tilde-launcher/tilde

#!/bin/sh
# ---------------------------------------------------------------------------
# tilde - manage user-submitted scripts and apps

# Copyright 2018, Ben Harris <ben@tilde.team>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License at <http://www.gnu.org/licenses/> for
# more details.

# Usage: tilde [-h|--help]

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

PROGNAME=${0##*/}
VERSION="0.1.0"
user=$(whoami)
hostname=$(hostname -f)

# check coreutils and wrap stat for portability
if stat -c"%U" /dev/null >/dev/null 2>/dev/null ; then
    # GNU environment
    stat_func () {
        stat -c '%U' "$1"
    }
else
    # BSD environment
    stat_func () {
        stat -f %Su "$1"
    }
fi

isroot() {
    [ "$(id -u)" = "0" ]
}

error_exit() {
    printf "%s\n" "${1:-"unknown Error"}" >&2
    exit 1
}

signal_exit() { # Handle trapped signals
    case $1 in
        INT)
            error_exit "program interrupted by user"
            ;;
        TERM)
            printf "\n%s: program terminated" "$PROGNAME" >&2
            exit
            ;;
        *)
            error_exit "$PROGNAME: terminating on unknown signal"
            ;;
    esac
}

prompt_confirm() {
    while true; do
        printf "%s [y/n]: " "${1:-continue?}"
        read -r REPLY
        case $REPLY in
            [yY]) printf "\n" ; return 0 ;;
            [nN]) printf "\n" ; return 1 ;;
            *) printf " \033[31m %s \n\033[0m" "invalid input" ;;
        esac
    done
}

help_message() {
    printf "%s version %s\n" "$PROGNAME" "$VERSION"
    printf "wrapper for user-submitted scripts\n"
    printf "supports submission and admin approval\n"
    usage
}

usage() {
    printf "\nusage: %s [help|list|submit|about|script_name]\n\n" "$PROGNAME"
    printf "  list                 - show a list of approved userscripts\n"
    printf "  submit               - start the submission flow for your own script\n"

    if isroot; then
        printf "  approve              - enter the approval queue\n"
        printf "  revoke <script_name> - send a script back to the author and remove from /tilde/bin\n"
    fi

    printf "  about <script_name>  - get the description for script_name\n"
    printf "  <script_name>        - run script_name with all remaining args are passed to the script\n"

    case ":$PATH:" in
        *:/tilde/bin:*)
            ;;
        *) 
            printf "\nadd /tilde/bin to your PATH to use approved scripts without this wrapper\n"
            printf "if you're using bash, run the following to add it quickly\n"
            printf "  echo 'export PATH=\$PATH:/tilde/bin' >> ~/.bashrc && source ~/.bashrc\n"
            ;;
    esac
}

verify_script_name() {
    if [ -z "$1" ]; then
        error_exit "please enter a script name"
    fi

    if command -v "$1"; then
        if [ "$(command -v "$1")" != "/home/$user/bin/$1" ]; then
            error_exit "$1 already exists. rename your script and try again."
        fi
    fi

    if [ -x "/tilde/bin/$1" ]; then
        error_exit "$1 is already taken. rename your script and try again."
    fi

    case $1 in
        about|description|list|ls|submit|about|help|apropos|submit|approve)
            error_exit "$1 is a subcommand of tilde. rename your script and try again."
            ;;
        *)
            return
            ;;
    esac
}


submission_checklist() {
    cat <<- _EOF_
requirements for submitting a user script or program:

  - placed in your ~/bin
  - executable
  - responds to help or --help
  - no name collisions with existing scripts or $PROGNAME subcommands

_EOF_
}


mail_body() {
    cat <<- _EOF_
Subject: tilde script submission from ${user}
From: ${user}@${hostname}
To: root@${hostname}

tilde script submission from ${user}

script name: $1

description:
-----------------------------------------------------------------------

$2

-----------------------------------------------------------------------
you'll find the script and description in: /tilde/pending-submissions/$user/$1

run this to see the approval queue:
sudo tilde approve
_EOF_
}


# Trap signals
trap "signal_exit TERM" TERM HUP
trap "signal_exit INT"  INT


# Parse command-line
case $1 in
    -h | --help | help)
        help_message; exit
        ;;

    -v | --version)
        printf "%s" "$VERSION"
        ;;

    -* | --*)
        usage
        error_exit "Unknown option $1"
        ;;

    list | ls)
        printf "available scripts:\n\n"
        for scr in /tilde/bin/*; do
            if [ -f "$scr" ]; then
                script_name=$(basename "$scr")
                target=$(readlink -f "$scr")
                printf "%s by %s\n" "$script_name" "$(stat_func "$target")"
                cat "/tilde/descriptions/$script_name"
                printf "\n"
            fi
        done
        ;;

    about | apropos | description)
        if [ -f "/tilde/descriptions/$2" ]; then
            cat "/tilde/descriptions/$2"
        else
            printf "%s not found. try %s list to see available user scripts.\n" "$2" "$PROGNAME"
        fi
        ;;

    submit)
        printf "hello, %s! so it's time to submit your script?\n" "$user"
        submission_checklist
        prompt_confirm "are you ready to continue?" || exit
        printf "enter the name of your script: "
        read -r script_name

        verify_script_name "$script_name"

        if [ -x "$HOME/bin/$script_name" ]; then
            printf "cool, found your script\n"
            if [ -x "/tilde/pending-submissions/$user/$script_name/$script_name" ]; then
                error_exit "you've already submitted $script_name"
            fi
        else
            error_exit "$script_name not found in ~/bin"
        fi

        printf "enter a description of your script: \n"
        read -r description
        printf "\nyour script, along with your description will be sent to the admins for approval\n"
        prompt_confirm "ready to submit?" || exit

        # submit now
        mkdir -p "/tilde/pending-submissions/$user/$script_name"
        ln -s "$HOME/bin/$script_name" "/tilde/pending-submissions/$user/$script_name/$script_name"
        printf "%s\n" "$description" > "/tilde/pending-submissions/$user/$script_name/description.txt"
        mail_body "$script_name" "$description" | sendmail root 
        printf "script submitted. thanks! :)\n"
        ;;

    approve)
        if ! isroot; then
            error_exit "re-run this as root to access the approval queue"
        fi

        printf "welcome to the approval queue\n\n"

        for user in /tilde/pending-submissions/*; do
            for scr in $user/*; do
                user=$(basename "$user")
                script_name=$(basename "$scr")
                [ -f "$scr/approved" ] && continue
                script="$scr/$script_name"

                if [ -f "$script" ]; then
                    printf "%s by %s\n" "$script_name" "$user"
                    cat "$scr/description.txt"
                    prompt_confirm "approve?" || continue

                    ln -s "$(readlink -f "$script")" "/tilde/bin/$script_name"
                    cp "$scr/description.txt" "/tilde/descriptions/$script_name"
                    touch "$scr/approved"
                    chmod 664 /tilde/descriptions/*
                    printf "your submission of %s has been approved and is now available at /tilde/bin/%s" "$script_name" "$script_name" \
                        | sendmail "$user"
                fi
            done
        done
        printf "~~done for now~~\n"
        ;;

    revoke)
        isroot || \
            error_exit "re-run this as sudo to access the revoke menu"
        [ -f "/tilde/bin/$2" ] || \
            error_exit "$2 isn't an approved script"

        prompt_confirm "revoke $2?"
        printf "please provide a reason: "
        read -r reason

        original_script=$(readlink -f "/tilde/bin/$2")
        author=$(stat_func "$original_script")
        rm "/tilde/bin/$2"
        rm "/tilde/descriptions/$2"
        rm -rf "/tilde/pending-submissions/$author/$2"

        printf "your script %s has been returned because: %s\nfeel free to resubmit\n" "$2" "$reason" \
            | sendmail "$author"

        printf "%s revoked and returned to author" "$2"
        ;;

    *)
        if [ -z "$1" ]; then
            help_message
            exit
        elif [ -x "/tilde/bin/$1" ]; then
            prog="/tilde/bin/$1"
            shift
            exec "$prog" "$@"
        else
            printf "%s not found. check %s list to see what's available\n\n" "$1" "$PROGNAME"
            help_message
            exit
        fi
        ;;

    esac