profile/helpers/common.sh

#!/usr/bin/env bash
# ------------------------------------------------------------------------------
# Copyright (c) 2013-2026 Geoffray Levasseur <fatalerrors@geoffray-levasseur.org>
# Protected by the BSD3 license. Please read bellow for details.
#
# * Redistribution and use in source and binary forms,
# * with or without modification, are permitted provided
# * that the following conditions are met:
# *
# *   Redistributions of source code must retain the above
# *   copyright notice, this list of conditions and the
# *   following disclaimer.
# *
# *   Redistributions in binary form must reproduce the above
# *   copyright notice, this list of conditions and the following
# *   disclaimer in the documentation and/or other materials
# *   provided with the distribution.
# *
# *   Neither the name of the copyright holder nor the names
# *   of any other contributors may be used to endorse or
# *   promote products derived from this software without
# *   specific prior written permission.
# *
# * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
# * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
# * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
# * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# * OF SUCH DAMAGE.
# ------------------------------------------------------------------------------


# ------------------------------------------------------------------------------
# Helpers shared by several modules. This file is loaded by profile.sh before
# any module (and by a module sourced alone); the helpers private to one module
# live in helpers/<module>.sh instead, loaded by the module itself through
# _profile_load_helpers.
#
# Option parsing: the project rule is to never use eval, so _getopt_split and
# _trap_restore rebuild argument lists and traps in pure bash.

# Split the output of getopt into the array whose name is $1, without eval and
# without xargs. getopt prints the normalised arguments as one shell-quoted
# line (options bare, every argument in single quotes, a quote inside an
# argument written '\''), for instance:
#     -s 'a b' --long 'it'\''s' -- 'file' ''
# Quoted text is taken verbatim (newlines included), an empty argument ('')
# yields an empty element, and nothing is ever evaluated. The usual call is
#     local -a _pargs=()
#     _getopt_split _pargs "$PARSED"
#     set -- "${_pargs[@]}"
# Usage: _getopt_split <array_name> <getopt_output>
_getopt_split()
{
    local -n _gs_out="$1"
    local s="$2" tok="" in_tok=0 run
    local run_re=$'^[^ \t\n\'\\\\]+'
    _gs_out=()

    while [[ -n "$s" ]]; do
        # shellcheck disable=SC1003 # '\' is a literal backslash
        case "${s:0:1}" in
            "'")
                s="${s:1}"
                if [[ "$s" == *\'* ]]; then
                    tok+="${s%%\'*}"
                    s="${s#*\'}"
                else
                    # Unterminated quote (never produced by getopt): keep the rest
                    tok+="$s"
                    s=""
                fi
                in_tok=1
                ;;
            '\')
                tok+="${s:1:1}"
                s="${s:2}"
                in_tok=1
                ;;
            ' '|$'\t'|$'\n')
                (( in_tok )) && _gs_out+=("$tok")
                tok=""
                in_tok=0
                s="${s:1}"
                ;;
            *)
                [[ "$s" =~ $run_re ]] || break
                run="${BASH_REMATCH[0]}"
                tok+="$run"
                s="${s:${#run}}"
                in_tok=1
                ;;
        esac
    done
    (( in_tok )) && _gs_out+=("$tok")
    return 0
}
export -f _getopt_split

# Put back traps saved with "trap -p" (one "trap -- 'command' SIGNAL" line per
# trap), without eval. Used to restore the caller's traps after temporarily
# replacing them. An empty argument restores nothing.
# Usage: _trap_restore "$(trap -p INT TERM)"
_trap_restore()
{
    local line
    local -a _tr_w=()
    while IFS= read -r line; do
        [[ "$line" == "trap -- "* ]] || continue
        _getopt_split _tr_w "$line"
        # _tr_w = (trap -- <command> <SIGNAL>)
        [[ ${#_tr_w[@]} -eq 4 ]] && trap -- "${_tr_w[2]}" "${_tr_w[3]}"
    done <<< "$1"
    return 0
}
export -f _trap_restore

# True when $1 is a non-negative integer. Every value that ends up in an
# arithmetic context must pass this first (this includes values coming from the
# configuration file): bash evaluates non-numeric strings inside [[ -gt ]] or
# $(( )) as expressions, which can run arbitrary commands.
# Usage: _is_uint <value>
_is_uint()
{
    [[ "$1" =~ ^[0-9]+$ ]]
}
export -f _is_uint

# Source the helpers private to a module: helpers/<module name>.sh, found next
# to the directory holding the module (profile.d/../helpers), the name being the
# module file name without ".sh". A module without helpers file is fine.
# Usage: _profile_load_helpers "${BASH_SOURCE[0]}"
_profile_load_helpers()
{
    local dir=. name="${1##*/}"
    [[ "$1" == */* ]] && dir="${1%/*}"
    name="$dir/../helpers/${name%.sh}.sh"
    [[ -r "$name" ]] || return 0
    # shellcheck source=/dev/null
    . "$name" || printf "[ Warning ] Failed to source helpers: %s\n" "$name" >&2
}
export -f _profile_load_helpers

# ------------------------------------------------------------------------------


# EOF