ttycomfy

#!/bin/bash
readv() { IFS='' read -rd '' $1; }

readv LICENSE << 'EOT'



    ttycomfy v0.2.0
    Copyright (c) 2020 Benjamin Isaac McCann
    ---D1TW Fair Distribution License v0.7.0---
    1)
    The Licensor, henceforth the "Original Publisher,"
    of the work hereby provided as Consideration,
    henceforth the "Original Work," hereby grants any person,
    henceforth an "Original Recipient," unrestricted permission
    to use, copy, and/or produce private derivative works
    of the Original Work, without being charged royalties.
    2)
    The Original Publisher hereby grants all Original Recipients
    limited permission to publish and/or sell copies and/or derivative
    works of the Original Work, without being charged royalties,
    subject to the following restrictions:
    2.a)
    The Original Publisher hereby reserves the exclusive right
    to relicense or sublicense the Original Work.
    2.b)
    Pursuant to paragraph 2.a, the Original Publisher hereby denies
    the publisher, henceforth a "Sub-Publisher," of any copy
    or derivative work, henceforth a "Sub-Publication,"
    of the Original Work, the permission to sublicense any portion
    of the Original Work, whether in distributing their Sub-Publication
    or otherwise.
    2.b.i)
    Pursuant to paragraph 2.b, a Sub-Publisher shall not misconstrue,
    explicitly or otherwise, any portion of the Original Work
    as being a consideration to any license agreement applicable
    to the Sub-Publisher's own Sub-Publication.
    2.b.ii)
    Pursuant to paragraph 2.b.i, in order to avoid so misconstruing
    any such portion of the Original Work, the Sub-Publisher shall
    explicitly disclaim from the license agreement applicable
    to the Sub-Publication all portions of the Original Work,
    and shall provide, separately, a verbatim copy of the text
    of this license agreement, accompanied by a written statement
    identifying said text as applicable to said portions
    of the Original Work, and identifying the Original Publisher
    as the Licensor of said portions.
    2.b.iii)
    Pursuant to paragraph 2.b, a Sub-Publisher shall respect,
    and not modify or elaborate upon, the permissions and restrictions
    which paragraph 1 has already extended to any potential recipient
    of the Sub-Publication, henceforth a "Sub-Recipient," with respect
    to the Sub-Recipient's use of any portion of the Original Work,
    including any portion provided to the Sub-Recipient
    via the Sub-Publication.
    3)
    Any license formed in violation of paragraphs 2.a through 2.b.iii,
    henceforth a "Noncompliant Sub-Publication License," is hereby
    null and void, insofar as it concerns, explicitly or otherwise,
    any portion of the Original Work. Insofar as the Original Work
    is not concerned, this license agreement shall not be taken
    to invalidate the Noncompliant Sub-Publication License in question;
    that is, only those portions concerning the Original Work
    are invalidated.
    3.a)
    Any Sub-Publisher acting in violation of paragraphs
    2.a through 2.b.iii shall be the sole liable party to any and all
    civil disputes brought by the Sub-Publisher, at the Sub-Publisher's
    behest, or on the Sub-Publisher's consenting behalf, on the grounds
    that the Sub-Recipient has violated any null and void portion
    (pursuant to paragraph 3) of the Noncompliant Sub-Publication License
    under which the Sub-Publication in question is provided. If any such
    dispute is brought on the Sub-Publisher's behalf, but without
    their consent, whoever brought the dispute shall be the sole
    liable party.
    4)
    In paragraphs 1 and 2, "without being charged royalties" shall not
    be understood to excuse an Original Recipient from paying a flat
    compensation fee charged by the Original Publisher prior
    to the formation of this license agreement, nor from paying
    any fees for optional services or privileges beyond those already
    guaranteed in paragraphs 1 and 2.
    5)
    The Original Work is provided "as is," without warranty of any kind,
    express or implied, including but not limited to the warranties
    of merchantability, fitness for a particular purpose,
    and noninfringement. In no event shall the Original Publisher
    be liable for any claim, damages, or other liability,
    whether in an action of contract, tort, or otherwise,
    arising from, out of, or in connection with the Original Work
    or the use or other dealings in the Original Work.
    6)
    Pursuant to paragraph 2.b.ii, the Licensor is required
    to inform the Licensee as now they shall: namely, that this specific
    license agreement does not cover as Consideration the text
    of the license agreement itself, which is licensed separately,
    but under the same terms. In this regard, the author, and licensor,
    of the text of this license agreement, is one Benjamin Isaac McCann,
    born in California in the United States in the year 1994,
    having authored the text of this license agreement in the year 2020,
    and having licensed it under itself to the general public.



EOT

catv() {
    if [[ "$1" == '-i' ]]; then
        echo "${!2}"
    else
        local line blanks
        echo "${!1}" | while read -r line; do
            if [[ "${line}" == '' ]]; then
                if [[ "${blanks}" != '' ]]; then
                    blanks=$((blanks + 1))
                fi
            else
                if [[ "${blanks}" != '' ]]; then
                    while [[ blanks -gt 0 ]]; do
                        echo
                        blanks=$((blanks - 1))
                    done
                fi
                echo "${line}"
                blanks=0
            fi
        done
    fi
}

terminit() {
    clear
    tput rmam
    tput civis
    stty -echo
}

termcleanup() {
    clear
    tput smam
    tput cnorm
    stty echo
}

getkey() {
    local key full
    if IFS= read -rsn1 key; then while true; do
        full+=$(echo -n "${key}" | cat -v)
        if IFS= read -rst0 key; then IFS= read -rsn1 key
        else
            echo "${full}"
            [[ "${full}" != "^D" ]]
            return $?
        fi
    done; else
        return 1
    fi
}

# =====================
# LINE BUFFER FUNCTIONS
# =====================

TERM_WIDTH=$(tput cols)
TERM_HEIGHT=$(($(tput lines) - 2))
LINE_BUFFER=()
LINE_BUFFER_SIZE=
LINE_BUFFER_SCROLL=0
LINE_BUFFER_ROW_INDEX=0
LINE_BUFFER_COLUMN_INDEX=0
LINE_BUFFER_DISPLAY_HEIGHT=$(($TERM_HEIGHT*3/4))
LINE_BUFFER_DISPLAY_ROW_OFFSET=$(($TERM_HEIGHT/5))
LINE_BUFFER_DISPLAY_COLUMN_OFFSET=$(($TERM_WIDTH/12))
LINE_BUFFER_NEEDS_REDRAW=true
LINE_BUFFER_ROW_SELECTED_SGR="\e[44m\e[37m"
LINE_BUFFER_COLUMN_SELECTED_SGR="\e[47m\e[34m"
LINE_BUFFER_DISABLE_COLUMNS=false

repositionlinebuf() {
    #echo "repositionlinebuf start" 1>&2
    # get variables and parameters
    local -n buf=LINE_BUFFER
    local -n count=LINE_BUFFER_SIZE
    local -n scroll=LINE_BUFFER_SCROLL
    local -n row=LINE_BUFFER_ROW_INDEX
    local -n col=LINE_BUFFER_COLUMN_INDEX
    local -n height=LINE_BUFFER_DISPLAY_HEIGHT
    local -n firstrow=LINE_BUFFER_DISPLAY_ROW_OFFSET
    local -n firstcol=LINE_BUFFER_DISPLAY_COLUMN_OFFSET
    local -n needredraw=LINE_BUFFER_NEEDS_REDRAW
    local -n rowselsgr=LINE_BUFFER_ROW_SELECTED_SGR
    local -n colselsgr=LINE_BUFFER_COLUMN_SELECTED_SGR
    local -n nocolumn=LINE_BUFFER_DISABLE_COLUMNS
    local width=$(($TERM_WIDTH - $firstcol))
    # update size
    count=${#buf[@]}
    # parse options
    local drow dcol
    local absolute=false
    #echo "parsing options" 1>&2
    while [[ ${1:0:2} == '--' ]]; do
        case "$1" in
        '--absolute')   absolute=true ;;
        '--nocolumn')   nocolumn=true ;;
        '--rowselsgr')  shift; rowselsgr=$1 ;;
        '--colselsgr')  shift; colselsgr=$1 ;;
        esac
        shift
    done
    if $absolute; then
        drow=$(($1 - $row))
        dcol=$(($2 - $col))
    else
        drow=$1
        dcol=$2
    fi
    #echo "calculation and bounds-checking" 1>&2
    # bounds-check display height
    #if [[ $height -gt $count ]]; then
    #    height=$count
    #fi
    # bounds-check deltas
    if [[ $drow == '' ]]; then drow=0; fi
    if [[ $dcol == '' ]]; then dcol=0; fi
    # declare calculation variables
    local newrow newcol scrollbottom newscroll newscrollbottom
    # don't have to do calculations if no movement
    if [[ ${drow}${dcol} == 00 ]]; then
        newrow=$row
        newcol=$col
        newscroll=$scroll
        scrollbottom=$(($scroll + $height - 1))
        newscrollbottom=$scrollbottom
    else
        # calculate initial new coords
        local newrow=$(($row + $drow))
        local newcol=$(($col + $dcol))
        # bounds-check new coords
        #echo "bounds-check loop" 1>&2
        while true; do
            # past last line -> lower-right
            if [[ $newrow -ge ${#buf[@]} ]]; then
                newrow=$((${#buf[@]} - 1))
                newcol=${#buf[newrow]}
                break
            # before first line -> upper-left
            elif [[ $newrow -lt 0 ]]; then
                newrow=0
                newcol=0
                break
            # past last column -> next line
            elif [[ $newcol -gt ${#buf[newrow]} ]]; then
                newcol=0
                newrow=$(($newrow + 1))
            # before first column -> previous line
            elif [[ $newcol -lt 0 ]]; then
                newrow=$(($newrow - 1))
                if [[ $newrow -lt 0 ]]; then
                    newrow=0
                fi
                newcol=${#buf[newrow]}
            else
                break
            fi
        done
        # recalculate deltas from bounds-checked new coords
        drow=$(($newrow - $row))
        dcol=$(($newcol - $col))
        # change scrolling based on index
        local scrollbottom=$(($scroll + $height - 1))
        local newscroll=$scroll
        # index above scroll top -> scroll up
        if [[ $newrow -lt $scroll ]]; then
            newscroll=$newrow
        fi
        # index below scroll bottom -> scroll down
        if [[ $newrow -gt $scrollbottom ]]; then
            newscroll=$(($newrow - $height + 1))
        fi
        # bounds-check scrolling
        if [[ $newscroll -lt 0 ]]; then
            newscroll=0
        fi
        local newscrollbottom=$((newscroll + $height - 1))
        if [[ $newscrollbottom -ge $count ]]; then
            newscroll=$(($count - $height))
            newscrollbottom=$(($count - 1))
        fi
        # end of coord / scroll calculations
    fi
    # post-calculations
    local srow=$(($row - $scroll + $firstrow))
    local snewrow=$(($newrow - $newscroll + $firstrow))
    local scol=$(($col + $firstcol))
    local snewcol=$(($newcol + $firstcol))
    # if scrolled or need redraw, do a full redraw
    local didfullredraw=false
    if [[ $scroll != $newscroll ]] || $needredraw; then
        # get in position
        echo -en "\e[${firstrow};${firstcol}H"
        # erase drawn characters
        for i in $(seq $scroll $scrollbottom); do
            printf "\e[0m%${width}s\e[${width}D\e[B" ''
        done
        # draw over them
        for i in $(seq $newscroll $newscrollbottom | tac); do
            if [[ ($i -ge ${#buf[@]}) || ($i -lt 0) || ("${buf[$i]}" == "") ]]; then
                echo -en "\e[A"
            else
                echo -en "\e[A"
                echo -En "${buf[$i]}"
                if [[ ${#buf[$i]} -ge $width ]]; then
                    echo -en "\e[$((${firstrow}+${i}));${firstcol}H"
                else
                    echo -en "\e[${#buf[$i]}D"
                fi
            fi
        done
        # done with full redraw
        needredraw=false
        didfullredraw=true
    fi
    # if did full redraw or changed row, redraw row selection
    local didrowredraw=false
    if [[ $newrow != $row ]] || $didfullredraw; then
        # only need to redraw previous selection
        # if it's not already redrawn
        if ! $didfullredraw; then
            echo -en "\e[${srow};${firstcol}H"
            if [[ "${buf[$row]}" == "" ]]; then
                echo -En " "
            else
                echo -En "${buf[$row]} "
            fi
        fi
        # always need to redraw new selection to show it's selected
        echo -en "\e[${snewrow};${firstcol}H${rowselsgr}"
        echo -En "${buf[$newrow]} "
        echo -en "\e[0m"
        # done with row redraw
        didrowredraw=true
    fi
    # if did row redraw or changed column, redraw column selection
    if [[ $newcol != $col ]] || $didrowredraw && ! $nocolumn; then
        # only need to redraw previous selection
        # if it's not already redrawn
        if ! $didrowredraw; then
            if [[ $newrow == $row ]]; then
                echo -en "\e[${srow};${scol}H${rowselsgr}"
                echo -En "${buf[$row]:$col:1}"
                echo -en "\e[0m"
            else
                echo -en "\e[${srow};${scol}H\e[0m"
                echo -En "${buf[$row]:$col:1}"
            fi
        fi
        # always need to redraw new selection to show it's selected
        local chr=${buf[newrow]:$newcol:1}
        # make sure it shows even at end of line
        if [[ $chr == '' ]]; then chr=' '; fi
        # draw it
        echo -en "\e[${snewrow};${snewcol}H"`
            `"${colselsgr}${chr}\e[0m"
    fi
    # update coords
    scroll=$newscroll
    row=$newrow
    col=$newcol
}

redrawlinebuf() {
    LINE_BUFFER_NEEDS_REDRAW=true
    repositionlinebuf
}

putlinebuf() {
    local -n buf=LINE_BUFFER
    local chr=$1
    local row=$2
    local col=$3
    # split line at position
    local line="${buf[$row]}"
    local firstpart="${line:0:$col}"
    local restpart="${line:$col}"
    # the line buffer is changing so needs redraw
    LINE_BUFFER_NEEDS_REDRAW=true
    # enter -> split line into two lines
    if [[ $chr == '' ]]; then
        buf=( "${buf[@]:0:$row}"
                "$firstpart"
                "$restpart"
                "${buf[@]:$(($row + 1))}"
        );
        repositionlinebuf --absolute $(($row + 1)) 0
    # backspace at beginning of line
    # -> merge line with previous
    elif [[ ($chr == '^?') && ($col == 0) && ($row != 0) ]]; then
        repositionlinebuf --absolute `
            ` $(($row - 1)) ${#buf[$(($row - 1))]}
        buf=( "${buf[@]:0:$(($row - 1))}"
                "${buf[$(($row - 1))]}${buf[$row]}"
                "${buf[@]:$(($row + 1))}"
        );
        LINE_BUFFER_NEEDS_REDRAW=true
        repositionlinebuf
    # backspace elsewhere
    # -> reconstruct line with character missing
    elif [[ ($chr == '^?') && ($col != 0) ]]; then
        buf=( "${buf[@]:0:$row}"
                "${firstpart:0:-1}${restpart}"
                "${buf[@]:$(($row + 1))}"
        );
        repositionlinebuf --absolute $row $(($col - 1))
    # single printable character
    # -> reconstruct line with character inserted
    elif [[ ${#chr} == 1 ]]; then
        buf=( "${buf[@]:0:$row}"
                "${firstpart}${chr:0:1}${restpart}"
                "${buf[@]:$(($row + 1))}"
        );
        repositionlinebuf --absolute $row $(($col + 1))
    fi
}

loadlinebuf() {
    mapfile -t LINE_BUFFER
    LINE_BUFFER_SCROLL=0
    LINE_BUFFER_NEEDS_REDRAW=true
    repositionlinebuf --absolute 0 0
}

dumplinebuf() {
    for line in "${LINE_BUFFER[@]}"; do
        echo "${line}"
    done
}

# =======================
# LINEBUF MASTER FUNCTION
# =======================

linebuf() {
    # parse options
    local readonly=false
    while [[ "${1:0:2}" == "--" ]]; do
        case "$1" in
        '--ro')     readonly=true ;;
        esac
        shift
    done
    # logic
    case $1 in
    load)       loadlinebuf ;;
    dump)       dumplinebuf ;;
    loadfile)   loadlinebuf "$(cat $1)" ;;
    dumpfile)   dumplinebuf > "$1" ;;
    go)         repositionlinebuf --absolute "${@:1}" ;;
    move)       repositionlinebuf "${@:1}" ;;
    redraw)     LINE_BUFFER_NEEDS_REDRAW=true; repositionlinebuf ;;
    nocol)      LINE_BUFFER_DISABLE_COLUMNS=true ;;
    yescol)     LINE_BUFFER_DISABLE_COLUMNS=false ;;
    row)        echo $LINE_BUFFER_ROW_INDEX ;;
    col)        echo $LINE_BUFFER_COLUMN_INDEX ;;
    put)        putlinebuf "$2" `
                    `$LINE_BUFFER_ROW_INDEX `
                    `$LINE_BUFFER_COLUMN_INDEX ;;
    get)
        echo "${LINE_BUFFER[$LINE_BUFFER_ROW_INDEX]:$LINE_BUFFER_COLUMN_INDEX:1}"
        ;;
    up)         repositionlinebuf -1 0 ;;
    down)       repositionlinebuf 1 0 ;;
    left)       repositionlinebuf 0 -1 ;;
    right)      repositionlinebuf 0 1 ;;
    home)
        if [[ $LINE_BUFFER_COLUMN_INDEX == 0 ]]; then
            local c=0
            while [[ "${LINE_BUFFER[$LINE_BUFFER_ROW_INDEX]:$c:1}" == ' ' ]]; do
                c=$((c + 1))
            done
            repositionlinebuf 0 $c
        else
            repositionlinebuf 0 -$LINE_BUFFER_COLUMN_INDEX
        fi ;;
    end)
        repositionlinebuf 0 `
            ` $((${#LINE_BUFFER[$LINE_BUFFER_ROW_INDEX]} `
                ` - $LINE_BUFFER_COLUMN_INDEX)) ;;
    pageup)     repositionlinebuf $((-$LINE_BUFFER_DISPLAY_HEIGHT/2 - 1)) ;;
    pagedown)   repositionlinebuf $(($LINE_BUFFER_DISPLAY_HEIGHT/2 + 1)) ;;
    key)
        case "$2" in
        '^[[A')             linebuf up ;;
        '^[[B')             linebuf down ;;
        '^[[C')
            if ! $LINE_BUFFER_DISABLE_COLUMNS; then
                linebuf right
            fi ;;
        '^[[D')
            if ! $LINE_BUFFER_DISABLE_COLUMNS; then
                linebuf left
            fi ;;
        '^[[1~'|'^[[7~')
            if ! $LINE_BUFFER_DISABLE_COLUMNS; then
                linebuf home
            fi ;;
        '^[[4~'|'^[[8~')
            if ! $LINE_BUFFER_DISABLE_COLUMNS; then
                linebuf end
            fi ;;
        '^[[5~')            linebuf pageup ;;
        '^[[6~')            linebuf pagedown ;;
        $(echo -e "\t"))
            if ! { $readonly || $LINE_BUFFER_DISABLE_COLUMNS; }; then
                for i in $(seq $((4 - $LINE_BUFFER_COLUMN_INDEX%4))); do
                    linebuf put ' '
                done
            fi ;;
        '^[^?')
            if ! { $readonly || $LINE_BUFFER_DISABLE_COLUMNS; }; then
                if [[ $LINE_BUFFER_COLUMN_INDEX -gt 0 ]]; then
                    for i in $(seq $((($LINE_BUFFER_COLUMN_INDEX + 3)%4 + 1))); do
                        linebuf put '^?'
                    done
                fi
            fi ;;
        *)
            if ! { $readonly || $LINE_BUFFER_DISABLE_COLUMNS; }; then
                linebuf put "$2"
            fi ;;
        esac ;;
    height)     LINE_BUFFER_DISPLAY_HEIGHT=$2 ;;
    firstrow)   LINE_BUFFER_DISPLAY_ROW_OFFSET=$2 ;;
    firstcol)   LINE_BUFFER_DISPLAY_COLUMN_OFFSET=$2 ;;
    esac
}

linebuftest() {
    terminit
    linebuf load < <(echo "${LICENSE}")
    local key; while key=$(getkey); do case $key in
    *)          linebuf key "$key" ;;
    esac; done
    termcleanup
    linebuf dump
}

# ====================
# STATUS BAR FUNCTIONS
# ====================

STATUS_BAR_ROW=$(($TERM_HEIGHT - 2))
STATUS_BAR_SGR="\e[47m\e[30m"
STATUS_BAR_ERROR_SGR="\e[41m\e[37m"
STATUS_BAR_PROMPT_SGR="\e[43m\e[30m"
STATUS_BAR_TEXT=

statusbar() {
    # opts
    local sgr=$STATUS_BAR_SGR
    local nosleep=false
    while [[ "${1:0:2}" == '--' ]]; do
        case "$1" in
        '--sgr')        shift; sgr="$1" ;;
        '--nosleep')    nosleep=true ;;
        esac
        shift
    done
    # logic
    local resp ret
    if [[ "$1" == '' ]]; then
        echo "${STATUS_BAR_TEXT}"
    else
        case "$1" in
        'clear')
            echo -en "\e[${STATUS_BAR_ROW};0H" 1>&2
            printf "%$((${TERM_WIDTH} - 1))s" '' 1>&2
            echo -en "\e[${STATUS_BAR_ROW};0H" 1>&2
            STATUS_BAR_TEXT=
            ;;
        'error')
            statusbar --sgr "${STATUS_BAR_ERROR_SGR}" "Error: $2"
            ;;
        'Y/n')
            statusbar --nosleep --sgr "${STATUS_BAR_PROMPT_SGR}" "$2 [Y/n]"
            local ret=0
            case $(getkey) in
            N|n) ret=1 ;;
            esac
            statusbar clear
            return $ret
            ;;
        'y/N')
            statusbar --nosleep --sgr "${STATUS_BAR_PROMPT_SGR}" "$2 [y/N]"
            local ret=1
            case $(getkey) in
            Y|y) ret=0 ;;
            esac
            statusbar clear
            return $ret
            ;;
        'prompt')
            statusbar --nosleep --sgr "${STATUS_BAR_PROMPT_SGR}" "$2:"
            stty echo
            read -r resp
            ret=$?
            stty -echo
            echo "${resp}"
            return $ret
            ;;
        'password')
            statusbar --nosleep --sgr "${STATUS_BAR_PROMPT_SGR}" "$2:"
            read -rs resp
            ret=$?
            echo "${resp}"
            return $ret
            ;;
        *)
            local msg=" $1 "
            echo -en "\e[${STATUS_BAR_ROW};0H" 1>&2
            printf "%$((${TERM_WIDTH} - 1))s" '' 1>&2
            echo -en "\e[${STATUS_BAR_ROW};0H" 1>&2
            STATUS_BAR_TEXT="$1"
            printf "%$((${TERM_WIDTH}/2 - ${#msg}/2))s" '' 1>&2
            echo -en "${sgr}${msg}\e[0m" 1>&2
            if ! $nosleep; then
                read -rst1.1 -n1
            fi
            ;;
        esac
    fi
}

# =====================
# PERMISSIONS FUNCTIONS
# =====================

subypass() {
    local user=$1
    local pass=$2
    local cmd="${@:3}"
    { sleep 0.25; echo $pass; } |
        script -eqc "su -c "'"'"${cmd}"'"'" - $user 2>&1 > /dev/null" > /dev/null
    return $?
}

auth() {
    local admin=
    local pass=
    if ! admin=$(statusbar prompt "System administrator username"); then
        statusbar "Cancelled"
        return 1
    fi
    if ! pass=$(statusbar password "Password for ${admin}"); then
        statusbar "Cancelled"
        return 1
    fi
    statusbar --nosleep "Authenticating.  "
    if ! subypass "$admin" "$pass" ":"; then
        statusbar error "Incorrect username or password"
        return 1
    fi
    statusbar --nosleep "Authenticating.. "
    if ! subypass "$admin" "$pass" "echo '""$pass""' | sudo -lS 2>&1 > /dev/null"; then
        statusbar error "User $admin is not a system administrator"
        return 1
    fi
    local action="$@"
    statusbar --nosleep "Authenticating..."
    if ! subypass "$admin" "$pass" "echo '""$pass"`
            `"' | sudo -S 2>&1 ${action}"; then
        statusbar error "Privileged command returned a nonzero exit code"
        return 1
    fi
    return 0
}

promptchmod() {
    # opts
    local usesu=false
    while [[ "${1:0:2}" == '--' ]]; do
        case "$1" in
        '--su') usesu=true ;;
        esac
        shift
    done
    # logic
    local mode="$1"
    local fname="$2"
    if statusbar y/N "Force access (chmod ${mode})?"; then
        if [[ -O "$fname" ]]; then
            if chmod "u$mode" "$fname"; then
                statusbar "Performed chmod."
                return 0
            else
                statusbar error "Couldn't chmod."
                return 1
            fi
        elif $usesu; then
            if auth chmod "o$mode" "$fname"; then
                statusbar "Performed chmod."
                return 0
            else
                return 1
            fi
        else
            statusbar error "No permission to chmod this file."
            return 1
        fi
    else
        return 1
    fi
}

realpath_if_allowed() {
    if ! realpath "$1" 2>/dev/null; then echo "$1"; fi
}

fileperms() {
    # opts
    local usepromptchmod=false
    local promptchmodopts=''
    local create=false
    while [[ "${1:0:2}" == '--' ]]; do
        case "$1" in
        '--chmod')  usepromptchmod=true ;;
        '--su')     promptchmodopts='--su' ;;
        '--create') create=true ;;
        esac
        shift
    done
    # logic
    local fname="$1"
    local dname="$(dirname $(readlink -m $fname))"
    local cont
    if [[ (-e "$dname") && (! -d "$dname") ]]; then
        statusbar error "$(basename $dname) is not a directory."
        echo '---'
        return 1
    elif [[ (! -e "$dname") ]]; then
        statusbar error "Directory $(basename $dname) does not exist."
        echo '---'
        return 1
    elif [[ (! -e "$fname") ]] && ! $create; then
        statusbar error "File $(basename $fname) does not exist."
        echo '---'
        return 1
    elif [[ (! -e "$fname") && (-w "$dname") && (-x "$dname") ]]; then
        statusbar "File $(basename $fname) to be created."
        echo '-w-'
        return 0
    elif [[ (! -e "$fname") ]] && $usepromptchmod; then
        if promptchmod $promptchmodopts +wx "$dname"; then
            statusbar "File $(basename $fname) to be created."
            echo '-w-'
            return 0
        else
            echo '---'
            return 1
        fi
    elif [[ (! -e "$fname") ]]; then
        statusbar error "No permission to create file $(basename $fname)."
        echo '---'
        return 1
    else
        local r=- w=- x=-
        if [[ -r "$fname" ]]; then
            r=r
        fi
        if [[ -w "$fname" ]]; then
            w=w
        fi
        if [[ -x "$fname" ]]; then
            x=x
        fi
        echo "$r$w$x"
        return 0
    fi
}

# =========================
# LINEBUF-BASED SUBPROGRAMS
# =========================

texteditor() {
    # opts
    local readonly=false
    while [[ "${1:0:2}" == '--' ]]; do
        case "$1" in
        '--ro') readonly=true ;;
        esac
        shift
    done
    # logic
    clear
    local fname="$@"
    local perms=$(fileperms --create --chmod --su "$fname")
    if $readonly; then
        perms="${perms:0:1}-${perms:2:1}"
    fi
    case "${perms:0:2}" in
    'rw')   linebuf yescol
            linebuf load < <(cat "$fname")
            statusbar --nosleep "Editing $fname" ;;
    '-w')   linebuf yescol
            linebuf load < <(echo)
            statusbar --nosleep "Editing $fname (new)" ;;
    'r-')   linebuf nocol
            linebuf load < <(cat "$fname")
            statusbar --nosleep "Viewing $fname" ;;
    '--')   statusbar error "Cannot access $fname"
            clear
            return 1 ;;
    esac
    local key; while key=$(getkey); do case $key in
    '^W')
        if [[ ${perms:1:1} == 'w' ]]; then :
            linebuf dump > "$fname"
            statusbar --nosleep "Saved $fname"
        else :
            statusbar error "Read-only mode"
        fi ;;
    *)
        statusbar clear
        if [[ ${perms:1:1} == 'w' ]]; then
            linebuf key "$key"
        else
            linebuf --ro key "$key"
        fi ;;
    esac; done
    clear
    return 0
}