Alien::Package - an object that represents a package

This is a perl object class that represents a package in an internal format usable by alien. The package may be a deb, a rpm, a tgz, or a slp package, etc. Objects in this class hold various fields of metadata from the actual packages they represent, as well as some fields pointing to the actual contents of the package. They can also examine an actual package on disk, and populate those fields. And they can build the actual package using the data stored in the fields.

A typical use of this object class will be to instantiate an object from a class derived from this one, such as Alien::Package::Rpm. Feed the object a rpm file, thus populating all of its fields. Then rebless the object into the destination class, such as Alien::Package::Deb. Finally, ask the object to build a package, and the package has been converted.

These fields are of course really just methods that all act similarly; allowing a value to be passed in to set them, or simply returning the value of the field if nothing is passed in. Child classes may override these fields to process input data, or to format output data. The general rule is that input data is modified to get things into a package-independant form, which is how the data is stored in the fields. When the value of a field is read, it too may be modified before it is returned, to change things into a form more suitable for the particular type of package.

name

The package's name.

version

The package's upstream version.

release

The package's distribution specific release number.

arch

The package's architecture, in the format used by Debian.

maintainer

The package's maintainer.

depends

The package's dependancies. Only dependencies that should exist on all target distributions can be put in here though (ie: lsb).

group

The section the package is in.

summary

A one line description of the package.

description

A longer description of the package. May contain multiple paragraphs.

copyright

A short statement of copyright.

origformat

What format the package was originally in.

distribution

What distribution family the package originated from.

binary_info

Whatever the package's package tool says when told to display info about the package.

conffiles

A reference to a list of all the conffiles in the package.

files

A reference to a list of all the files in the package.

changelogtext

The text of the changelog

postinst

The postinst script of the package.

postrm

The postrm script of the package.

preinst

The preinst script of the package.

prerm

The prerm script of the package.

usescripts

Only use the above scripts fields when generating the package if this is set to a true value.

unpacked_tree

Points to a directory where the package has been unpacked.

owninfo

If set this will be a reference to a hash, with filename as key, that holds ownership/group information for files that cannot be represented on the filesystem. Typically that is because the owners or groups just don't exist yet. It will be set at unpack time.

modeinfo

If set this will be a reference to a hash, with filename as key, that holds mode information for setuid files that have an entry in owninfo. It will be set at unpack time.

init

This is called by new(). It's a handy place to set fields, etc, without having to write your own new() method.

install

Simply installs a package file. The filename is passed. This has to be overridden in child classes.

test

Test a package file. The filename is passed, should return an array of lines of test results. Child classses may implement this.

filename

Set/get the filename of the package the object represents. When it is set, it performs a scan of the file, populating most other fields with data from it. (This is just a stub; child classes should override it to actually do something.)

scripts

Returns a list of all non-empty maintainer scripts in the package.

scan

This method scans the file associated with an object, and populates as many other fields as it can with data from it.

unpack

This method unpacks the package into a temporary directory. It sets unpacked_tree to point to that directory. (This is just a stub method that makes a directory below the current working directory, and sets unpacked_tree to point to it. It should be overridden by child classes to actually unpack the package as well.)

prep

This method causes the object to prepare a build tree to be used in building the object. It expects that the unpack method has already been called. It takes the tree generated by that method, and mangles it somehow, to produce a suitable build tree. (This is just a stub method that all child classes should override.)

cleantree

This method should clean the unpacked_tree of any effects the prep and build methods might have on it.

revert

This method should ensure that the object is in the same state it was in before the prep method was called.

build

This method takes a prepped build tree, and simply builds a package from it. It should put the package in the current directory, and should return the filename of the generated package. (This is just a stub method that all child classes should override.)

DESTROY

When an object is destroyed, it cleans some stuff up. In particular, if the package was unpacked, it is time now to wipe out the temporary directory.

AUTOLOAD

Handles all fields, by creating accessor methods for them the first time they are accessed.

$Alien::Package::verbose

If set to a nonzero value, the shell commands that are run should be output. If set to a value greater than 1, any output of the commands should also be output.

These methods can be called on either an object or on the class itself.

new

Returns a new object of this class. Optionally, you can pass in named parameters that specify the values of any fields in the class.

checkfile

Pass it a filename, and it will return true if it looks like the file is a package of the type handled by the class.

do

Runs a shell command. Is verbose or not depending on the value of CW$Alien::Package::verbose. Returns true if the command succeeds, false on failure.

runpipe

This is similar to backticks, but honors CW$Alien::Package::verbose, logging the command run if asked to. The output of the command is returned. The first parameter controls what to do on error. If it's true then any errors from the command will be ignored (and $? will be set). If it's false, errors will abort alien.

Joey Hess <joey@kitenet.net>