packager: C<pp>
=over 4
=item * Combines scanning, zipping and loader-embedding:
% pp -o out.exe src.pl # self-contained .exe
% out.exe # runs anywhere on the same OS
=item * Bundle additional modules:
% pp -o out.exe -M CGI src.pl # pack CGI + its dependencies, too
=item * Pack one-liners:
% pp -o out.exe -e 'print "Hi!"' # turns one-liner into executable
=item * Generate PAR files instead of executables:
% pp -p src.pl # makes 'source.par'
% pp -B -p src.pl # include core modules
=back
=head2 How it works
=over 4
=item * Command-line options are almost identical to C<perlcc>'s
=over 4
=item * Also supports C<gcc>-style long options:
% pp --gui --verbose --output=out.exe src.pl
=back
=item * Small initial overhead; no runtime overhead
=item * Dependencies are POD-stripped before packing
=item * Loads modules directly into memory on demand
=item * Shared libraries (DLLs) are extracted with File::Temp
=item * Works on Perl 5.6.0 or above
=item * Tested on Win32 (VC++ and MinGW), FreeBSD, NetBSD, Linux, MacOSX, Cygwin, AIX, Solaris, HP-UX, Tru64...
=back
=head2 Aggregating multiple programs
=over 4
=item * A common question:
> I have used pp to make several standalone applications which work
> great, the only problem is that for each executable that I make, I am
> assuming the parl.exe is somehow bundled into the resulting exe.
=item * The obvious workaround:
You can ship parl.exe by itself, along with .par files built
by "pp -p", and run those PAR files by associating them to parl.exe.
=item * On platforms that have C<ln>, there is a better solution:
% pp --output=a.out a.pl b.pl # two scripts in one!
% ln a.out b.out # symlink also works
% ./a.out # runs a.pl
% ./b.out # runs b.pl
=back
=head2 Cross-platform Packages
=over 4
=item * Of course, there is no cross-platform binary format
=item * Pure-perl PAR packages are cross-platform by default
=over 4
=item * However, XS modules are specific to Perl version and platform
=item * Multiple versions of a XS module can co-exist in a PAR file
=back
=item * Suppose we need C<out.par> on both Win32 and Finix:
C:\> pp --multiarch --output=out.par src.pl
...copy src.pl and out.par to a Finix machine...
% pp --multiarch --output=out.par src.pl
=item * Now it works on both platforms:
% parl out.par # runs src.pl
% perl -MPAR=out.par -e '...' # uses modules inside out.par
=back
=head2 The Anatomy of a PAR file
=over 4
=item * Modules can reside in several directories:
/ # casual packaging only
/lib/ # standard location
/arch/ # for creating from blib/
/i386-freebsd/ # i.e. $Config{archname}
/5.8.0/ # i.e. Perl version number
/5.8.0/i386-freebsd/ # combination of the two above
=item * Scripts are stored in one of the two locations:
/ # casual packaging only
/script/ # standard location
=item * Shared libraries may be architecture- or perl-version-specific:
/shlib/(5.8.0/)?(i386-freebsd/)?
=item * PAR files may recursively contain other PAR files:
/par/(5.8.0/)?(i386-freebsd/)?
=back
=head2 Special files
=over 4
=item * MANIFEST
=over 4
=item * Index of all files inside PAR
=item * Can be parsed with C<ExtUtils::Manifest>
=back
=item * META.yml
=over 4
=item * Dependency, license, runtime options
=item * Can be parsed with C<YAML>
=back
=item * SIGNATURE
=over 4
=item * OpenPGP-signed digital signature
=item * Can be parsed and verified with C<Module::Signature>
=back
=back
=head2 Advantages over perlcc, PerlApp and Perl2exe
=over 4
=item * This is not meant to be a flame
=over 4
=item * All three maintainers have contributed to PAR directly; I'm grateful
=back
=item * perlcc
=over 4
=item * "The code generated in this way is not guaranteed to work... Use for production purposes is strongly discouraged." (from perldoc perlcc)
=item * I<Guaranteed to not work> is more like it
=back
=item * PerlApp / Perl2exe
=over 4
=item * Expensive: Need to pay for each upgrade
=item * Non-portable: Only available for limited platforms
=item * Proprietary: Cannot extend its features or fix bugs
=item * Obfuscated: Vendor and black-hats can see your code, but you can't
=item * Inflexible: Does not work with existing Perl installations
=back
=back
=head2 MANIFEST: Best viewed with Mozilla
=over 4
=item * The URL of C<MANIFEST> inside C</home/autrijus/foo.par>:
jar:file:///home/autrijus/foo.par!/MANIFEST
=item * Open it in a Gecko browser (e.g. Netscape 6+) with Javascript enabled:
=item * No needed to unzip anything; just click on files to view them
=back
=head2 META.yml: Metadata galore
=over 4
=item * Static, machine-readable distribution metadata
=over 4
=item * Supported by C<Module::Build>, C<ExtUtils::MakeMaker>, C<Module::Install>
=back
=item * A typical C<pp>-generated C<META.yml> looks like this:
build_requires: {}
conflicts: {}
dist_name: out.par
distribution_type: par
dynamic_config: 0
generated_by: 'Perl Packager version 0.03'
license: unknown
par:
clean: 0
signature: ''
verbatim: 0
version: 0.68
=item * The C<par:> settings controls its runtime behavior
=back
=head2 SIGNATURE: Signing and verifying packages
=over 4
=item * OpenPGP clear-signed manifest with SHA1 digests
=over 4
=item * Supported by C<Module::Signature>, C<CPANPLUS> and C<Module::Build>
=back
=item * A typical C<SIGNATURE> looks like this:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
SHA1 8a014cd6d0f6775552a01d1e6354a69eb6826046 AUTHORS
...
-----BEGIN PGP SIGNATURE-----
...
-----END PGP SIGNATURE-----
=item * Use C<pp> and C<cpansign> to work with signatures:
% pp -s -o foo.par bar.pl # make and sign foo.par from bar.pl
% cpansign -s foo.par # sign this PAR file
% cpansign -v foo.par # verify this PAR file
=back
=head2 Perl Servlets with Apache::PAR
=over 4
=item * Framework for self-contained Web applications
=over 4
=item * Similar to Java's "Web Application Archive" (WAR) files
=item * Works with mod_perl 1.x or 2.x
=back
=item * A complete web application inside a C<.par> file
=over 4
=item * Apache configuration, static files, Perl modules...
=item * Supports Static, Registry and PerlRun handlers
=item * Can also load all PARs under a directory
=back
=item * One additional special file: C<web.conf>
Alias /myapp/cgi-perl/ ##PARFILE##/
<Location /myapp/cgi-perl>
Options +ExecCGI
SetHandler perl-script
PerlHandler Apache::PAR::Registry
</Location>
=back
=head2 Hon Dah, A-par-che!
=over 4
=item * First, make a C<hondah.par> from an one-liner:
# use the "web.conf" from the previous slide
% pp -p -o hondah.par -e 'print "Hon Dah!\n"' \
--add web.conf
% chmod a+x hondah.par
=item * Add this to C<httpd.conf>, then restart apache:
<IfDefine MODPERL2>
PerlModule Apache2
</IfDefine>
PerlAddVar PARInclude /home/autrijus/hondah.par
PerlModule Apache::PAR
=item * Test it out:
% GET http://localhost/myapp/cgi-perl/main.pl
Hon Dah!
=item * Instant one-liner web application that works!
=back
=head2 On-demand library fetching
=over 4
=item * With LWP installed, your can use remote PAR files:
use PAR;
use lib 'http://aut.dyndns.org/par/DBI-latest.par';
use DBI; # always up to date!
=item * Modules are now cached under C<$ENV{PAR_GLOBAL_TEMP}>
=item * Auto-updates with C<LWP::Simple::mirror>
=over 4
=item * Download only if modified
=item * Safe for offline use after the first time
=item * May use C<SIGNATURE> to prevent DNS-spoofing
=back
=item * Makes large-scale deployment a breeze
=over 4
=item * Upgrades from a central location
=item * No installers needed
=back
=back
=head2 Code Obfuscation
=over 4
=item * Also known as I<source-hiding> techniques
=over 4
=item * It is I<not> encryption
=item * Offered by PerlApp, Perl2Exe, Stunnix...
=back
=item * Usually easy to defeat
=over 4
=item * Take optree dump from memory, feed to C<B::Deparse>
=item * If you just want to stop a casual C<grep>, "deflate" already works
=back
=item * PAR now supports pluggable I<input filters> with C<pp -f>
=over 4
=item * Bundled examples: Bleach, PodStrip and PatchContent
=item * True encryption using C<Crypt::*>
=item * Or even _product activation_ over the internet
=back
=item * Alternatively, just keep core logic in your server and use RPC
=back
=head2 Accessing packed files
=over 4
=item * To get the host archive from a packed program:
my $zip = PAR::par_handle($0); # an Archive::Zip object
my $content = $zip->contents('MANIFEST');
=item * Same thing, but with C<read_file()>:
my $content = PAR::read_file('MANIFEST');
=item * Loaded PAR files are stored in C<%PAR::LibCache>:
use PAR '/home/mylibs/*.par';
while (my ($filename, $zip) = each %PAR::LibCache) {
print "[$filename - MANIFEST]\n";
print $zip->contents('MANIFEST');
}
=back
=head2 Packing GUI applications
=over 4
=item * GUI toolkits often need to link with shared libraries:
# search for libncurses under library paths and pack it
% pp -l ncurses curses_app.pl # same for Tk, Wx, Gtk, Qt...
=item * Use C<pp --gui> on Win32 to eliminate the console window:
# pack 'src.pl' into a console-less 'out.exe' (Win32 only)
% pp --gui -o out.exe src.pl
=item * "Can't locate Foo/Widget/Bar.pm in @INC"?
=over 4
=item * Some toolkits (notably Tk) autoloads modules without C<use> or C<require>
=item * Hence C<pp> and C<Module::ScanDeps> may fail to detect them
=item * Tk problems mostly fixed by now, but other toolkits may still break
=item * You can work around it with C<pp -M> or an explicit C<require>
=item * Or better, send a short test-case to C<par@perl.org> so we can fix it
=back
=back
=head2 Precompiled CPAN distributions
=over 4
=item * Installing XS extensions from CPAN was difficult
=over 4
=item * Some platforms do not come with a compiler (Win32, MacOSX...)
=item * Some headers or libraries may be missing
=item * PAR.pm itself used to suffer from both problems
=back
=item * ...but not anymore -- C<Module::Install> to the rescue!
# same old Makefile.PL, with a few changes
use inc::Module::Install; # was "use ExtUtils::MakeMaker;"
WriteMakefile( ... ); # same as the original
check_nmake(); # make sure the user have nmake
par_base('AUTRIJUS'); # your CPAN ID or a URL
fetch_par() unless can_cc(); # use precompiled PAR only if necessary
=item * Users will not notice anything, except now it works
=over 4
=item * Of course, you still need to type C<make par> and upload the precompiled package
=item * PAR users can also install it directly with C<parl -i>
=back
=back
=head2 Thank you!
=over 4
=item * Additional resources
=over 4
=item * Mailing list: C<par@perl.org>
=item * Subscribe: Send a blank email to C<par-subscribe@perl.org>
=item * List archive: L<http://nntp.x.perl.org/group/perl.par>
=item * PAR::Intro: L<http://search.cpan.org/dist/PAR/lib/PAR/Intro.pod>
=item * Apache::PAR: L<http://search.cpan.org/dist/Apache-PAR/>
=item * Module::Install: L<http://search.cpan.org/dist/Module-Install/>
=back
=item * Any questions?
=back
=head2 Overview of PAR.pm's Implementation
=over 4
=item * Here begins the scary part
=over 4
=item * Grues, Dragons and Jabberwocks abound...
=item * You are going to learn weird things about Perl internals
=back
=item * PAR invokes four areas of Perl arcana:
=over 4
=item * @INC code references
=item * On-the-fly source filtering
=item * Overriding C<DynaLoader::bootstrap()> to handle XS modules
=item * Making self-bootstrapping binary executables
=back
=item * The first two only works on 5.6 or later
=over 4
=item * DynaLoader and C<%INC> are there since Perl 5 was born
=item * PAR currently needs 5.6, but a 5.005 port is possible
=back
=back
=head2 Code References in @INC
=over 4
=item * On 1999-07-19, Ken Fox submitted a patch to P5P
=over 4
=item * To _enable using remote modules_ by putting hooks in @INC
=item * It's accepted to come in Perl 5.6, but undocumented until 5.8
=item * Type C<perldoc -f require> to read the nitty-gritty details
=back
=item * Coderefs in @INC may return a fh, or undef to 'pass':
push @INC, sub {
my ($coderef, $filename) = @_; # $coderef is \&my_sub
open my $fh, "wget ftp://example.com/$filename |";
return $fh; # using remote modules, indeed!
};
=item * Perl 5.8 let you open a file handle to a string, so we just use that:
open my $fh, '<', \($zip->memberNamed($filename)->contents);
return $fh;
=item * But Perl 5.6 does not have that, and I don't want to use temp files...
=back
=head2 Source Filtering without Filter::* Modules
=over 4
=item * ... Undocumented features to the rescue!
=over 4
=item * It turns out that @INC hooks can return B<two> values
=item * The first is still the file handle
=item * The second is a code reference for line-by-line source filtering!
=back
=item * This is how C<Acme::use::strict::with::pride> works:
# Force all modules used to use strict and warnings
open my $fh, "<", $filename or return;
my @lines = ("use strict; use warnings;\n", "#line 1 \"$full\"\n");
return ($fh, sub {
return 0 unless @lines;
push @lines, $_; $_ = shift @lines; return length $_;
});
=back
=head2 Source Filtering without Filter::* Modules (cont.)
=over 4
=item * But we don't really have a filehandle for anything
=item * Another undocumented feature saves the day!
=item * We can actually omit the first return value altogether:
# Return all contents line-by-line from the file inside PAR
my @lines = split(
/(?<=\n)/,
$zip->memberNamed($filename)->contents
);
return (sub {
$_ = shift(@lines);
return length $_;
});
=back
=head2 Overriding DynaLoader::bootstrap
=over 4
=item * XS modules have dynamically loaded libraries
=over 4
=item * They cannot be loaded as part of a zip file, so we extract them out
=item * Must intercept DynaLoader's library-finding process
=back
=item * Module names are passed to C<bootstrap> for XS loading
=over 4
=item * During the process, it calls C<dl_findfile> to locate the file
=item * So we install pre-hooks around both functions
=back
=item * Our C<_bootstrap> just checks if the library is in PARs
=over 4
=item * If yes, extract it to a C<File::Temp> temp file
=over 4
=item * The file will be automatically cleaned up when the program ends
=back
=item * It then pass the arguments to the original C<bootstrap>
=item * Finally, our C<dl_findfile> intercepts known filenames and return it
=back
=back
=head2 Anatomy of a Self-Contained PAR executable
=over 4
=item * The par script ($0) itself
=over 4
=item * May be in plain-text or native executable format
=back
=item * Any number of embedded files
=over 4
=item * Typically used to bootstrap PAR's various dependencies
=item * Each section begins with the magic string "FILE"
=item * Length of filename in pack('N') format and the filename (auto/.../)
=item * File length in pack('N') and the file's content (not compressed)
=back
=item * One PAR file
=over 4
=item * Just a regular zip file with the magic string C<"PK\003\004">
=back
=item * Ending section
=over 4
=item * A pack('N') number of the total length of FILE and PAR sections
=item * Finally, there must be a 8-bytes magic string: C<"\012PAR.pm\012">
=back
=back
=head2 Self-Bootstrapping Tricks
=over 4
=item * All we can expect is a working perl interpreter
=over 4
=item * The self-contained script *must not* use any modules at all
=item * But to process PAR files, we need XS modules like Compress::Zlib
=back
=item * Answer: bundle all modules + libraries used by PAR.pm
=over 4
=item * That's what the C<FILE> section in the previous slide is for
=item * Load modules to memory, and write object files to disk
=item * Then use a local C<@INC> hook to load them on demand
=back
=item * Minimizing the amount of temporary files
=over 4
=item * First, try to load PerlIO::scalar and File::Temp
=item * Set up an END hook to unlink all temp files up to this point
=item * Load other bundled files, and look in the compressed PAR section
=item * This can be much easier with a pure-perl C<inflate()>; patches welcome!
=back
=back
=head2 Thank you (again)!
=over 4
=item * Any questions, I<please>?
=back
=cut
=head1 SEE ALSO
L<PAR>, L<pp>, L<par.pl>, L<parl>
L<ex::lib::zip>, L<Acme::use::strict::with::pride>
L<App::Packer>, L<Apache::PAR>, L<CPANPLUS>, L<Module::Install>
=head1 AUTHORS
Audrey Tang E<lt>cpan@audreyt.orgE<gt>
You can write
to the mailing list at E<lt>par@perl.orgE<gt>, or send an empty mail to
E<lt>par-subscribe@perl.orgE<gt> to participate in the discussion.
Please submit bug reports to E<lt>bug-par@rt.cpan.orgE<gt>.
=head1 COPYRIGHT
Copyright 2003, 2004, 2005, 2006 by Audrey Tang E<lt>cpan@audreyt.orgE<gt>.
This document is free documentation; you can redistribute it and/or
modify it under the same terms as Perl itself.
See F<LICENSE>.
=cut
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