path: root/docs/cpt.org

#+TITLE: Carbs Packaging Tools
#+SUBTITLE: User Manual
#+AUTHOR: Cem Keylan
#+EMAIL: cem@ckyln.com
#+TEXINFO_FILENAME: cpt.info
#+TEXINFO_DIR_CATEGORY: Development
#+TEXINFO_DIR_TITLE: Carbs Packaging Tools: (cpt)
#+TEXINFO_DIR_DESC: Carbs Package Management Library
#+INCLUDE: ./config.org
#+OPTIONS: html-scripts:nil todo:nil

#+MACRO: index (eval (format (if (org-export-derived-backend-p org-export-current-backend 'texinfo) "%s Index\n:PROPERTIES:\n:INDEX: %s\n:DESCRIPTION: %ss mentioned in this manual\n:END:\n" "%s%s%s :noexport:\n") $1 $2 $1))

This is a reference document containing both the user-guide and the development
manual for *Carbs Packaging Tools* version {{{version}}}. For development logs
see [[https://fossil.carbslinux.org/cpt][the fossil repository]].

* Copying
:PROPERTIES:
:COPYING:  t
:END:

Copyright \copy 2020-2021 Cem Keylan

#+begin_quote
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License, Version 1.3 or any later version
published by the Free Software Foundation; with no Invariant Sections, with no
Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in
the section entitled "GNU Free Documentation License."
#+end_quote

* Preface
:PROPERTIES:
:DESCRIPTION: Introduction to Carbs Packaging Tools
:END:

Carbs Linux uses its own package management toolchain named =cpt= which was
initially forked from the [[https://github.com/kisslinux/kiss][kiss]] package manager. Unlike =kiss=, however, its main
goal is being easily extendable. Instead of being a single file package manager,
it revolves around the shell library =cpt-lib=, and many tools that wrap around
it. This document aims to document both the usage of the distributed tools and
document the library functions.

If you happen to find something that is not properly covered by the
documentation, or an area that can be improved, please feel free to submit a
patch, or [[https://fossil.carbslinux.org/cpt/tktnew][open a ticket]].

* Usage
:PROPERTIES:
:DESCRIPTION: Basic usage of Carbs Packaging Tools
:END:

=cpt= is formed of many tools combined in a single environment, similar to
=git=. When you run =cpt= without any arguments, it will show all available
tools and their explanations. Here is an example call with extra scripts on my
system:

#+BEGIN_EXAMPLE
  -> Carbs Packaging Tool
  -> add               Commit the current directory as a new package
  -> alternatives      List and swap to alternatives
  -> build             Build a package
  -> bump              Commit the current directory as a version bump
  -> cargo-urlgen      Create static cargo sources for Rust packages
  -> cargolock-urlgen  Convert the given Cargo.lock file to sources
  -> cat               Concatanate package files in the installed package database
  -> changelog         Print the git log of the specific package
  -> chbuild           Create/destroy temporary chroots
  -> checkmissing      Verify package manifests
  -> checksum          Generate checksums
  -> chroot            Enter a chroot
  -> commit            Commit a package without the prefix of 'package:'
  -> depends           Display a package's dependencies
  -> download          Download sources for the given package
  -> exec              Execute a command inside the alternatives system
  -> export            Turn an installed package into a CPT tarball
  -> fork              Fork a package to the current directory
  -> getchoice         Prints the full path to a file in the alternatives system.
  -> install           Install a package
  -> link              Link a forked package's files to the other repository
  -> list              List installed packages
  -> maintainer        Find the maintainer of a package
  -> manifest          Display all files owned by a package
  -> manifest-tree     Display all files owned by a package with a tree view
  -> new               Create a boilerplate CPT package
  -> orphans           List orphaned packages
  -> owns              Check which package owns a file
  -> rel               Bump the release number of a package
  -> remove            Remove a package
  -> repodepends       Display a package's dependencies in the repository
  -> reporevdepends    Display packages on the repository which depend on package
  -> reset             Remove all packages except for the base
  -> revdepends        Display packages which depend on package
  -> search            Search for a package
  -> size              Show the size on disk for a package
  -> source            Extract sources of a given package to the current directory
  -> update            Check for updates
#+END_EXAMPLE

The documentation of =cpt= aims to keep tool flags and related usage information
on concise manual pages, while moving the rest of the information to this User
Manual to avoid unwarranted duplication. To learn more on a specific usage of a
tool, use the ~man~ program:

#+begin_src sh
man cpt-build
#+end_src

* Configuration
:PROPERTIES:
:DESCRIPTION: Configuring the package manager
:END:

The package manager does *NOT* have a configuration file, but there are a
variety of ways in order to interact with and configure the package manager.

** Configuration directory

Some features of the package manager can be configured from the files found
under {{{conf_dir}}}. Even though this doesn't sound like the premise of "no
configuration" files, these files are completely optional to the package
manager, and still the majority of configuration is done through environment
variables. The files on this directory are for configuration that don't have a
big impact on how the package manager behaves, and are not feasible to be used
inside simple environment variables (such as the base package list and
package manager hooks).

*** CPT Base
:PROPERTIES:
:DESCRIPTION: Defining base packages
:END:

#+CINDEX: Base packages

The file {{{conf_dir(base)}}} can be used in order to define the base to the
package manager. Base packages are the packages that receive special treatment
by utilities such as =cpt-reset=, and =cpt-orphans=.

#+begin_example
# This file defines the base packages of the system. You can add or remove
# package names in order to redefine the base. This file will be used by
# cpt-orphans and cpt-reset. If this file doesn't exist on /etc/cpt/base, both
# of the tools will assume that there is no defined base, so use with caution.
baselayout
binutils
byacc
busybox
bzip2
ca-certificates
curl
flex
gcc
git
rsync
gzip
cpt
bearssl
linux-headers
m4
make
musl
pkgconf
xz
zlib
#+end_example

*** Systemwide hooks

A collection of hooks can be installed under {{{conf_dir(hooks/)}}}. All of the
files installed under this directory will then be sourced by the package manager
whenever a hook is called. Some examples for system hooks can be found under the
{{{data_dir(cpt/examples/hooks/)}}} directory.

** Environment Variables
:PROPERTIES:
:DESCRIPTION: Change the behaviour of cpt through environment configuration
:END:

Since there is no configuration file for =cpt=, the package manager is
configured through environment variables. These can be set per operation, or be
set to your shell configuration or =~/.profile=. Here are the environment
variables that alter the behaviour of =cpt=, some of them have separate sections
to provide detailed information.

- ~CPT_PATH~ ::

  #+VINDEX: CPT_PATH
  Set the locations of your repositories. It is similar to the ~PATH~ variable.

- ~CPT_CACHE~  ::

  #+VINDEX: CPT_CACHE
  The cache directory for =cpt=. Default: ~$XDG_CACHE_HOME/cpt~.

- ~CPT_CHOICE~ ::

  #+VINDEX: CPT_CHOICE
  If this is set to 0, a package installation will be aborted on conflicts.

- ~CPT_COLOR~ ::

  #+VINDEX: CPT_COLOR
  If this is set to 1, =cpt= tools will be forced to display coloured output. If
  set to 0, they will be forced to display them without colours. Otherwise,
  =cpt= will output colour as long as it is outputting to a terminal.

- ~CPT_DEBUG~ ::

  #+VINDEX: CPT_DEBUG
  If set to 1, temporary directories will not be removed after the operation.

- ~CPT_DOWNLOADER~ ::

  The tool to be used to download package sources. One of =curl=, =wget=,
  =wget2=, =axel=, =aria2c=. Defaults to the first one found in that order.

- ~CPT_FETCH~ ::

  #+VINDEX: CPT_FETCH
  If set to 0, ~cpt-update~ will not fetch repositories.

- ~CPT_FORCE~ ::

  #+VINDEX: CPT_FORCE
  If set to 1, =cpt= tools will force operation.

- ~CPT_HOOK~ ::

  #+VINDEX: CPT_HOOK
  Absolute path to the package manager hook file.

- ~CPT_KEEPLOG~ ::

  #+VINDEX: CPT_KEEPLOG
  If set to 1, =cpt= will keep logs regardless of operation success.

- ~CPT_PID~ ::

  #+VINDEX: CPT_PID
  Set the temporary build directory name.

- ~CPT_PROMPT~ ::

  #+VINDEX: CPT_PROMPT
  If set to 0, =cpt= will not prompt you for anything.

- ~CPT_REPO_CACHE~ ::

  #+VINDEX: CPT_REPO_CACHE
  If set to 0, =cpt= will not use or write repository information cache.

- ~CPT_ROOT~ ::

  #+VINDEX: CPT_ROOT
  If this variable is set, =cpt= will assume the given path as the system root.

- ~CPT_TEST~ ::

  #+VINDEX: CPT_TEST
  If set to 1, ~cpt-build~ will run tests whenever available.

- ~CPT_TMPDIR~ ::

  #+VINDEX: CPT_TMPDIR
  The directory to create the temporary directories.

- ~CPT_VERBOSE~ ::

  #+VINDEX: CPT_VERBOSE
  If this variable is set to 1, the package manager will print more information.

*** =CPT_PATH=
:PROPERTIES:
:DESCRIPTION: Set the locations of your repositories
:END:

#+CINDEX: Setting up repositories
Similar to the =PATH= variable, =cpt= find repositories from the =CPT_PATH=
variable. Here is an example:

#+begin_src sh
  CPT_PATH=$HOME/repos/repo1:$HOME/repos/repo2:$HOME/repos/repo3
#+end_src

This is a simplistic and a structured example for repository locations, but it
doesn't necessarily need to be as tidy as the example above. Here is an example
for something a little more complex.

#+begin_src sh
  CPT_PATH=$HOME/repos/overrides:/var/db/cpt/repo/core:/var/db/cpt/repo/extra:$HOME/repos/personal
#+end_src

This example brings us to the next section of this document.

**** Repository preferences
:PROPERTIES:
:DESCRIPTION: Prioritise package repositories
:END:

#+CINDEX: package conflicts
When you are using multiple repositories from multiple vendors, you will find
out that some repositories have the same packages. =cpt= doesn't care about
conflicting packages. If you want to build a package that exists on multiple
repositories, =cpt= will build the first matching package. This means that if
=grep= package (for the sake of an example) exists on both
=$HOME/repos/personal= and =$HOME/repos/carbs/extra=, and you want
to install from your personal repository, you must set =CPT_PATH= so that your
personal repository is listed before the =extra= repository.

#+begin_src sh
  CPT_PATH=$HOME/repos/personal:$HOME/repos/carbs/extra
#+end_src

**** Setting the =CPT_PATH=
:PROPERTIES:
:DESCRIPTION: Set the value of CPT_PATH on your shell configuration
:END:

You can set the =CPT_PATH= variable on your shell configuration or your
=.profile= file in a way that is easy to read.

The below example sets =CPT_PATH= in a way that is easy to understand which
repository comes first:

#+begin_src sh
  CPT_PATH=$HOME/repos/overrides
  CPT_PATH=$CPT_PATH:$HOME/repos/carbs/core
  CPT_PATH=$CPT_PATH:$HOME/repos/carbs/extra
  CPT_PATH=$CPT_PATH:$HOME/repos/carbs/xorg
  CPT_PATH=$CPT_PATH:$HOME/repos/personal
  export CPT_PATH
#+end_src

*** =CPT_COMPRESS=
:PROPERTIES:
:DESCRIPTION: Compression tool to use in cpt
:END:

When setting the =CPT_COMPRESS= value, you should set the name of the default
suffixes for the program. Available values are:

- =gz=
- =zst=
- =bz2=
- =xz=
- =lz=

Defaults to =gz=.

*** =CPT_FORCE=
:PROPERTIES:
:DESCRIPTION: Force operations on cpt
:END:

If this is set to 1, some of the =cpt= tools will continue regardless of
errors or skip certain checks. Here are some examples:

- =cpt-install= will install a package without verifying its manifest.
- =cpt-install= will install a package even when there are missing dependencies.
- =cpt-remove= will remove packages even when there are other packages that
  depend on the current package.

Defaults to 0.

*** =CPT_PID=
:PROPERTIES:
:DESCRIPTION: Set reproducible temporary directories
:END:

If this variable is set, the temporary files will be created with this variable
as the suffix, instead of the PID of the =cpt= process. The advantage is that
you can know exactly where the build directory is located, while the
disadvantage is that there will be issues with multiple operations at the same
time. So the best way to use this variable is during one-time =cpt= calls.

#+BEGIN_EXAMPLE
  CPT_PID=mesa cpt b mesa
#+END_EXAMPLE

By running the above, you will know that the created build directories will end
with the =*-mesa= suffix.

** Hooks
:PROPERTIES:
:DESCRIPTION: Use hooks to customize the package manager operations
:END:

Hooks can be used in order to change the runtime behaviour of the package manager.
There are a variety of package hooks, mostly self explanatory:

- pre-build    :: Run just before the ~build~ script is run
- post-build   :: Run after the ~build~ script is run successfully
- build-fail   :: Run if the ~build~ script fails
- pre-test     :: Run before the ~test~ script is run
- test-fail    :: Run if the ~test~ script fails
- pre-install  :: Run before a package is installed for each package
- post-install :: Run after a package is installed for each package
- end-install  :: Run after all given packages are installed
- pre-remove   :: Run before a package is removed for each package
- post-remove  :: Run after a package is removed for each package
- end-remove   :: Run after all given packages are removed
- pre-fetch    :: Run before all repositories are fetched
- post-fetch   :: Run after all repositories are fetched
- post-package :: Run after a tarball for a package is created

In order to use hooks, you will need to set the =CPT_HOOK= variable pointing to
your hook file. Your hook file *MUST* be a POSIX shell script as its contents
are sourced by the package manager.

The hook is given 3 variables when it is executed. Those are:

- ~$TYPE~ ::
  The type of the hook, (=pre-build=, =post-build=, etc.)
- ~$PKG~  ::
  The package that =cpt= is currently working on. Can be null.
- ~$DEST~ ::
  The destination of the operation. Can be null.

** Editing the build file during pre-build
:PROPERTIES:
:DESCRIPTION: Modify a package build with your hooks
:END:

You can edit the =build= file during pre-build. The file is copied from the
repository to the build directory named as =.build.cpt=. You can use =sed= or
any other tool to edit the build file. After the build is complete, a =diff=
file will be placed to the package database named as =build.diff=. Here is an
example =build= file manipulation during the pre-build hook.

#+BEGIN_SRC sh
cat <<EOF> .build.cpt
#!/bin/sh -e

for patch in bash50-0??; do
    patch -p0 < "\$patch"
done

export LDFLAGS=-static

./configure \
    --prefix=/usr \
    --without-bash-malloc \
    --disable-nls

export MAKEFLAGS="TERMCAP_LIB=/usr/lib/libncursesw.a $MAKEFLAGS"

make
make DESTDIR="\$1" install

ln -s bash "\$1/usr/bin/sh"
EOF
#+END_SRC

* Packaging System
:PROPERTIES:
:DESCRIPTION: More detail on creating packages
:END:

A package is a directory formed of several files, from these files, only
~build~, ~checksums~, and ~version~ files are mandatory.

This section talks about files that are interpreted specially by the package
manager. Any other file can be added to the package directory at the discretion
of the package maintainer. Everything in the package directory will also be
added to the package database that is located on =/var/db/cpt/installed=. These
can be patches, configuration files, etc.

Below is a table that provides a small summary for each file, see the relevant
section to learn detailed information on each of them.

| File         | Language                           | Executable | Mandatory |
|--------------+------------------------------------+------------+-----------|
| build        | any                                | yes        | yes       |
| checksums    | generated by =cpt-checksum=        | no         | no        |
| meta         | key-value pairs as in RFC822[fn:1] | no         | no[fn:2]  |
| depends      | custom format                      | no         | no        |
| sources      | custom format                      | no         | no        |
| version      | custom format                      | no         | yes       |
| message      | plaintext                          | no         | no        |
| post-install | any                                | yes        | no        |
| test         | any                                | yes        | no        |

** build
:PROPERTIES:
:DESCRIPTION: The build script
:END:

Typically =build= files are shell scripts that run commands to prepare the source
code to be installed on the target system. Even though we will be assuming that
the =build= file is a POSIX shell script (for portability's sake), =build=
files can be any executable program from binary programs to =perl= scripts.

The contents of a build script do not need to follow a certain rule for the
package manager, except for the fact that the user needs the permission to
execute the file.

An important advice is to append an '-e' to the shebang (#!/bin/sh -e) so that
the build script exits on compilation error.

Build is run with three arguments (=$#=)

- Location of the package directory (DESTDIR)
- Package version
- System architecture

** sources
:PROPERTIES:
:DESCRIPTION: The file containing package sources
:END:

=sources= file is a list of files and sources that will be put to the build
directory during the build process. Those can be remote sources (such as tarballs),
git repositories, and files that reside on the package directory.

The syntax is pretty simple for the =soures= file; =src dest=. The =dest=
parameter is optional. It is the directory that the source will be placed in.
Here is the =sources= file for the =gst-plugins= package:

#+BEGIN_EXAMPLE
  https://gstreamer.freedesktop.org/src/gst-plugins-good/gst-plugins-good-1.16.2.tar.xz good
  https://gstreamer.freedesktop.org/src/gst-plugins-bad/gst-plugins-bad-1.16.2.tar.xz   bad
  https://gstreamer.freedesktop.org/src/gst-plugins-ugly/gst-plugins-ugly-1.16.2.tar.xz ugly
  https://gstreamer.freedesktop.org/src/gst-libav/gst-libav-1.16.2.tar.xz               libav
#+END_EXAMPLE

This file is read from the package manager as space seperated. Files that begin
with a =#= comment are ignored. The first value points to the location of the
source.

If it starts with a protcol url, (such as ftp:// http:// https://) it will be
downloaded with =curl=.

If the source is a git repository, it shall be prefixed with a =git+= git(1) will
be used to do a shallow clone of the repository. If the commit is suffixed by a
history pointer, git will checkout the relevant revision. So,

- =git+git://example.com/pub/repo@v1.2.3= :: will checkout the tag named "v1.2.3"
- =git+git://example.com/pub/repo#development= :: will checkout the branch named "development"
- =git+git://example.com/pub/repo#1a314s87= :: will checkout the commit named "1a314s87"

Other files are assumed to be residing in the package directory. They should be
added with their paths relative to the package directory.

** checksums
:PROPERTIES:
:DESCRIPTION: The file containing sha256sum of the sources
:END:

=checksums= file is generated by the ~cpt c pkg~ command. It is generated
according to the order of the sources file. That's why you shouldn't be editing
it manually. The checksums file is created with the digests of the files using
the sha256 algorithm.

** version
:PROPERTIES:
:DESCRIPTION: The file containing version information for a package
:END:

The version file includes the version of the software and the release number of
of the package on a space seperated format. The contents of the file should look
like below.

#+BEGIN_EXAMPLE
  1.3.2 1
#+END_EXAMPLE

** depends
:PROPERTIES:
:DESCRIPTION: The file containing the dependencies of a package
:END:

This is a list of dependencies that must be installed before a package build. You
can append "make" after a dependency to mark a package is only required during
the build process of a package. Packages marked as a make dependency can be
removed after the build. There are also "test" dependencies. These dependencies
are only installed if either the =CPT_TEST= is set to 1, or the build is run
with the =-t= or =--test= options. So, a package package could have
the following =depends= file:

#+BEGIN_EXAMPLE
  linux-headers make
  python        test
  zlib
#+END_EXAMPLE

** meta
:PROPERTIES:
:DESCRIPTION: File containing more information on packages
:END:

=meta= is a non-mandatory package file that can be used to provide information
otherwise non-relevant to the functions of the package manager. This file can
later be queried with the [[=pkg_query_meta()=][pkg_query_meta()]] function. The file has a simple
markup format, it must adhere to the =KEY: VAL= format. An example for the =cpt=
package would be as follows:

#+begin_example
description: Carbs Packaging Tools
license: MIT
maintainer: Linux User <linux-user@example.com>
#+end_example

Even though =meta= is not mandatory by the packaging system, it is a mandatory
file for submitting packages to Carbs Linux repositories.

** post-install
:PROPERTIES:
:DESCRIPTION: The post-installation script
:END:

=post-install= files have the same requirements as the build script. They
will be run after the package is installed as root (or as the user if the user
has write permissions on =CPT_ROOT=).

** message
:PROPERTIES:
:DESCRIPTION: The post-installation message to be displayed
:END:

This plaintext file will be outputted with =cat= after every package is
installed.

** test
:PROPERTIES:
:DESCRIPTION: The test script for a package
:END:

#+VINDEX: CPT_TEST
Test files are mainly for the repository maintainer to test the packages, and
will only run if the user has the =CPT_TEST= variable set, or the build is
run with the =-t= or =--test= options. This script is run on the
build directory. It is run right after the build script is finished.

* Package Repositories
:PROPERTIES:
:DESCRIPTION: Ways of distributing packages
:END:

*cpt* has backends to support the use of a variety of distribution methods. You
can currently use Git, Mercurial, Fossil, and Rsync to distribute a package
repository. That, however, does not mean that you need to setup either of those,
if you are simply going for a local repository on your system.

#+CINDEX: Setting up repositories
In the broad sense, a package repository is any directory that contains packages
that were described in [[Packaging System]]. This means that as long as you can
serve them, there is not much needed to do in order to distribute a repository.
The following subsections aim to detail the notes and the caveats of certain
distribution methods.

** Rsync Repositories
:PROPERTIES:
:DESCRIPTION: Information on using or creating rsync repositories
:END:

Rsync repositories are simple to serve and simple to use. In the repository
directory, there needs to be a =.rsync= file that points to the remote of the
repository. This is used in order to fetch changes from the upstream. =.rsync=
file looks like this for the core repository:

#+BEGIN_EXAMPLE
  rsync://carbslinux.org/repo/core
#+END_EXAMPLE

Rsync repositories have some few distinctions when it comes to fetching them.
They can be either synced individually or as a "root". There are 2 important
files, those are =.rsync= and =.rsync_root=. Here is the Carbs Linux
rsync repository structure.

#+BEGIN_EXAMPLE
             /
     -----------------
    |                |
  .rsync           core/
            ----------------
            |              |
          .rsync      .rsync_root
#+END_EXAMPLE

Unlike git repositories, they don't have a defined "root" directory. This is
both an advantage and a disadvantage. This way, we can sync individual
repositories, but that also means we need extra files to define root directories
and repository locations. Here is the content for each of these files:

#+BEGIN_EXAMPLE
  /.rsync:           rsync://carbslinux.org/repo
  /core/.rsync:      rsync://carbslinux.org/repo/core
  /core/.rsync_root: ..
#+END_EXAMPLE

The =.rsync_root= file on the core repository points to the upper directory.
If a =.rsync= file exists on the upper directory, this means that is the whole
repository and will sync the entire repository instead of each individual repository.

If the upper directory doesn't have this =.rsync= file, this means that this
is an individual repository, and the package manager will fetch accordingly.

*** Setting up an Rsync repository
:PROPERTIES:
:DESCRIPTION: Set up a repository for distribution
:END:

Carbs Linux repositories automatically sync from the git repostitories and serve
it through the rsync daemon. Here is a sample shell script that I use in order to
sync repositories. Feel free to customize for your own use.

#+BEGIN_SRC sh
  #!/bin/sh
  HOSTNAME="rsync://carbslinux.org/repo"
  GITDIR="/pub/git/repo"
  SHAREDIR="/pub/share/repo"
  git -C "$GITDIR" pull

  rsync -avcC --delete --include=core --exclude=.rsync,.rsync_root "$GITDIR/." "$SHAREDIR"

  printf '%s\n' "$HOSTNAME" > "$GITDIR/.rsync"
  for dir in "$GITDIR/"*; do
      [ -d "$dir" ] || continue
      [ -f "$dir/.rsync" ] ||
      printf '%s/%s\n' "$HOSTNAME" "${dir##*/}" > "$dir/.rsync"
      printf '..\n' > "$dir/.rsync_root"
  done
#+END_SRC

You can then create an *rsync* user for serving the repositories.

#+BEGIN_EXAMPLE
  $ adduser -SD rsync
#+END_EXAMPLE

Create =/etc/rsyncd.conf= and a service configuration as well.

#+BEGIN_EXAMPLE
  uid = rsync
  gid = rsync
  address = example.com
  max connections = 10
  use chroot = yes

  [repo]
      path = /pub/share/repo
      comment = My repository
#+END_EXAMPLE

Create a service file at =/etc/sv/rsync/run= (runit):

#+BEGIN_SRC sh
  #!/bin/sh -e
  exec rsync --daemon --no-detach
#+END_SRC

** Fossil repositories
:PROPERTIES:
:DESCRIPTION: Advantages and disadvantages of Fossil
:END:

Setting up a Fossil repository is no different than setting up any other
repository. There are certainly many advantages of using Fossil as a means of
distributing packages. You can create a Linux distribution and have your
website, forum, documentation, and your package repository entirely contained
inside a single Fossil repository. Fossil's built-in wiki and forum features
make it the ultimate single-tool distribution software.

However, the biggest caveat of Fossil is that it doesn't allow symlinks by
default unless it's manually set by the user, and this feature cannot even be
set globally. Symbolic links aren't quite common within distribution
repositories, but they come in handy where there are two packages that use the
same source files (=emacs= and =emacs-nox=, or =libelf= and =libdw= from
elfutils). If symbolic links are too big of a deal for your repository, this can
be a huge issue for you.

** Message of the Day
:PROPERTIES:
:DESCRIPTION: Communicate with the users using your repository
:END:

If a file named =MOTD= (all uppercase) is found on the root directory of the
package repository, its contents will be printed to the standard output when the
users are updating their repositories. This method can be used to communicate
messages to the users, such as package removals or otherwise important
information.

* Comparison Between CPT and KISS

Lots of things have changed since ~cpt~ was forked from ~kiss~ in terms of
functionalities and ideals. This section aims to describe the similarities and
differences of both package managers as neutral as possible. Keep in mind that
this is the ~cpt~ documentation, so it may be biased regardless.

- Package Manager ::

  While ~kiss~ aims to be a simple single file package manager, ~cpt~ aims to be
  an extendable package manager library. ~kiss~ has all of its features
  built-in, while ~cpt~ has all of its features separated into small tools.
  These tools can be called from the main ~cpt~ tool (in order to keep
  ~kiss~-like usage) or with their names directly (e.g ~cpt-build~).

- Configuration ::

  Neither ~kiss~ nor ~cpt~ use configuration files. Instead, they are configured
  through environment variables. Additionally, all ~cpt~ tools can receive flags
  that alter their functionality. ~kiss~ does not accept flags.

- Package Repositories ::

  In addition to git repositories, ~cpt~ also supports Rsync, Fossil, and
  Mercurial repositories.

- Package Sources ::

  In addition to git repositories for sources, ~cpt~ also supports Mercurial and
  Fossil repositories.

- Post-Installation Messages ::

  ~kiss~ and ~cpt~ interact with =post-install= messages differently. ~kiss~
  does not differentiate between post-installation scripts and post-installation
  messages, and will save the output of all scripts named =post-install= to be
  printed after the installation of all packages are complete. ~cpt~ on the
  other hand, separates these with the =message= file. ~cpt~ runs =post-install=
  without saving the output to be printed a second time. It instead prints all
  =message= files after the installation is over.

- Portability ::

  ~kiss~ aims to be as portable as possible. ~cpt~ aims to be portable, but
  favours performance. ~cpt~ depends on ~rsync~ for package installation, while
  ~kiss~ has removed the dependency in favour of portability.

* CPT Library
:PROPERTIES:
:DESCRIPTION: Documentation of the Library
:END:

=cpt-lib= is the library of Carbs Packaging Tools which can be used to extend
the functionality of the package manager. This is the API documentation of the
package manager library.

** Calling the library
:PROPERTIES:
:DESCRIPTION: Including the library on your code
:END:

You can call the library on your scripts by adding the following line to your
files:

#+begin_src sh
  #!/bin/sh -e
  . cpt-lib
#+end_src

This will load the library inside your script, and will set some environment
variables that are used inside the package manager.

** Variables

This section lists some of the variables defined by the package manager that can
be used in scripts. These variables usually cannot be defined by the user, so
they are not part of the [[* Environment Variables][variables]] section above.

#+VINDEX: cpt_version
- =$cpt_version= ::
  Package manager version.
#+VINDEX: cpt_confdir
- =$cpt_confdir= ::
  Location of the CPT system configuration directory. This is usually either
  =/etc/cpt= or =PREFIX/etc/cpt=.
#+VINDEX: pkg_db
- =$pkg_db= ::
  Location of the package database without the root (=var/db/cpt/installed=).
#+VINDEX: sys_db
#+VINDEX: CPT_ROOT
- =$sys_db= ::
  Location of the package manager database, making use of the current
  =$CPT_ROOT= (=$CPT_ROOT/$pkg_db=). This is the database you probably want to
  use.
#+CINDEX: Base packages
#+VINDEX: cpt_base
- =$cpt_base= ::
  Location of the file that defines the base packages.

#+CINDEX: Scripts that use CPT cache directories
If for some reason, your script interacts with the directories created and
managed by the package manager you should use the following variables instead of
the user assigned variables such as =$CPT_CACHE= or =$CPT_TMPDIR=. The variables
below are the ones used for package operations (which are assigned by using a
combination of user-assigned values and their fallbacks).

#+VINDEX: cac_dir
- =$cac_dir= ::
  Cache directory used by the package manager.
- =$src_dir= ::
  Directory containing downloaded sources for packages.
- =$log_dir= ::
  Directory where logs are saved.
- =$bin_dir= ::
  Directory where built package tarballs are saved.
- =$tmp_dir= ::
  Temporary directory for the package manager operations.

** Option parsing
:PROPERTIES:
:DESCRIPTION: Easy way of parsing options with cpt-lib
:END:

=cpt-lib= includes a POSIX-shell option parser inside named =getoptions=. You
can see its own [[https://github.com/ko1nksm/getoptions/blob/v2.5.0/README.md][documentation]] for writing an option parser. The built-in version
of the =getoptions= library is 2.5.0 and there are no plans for updating it
apart from bug fixes.

*** Defining a parser
:PROPERTIES:
:DESCRIPTION: Correct way of using getoptions
:END:

Some functions are called and set automatically when you call =cpt-lib=, so you
shouldn't define the option parser after calling the library, as some of the
variables will already be set.

If the function =parser_definition()= as defined when =cpt-lib= is called,
cpt-lib will handle the option parsing itself by calling =getoptions=
inside. Here is the proper way of doing it.

#+begin_src sh
  #!/bin/sh -e

  parser_definition() {
      # The rest arguments MUST be defined as 'REST'
      setup REST help:usage                  -- "usage: ${0##*/} [options] [pkg...]"
      msg                                    -- '' 'Options:'
      flag CPT_TEST -t export:1 init:@export -- "Enable tests"

      global_options
  }

  . cpt-lib
#+end_src

*** =global_options()=
:PROPERTIES:
:DESCRIPTION: Convenience function for defining common flags
:END:

The =global_options()= function is a simple convenience call to include flags
that can be used inside most =cpt= tools. It defines the following flags:

| Flag | Long Option   | Calls         |
|------+---------------+---------------|
| ~-f~ | ~--force~     | =CPT_FORCE=   |
| ~-y~ | ~--no-prompt~ | =CPT_PROMPT=  |
|      | ~--root~      | =CPT_ROOT=    |
| ~-h~ | ~--help~      | =usage()=     |
| ~-v~ | ~--version~   | =version()=   |
|      | ~--verbose~   | =CPT_VERBOSE= |

This function can take two arguments:

- =silent= :: If this argument is specified, the function does not print the usage
  information defined by its flags.
- =compact= :: If this argument is specified, the function only prints the help
  output of the ~--help~ and ~--version~ flags.

** Message functions
:PROPERTIES:
:DESCRIPTION: Communicate to users
:END:
=cpt= has various functions to print information to users.
*** =out()=
:PROPERTIES:
:DESCRIPTION: Print a message as-is
:END:

=out()= is a really simple function that prints messages to the standard
output. It prints every argument with a newline. It is not meant to communicate
with the user, it just exists to have a simple function to interact with other
functions.

#+begin_src sh
  $ out "This is an example call" "How are you?"
  This is an example call
  How are you?
#+end_src

*** =log()=
:PROPERTIES:
:DESCRIPTION: Print a message prettily
:END:

=log()= is the most commonly used message function in the package manager. It is
used to pretty print messages with visual cues, so it is easier to read and
understand for the users. It changes message output for each argument it
receives (takes up to three arguments).

- If it takes a single argument, it prints a yellow leading arrow followed by
  colorless text.
- If it takes two arguments, it prints a yellow leading arrow followed by the
  first argument (colored blue), and then followed by colorless second argument.
- If it takes three arguments, instead of a yellow arrow, it prints the third
  argument in yellow, followed by the same two arguments as above.

*** =die()=
:PROPERTIES:
:DESCRIPTION: Print a message and exit with error
:END:

=die()= wraps the =log()= function and exits with an error (1). It takes one or
two arguments, which are sent to the =log()= function. The third argument for
=log()= is set as =!>=.

*** =warn()=
:PROPERTIES:
:DESCRIPTION: Print a warning message
:END:

=warn()= is another function that wraps =log()=. In place of the third argument,
it uses the word =WARNING=.

*** =prompt()=
:PROPERTIES:
:DESCRIPTION: Ask the user whether they want to continue
:END:

=prompt()= is an interactive function that waits for user input to continue.
It takes a single argument string to print a message, and then asks the user
whether they want to continue or not. Prompts can be disabled by the user if
they use a flag to disable them or set =CPT_PROMPT= to 0.

** Text functions
:PROPERTIES:
:DESCRIPTION: Manipulate or check text
:END:

Following functions are used to manipulate, check, or interact with text.

*** =contains()=
:PROPERTIES:
:DESCRIPTION: Check if a "string list" contains a word
:END:

=contains= function can be used to check whether a list variable contains a
given string. If the string is inside the list, it will return 0, otherwise 1.

#+begin_src sh
# Usage
contains "$LIST" foo

contains "foo bar" foo  # Returns 0
contains "foo bar" baz  # Returns 1
#+end_src

*** =regesc()=
:PROPERTIES:
:DESCRIPTION: Escape regular expression characters
:END:

=regesc()= can be used to escape regular expression characters that are defined
in POSIX BRE. Those characters are, =$=, =.=, =*=, =[=, =\\=, and =^=.

#+begin_src sh
regesc '^[$\'  # Returns \^\[\$\\
#+end_src

*** =pop()=
:PROPERTIES:
:DESCRIPTION: Remove an item from a string list
:END:

=pop()= can be used to remove a word from a "string list" without a =sed=
call. Word splitting is intentional when using this function.

#+begin_src sh
# Usage
pop foo from $LIST

pop foo from foo baz bar # Returns baz bar
#+end_src

*** =sepchar()=
:PROPERTIES:
:DESCRIPTION: Separate characters from a string
:END:

This function can be used to separate characters from the given string without
resorting to external resources.

#+begin_src sh
sepchar mystring
# Prints:
# m
# y
# s
# t
# r
# i
# n
# g
#+end_src

** Portability functions
:PROPERTIES:
:DESCRIPTION: Functions to replace non-POSIX commands
:END:

These helper functions are used so that we don't depend on non-POSIX programs for
certain functionality. They are prefixed with the =_= character.

*** =_seq()=
:PROPERTIES:
:DESCRIPTION: 'seq(1)' but no newline
:END:

This function is similar to =seq(1)= except that it only takes a single argument
and doesn't print any newlines. It is suitable to be used in =for= loops.

#+begin_src sh
_seq 5
# Prints:
# 1 2 3 4 5
#+end_src

*** =_stat()=
:PROPERTIES:
:DESCRIPTION: 'stat %U' replacement
:END:

This function imitates =stat %U=. =stat= isn't defined by POSIX, and this is
also a GNU extension. This function returns the owner of a file. If the owner
cannot be found, it will return =root=.

*** =_readlinkf()=
:PROPERTIES:
:DESCRIPTION: 'readlink -f' replacement
:END:

This function was taken from [[https://github.com/ko1nksm/readlinkf][POSIX sh readlinkf library by Koichi Nakashima]].
=readlink= is also not defined by POSIX, so this function uses =ls= to follow
symbolic links until it reaches the actual file.

** System Functions
:PROPERTIES:
:DESCRIPTION: Functions to manipulate your system
:END:
*** =as_root()=
:PROPERTIES:
:DESCRIPTION: Run a command as the root user
:END:

=as_root()= calls the rest of the arguments as a different user. Unless a ~$user~
environment variable is set, it will call the following arguments as the root
user. It supports the following programs for privilege escalation with the
following order:

1. =ssu=
2. =sudo=
3. =doas=
4. =su=

The program called for this operation can be overridden using the ~$CPT_SU~
variable.

** Package Functions
:PROPERTIES:
:DESCRIPTION: Manipulate, or query anything related to packages
:END:

Obviously, package functions are the most important ones for =cpt-lib=, those
are the ones you will use to build, to query, to manipulate, or to otherwise
interact with packages.

*** =pkg_build()=

This function builds all given packages. It resolves dependencies for the given
packages, lints the package, extracts its sources and runs the ~build~ script.

#+begin_src sh
# Example

# Create the cache directories first, this is where the package will be built.
create_cache

# Build the package(s) you want to build.
pkg_build cpt
#+end_src

*** =pkg_depends()=

This function calculates the dependencies for the requested package, returning
the variable ~$deps~. This variable can then be passed to [[=pkg_order()=][pkg_order()]] in order
to generate an ordered list for building packages.

*** =pkg_order()=

This function receives package names and returns ~$order~ and ~$redro~ variables
that can be used for building and removing packages.

*** =pkg_owner()=
:PROPERTIES:
:DESCRIPTION: Check which package owns the given file
:END:

This function can be used to determine the owner of a package. The first
argument is used for flags that will be passed to =grep=, and the second one is
for the file query. Rest of the arguments can be used in order to specify the
manifests to be used, but it is optional. =pkg_owner()= will search for all the
installed packages if no other arguments are given.

#+begin_src sh
# Example
pkg_owner -lFx /usr/bin/grep  # Returns 'busybox'

# An example call made by `pkg_fix_deps()` to figure out whether the built
# package contains the file it depends.
pkg_owner -l "/${dep#/}\$" "$PWD/manifest" >/dev/null && continue
pkg_owner -l "/${dep#/}\$" "$@" ||:
#+end_src

*** =pkg_isbuilt()=
:PROPERTIES:
:DESCRIPTION: Check whether the given package is built
:END:

This function returns with success when the given package has a built tarball
with the matching version and release strings from the repository.

*** =pkg_lint()=
:PROPERTIES:
:DESCRIPTION: Check whether a package directory fits the standards
:END:

This function checks whether a given package fits the proper package
specification. This function *does not return with failure, it exits outright*
if it fails.

*** =pkg_find()=
:PROPERTIES:
:DESCRIPTION: Query package locations
:END:

=pkg_find()= is the tool for searching packages. It accepts up to 3 arguments.

- $1: Query ::
  This is the only mandatory argument. It accepts globbing, meaning that shell
  wildcards can be used in the query.
- $2: Match ::
  If this exists =pkg_find()= will print every single match found in the search
  path. If it doesn't, =pkg_find()= will print the first match and exit.
- $3: Type ::
  This is the argument to be passed to the =test= function. Unless this argument
  is given, it defaults to =-d=, which tests for directories.

#+begin_src sh
# Returns the first match of cpt
pkg_find cpt

# Returns all matches of cpt
pkg_find cpt all

# Returns all globbed matches for cpt* (e.g. cpt and cpt-extra)
pkg_find 'cpt*' all

# Returns all matching cpt-* executables on user's PATH
SEARCH_PATH=$PATH pkg_find 'cpt-*' all -x
#+end_src

*** =pkg_get_base()=
:PROPERTIES:
:DESCRIPTION: List system base packages
:END:

This function returns the base packages as defined in the base file. If an
optional argument is present, it will print all package names in a single line.
If it is not given any arguments, it will return one package per line. See [[CPT
Base]] for more information on base packages.

*** =pkg_gentree()=
:PROPERTIES:
:DESCRIPTION: Generate a dependency tree for the given package
:END:

This function generates a dependency tree for the given package. The output and
the dependency generation can be configured through a series of keys given as
the second argument. Those keys are:

- =b= :: Include the base packages to the dependency tree.
- =f= :: Include the given package itself to the generated tree.
- =x= :: Do not include make dependencies of the package.
- =r= :: Print the generated tree in reverse order.
- =n= :: Print all packages in a single line instead of a package per line.

**** Examples
:PROPERTIES:
:DESCRIPTION: Example usage for the =pkg_gentree= function
:END:

This example uses the =cpt= package for Carbs Linux. The package itself is
listed to depend on =curl= and =rsync=. Here is the output of calling the
function for cpt directly:

#+begin_example
$ pkg_gentree cpt
bearssl
ca-certificates
zlib
curl
rsync
#+end_example

The example above shows that even though =cpt= itself only depends on =curl= and
=rsync=, we also indirectly need =zlib=, =bearssl= (for =curl=), and
=ca-certificates= (for =bearssl=).

#+begin_src sh
# Print the dependency tree reverse sorted in a single line:
$ pkg_gentree cpt rn
rsync curl zlib ca-certificates bearssl
#+end_src

*** =pkg_query_meta()=

This function is used to query the [[meta][meta file]] inside package directories. It can
be used to retrieve information on a package that is otherwise irrelevant to the
package manager itself. It takes two arguments, first being the package (or the
full path to a package directory) and the second being the key to be retrieved.
If the package does not have a =meta= file or the file does not contain the
requested key, the function will return with 1.

#+begin_src sh
$ pkg_query_meta cpt description
Carbs Packaging Tools

$ pkg_query_meta /path/to/cpt license
MIT
#+end_src

* {{{index(Concept, cp)}}}
* {{{index(Variable,vr)}}}

* Footnotes

[fn:1] https://datatracker.ietf.org/doc/html/rfc822#section-3.2
[fn:2] Not mandatory for the packaging system, but mandatory for inclusion in
the repositories