#!/bin/sh

# This script starts an instance of Xvfb, the "fake" X server, runs a command

# with that server available, and kills the X server when done.  The return

# value of the command becomes the return value of this script.

#

# If anyone is using this to build a Debian package, make sure the package

# Build-Depends on xvfb and xauth.

set -e

PROGNAME=xvfb-run

SERVERNUM=99

AUTHFILE=

ERRORFILE=/dev/null

XVFBARGS="-screen 0 640x480x8"

LISTENTCP="-nolisten tcp"

XAUTHPROTO=.

# Query the terminal to establish a default number of columns to use for

# displaying messages to the user.  This is used only as a fallback in the event

# the COLUMNS variable is not set.  ($COLUMNS can react to SIGWINCH while the

# script is running, and this cannot, only being calculated once.)

DEFCOLUMNS=$(stty size 2>/dev/null | awk '{print $2}') || true

if ! expr "$DEFCOLUMNS" : "[[:digit:]]\+$" >/dev/null 2>&1; then

    DEFCOLUMNS=80

fi

# Display a message, wrapping lines at the terminal width.

message () {

    echo "$PROGNAME: $*" | fmt -t -w ${COLUMNS:-$DEFCOLUMNS}

}

# Display an error message.

error () {

    message "error: $*" >&2

}

# Display a usage message.

usage () {

    if [ -n "$*" ]; then

        message "usage error: $*"

    fi

    cat <<EOF

Usage: $PROGNAME [OPTION ...] COMMAND

Run COMMAND (usually an X client) in a virtual X server environment.

Options:

-a        --auto-servernum          try to get a free server number, starting at

                                    --server-num

-e FILE   --error-file=FILE         file used to store xauth errors and Xvfb

                                    output (default: $ERRORFILE)

-f FILE   --auth-file=FILE          file used to store auth cookie

                                    (default: ./.Xauthority)

-h        --help                    display this usage message and exit

-n NUM    --server-num=NUM          server number to use (default: $SERVERNUM)

-l        --listen-tcp              enable TCP port listening in the X server

-p PROTO  --xauth-protocol=PROTO    X authority protocol name to use

                                    (default: xauth command's default)

-s ARGS   --server-args=ARGS        arguments (other than server number and

                                    "-nolisten tcp") to pass to the Xvfb server

                                    (default: "$XVFBARGS")

EOF

}

# Find a free server number by looking at .X*-lock files in /tmp.

find_free_servernum() {

    # Sadly, the "local" keyword is not POSIX.  Leave the next line commented in

    # the hope Debian Policy eventually changes to allow it in /bin/sh scripts

    # anyway.

    #local i

    i=$SERVERNUM

    while [ -f /tmp/.X$i-lock ]; do

        i=$(($i + 1))

    done

    echo $i

}

# Clean up files

clean_up() {

    if [ -e "$AUTHFILE" ]; then

        XAUTHORITY=$AUTHFILE xauth remove ":$SERVERNUM" >>"$ERRORFILE" 2>&1

    fi

    if [ -n "$XVFB_RUN_TMPDIR" ]; then

        if ! rm -r "$XVFB_RUN_TMPDIR"; then

            error "problem while cleaning up temporary directory"

            exit 5

        fi

        XVFB_RUN_TMPDIR=

    fi

    if [ -n "$XVFBPID" ]; then

        kill "$XVFBPID"

    fi

}

# Parse the command line.

ARGS=$(getopt --options +ae:f:hn:lp:s:w: \

       --long auto-servernum,error-file:,auth-file:,help,server-num:,listen-tcp,xauth-protocol:,server-args:,wait: \

       --name "$PROGNAME" -- "$@")

GETOPT_STATUS=$?

if [ $GETOPT_STATUS -ne 0 ]; then

    error "internal error; getopt exited with status $GETOPT_STATUS"

    exit 6

fi

eval set -- "$ARGS"

while :; do

    case "$1" in

        -a|--auto-servernum) SERVERNUM=$(find_free_servernum); AUTONUM="yes" ;;

        -e|--error-file) ERRORFILE="$2"; shift ;;

        -f|--auth-file) AUTHFILE="$2"; shift ;;

        -h|--help) SHOWHELP="yes" ;;

        -n|--server-num) SERVERNUM="$2"; shift ;;

        -l|--listen-tcp) LISTENTCP="" ;;

        -p|--xauth-protocol) XAUTHPROTO="$2"; shift ;;

        -s|--server-args) XVFBARGS="$2"; shift ;;

        -w|--wait) shift ;;

        --) shift; break ;;

        *) error "internal error; getopt permitted \"$1\" unexpectedly"

           exit 6

           ;;

    esac

    shift

done

if [ "$SHOWHELP" ]; then

    usage

    exit 0

fi

if [ -z "$*" ]; then

    usage "need a command to run" >&2

    exit 2

fi

if ! which xauth >/dev/null; then

    error "xauth command not found"

    exit 3

fi

# tidy up after ourselves

trap clean_up EXIT TERM

# If the user did not specify an X authorization file to use, set up a temporary

# directory to house one.

if [ -z "$AUTHFILE" ]; then

    XVFB_RUN_TMPDIR="$(mktemp -d -t $PROGNAME.XXXXXX)"

    # Create empty file to avoid xauth warning

fi

# Start Xvfb.

MCOOKIE=$(mcookie)

tries=10

while [ $tries -gt 0 ]; do

    tries=$(( $tries - 1 ))

    XAUTHORITY=$AUTHFILE xauth source - << EOF >>"$ERRORFILE" 2>&1

add :$SERVERNUM $XAUTHPROTO $MCOOKIE

EOF

    # handle SIGUSR1 so Xvfb knows to send a signal when it's ready to accept

    # connections

    trap : USR1

    (trap '' USR1; XAUTHORITY=$AUTHFILE exec Xvfb ":$SERVERNUM" $XVFBARGS $LISTENTCP >>"$ERRORFILE" 2>&1) &

    XVFBPID=$!

    wait || :

    if kill -0 $XVFBPID 2>/dev/null; then

        break

    elif [ -n "$AUTONUM" ]; then

        # The display is in use so try another one (if '-a' was specified).

        SERVERNUM=$((SERVERNUM + 1))

        SERVERNUM=$(find_free_servernum)

        continue

    fi

    error "Xvfb failed to start" >&2

    XVFBPID=

    exit 1

done

# Start the command

DISPLAY=:$SERVERNUM XAUTHORITY=$AUTHFILE "$@" 2>&1 &

wait $!

# vim:set ai et sts=4 sw=4 tw=80: