path: root/src/cpt-lib.in

#!/bin/sh -ef
# @DOCSTRING@
# shellcheck source=/dev/null
#
# This is the Carbs Packaging Toolchain written for Carbs Linux.
# It was originally forked from the kiss package manager by
# Dylan Araps.
#
# Currently maintained by Cem Keylan.

version() {
    out "Carbs Packaging Tools, version @VERSION@" \
        @LICENSE@

    exit 0
}

out() {
    # Print a message as is.
    printf '%s\n' "$@"
}

log() {
    # Print a message prettily.
    #
    # All messages are printed to stderr to allow the user to hide build
    # output which is the only thing printed to stdout.
    #
    # '${3:-->}':         If the 3rd argument is missing, set prefix to '->'.
    # '${2:+colorb}':     If the 2nd argument exists, set text style of '$1'.
    printf '%b%s %b%b%s%b %s\n' \
           "$colory" "${3:-->}" "$colre" "${2:+$colorb}" "$1" "$colre" "$2" >&2
}

warn() {
    # Print a warning message
    log "$1" "$2" "${3:-WARNING}"
}

outv() {
    # Call `out()` when CPT_VERBOSE is set.
    [ "$CPT_VERBOSE" = 1 ] || return 0
    out "$@"
}

logv() {
    # Call `log()` when CPT_VERBOSE is set.
    [ "$CPT_VERBOSE" = 1 ] || return 0
    log "$@"
}

warnv() {
    # Call `warn()` when CPT_VERBOSE is set.
    [ "$CPT_VERBOSE" = 1 ] || return 0
    warn "$@"
}

die() {
    # Print a message and exit with '1' (error).
    log "$1" "$2" "!>"
    exit 1
}

trap_set() {
    # Function to set the trap value.
    case ${1:-cleanup} in
        cleanup)
            trap pkg_clean EXIT
            trap 'pkg_clean; exit 1' INT
            ;;
        handle-int)
            trap pkg_clean INT
            ;;
        block) trap '' INT ;;
        unset) trap - EXIT INT ;;
    esac
}

sepchar() (
    # Seperate every character on the given string without resorting to external
    # processes.
    [ "$1" ] || return 0; str=$1; set --
    while [ "$str" ]; do
        str_tmp=$str
        for i in $(_seq $(( ${#str} - 1 ))); do
            str_tmp=${str_tmp%?}
        done
        set -- "$@" "$str_tmp"
        str=${str#$str_tmp}
    done
    printf '%s\n' "$@"
)

_re() {
    # Check that the string supplied in $2 conforms to the regular expression
    # of $1.
    printf %s "${2:?}" | grep -Eq "$1"
}

_seq() (
    # Pure shell counter meant to be used in 'for' loops.
    i=0 buf=''
    while [ "$(( i += 1 ))" -le "$1" ]; do
        buf="$buf $i "
    done
    printf '%s' "$buf"
)

_multiply_char() (
    buf=
    for i in $(_seq "$2"); do
        buf="$buf$1"
    done
    out "$buf"
)

_stat() (
    _user=; eval set -- "$(ls -ld "$1")"
    id -u "${_user:=$3}" >/dev/null 2>&1 || _user=root
    printf '%s' "$_user"
)

_readlinkf() (
    # Public domain POSIX sh readlink function by Koichi Nakashima
    [ "${1:-}" ] || return 1
    max_symlinks=40
    CDPATH='' # to avoid changing to an unexpected directory

    target=$1
    [ -e "${target%/}" ] || target=${1%"${1##*[!/]}"} # trim trailing slashes
    [ -d "${target:-/}" ] && target="$target/"

    cd -P . 2>/dev/null || return 1
    while [ "$max_symlinks" -ge 0 ] && max_symlinks=$((max_symlinks - 1)); do
        if [ ! "$target" = "${target%/*}" ]; then
            case $target in
                /*) cd -P "${target%/*}/" 2>/dev/null || break ;;
                *) cd -P "./${target%/*}" 2>/dev/null || break ;;
            esac
            target=${target##*/}
        fi

        if [ ! -L "$target" ]; then
            target="${PWD%/}${target:+/}${target}"
            printf '%s\n' "${target:-/}"
            return 0
        fi

        # `ls -dl` format: "%s %u %s %s %u %s %s -> %s\n",
        #   <file mode>, <number of links>, <owner name>, <group name>,
        #   <size>, <date and time>, <pathname of link>, <contents of link>
        # https://pubs.opengroup.org/onlinepubs/9699919799/utilities/ls.html
        link=$(ls -dl -- "$target" 2>/dev/null) || break
        target=${link#*" $target -> "}
    done
    return 1
)

_get_digest() {
    # Get digest algorithm from the given file. It looks for a header on the
    # file declaring the digest algorithm. Currently only BLAKE3 is supported.
    # If the file does not include a header, the function will assume that it is
    # using sha256 as a digest algorithm. If the given file doesn't exist it will
    # return 1.
    [ -r "$1" ] || return 1
    read -r chk < "$1"
    case $chk in
        %BLAKE3) chk=b3sum ;;
        %*) die "Unknown digest algorithm: '${chk#\%}'" ;;
        *) chk=sh256
    esac
    out "$chk"
}

# This is the public domain getoptions shell library. It also forms a usage
# function.
# URL: https://github.com/ko1nksm/getoptions (v2.5.0)
# License: Creative Commons Zero v1.0 Universal
# shellcheck disable=2016,2086
getoptions() {
    _error='' _on=1 _off='' _export='' _plus='' _mode='' _alt='' _rest=''
    _flags='' _nflags='' _opts='' _help='' _abbr='' _cmds='' _init=@empty IFS=' '

    _0() { echo "$@"; }
    for i in 1 2 3 4 5; do eval "_$i() { _$((${i-}-1)) \"   \$@\"; }"; done

    quote() {
        q="$2'" r=''
        while [ "$q" ]; do r="$r${q%%\'*}'\''" && q=${q#*\'}; done
        q="'${r%????}'" && q=${q#\'\'} && q=${q%\'\'}
        eval "$1=\${q:-\"''\"}"
    }
    code() {
        [ "${1#:}" = "$1" ] && c=3 || c=4
        eval "[ ! \${$c:+x} ] || $2 \"\$$c\""
    }
    kv() { eval "${2-}${1%%:*}=\${1#*:}"; }
    loop() { [ $# -gt 1 ] && [ "$2" != -- ]; }

    invoke() { eval '"_$@"'; }
    prehook() { invoke "$@"; }
    for i in setup flag param option disp msg; do
        eval "$i() { prehook $i \"\$@\"; }"
    done

    args() {
        on=$_on off=$_off export=$_export init=$_init _hasarg=$1 && shift
        while loop "$@" && shift; do
            case $1 in
                -?) [ "$_hasarg" ] && _opts="$_opts${1#-}" || _flags="$_flags${1#-}" ;;
                +?) _plus=1 _nflags="$_nflags${1#+}" ;;
                [!-+]*) kv "$1"
            esac
        done
    }
    defvar() {
        case $init in
            @none) : ;;
            @export) code "$1" _0 "export $1" ;;
            @empty) code "$1" _0 "${export:+export }$1=''" ;;
            @unset) code "$1" _0 "unset $1 ||:" "unset OPTARG ||:; ${1#:}" ;;
            *)
                case $init in @*) eval "init=\"=\${${init#@}}\""; esac
                case $init in [!=]*) _0 "$init"; return 0; esac
                quote init "${init#=}"
                code "$1" _0 "${export:+export }$1=$init" "OPTARG=$init; ${1#:}"
        esac
    }
    _setup() {
        [ "${1#-}" ] && _rest=$1
        while loop "$@" && shift; do kv "$1" _; done
    }
    _flag() { args '' "$@"; defvar "$@"; }
    _param() { args 1 "$@"; defvar "$@"; }
    _option() { args 1 "$@"; defvar "$@"; }
    _disp() { args '' "$@"; }
    _msg() { args '' _ "$@"; }

    cmd() { _mode=@ _cmds="$_cmds${_cmds:+|}'$1'"; }
    "$@"
    cmd() { :; }
    _0 "${_rest:?}=''"

    _0 "$2() {"
    _1 'OPTIND=$(($#+1))'
    _1 'while OPTARG= && [ $# -gt 0 ]; do'
    [ "$_abbr" ] && getoptions_abbr "$@"

    args() {
        sw='' validate='' pattern='' counter='' on=$_on off=$_off export=$_export
        while loop "$@" && shift; do
            case $1 in
                --\{no-\}*) i=${1#--?no-?}; sw="$sw${sw:+|}'--$i'|'--no-$i'" ;;
                [-+]? | --*) sw="$sw${sw:+|}'$1'" ;;
                *) kv "$1"
            esac
        done
        quote on "$on"
        quote off "$off"
    }
    setup() { :; }
    _flag() {
        args "$@"
        [ "$counter" ] && on=1 off=-1 v="\$((\${$1:-0}+\$OPTARG))" || v=''
        _3 "$sw)"
        _4 '[ "${OPTARG:-}" ] && OPTARG=${OPTARG#*\=} && set "noarg" "$1" && break'
        _4 "eval '[ \${OPTARG+x} ] &&:' && OPTARG=$on || OPTARG=$off"
        valid "$1" "${v:-\$OPTARG}"
        _4 ';;'
    }
    _param() {
        args "$@"
        _3 "$sw)"
        _4 '[ $# -le 1 ] && set "required" "$1" && break'
        _4 'OPTARG=$2'
        valid "$1" '$OPTARG'
        _4 'shift ;;'
    }
    _option() {
        args "$@"
        _3 "$sw)"
        _4 'set -- "$1" "$@"'
        _4 '[ ${OPTARG+x} ] && {'
        _5 'case $1 in --no-*) set "noarg" "${1%%\=*}"; break; esac'
        _5 '[ "${OPTARG:-}" ] && { shift; OPTARG=$2; } ||' "OPTARG=$on"
        _4 "} || OPTARG=$off"
        valid "$1" '$OPTARG'
        _4 'shift ;;'
    }
    valid() {
        set -- "$validate" "$pattern" "$1" "$2"
        [ "$1" ] && _4 "$1 || { set -- ${1%% *}:\$? \"\$1\" $1; break; }"
        [ "$2" ] && {
            _4 "case \$OPTARG in $2) ;;"
            _5 '*) set "pattern:'"$2"'" "$1"; break'
            _4 "esac"
        }
        code "$3" _4 "${export:+export }$3=\"$4\"" "${3#:}"
    }
    _disp() {
        args "$@"
        _3 "$sw)"
        code "$1" _4 "echo \"\${$1}\"" "${1#:}"
        _4 'exit 0 ;;'
    }
    _msg() { :; }

    [ "$_alt" ] && _2 'case $1 in -[!-]?*) set -- "-$@"; esac'
    _2 'case $1 in'
    _wa() { _4 "eval 'set -- $1' \${1+'\"\$@\"'}"; }
    _op() {
        _3 "$1) OPTARG=\$1; shift"
        _wa '"${OPTARG%"${OPTARG#??}"}" '"$2"'"${OPTARG#??}"'
        _4 "$3"
    }
    _3 '--?*=*) OPTARG=$1; shift'
    _wa '"${OPTARG%%\=*}" "${OPTARG#*\=}"'
    _4 ';;'
    _3 '--no-*) unset OPTARG ;;'
    [ "$_alt" ] || {
        [ "$_opts" ] && _op "-[$_opts]?*" '' ';;'
        [ ! "$_flags" ] || _op "-[$_flags]?*" - 'OPTARG= ;;'
    }
    [ "$_plus" ] && {
        [ "$_nflags" ] && _op "+[$_nflags]?*" + 'unset OPTARG ;;'
        _3 '+*) unset OPTARG ;;'
    }
    _2 'esac'
    _2 'case $1 in'
    "$@"
    rest() {
        _4 'while [ $# -gt 0 ]; do'
        _5 "$_rest=\"\${$_rest}" '\"\${$(($OPTIND-$#))}\""'
        _5 'shift'
        _4 'done'
        _4 'break ;;'
    }
    _3 '--)'
    [ "$_mode" = @ ] || _4 'shift'
    rest
    _3 "[-${_plus:++}]?*)"
    case $_mode in [=#]) rest ;; *) _4 'set "unknown" "$1"; break ;;'; esac
    _3 '*)'
    case $_mode in
        @)
        _4 "case \$1 in ${_cmds:-*}) ;;"
        _5 '*) set "notcmd" "$1"; break'
        _4 'esac'
        rest ;;
        [+#]) rest ;;
        *) _4 "$_rest=\"\${$_rest}" '\"\${$(($OPTIND-$#))}\""'
    esac
    _2 'esac'
    _2 'shift'
    _1 'done'
    _1 '[ $# -eq 0 ] && { OPTIND=1; unset OPTARG; return 0; }'
    _1 'case $1 in'
    _2 'unknown) set "Unrecognized option: $2" "$@" ;;'
    _2 'noarg) set "Does not allow an argument: $2" "$@" ;;'
    _2 'required) set "Requires an argument: $2" "$@" ;;'
    _2 'pattern:*) set "Does not match the pattern (${1#*:}): $2" "$@" ;;'
    _2 'notcmd) set "Not a command: $2" "$@" ;;'
    _2 '*) set "Validation error ($1): $2" "$@"'
    _1 'esac'
    [ "$_error" ] && _1 "$_error" '"$@" >&2 || exit $?'
    _1 'echo "$1" >&2'
    _1 'exit 1'
    _0 '}'

    [ ! "$_help" ] || eval "shift 2; getoptions_help $1 $_help" ${3+'"$@"'}
}
# URL: https://github.com/ko1nksm/getoptions (v2.5.0)
# License: Creative Commons Zero v1.0 Universal
getoptions_help() {
    _width='30,12' _plus='' _leading='  '

    pad() { p=$2; while [ ${#p} -lt "$3" ]; do p="$p "; done; eval "$1=\$p"; }
    kv() { eval "${2-}${1%%:*}=\${1#*:}"; }
    sw() { pad sw "$sw${sw:+, }" "$1"; sw="$sw$2"; }

    args() {
        _type=$1 var=${2%% *} sw='' label='' hidden='' && shift 2
        while [ $# -gt 0 ] && i=$1 && shift && [ "$i" != -- ]; do
            case $i in
                --*) sw $((${_plus:+4}+4)) "$i" ;;
                -?) sw 0 "$i" ;;
                +?) [ ! "$_plus" ] || sw 4 "$i" ;;
                *) [ "$_type" = setup ] && kv "$i" _; kv "$i"
            esac
        done
        [ "$hidden" ] && return 0 || len=${_width%,*}

        [ "$label" ] || case $_type in
            setup | msg) label='' len=0 ;;
            flag | disp) label="$sw " ;;
            param) label="$sw $var " ;;
            option) label="${sw}[=$var] "
        esac
        [ "$_type" = cmd ] && label=${label:-$var } len=${_width#*,}
        pad label "${label:+$_leading}$label" "$len"
        [ ${#label} -le "$len" ] && [ $# -gt 0 ] && label="$label$1" && shift
        echo "$label"
        pad label '' "$len"
        for i; do echo "$label$i"; done
    }

    for i in setup flag param option disp 'msg -' cmd; do
        eval "${i% *}() { args $i \"\$@\"; }"
    done

    echo "$2() {"
    echo "cat<<'GETOPTIONSHERE'"
    "$@"
    echo "GETOPTIONSHERE"
    echo "}"
}

# 2086:
#   The lack of quotes are intentional. We do this so `getoptions()` do not try
#   to parse the empty string.
# 2120:
#   The library does not call this function with any positional arguments, but
#   that does not mean that other programs will not do it, so this can also be
#   safely ignored.
# shellcheck disable=2086,2120
global_options() {
    # These are options that are supported by most utilities. If the optional
    # argument 'silent' is given, the usage will not print these options, but
    # the arguments will still be accepted. Sometimes it doesn't make sense to
    # pollute the screen with options that will be rarely ever used.
    case $1 in
        silent) h=hidden:1 ;;
        *) msg -- '' 'Global Options:'; h=''
    esac
    flag  CPT_FORCE  -f --force                $h init:@export -- "Force operation"
    flag  CPT_PROMPT -y --no-prompt on:0 off:0 $h init:@export -- "Do not prompt for confirmation"
    param CPT_ROOT      --root                 $h init:@export -- "Use an alternate root directory"
    disp :usage      -h --help                 $h              -- "Show this help message"
    disp :version    -v --version              $h              -- "Print version information"
    flag CPT_VERBOSE    --verbose              $h init:@export -- "Be more verbose"
}

contains() {
    # Check if a "string list" contains a word.
    case " $1 " in *" $2 "*) return 0; esac; return 1
}

regesc() {
    # Escape special regular expression characters as
    # defined in POSIX BRE. '$.*[\^'
    printf '%s\n' "$1" |
    sed 's|\\|\\\\|g;s|\[|\\[|g;s|\$|\\$|g;s|\.|\\.|g;s|\*|\\*|g;s|\^|\\^|g'
}

pkg_download() {
    # $1: URL
    # $2: Output (Optional)
    set -- "$1" "${2:-${1##*/}}"
    case ${dl_prog##*/} in
        aria2c|axel) set -- -o "$2" "$1"   ;;
        curl)        set -- -fLo "$2" "$1" ;;
        wget|wget2)  set -- -O "$2" "$1"   ;;
    esac

    "$dl_prog" "$@" || {
        rm -f "$2"
        return 1
    }
}

prompt() {
    # If a CPT_NOPROMPT variable is set, continue.
    # This can be useful for installation scripts and
    # bootstrapping.
    [ "$CPT_PROMPT" = 0 ] && return 0

    # Ask the user for some input.
    [ "$1" ] && log "$1"
    log "Continue?: Press Enter to continue or Ctrl+C to abort here"

    # POSIX 'read' has none of the "nice" options like '-n', '-p'
    # etc etc. This is the most basic usage of 'read'.
    # '_' is used as 'dash' errors when no variable is given to 'read'.
    read -r _ || return 1
}

as_root() {
    # Simple function to run a command as root using either 'sudo',
    # 'doas' or 'su'. Hurrah for choice.
    [ "$uid" = 0 ] || log "Using '${su:-su}' (to become ${user:=root})"

    # We are exporting package manager variables, so that we still have the
    # same repository paths / access to the same cache directories etc.
    set -- HOME="$HOME" \
           USER="$user" \
           XDG_CACHE_HOME="$XDG_CACHE_HOME" \
           CPT_CACHE="$CPT_CACHE" \
           CPT_CHOICE="$CPT_CHOICE" \
           CPT_COMPRESS="$CPT_COMPRESS" \
           CPT_DEBUG="$CPT_DEBUG" \
           CPT_FETCH="$CPT_FETCH" \
           CPT_FORCE="$CPT_FORCE" \
           CPT_HOOK="$CPT_HOOK" \
           CPT_KEEPLOG="$CPT_KEEPLOG" \
           CPT_PATH="$CPT_PATH" \
           CPT_PID="$CPT_PID" \
           CPT_PROMPT="$CPT_PROMPT" \
           CPT_REPO_CACHE="$CPT_REPO_CACHE" \
           CPT_ROOT="$CPT_ROOT" \
           CPT_TMPDIR="$CPT_TMPDIR" \
           CPT_VERBOSE="$CPT_VERBOSE" \
           "$@"

    case ${su##*/} in
        sls)
            warn "'sls' is deprecated, use 'ssu' instead."
            "$su" -u "$user" -- env "$@"
            ;;
        ssu|sudo|doas) "$su" -u "$user" -- env "$@" ;;
        su)   su -c "env $* <&3" "$user" 3<&0 </dev/tty ;;
        *)    die "Invalid CPT_SU value: $su" ;;
    esac
}

pop() {
    # Remove an item from a "string list". This allows us
    # to remove a 'sed' call and reuse this code throughout.
    del=$1
    shift 2

    for i do [ "$i" = "$del" ] || printf %s " $i "; done
}

run_hook() {
    # Store the CPT_HOOK variable so that we can revert it if it is changed.
    oldCPT_HOOK=$CPT_HOOK

    # If a fourth parameter 'root' is specified, source the hook from a
    # predefined location to avoid privilige escalation through user scripts.
    [ "$4" ] && CPT_HOOK=$CPT_ROOT/etc/cpt-hook

    [ -f "$CPT_HOOK" ] || { CPT_HOOK=$oldCPT_HOOK; return 0 ;}

    if [ "$2" ]; then
        logv "$2" "Running $1 hook"
    else
        logv "Running $1 hook"
    fi

    TYPE=${1:-null} PKG=${2:-null} DEST=${3:-null} . "$CPT_HOOK"
    CPT_HOOK=$oldCPT_HOOK
}

decompress() {
    case $1 in
        *.tar|*.cpio) cat       ;;
        *.bz2)        bzip2 -cd ;;
        *.lz)         lzip  -cd ;;
        *.xz|*.txz)   xz -dcT 0 ;;
        *.tgz|*.gz)   gzip -cd  ;;
        *.zst)        zstd -cd  ;;
    esac < "$1"
}

sh256() {
    # This is a sha256sum function for outputting a standard hash digest. sha256
    # on BSD systems require an '-r' flag for outputting the same way with
    # sha256sum, and still, it outputs a single space between the hash and the
    # file whereas sha256sum outputs double spaces. It fallbacks to openssl, but
    # that is rarely ever needed.
    { sha256sum "$1" 2>/dev/null   ||
      sha256 -r "$1" 2>/dev/null   ||
      openssl dgst -r -sha256 "$1" ||
      die "No sha256 program could be run." ;} |

        while read -r hash _; do printf '%s  %s\n' "$hash" "$1"; done
}

pkg_owner() {
    set +f

    [ "$3" ] || set -- "$1" "$2" "$sys_db"/*/manifest

    pkg_owner=$(grep "$@")
    pkg_owner=${pkg_owner%/*}
    pkg_owner=${pkg_owner##*/}

    set -f -- "$pkg_owner"; unset pkg_owner
    [ "$1" ] && printf '%s\n' "$1"
}

pkg_isbuilt() (
    # Check if a package is built or not.
    read -r ver rel < "$(pkg_find "$1")/version"

    set +f
    for tarball in "$bin_dir/$1#$ver-$rel.tar."*; do
        [ -f "$tarball" ] && return 0
    done
    return 1
)

pkg_lint() {
    # Check that each mandatory file in the package entry exists.
    log "$1" "Checking repository files"

    repo_dir=$(pkg_find "$1")

    cd "$repo_dir" || die "'$repo_dir' not accessible"
    [ -f sources ] || warnv "$1" "Sources file not found"
    [ -x build ]   || die "$1" "Build file not found or not executable"
    [ -s version ] || die "$1" "Version file not found or empty"

    read -r _ release 2>/dev/null < version || die "Version file not found"
    [ "$release" ] || die "Release field not found in version file"

    # If we have a second argument, we are generating the checksums file,
    # so we don't need to check whether there is one.
    [ -z "$2" ] || return 0

    # Check for a checksums file only if there is a sources file.
    [ -f sources ]   || return 0
    [ -f checksums ] || die "$pkg" "Checksums are missing"
}

pkg_find() {
    # Use a SEARCH_PATH variable so that we can get the sys_db into
    # the same variable as CPT_PATH. This makes it easier when we are
    # searching for executables instead of CPT_PATH.
    : "${SEARCH_PATH:=$CPT_PATH:$sys_db}"

    # Figure out which repository a package belongs to by
    # searching for directories matching the package name
    # in $CPT_PATH/*.
    query=$1 match=$2 type=$3 IFS=:; set --

    # Word splitting is intentional here.
    # shellcheck disable=2086
    for path in $SEARCH_PATH ; do
        set +f

        for path2 in "$path/"$query; do
            test "${type:--d}" "$path2" && set -f -- "$@" "$path2"
        done
        # Break early if we only want a single match for a slight increase
        # in speed. We don't need to search for the entire path.
        [ "$1" ] && [ -z "$match" ] && break
    done

    IFS=$old_ifs

    # A package may also not be found due to a repository not being
    # readable by the current user. Either way, we need to die here.
    [ "$1" ] || die "Package '$query' not in any repository"

    # Show all search results if called from 'cpt search', else
    # print only the first match.
    [ "$match" ] && printf '%s\n' "$@" || printf '%s\n' "$1"
}

pkg_list() {
    # List installed packages. As the format is files and
    # directories, this just involves a simple for loop and
    # file read.

    # Change directories to the database. This allows us to
    # avoid having to 'basename' each path. If this fails,
    # set '$1' to mimic a failed glob which indicates that
    # nothing is installed.
    cd "$sys_db" 2>/dev/null || set -- "$sys_db/"\*

    # Optional arguments can be passed to check for specific
    # packages. If no arguments are passed, list all. As we
    # loop over '$@', if there aren't any arguments we can
    # just set the directory contents to the argument list.
    [ "$1" ] || { set +f; set -f -- *; }

    # If the 'glob' above failed, exit early as there are no
    # packages installed.
    [ "$1" = "$sys_db/"\* ] && return 1

    # Loop over each package and print its name and version.
    for pkg do
        [ -d "$pkg" ] || { log "$pkg" "not installed"; return 1; }

        read -r version 2>/dev/null < "$pkg/version" || version=null
        printf '%s\n' "$pkg $version"
    done
}

pkg_cache() {
    read -r version release 2>/dev/null < "$(pkg_find "$1")/version"

    # Initially assume that the package tarball is built with the CPT_COMPRESS
    # value.
    if [ -f "$bin_dir/$1#$version-$release.tar.$CPT_COMPRESS" ]; then
        tar_file="$bin_dir/$1#$version-$release.tar.$CPT_COMPRESS"
    else
        set +f; set -f -- "$bin_dir/$1#$version-$release.tar."*
        tar_file=$1
    fi

    [ -f "$tar_file" ]
}

pkg_sources() {
    # Download any remote package sources. The existence of local
    # files is also checked.
    repo_dir=$(pkg_find "$1")

    # Support packages without sources. Simply do nothing.
    [ -f "$repo_dir/sources" ] || return 0

    log "$1" "Downloading sources"

    # Store each downloaded source in a directory named after the
    # package it belongs to. This avoid conflicts between two packages
    # having a source of the same name.
    mkdir -p "$src_dir/$1" && cd "$src_dir/$1"

    repo_dir=$(pkg_find "$1")

    while read -r src dest || [ "$src" ]; do
        # Remote repository or comment.
        if _re "$re_vcs_or_com" "$src"; then :

        # Remote source (cached).
        elif [ -f "${src##*/}" ]; then
            log "$1" "Found cached source '${src##*/}'"

        # Remote source.
        elif [ -z "${src##*://*}" ]; then
            log "$1" "Downloading $src"

            # We don't want our trap to exit immediately here if we receive an
            # interrupt, we handle this ourselves.
            trap_set handle-int

            # Download the source
            pkg_download "$src" || die "$1" "Failed to download $src"

            # Restore original trap value.
            trap_set cleanup

        # Local source.
        elif [ -f "$repo_dir/$src" ]; then
            log "$1" "Found local file '$src'"

        else
            die "$1" "No local file '$src'"
        fi
    done < "$repo_dir/sources"
}

pkg_extract() {
    # Extract all source archives to the build directory and copy over
    # any local repository files.
    repo_dir=$(pkg_find "$1")

    # Support packages without sources. Simply do nothing.
    [ -f "$repo_dir/sources" ] || return 0

    log "$1" "Extracting sources"

    while read -r src dest || [ "$src" ]; do
        mkdir -p "$mak_dir/$1/$dest" && cd "$mak_dir/$1/$dest"

        case $src in

            # VCS Repository
            git+*|hg+*|fossil+*)
                backend=${src%%+*}
                url=${src##${backend}+} com=${url##*[@#]} com=${com#${url%[@#]*}}

                log "$1" "Cloning ${url%[#@]*}"
                "pkg_vcs_clone_$backend" "${url%[#@]*}" "$com"
            ;;

            # Comment or blank line.
            \#*|'') continue ;;

            # Only 'tar', 'cpio', and 'zip' archives are currently supported for
            # extraction. Other filetypes are simply copied to '$mak_dir'
            # which allows for manual extraction.
            *://*.tar|*://*.tar.??|*://*.tar.???|*://*.tar.????|*://*.tgz|\
            *://*.txz|*://*.cpio|*://*.cpio.??|*://*.cpio.???|*://*.cpio.????)
                decompress "$src_dir/$1/${src##*/}" | pax -rs '|[^/]*|.|' ;;

            *://*.zip)
                unzip "$src_dir/$1/${src##*/}" ||
                    die "$1" "Couldn't extract ${src##*/}"

            ;;

            *)
                # Local file.
                if [ -f "$repo_dir/$src" ]; then
                    cp -f "$repo_dir/$src" .

                # Remote file.
                elif [ -f "$src_dir/$1/${src##*/}" ]; then
                    cp -f "$src_dir/$1/${src##*/}" .

                else
                    die "$1" "Local file $src not found"
                fi
            ;;
        esac
    done < "$repo_dir/sources"
}

pkg_depends() {
    # Resolve all dependencies and generate an ordered list.
    # This does a depth-first search. The deepest dependencies are
    # listed first and then the parents in reverse order.
    contains "$deps" "$1" || {
        # Filter out non-explicit, aleady installed dependencies.
        # Only filter installed if called from 'pkg_build()'.
        [ "$pkg_build" ] && [ -z "$2" ] &&
            (pkg_list "$1" >/dev/null) && return

        while read -r dep type || [ "$dep" ]; do
            # Skip comments and empty lines.
            [ "${dep##\#*}" ] || continue
            # Skip test dependencies unless $CPT_TEST is set to 1.
            #
            # Skip make dependencies on the 'tree' operation for child packages
            # or when the 'first-nomake' argument is given.
            case $type in
                test) [ "$CPT_TEST" = 1 ] || continue ;;
                make) [ "$2" = tree ] && [ -z "${3#first-nomake}" ] && continue
            esac

            # Recurse through the dependencies of the child packages. Forward
            # the 'tree' operation.
            if [ "$2" = tree ]; then
                pkg_depends "$dep" tree
            else
                pkg_depends "$dep"
            fi
        done 2>/dev/null < "$(pkg_find "$1")/depends" ||:

        # After child dependencies are added to the list,
        # add the package which depends on them.
        [ "$2" = explicit ] || [ "$3" ] || deps="$deps $1 "
    }
}

pkg_order() {
    # Order a list of packages based on dependence and
    # take into account pre-built tarballs if this is
    # to be called from 'cpt i'.
    order=; redro=; deps=

    for pkg do case $pkg in
        *.tar.*) deps="$deps $pkg "  ;;
        *)       pkg_depends "$pkg" raw
    esac done

    # Filter the list, only keeping explicit packages.
    # The purpose of these two loops is to order the
    # argument list based on dependence.
    for pkg in $deps; do ! contains "$*" "$pkg" || {
        order="$order $pkg "
        redro=" $pkg $redro"
    } done

    deps=
}

pkg_strip() {
    # Strip package binaries and libraries. This saves space on the
    # system as well as on the tarballs we ship for installation.

    # Package has stripping disabled, stop here.
    [ -f "$mak_dir/$pkg/nostrip" ] && return

    log "$1" "Stripping binaries and libraries"

    find "$pkg_dir/$1" -type f | while read -r file; do
        case $(od -A o -t c -N 18 "$file") in
            # REL (object files (.o), static libraries (.a)).
            *177*E*L*F*0000020\ 001\ *|*\!*\<*a*r*c*h*\>*)
                strip -g -R .comment -R .note "$file"
            ;;

            # EXEC (static binaries).
            # DYN (shared libraries, dynamic binaries).
            # Shared libraries keep global symbols in a separate ELF section
            # called '.dynsym'. '--strip-all/-s' does not touch the dynamic
            # symbol entries which makes this safe to do.
            *177*E*L*F*0000020\ 00[23]\ *)
                strip -s -R .comment -R .note "$file"
            ;;
        esac
    done 2>/dev/null ||:
}

pkg_fix_deps_fullpath() {
    # Return the canonical path of libraries extracted by readelf.
    while read -r dep _ rslv _; do
        [ "$dep" = "$1" ] || continue
        printf '%s\n' "$rslv"
    done
}

pkg_fix_deps() {
    # Dynamically look for missing runtime dependencies by checking each binary
    # and library with either 'ldd' or 'readelf'. This catches any extra
    # libraries and or dependencies pulled in by the package's build suite.
    log "$1" "Checking for missing dependencies (using ${elf_prog##*/})"

    # Go to the directory containing the built package to
    # simplify path building.
    cd "$pkg_dir/$1/$pkg_db/$1"

    # Make a copy of the depends file if it exists to have a
    # reference to 'diff' against.
    if [ -f depends ]; then
        cp -f depends "$mak_dir/d"
        dep_file=$mak_dir/d
    else
        dep_file=/dev/null
    fi

    # Generate a list of all installed manifests.
    pkg_name=$1
    set +f; set -f -- "$sys_db/"*/manifest

    # Get a list of binaries and libraries, false files
    # will be found, however it's faster to get 'ldd' to check
    # them anyway than to filter them out.
    find "$pkg_dir/$pkg_name/" -type f 2>/dev/null |

    while read -r file; do
        # We call ldd regardless here, because we also use it to retrieve the
        # fullpath of a library when using readelf. Best use we have here is
        # saving it in a buffer, so we don't use the dynamic loader everytime we
        # need to reference it.
        lddbuf=$(ldd -- "$file" 2>/dev/null) ||:

        case ${elf_prog:-ldd} in
            *readelf) "$elf_prog" -d "$file" 2>/dev/null  ;;
            *)        pirntf '%s\n' "$lddbuf" ;;
        esac |
        while read -r dep; do
            # Skip lines containing 'ldd'.
            [ "${dep##*ldd*}" ] || continue
            case $dep in *NEEDED*\[*\] | *'=>'*) ;; *) continue; esac

            # readelf output:
            # 0x0000 (NEEDED) Shared library: [libc.so]
            dep=${dep##*\[}
            dep=${dep%%\]*}

            # Retrieve the fullpath of the library from our ldd buffer.
            case $elf_prog in
                *readelf) line=$(printf '%s\n' "$lddbuf" |
                                 pkg_fix_deps_fullpath "$line")
            esac

            # ldd output:
            # libc.so => /lib/ld-musl-x86_64.so.1
            dep=${dep#* => }
            dep=${dep% *}

            # Figure out which package owns the file. Skip file if it is owned
            # by the current package. This also handles cases where a '*-bin'
            # package exists on the system, so the package manager doesn't think
            # that the package we are building depends on the *-bin version of
            # itself, or any other renamed versions of the same software.
            pkg_owner -l "/${dep#/}\$" "$PWD/manifest" >/dev/null && continue
            pkg_owner -l "/${dep#/}\$" "$@" ||:
        done ||:
    done >> depends

    # Remove duplicate entries from the new depends file.
    # This removes duplicate lines looking *only* at the
    # first column.
    sort -uk1,1 -o depends depends 2>/dev/null ||:

    # Display a diff of the new dependencies against the old ones.
    diff -U 3 "$dep_file" depends 2>/dev/null ||:

    # Remove the depends file if it is empty.
    [ -s depends ] || rm -f depends
}

pkg_manifest() (
    # Generate the package's manifest file. This is a list of each file
    # and directory inside the package. The file is used when uninstalling
    # packages, checking for package conflicts and for general debugging.
    log "$1" "Generating manifest"

    # This function runs as a sub-shell to avoid having to 'cd' back to the
    # prior directory before being able to continue.
    cd "${2:-$pkg_dir}/$1"

    # find: Print all files and directories and append '/' to directories.
    # sort: Sort the output in *reverse*. Directories appear *after* their
    #       contents.
    # sed:  Remove the first character in each line (./dir -> /dir) and
    #       remove all lines which only contain '.'.
    find . -type d -exec printf '%s/\n' {} + -o -print |
        sort -r | sed '/^\.$/d;/^\.\/$/d;ss.ss' > "${2:-$pkg_dir}/$1/$pkg_db/$1/manifest"
)

pkg_etcsums() (
    # This function runs as a sub-shell to avoid having to 'cd' back to the
    # prior directory before being able to continue.
    cd "$pkg_dir/$1/etc" 2>/dev/null || return 0; cd ..

    # Generate checksums for each configuration file in the package's
    # /etc/ directory for use in "smart" handling of these files.
    log "$1" "Generating etcsums"

    # Try to get the digest algorithm from the installed etcsums file. This
    # makes sure that old packages continue to have the same digest algorithm
    # and not a bunch of '.new' files are installed. It's not foolproof at all,
    # but at least it keeps the /etc directory as clean as possible.
    digest=$(_get_digest "$sys_db/$1/etcsums") || digest=b3sum

    case $digest in b3sum) out "%BLAKE3"; esac > "$pkg_dir/$1/$pkg_db/$1/etcsums"
    find etc -type f | while read -r file; do
        "$digest" "$file"
    done >> "$pkg_dir/$1/$pkg_db/$1/etcsums"
)

pkg_tar() {
    # Create a tarball from the built package's files.
    # This tarball also contains the package's database entry.
    log "$1" "Creating tarball"

    # Read the version information to name the package.
    read -r version release < "$(pkg_find "$1")/version"

    # Create a tarball from the contents of the built package.
    cd "$pkg_dir/$1"
    pax -w .  |
        case $CPT_COMPRESS in
            bz2) bzip2 -z ;;
            xz)  xz -zT 0 ;;
            gz)  gzip -6  ;;
            zst) zstd -3  ;;
            lz)  lzip -6  ;;
            *)   gzip -6  ;;  # Fallback to gzip
        esac \
    > "$bin_dir/$1#$version-$release.tar.$CPT_COMPRESS"

    log "$1" "Successfully created tarball"

    run_hook post-package "$1" "$bin_dir/$1#$version-$release.tar.$CPT_COMPRESS"
}

pkg_build() {
    # Build packages and turn them into packaged tarballs. This function
    # also checks checksums, downloads sources and ensure all dependencies
    # are installed.
    pkg_build=1

    log "Resolving dependencies"

    for pkg do contains "$explicit" "$pkg" || {
        pkg_depends "$pkg" explicit

        # Mark packages passed on the command-line
        # separately from those detected as dependencies.
        explicit="$explicit $pkg "
    } done

    [ "$pkg_update" ] || explicit_build=$explicit

    # If an explicit package is a dependency of another explicit
    # package, remove it from the explicit list as it needs to be
    # installed as a dependency.
    # shellcheck disable=2086
    for pkg do
        contains "$deps" "$pkg" && explicit=$(pop "$pkg" from $explicit)
    done

    # See [1] at top of script.
    # shellcheck disable=2046,2086
    set -- $deps $explicit

    log "Building: $*"

    # Only ask for confirmation if more than one package needs to be built.
    [ $# -gt 1 ] || [ "$pkg_update" ] && prompt

    log "Checking for pre-built dependencies"

    for pkg do pkg_lint "$pkg"; done

    # Install any pre-built dependencies if they exist in the binary
    # directory and are up to date.
    for pkg do ! contains "$explicit_build" "$pkg" && pkg_cache "$pkg" && {
        log "$pkg" "Found pre-built binary, installing"
        (CPT_FORCE=1 cpt-install "$tar_file")

        # Remove the now installed package from the build list.
        # See [1] at top of script.
        # shellcheck disable=2046,2086
        set -- $(pop "$pkg" from "$@")
    } done

    for pkg do pkg_sources "$pkg"; done

    pkg_verify "$@"

    # Finally build and create tarballs for all passed packages and
    # dependencies.
    for pkg do
        log "$pkg" "Building package ($((in = in + 1))/$#)"

        mkdir -p "$mak_dir/$pkg"
        pkg_extract "$pkg"
        repo_dir=$(pkg_find "$pkg")

        read -r build_version _ < "$repo_dir/version"

        # Copy the build file to the build directory to users to modify it
        # temporarily at runtime.
        cp -f "$repo_dir/build" "$mak_dir/$pkg/.build.cpt"

        # Install built packages to a directory under the package name
        # to avoid collisions with other packages.
        mkdir -p "$pkg_dir/$pkg/$pkg_db"

        # Move to the build directory.
        cd "$mak_dir/$pkg"

        log "$pkg" "Starting build"

        run_hook pre-build "$pkg" "$pkg_dir/$pkg"

        # Notify the user if the build script is changed during the pre-build
        # hook.
        diff -q "$repo_dir/build" .build.cpt ||
            log "$pkg" "Executing the modified build file"

        # Call the build script, log the output to the terminal
        # and to a file. There's no PIPEFAIL in POSIX shelll so
        # we must resort to tricks like killing the script ourselves.
        { ./.build.cpt "$pkg_dir/$pkg" "$build_version" "$sys_arch" 2>&1 || {
            log "$pkg" "Build failed"
            log "$pkg" "Log stored to $log_dir/$pkg-$time-$pid"
            run_hook build-fail "$pkg" "$pkg_dir/$pkg"
            pkg_clean
            kill 0
        } } | tee "$log_dir/$pkg-$time-$pid"

        # Run the test script if it exists and the user wants to run tests. This
        # is turned off by default.
        [ -x "$repo_dir/test" ] && [ "$CPT_TEST" = 1 ] && {
            run_hook pre-test "$pkg" "$pkg_dir/$pkg"
            log "$pkg" "Running tests"
            "$repo_dir/test" "$pkg_dir/$pkg" "$build_version" "$sys_arch" 2>&1 || {
                log "$pkg" "Test failed"
                log "$pkg" "Log stored to $log_dir/$pkg-$time-$pid"
                run_hook test-fail "$pkg" "$pkg_dir/$pkg"
                pkg_clean
                kill 0
        } } | tee -a "$log_dir/$pkg-$time-$pid"

        # Delete the log file if the build succeeded to prevent
        # the directory from filling very quickly with useless logs.
        [ "$CPT_KEEPLOG" = 1 ] || rm -f "$log_dir/$pkg-$time-$pid"

        # Copy the repository files to the package directory.
        # This acts as the database entry.
        cp -LRf "$repo_dir" "$pkg_dir/$pkg/$pkg_db/"

        # Copy the modified build file to the package directory.
        pkg_build="$pkg_dir/$pkg/$pkg_db/$pkg/build"
        diff -U 3 "$pkg_build" .build.cpt > "$pkg_build.diff" &&
            rm -f "$pkg_build.diff"

        # We don't want the package manager to track 'dir' pages of the info
        # directory. We don't want every single package to create their own dir
        # files either.
        rm -f "$pkg_dir/$pkg/usr/share/info/dir"

        # We never ever want this. Let's end the endless conflicts
        # and remove it.
        find "$pkg_dir/$pkg" -name charset.alias -exec rm -f {} +

        # Remove libtool's '*.la' library files. This removes cross-build
        # system conflicts that may arise. Build-systems change, libtool
        # is getting deprecated, we don't want a package that depends on
        # some package's '.la' files.
        find "$pkg_dir/$pkg" -name '*.la' -exec rm -f {} +

        log "$pkg" "Successfully built package"

        run_hook post-build "$pkg" "$pkg_dir/$pkg"

        # Create the manifest file early and make it empty.
        # This ensures that the manifest is added to the manifest.
        : > "$pkg_dir/$pkg/$pkg_db/$pkg/manifest"

        # If the package contains '/etc', add a file called
        # 'etcsums' to the manifest. See comment directly above.
        [ -d "$pkg_dir/$pkg/etc" ] &&
            : > "$pkg_dir/$pkg/$pkg_db/$pkg/etcsums"

        pkg_strip    "$pkg"
        pkg_manifest "$pkg"
        pkg_fix_deps "$pkg"
        pkg_manifest "$pkg"
        pkg_etcsums  "$pkg"
        pkg_tar      "$pkg"

        # Install only dependencies of passed packages.
        # Skip this check if this is a package update.
        contains "$explicit" "$pkg" && [ -z "$pkg_update" ] && continue

        log "$pkg" "Needed as a dependency or has an update, installing"

        (CPT_FORCE=1 cpt-install "$pkg")
    done

    # End here as this was a system update and all packages have been installed.
    [ "$pkg_update" ] && return

    log "Successfully built package(s)"

    # Turn the explicit packages into a 'list'.
    # See [1] at top of script.
    # shellcheck disable=2046,2086
    set -- $explicit

    # Only ask for confirmation if more than one package needs to be installed.
    [ $# -gt 1 ] && prompt "Install built packages? [$*]" && {
        cpt-install "$@"
        return
    }

    log "Run 'cpt i $*' to install the package(s)"
}

pkg_checksums() {
    # Generate checksums for packages.
    repo_dir=$(pkg_find "$1")

    [ -f "$repo_dir/sources" ] || return 0

    case ${2:-b3sum} in b3sum) out "%BLAKE3"; esac

    while read -r src _ || [ "$src" ]; do

        # Skip checksums if it's a comment, or a VCS repository.
        if _re "$re_vcs_or_com" "$src"; then continue

        # File is local to the package.
        elif [ -f "$repo_dir/$src" ]; then
            src_path=$repo_dir/${src%/*}

        # File is remote and was downloaded.
        elif [ -f "$src_dir/$1/${src##*/}" ]; then
            src_path=$src_dir/$1

        # Die here if source for some reason, doesn't exist.
        else
            die "$1" "Couldn't find source '$src'"
        fi

        # An easy way to get 'b3sum' to print with the 'basename'
        # of files is to 'cd' to the file's directory beforehand.
        (cd "$src_path" && "${2:-b3sum}" "${src##*/}") ||
            die "$1" "Failed to generate checksums"
    done < "$repo_dir/sources"
}

pkg_verify() {
    # Verify all package checksums. This is achieved by generating a new set of
    # checksums and then comparing those with the old set.
    vcmd="NR==FNR{a[\$1];next}/^git  .*/{next}!((\$1)in a){exit 1}"

    for pkg; do
        repo_dir=$(pkg_find "$pkg")

        [ -f "$repo_dir/sources" ] || continue

        # Determine the type of digest algorithm from the checksums file to do
        # verification with.
        digest="$(_get_digest "$repo_dir/checksums")"

        pkg_checksums "$pkg" "$digest" | awk "$vcmd" - "$repo_dir/checksums" || {
        log "$pkg" "Checksum mismatch"

        # Instead of dying above, log it to the terminal. Also define a
        # variable so we *can* die after all checksum files have been
        # checked.
        mismatch="$mismatch$pkg "
    } done

    [ -z "$mismatch" ] || die "Checksum mismatch with: ${mismatch% }"
}

pkg_conflicts() {
    # Check to see if a package conflicts with another.
    log "$1" "Checking for package conflicts"

    # Filter the tarball's manifest and select only files
    # and any files they resolve to on the filesystem
    # (/bin/ls -> /usr/bin/ls).
    while read -r file; do
        case $file in */) continue; esac

        # Use $CPT_ROOT in filename so that we follow its symlinks.
        file=$CPT_ROOT/${file#/}

        # We will only follow the symlinks of the directories, so we reserve the
        # directory name in this 'dirname' value. If we cannot find it in the
        # system, we don't need to make this much more complex by trying so hard
        # to find it. Simply use the original directory name.
        dirname="$(_readlinkf "${file%/*}" 2>/dev/null)" ||
            dirname="${file%/*}"


        # Combine the dirname and file values, and print them into the
        # temporary manifest to be parsed.
        printf '%s/%s\n' "${dirname#$CPT_ROOT}" "${file##*/}"

    done < "$tar_dir/$1/$pkg_db/$1/manifest" > "$CPT_TMPDIR/$pid/manifest"

    p_name=$1

    # Generate a list of all installed package manifests
    # and remove the current package from the list.
    # shellcheck disable=2046,2086
    set -- $(set +f; pop "$sys_db/$p_name/manifest" from "$sys_db"/*/manifest)

    [ -s "$CPT_TMPDIR/$pid/manifest" ] || return 0

    # In rare cases where the system only has one package installed
    # and you are reinstalling that package, grep will try to read from
    # standard input if we continue here.
    #
    # Also, if we don't have any packages installed grep will give an
    # error. This will not cause the installation to fail, but we don't
    # need to check for conflicts if that's the case anyway. If we have
    # only zero packages or one package, just stop wasting time and continue
    # with the installation.
    [ "$1" ] && [ -f "$1" ] || return 0

    # Store the list of found conflicts in a file as we will be using the
    # information multiple times. Storing it in the cache dir allows us
    # to be lazy as they'll be automatically removed on script end.
    sed '/\/$/d' "$@" | sort "$CPT_TMPDIR/$pid/manifest" - | uniq -d > "$CPT_TMPDIR/$pid/conflict" ||:

    # Enable alternatives automatically if it is safe to do so.
    # This checks to see that the package that is about to be installed
    # doesn't overwrite anything it shouldn't in '/var/db/cpt/installed'.
    "$grep" -q "/var/db/cpt/installed/" "$CPT_TMPDIR/$pid/conflict" ||
        choice_auto=1

    # Use 'grep' to list matching lines between the to
    # be installed package's manifest and the above filtered
    # list.
    if [ "$CPT_CHOICE" != 0 ] && [ "$choice_auto" = 1 ]; then

        # This is a novel way of offering an "alternatives" system.
        # It is entirely dynamic and all "choices" are created and
        # destroyed on the fly.
        #
        # When a conflict is found between two packages, the file
        # is moved to a directory called "choices" and its name
        # changed to store its parent package and its intended
        # location.
        #
        # The package's manifest is then updated to reflect this
        # new location.
        #
        # The 'cpt choices' command parses this directory and
        # offers you the CHOICE of *swapping* entries in this
        # directory for those on the filesystem.
        #
        # The choices command does the same thing we do here,
        # it rewrites manifests and moves files around to make
        # this work.
        #
        # Pretty nifty huh?
        while read -r con; do
            printf '%s\n' "Found conflict $con"

            # Create the "choices" directory inside of the tarball.
            # This directory will store the conflicting file.
            mkdir -p "$tar_dir/$p_name/${cho_dir:=var/db/cpt/choices}"

            # Construct the file name of the "db" entry of the
            # conflicting file. (pkg_name>usr>bin>ls)
            con_name=$(printf %s "$con" | sed 's|/|>|g')

            # Move the conflicting file to the choices directory
            # and name it according to the format above.
            mv -f "$tar_dir/$p_name/$con" \
                  "$tar_dir/$p_name/$cho_dir/$p_name$con_name" 2>/dev/null || {
                log "File must be in ${con%/*} and not a symlink to it"
                log "This usually occurs when a binary is installed to"
                log "/sbin instead of /usr/bin (example)"
                log "Before this package can be used as an alternative,"
                log "this must be fixed in $p_name. Contact the maintainer"
                die "by checking 'git log' or by running 'cpt-maintainer'"
            }
        done < "$CPT_TMPDIR/$pid/conflict"

        # Rewrite the package's manifest to update its location
        # to its new spot (and name) in the choices directory.
        pkg_manifest "$p_name" "$tar_dir" 2>/dev/null

    elif [ -s "$CPT_TMPDIR/$pid/conflict" ]; then
        log "Package '$p_name' conflicts with another package" "" "!>"
        log "Run 'CPT_CHOICE=1 cpt i $p_name' to add conflicts" "" "!>"
        die "as alternatives."
    fi
}

pkg_swap() {
    # Swap between package alternatives.
    pkg_list "$1" >/dev/null

    alt=$(printf %s "$1$2" | sed 's|/|>|g')
    cd "$sys_db/../choices"

    [ -f "$alt" ] || [ -h "$alt" ] ||
        die "Alternative '$1 $2' doesn't exist"

    if [ -f "$2" ]; then
        # Figure out which package owns the file we are going to swap for
        # another package's.
        #
        # Print the full path to the manifest file which contains
        # the match to our search.

        pkg_owns=$(pkg_owner -lFx "$2") ||
            die "File '$2' exists on filesystem but isn't owned"

        log "Swapping '$2' from '$pkg_owns' to '$1'"

        # Convert the current owner to an alternative and rewrite
        # its manifest file to reflect this. We then resort this file
        # so no issues arise when removing packages.
        cp  -Pf "$CPT_ROOT/$2" "$pkg_owns>${alt#*>}"
        sed "s#^$(regesc "$2")\$#${PWD#$CPT_ROOT}/$pkg_owns>${alt#*>}#" \
            "../installed/$pkg_owns/manifest" |
            sort -r -o "../installed/$pkg_owns/manifest"
    fi

    # Convert the desired alternative to a real file and rewrite
    # the manifest file to reflect this. The reverse of above.
    mv -f "$alt" "$CPT_ROOT/$2"
    sed "s#^${PWD#$CPT_ROOT}/$(regesc "$alt")\$#$2#" "../installed/$1/manifest" |
        sort -r -o "../installed/$1/manifest"
}

pkg_etc() {
    [ -d "$tar_dir/$pkg_name/etc" ] || return 0

    (cd "$tar_dir/$pkg_name"

    # Create all directories beforehand.
    find etc -type d | while read -r dir; do
        mkdir -p "$CPT_ROOT/$dir"
    done

    digest=$(_get_digest "$mak_dir/c") || digest=b3sum

    # Handle files in /etc/ based on a 3-way checksum check.
    find etc ! -type d | while read -r file; do
        { sum_new=$("$digest" "$file")
          sum_sys=$(cd "$CPT_ROOT/"; "$digest" "$file")
          sum_old=$("$grep" "$file$" "$mak_dir/c"); } 2>/dev/null ||:

        logv "$pkg_name" "Doing 3-way handshake for $file"
        outv "Previous: ${sum_old:-null}"
        outv "System:   ${sum_sys:-null}"
        outv "New:      ${sum_new:-null}"

        # Use a case statement to easily compare three strings at
        # the same time. Pretty nifty.
        case ${sum_old:-null}${sum_sys:-null}${sum_new} in
            # old = Y, sys = X, new = Y
            "${sum_new}${sum_sys}${sum_old}")
                logv "Skipping $file"
                continue
            ;;

            # old = X, sys = X, new = X
            # old = X, sys = Y, new = Y
            # old = X, sys = X, new = Y
            "${sum_old}${sum_old}${sum_old}"|\
            "${sum_old:-null}${sum_sys}${sum_sys}"|\
            "${sum_sys}${sum_old}"*)
                logv "Installing $file"
                new=
            ;;

            # All other cases.
            *)
                warn "$pkg_name" "saving /$file as /$file.new" "->"
                new=.new
            ;;
        esac

        cp -fPp "$file"  "$CPT_ROOT/${file}${new}"
        chown root:root "$CPT_ROOT/${file}${new}" 2>/dev/null
    done) ||:
}

pkg_remove() {
    # Remove a package and all of its files. The '/etc' directory
    # is handled differently and configuration files are *not*
    # overwritten.
    pkg_list "$1" >/dev/null || return

    # Make sure that nothing depends on this package.
    [ "$CPT_FORCE" = 1 ] || {
        log "$1" "Checking for reverse dependencies"

        (cd "$sys_db"; set +f; grep -lFx -- "$1" */depends) &&
            die "$1" "Can't remove package, others depend on it"
    }
    # Block being able to abort the script with 'Ctrl+C' during removal.
    # Removes all risk of the user aborting a package removal leaving
    # an incomplete package installed.
    trap_set block

    if [ -x "$sys_db/$1/pre-remove" ]; then
        log "$1" "Running pre-remove script"
        "$sys_db/$1/pre-remove" ||:
    fi

    # Create a temporary list of all directories, so we don't accidentally
    # remove anything from packages that create empty directories for a
    # purpose (such as baselayout).
    manifest_list="$(set +f; pop "$sys_db/$1/manifest" from "$sys_db/"*/manifest)"
    # shellcheck disable=2086
    [ "$manifest_list" ] && grep -h '/$' $manifest_list | sort -ur > "$mak_dir/dirs"

    run_hook pre-remove "$1" "$sys_db/$1" root

    while read -r file; do
        # The file is in '/etc' skip it. This prevents the package
        # manager from removing user edited configuration files.
        [ "${file##/etc/*}" ] || continue

        if [ -d "$CPT_ROOT/$file" ]; then
            "$grep" -Fxq "$file" "$mak_dir/dirs" 2>/dev/null && continue
            rmdir "$CPT_ROOT/$file" 2>/dev/null || continue
        else
            rm -f "$CPT_ROOT/$file"
        fi
    done < "$sys_db/$1/manifest"

    # Reset 'trap' to its original value. Removal is done so
    # we no longer need to block 'Ctrl+C'.
    trap_set cleanup

    run_hook post-remove "$1" "$CPT_ROOT/" root

    log "$1" "Removed successfully"
}

pkg_install() {
    # Install a built package tarball.

    # Install can also take the full path to a tarball.
    # We don't need to check the repository if this is the case.
    if [ -f "$1" ] && [ -z "${1%%*.tar*}" ] ; then
        tar_file=$1
        pkg_name=${1##*/}
        pkg_name=${pkg_name%#*}

    else
        pkg_cache "$1" ||
            die "package has not been built, run 'cpt b pkg'"

        pkg_name=$1
    fi

    mkdir -p "$tar_dir/$pkg_name"
    cd       "$tar_dir/$pkg_name"

    log "$pkg_name" "Extracting $tar_file"

    # Extract the tarball to catch any errors before installation begins.
    decompress "$tar_file" | pax -rpp

    [ -f "./$pkg_db/$pkg_name/manifest" ] ||
        die "'${tar_file##*/}' is not a valid CPT package"

    # Ensure that the tarball's manifest is correct by checking that
    # each file and directory inside of it actually exists.
    [ "$CPT_FORCE" != 1 ] && log "$pkg_name" "Checking package manifest" &&
        while read -r line; do
            # Skip symbolic links
            [ -h "./$line" ] ||
            [ -e "./$line" ] || {
                log "File $line missing from tarball but mentioned in manifest" "" "!>"
                tarball_fail=1
            }
    done < "$pkg_db/$pkg_name/manifest"
    [ "$tarball_fail" ] && {
        log "You can still install this package by setting CPT_FORCE variable"
        die "$pkg_name" "Missing files in manifest"
    }

    log "$pkg_name" "Checking that all dependencies are installed"

    # Make sure that all run-time dependencies are installed prior to
    # installing the package.
    [ -f "$pkg_db/$pkg_name/depends" ] &&
    [ "$CPT_FORCE" != 1 ] &&
        while read -r dep dep_type || [ "$dep" ]; do
            [ "${dep##\#*}" ] || continue
            [ "$dep_type" ]   || pkg_list "$dep" >/dev/null ||
                install_dep="$install_dep'$dep', "
        done < "$pkg_db/$pkg_name/depends"

    [ "$install_dep" ] && die "$1" "Package requires ${install_dep%, }"

    run_hook pre-install "$pkg_name" "$tar_dir/$pkg_name" root
    pkg_conflicts "$pkg_name"

    log "$pkg_name" "Installing package incrementally"

    # Block being able to abort the script with Ctrl+C during installation.
    # Removes all risk of the user aborting a package installation leaving
    # an incomplete package installed.
    trap_set block

    # If the package is already installed (and this is an upgrade) make a
    # backup of the manifest and etcsums files.
    cp -f "$sys_db/$pkg_name/manifest" "$mak_dir/m" 2>/dev/null ||:
    cp -f "$sys_db/$pkg_name/etcsums"  "$mak_dir/c" 2>/dev/null ||:

    # This is repeated multiple times. Better to make it a function.
    pkg_rsync() {
        rsync "--chown=$USER:$USER" --chmod=Du-s,Dg-s,Do-s \
              -WhHKa --no-compress --exclude /etc "${1:---}" \
              "$tar_dir/$pkg_name/" "$CPT_ROOT/"
    }

    # Install the package by using 'rsync' and overwrite any existing files
    # (excluding '/etc/').
    pkg_rsync --info=progress2
    pkg_etc

    # Remove any leftover files if this is an upgrade.
    "$grep" -vFxf "$sys_db/$pkg_name/manifest" "$mak_dir/m" 2>/dev/null |

    while read -r file; do
        file=$CPT_ROOT/$file

        # Skip deleting some leftover files.
        case $file in /etc/*) continue; esac

        # Remove files.
        if [ -f "$file" ] && [ ! -L "$file" ]; then
            rm -f "$file"

        # Remove file symlinks.
        elif [ -h "$file" ] && [ ! -d "$file" ]; then
            unlink "$file" ||:

        # Skip directory symlinks.
        elif [ -h "$file" ] && [ -d "$file" ]; then :

        # Remove directories if empty.
        elif [ -d "$file" ]; then
            rmdir "$file" 2>/dev/null ||:
        fi
    done ||:

    log "$pkg_name" "Verifying installation"
    { pkg_rsync; pkg_rsync; } ||:

    # Reset 'trap' to its original value. Installation is done so
    # we no longer need to block 'Ctrl+C'.
    trap_set cleanup

    if [ -x "$sys_db/$pkg_name/post-install" ]; then
        log "$pkg_name" "Running post-install script"
        "$sys_db/$pkg_name/post-install" ||:
    fi

    run_hook post-install "$pkg_name" "$sys_db/$pkg_name" root

    log "$pkg_name" "Installed successfully"
}

pkg_repository_update() {
    # Function to update the given package repository.
    cd "$1"
    repo_type=$(pkg_vcs_info)
    repo_root=${repo_type#$PWD:}
    repo_type=${repo_type##*:} repo_root=${repo_root%:*}
    contains "$repos" "$repo_root" || {
        repos="$repos $repo_root "
        cd "$repo_root"

        "pkg_vcs_pull_$repo_type"

        # Repositories can contain a "Message of the Day" file in order to
        # relay important information to their users.
        ! [ -r "$repo_root/MOTD" ] || {
            printf '%s\n%s\n%s\n\n' \
                "$(_multiply_char '=' 60)" \
                "Message of the Day [$PWD]" \
                "$(_multiply_char '=' 60)"
            cat "$repo_root/MOTD"
            printf '\n%s\n' "$(_multiply_char '=' 60)"
        }
    }
}

pkg_vcs_clone_git() {
    # $1: Clone URL
    # $2: Branch or Commit Object
    git init
    git remote add origin "${1%[#@]*}"
    case $2 in
        @*) git fetch -t --depth=1 origin "${2#@}" || git fetch ;;
        *)  git fetch --depth=1 origin "$2"        || git fetch
    esac
    git checkout "${2:-FETCH_HEAD}"
}

pkg_vcs_clone_hg() {
    # $1: Clone URL
    # $2: Branch or Commit Object
    hg clone -u "${2:-tip}" "${1%[#@]*}" .
}

pkg_vcs_clone_fossil() {
    # $1: Clone URL
    # $2: Branch or Commit Object
    fossil open -f "${1%[#@]*}" "${2:-trunk}"
}

pkg_vcs_pull_fossil() {
    # Pull function for Fossil.
    log "$PWD" " "
    [ "$(fossil remote 2>/dev/null)" != off ] || {
        out "No remote, skipping."
        return 0
    }

    # Ensure we have proper permissions to do the pull operation.
    if [ -w "$PWD" ] && [ "$uid" != 0 ]; then
        fossil pull
        fossil update
    else
        pkg_vcs_as_root "fossil pull && fossil update"
    fi
}

pkg_vcs_pull_git() {
    # Pull function for Git.
    if [ "$(git remote 2>/dev/null)" ]; then
        # Display a message if signing is enabled for this repository.
        case $(git config merge.verifySignatures) in
            true) log "$PWD" "[signed] " ;;
            *)    log "$PWD" " " ;;
        esac

        # Ensure we have proper permissions to do the pull operation.
        if [ -w "$PWD" ] && [ "$uid" != 0 ]; then
            git fetch
            git merge
            git submodule update --remote --init -f
        else
            pkg_vcs_as_root \
                "git fetch && git merge && git submodule update --remote --init -f"
        fi
    else
        log "$PWD" " "
        # Skip if there are no submodules
        [ -f .gitmodules ] || {
            out "No remote, skipping."
            return 0
        }
        if [ -w "$PWD" ] && [ "$uid" != 0 ]; then
            git submodule update --remote --init -f
        else
            pkg_vcs_as_root "git submodule update --remote --init -f"
        fi
    fi
}

pkg_vcs_pull_hg() {
    # Pull function for Mercurial.
    log "$PWD" " "
    [ "$(hg showconfig paths 2>/dev/null)" ] || {
        out "No remote, skipping."
        return 0
    }

    if [ -w "$PWD" ] && [ "$uid" != 0 ]; then
        hg pull
        hg update
    else
        pkg_vcs_as_root "hg pull && hg update"
    fi
}

pkg_vcs_pull_rsync() {
    # Pull function for rsync repositories. The details of our rsync
    # repositories are explained in the user manual.
    log "$PWD" " "

    # Read remote repository address from the '.rsync' file.
    read -r remote < .rsync
    if [ -w "$PWD" ] && [ "$uid" != 0 ]; then
        rsync -acvzzC --include=core --delete "$remote/" "$PWD"
    else
        pkg_vcs_as_root "rsync -acvzzC --include=core --delete \"$remote/\" \"$PWD\""
    fi
}

pkg_vcs_pull_local() {
    # Local repository. We don't do a "pull" here, we just notify the user that
    # this is the case.
    log "$PWD" " "
    out "Not a remote repository, skipping."
}

pkg_vcs_as_root() (
    # Helper function for pkg_vcs_pull* functions used for proper
    # privilege escalation.
    [ "$uid" = 0 ] || log "$PWD" "Need root to update"

    # Find out the owner of the repository and spawn the operation as the user
    # below.
    #
    # This prevents the VCS from changing the original ownership of files and
    # directories in the rare case that the repository is owned by a third user.
    user=$(_stat "$PWD")

    [ "$user" = root ] || log "Dropping permissions to $user for pull"
    case ${su##*/} in su) set -- "'$1'"; esac

    # Spawn a subhsell to run multiple commands as root at once. This makes
    # things easier on users who aren't using persist/timestamps for auth
    # caching.
    as_root sh -c "$@"
)

pkg_vcs_info() {
    # Finds and returns repository information for the current directory. It
    # will return current directory, repository root, and the type of repository
    # in a colon separated format.

    : "${repo_file:=$cac_dir/repository-cache}"
    set --

    if [ "$CPT_REPO_CACHE" != 0 ] && information=$(grep "^$PWD:" "$repo_file" 2>/dev/null); then
        # Repository information is already cached.
        printf '%s\n' "$information" | sed 1q
        return
    elif rootdir=$(git rev-parse --show-toplevel 2>/dev/null); then
        # Git repository
        backend=git
    elif rootdir=$(hg root 2>/dev/null); then
        # Mercurial repository
        backend=hg
    elif rootdir=$(fossil info 2>/dev/null | grep ^local-root:); then
        # Fossil repository
        backend=fossil

        # We want to remove the initial spacing before the root directory, and
        # the leading dash on the root directory.
        rootdir=${rootdir#local-root: *} rootdir=${rootdir%/}
    elif [ -f .rsync ]; then
        backend=rsync
        rootdir=$PWD

        # If an .rsync_root file exists, we check that the repository root
        # exists. If it does, we change to that directory to do the fetch.
        # This way, we allow for partial repositories while making sure that
        # we can fetch the repository in a single operation.
        [ -f .rsync_root ] && {
            read -r rsync_root < .rsync_root
            [ -f "$rsync_root/.rsync" ] && rootdir=$(_readlinkf "$rsync_root")
        }
    else
        # Local repository
        backend=local
        rootdir=$PWD
    fi

    # We cache all these information, so that we don't have to spend much time
    # looking these up the next time we are doing it. If CPT_REPO_CACHE is set
    # to 0, we will not write this cache.
    [ "$CPT_REPO_CACHE" = 0 ] || set -- "$repo_file"
    printf '%s:%s:%s\n' "$PWD" "$rootdir" "$backend" | tee -a "$@"
}

pkg_fetch() {
    log "Updating repositories"

    run_hook pre-fetch

    # Create a list of all repositories.
    # See [1] at top of script.
    # shellcheck disable=2046,2086
    { IFS=:; set -- $CPT_PATH; IFS=$old_ifs ;}

    # Update each repository in '$CPT_PATH'. It is assumed that
    # each repository is 'git' tracked.
    for repo; do pkg_repository_update "$repo"; done

    run_hook post-fetch
}

pkg_updates(){
    # Check all installed packages for updates. So long as the installed
    # version and the version in the repositories differ, it's considered
    # an update.
    [ "$CPT_FETCH" = 0 ] || pkg_fetch

    log "Checking for new package versions"

    set +f

    for pkg in "$sys_db/"*; do
        pkg_name=${pkg##*/}

        # Read version and release information from the installed packages
        # and repository.
        read -r db_ver db_rel < "$pkg/version"
        read -r re_ver re_rel < "$(pkg_find "$pkg_name")/version"

        # Compare installed packages to repository packages.
        [ "$db_ver-$db_rel" != "$re_ver-$re_rel" ] && {
            printf '%s\n' "$pkg_name $db_ver-$db_rel ==> $re_ver-$re_rel"
            outdated="$outdated$pkg_name "
        }
    done

    set -f

    # If the download option is specified only download the outdated packages
    # and exit.
    # shellcheck disable=2154
    [ "$download_only" = 1 ] && {
        log "Only sources for the packages will be acquired"
        prompt

        for pkg in $outdated; do
            pkg_sources "$pkg"
        done

        exit 0
    }

    contains "$outdated" cpt && {
        log "Detected package manager update"
        log "The package manager will be updated first"

        prompt

        pkg_build cpt
        cpt-install cpt

        log "Updated the package manager"
        log "Re-run 'cpt update' to update your system"

        exit 0
    }

    [ "$outdated" ] || {
        log "Everything is up to date"
        return
    }

    log "Packages to update: ${outdated% }"

    # Tell 'pkg_build' to always prompt before build.
    pkg_update=1

    # Build all packages requiring an update.
    # See [1] at top of script.
    # shellcheck disable=2046,2086
    {
        pkg_order $outdated
        pkg_build $order
    }

    log "Updated all packages"
}

pkg_get_base() (
    # Print the packages defined in the /etc/cpt-base file.
    # If an argument is given, it prints a space seperated list instead
    # of a list seperated by newlines.

    # cpt-base is an optional file, return with success if it doesn't exist.
    [ -f "$CPT_ROOT/etc/cpt-base" ] || return 0

    # If there is an argument, change the format to use spaces instead of
    # newlines.
    format='%s\n'
    [ "$#" -eq 0 ] || format='%s '; set --

    # Older versions of shellcheck warns us that the variable is changing on the
    # subshell. That is our purpose here, thank you very much.
    # shellcheck disable=SC2030
    while read -r pkgname _; do
        [ "${pkgname##\#*}" ] || continue
        set -- "$@" "$pkgname"
        deps=$(pkg_gentree "$pkgname" xn)
        for dep in $deps; do
            contains "$*" "$dep" || set -- "$@" "$dep"
        done
    done < "$CPT_ROOT/etc/cpt-base"

    # Format variable is intentional.
    # shellcheck disable=2059
    printf "$format" "$@"
)

pkg_gentree() (
    # Generate an ordered dependency tree of a package. Useful for testing
    # whether the generated dependency tree is enough to actually building a
    # given package. A second argument can be given as a combination of
    # characters (similar to 'tar(1)' keys) which will be used as an option
    # parser. See the documentation for more information on the keys.
    deps='' reverse='' format='%s\n' make_deps=first
    for op in $(sepchar "$2"); do
        case "$op" in
            b) deps=$(pkg_get_base nonl) ;;
            f) make_deps='' ;;
            x) make_deps=first-nomake ;;
            r) reverse=1 ;;
            n) format='%s ' ;;
            *) die "pkg_gentree: Unknown key '$op'"
        esac
    done
    pkg_depends "$1" tree "$make_deps"

    # Unless 'f' is given, pop the package from the list so that we don't list
    # the package (for example if it's part of the base package list). Normally
    # this should happen only when 'b' is used, so getting the package when no
    # keys are supplied points to a circular dependency, which isn't supported
    # by the package manager.
    #
    # Word splitting is intentional.
    # shellcheck disable=2086
    [ -z "${2##*f*}" ] || deps=$(pop "$1" from $deps)

    eval set -- "$deps"
    pkg_order "$@"
    if [ "$reverse" ]; then eval set -- "$redro"; else eval set -- "$order"; fi
    [ "$1" ] || return 0

    # Format variable is intentional.
    # shellcheck disable=2059
    printf "$format" "$@"
)

pkg_query_meta() {
    # Query the 'meta' file of the given meta package. If there is no meta file,
    # or the key being queried is unavailable, the function will return with
    # error. Full path can be specified instead of package names.
    case $1 in
        */*) repo_dir=$1 ;;
        *)   repo_dir=$(pkg_find "$1")
    esac
    [ -f "$repo_dir/meta" ] || return
    while IFS=': ' read -r key val; do
        case $key in
            "$2") printf '%s\n' "$val"; return 0
        esac
    done < "$repo_dir/meta"
    return 1
}

pkg_clean() {
    # Clean up on exit or error. This removes everything related
    # to the build.
    [ "$CPT_DEBUG" != 1 ] || return 0

    # Block 'Ctrl+C' while cache is being cleaned.
    trap_set block

    # Remove temporary items.
    rm -rf -- "${CPT_TMPDIR:=$cac_dir/proc}/$pid"
}

create_tmp() {
    # Create the required temporary directories and set the variables which
    # point to them.
    mkdir -p "${mak_dir:=$tmp_dir/build}" \
             "${pkg_dir:=$tmp_dir/pkg}" \
             "${tar_dir:=$tmp_dir/export}"
}

create_cache() {
    # DEPRECATED, use create_tmp() instead.
    #
    # If an argument is given, skip the creation of other cache directories.
    [ "$1" ] || create_tmp
}

# main()
{
    set -ef

    # If a parser definition exists, let's run it ourselves. This makes sure we
    # get the variables as soon as possible.
    command -v parser_definition >/dev/null && {
        eval "$(getoptions parser_definition parse "$0")"
        parse "$@"
        eval set -- "$REST"
    }

    # The PID of the current shell process is used to isolate directories
    # to each specific CPT instance. This allows multiple package manager
    # instances to be run at once. Store the value in another variable so
    # that it doesn't change beneath us.
    pid=${CPT_PID:-$$}

    # Create the cache directories for CPT and set the variables which point
    # to them. This is seperate from temporary directories created in
    # create_cache(). That's because we need these variables set on most
    # occasions.
    #
    # A temporary directory can be specified apart from the cache directory in
    # order to build in a user specified directory. /tmp could be used in order
    # to build on ram, useful on SSDs. The user can specify CPT_TMPDIR for this.
    # We create the temporary directory here to avoid permission issues that can
    # arise from functions that call as_root().
    mkdir -p "${cac_dir:=${CPT_CACHE:=${XDG_CACHE_HOME:-$HOME/.cache}/cpt}}" \
             "${CPT_TMPDIR:=$cac_dir/proc}" \
             "${src_dir:=$cac_dir/sources}" \
             "${log_dir:=$cac_dir/logs}" \
             "${bin_dir:=$cac_dir/bin}"

    # We don't create the temporary $pid directory until `create_tmp()` is
    # called, but we still declare its variable here.
    : "${tmp_dir:=${CPT_TMPDIR:=$cac_dir/proc}/$pid}"

    # Set the location to the repository and package database.
    pkg_db=var/db/cpt/installed

    # Force the C locale to speed up things like 'grep' which disable unicode
    # etc when this is set. We don't need unicode and a speed up is always
    # welcome.
    export LC_ALL=C LANG=C

    # Catch errors and ensure that build files and directories are cleaned
    # up before we die. This occurs on 'Ctrl+C' as well as success and error.
    trap_set cleanup

    # Prefer GNU grep if installed as it is much much faster than busybox's
    # implementation. Very much worth it if you value performance over
    # POSIX correctness (grep quoted to avoid shellcheck false-positive).
    grep=$(command -v ggrep) || grep='grep'

    # Figure out which 'sudo' command to use based on the user's choice or
    # what is available on the system.
    su=${CPT_SU:-$(command -v ssu    ||
                   command -v doas   ||
                   command -v sudo   ||
                   command -v sls)}  || su=su

    # Store the date and time of script invocation to be used as the name
    # of the log files the package manager creates uring builds.
    time=$(date '+%Y-%m-%d-%H:%M')

    # Use readelf for fixing dependencies if it is available, fallback to
    # ldd. readelf shows only the actual dependencies and doesn't include
    # the libraries required by the dependencies.
    elf_prog=${CPT_ELF:="$(
               command -v readelf       ||
               command -v llvm-readelf  ||
               command -v eu-readelf)"} || elf_prog=ldd

    # Use one of the following programs to download package sources. Downloads
    # are made using the `pkg_download()` function.
    dl_prog=${CPT_DOWNLOADER:="$(
              command -v curl      ||
              command -v wget      ||
              command -v wget2     ||
              command -v axel      ||
              command -v aria2c)"} || dl_prog=curl

    # Make note of the user's current ID to do root checks later on.
    # This is used enough to warrant a place here.
    uid=$(id -u)

    # Save IFS, so we can restore it back to what it was before.
    old_ifs=$IFS

    # Make sure that the CPT_ROOT doesn't end with a '/'. This might
    # break some operations.
    [ -z "$CPT_ROOT" ] || [ "${CPT_ROOT##*/}" ] || {
        warn "" "Your CPT_ROOT variable shouldn't end with '/'"
        CPT_ROOT=${CPT_ROOT%/}
    }

    # Define an optional sys_arch variable in order to provide
    # information to build files with architectural information.
    sys_arch=$(uname -m 2>/dev/null) ||:

    # Define this variable but don't create its directory structure from
    # the get go. It will be created as needed by package installation.
    sys_db=$CPT_ROOT/$pkg_db

    # Regular expression used in pkg_checksums() and pkg_sources() in order to
    # identify VCS and comments
    re_vcs_or_com='^(#|(fossil|git|hg)\+)'

    # This allows for automatic setup of a CPT chroot and will
    # do nothing on a normal system.
    mkdir -p "$CPT_ROOT/" 2>/dev/null ||:

    # Set a value for CPT_COMPRESS if it isn't set.
    : "${CPT_COMPRESS:=gz}"

    # Unless being piped or the user specifically doesn't want colors, set
    # colors. This can of course be overriden if the user specifically want
    # colors during piping.
    if { [ "$CPT_COLOR" != 0 ] && [ -t 1 ] ;} || [ "$CPT_COLOR" = 1 ]; then
        colory="\033[1;33m" colorb="\033[1;34m" colre="\033[m"
    fi

}

# If the library is being called with its own name, run arguments.
if [ "${0##*/}" = cpt-lib ]; then
    pd() {
        setup REST help:usage -- "usage: ${0##*/} [funcall...]"
        global_options
    }
    eval "$(getoptions pd parse "$0")"
    parse "$@"
    eval set -- "$REST"
    "$@"
fi