#!/bin/sh
# xvfb-run-eepp: xvfb-run variant with race-safe automatic display selection.
# Defaults tuned for eepp GUI tests:
#   --auto-servernum enabled by default
#   --server-args "-screen 0 1280x1024x24" enabled by default
#   ASAN_OPTIONS includes detect_leaks=0 for the child process

set -e

PROGNAME=${0##*/}
SERVERNUM=99
MAX_SERVERNUM=599
AUTO_SERVERNUM=yes
AUTHFILE=
ERRORFILE=/dev/null
STARTWAIT=3
XVFBARGS="-screen 0 1280x1024x24"
LISTENTCP="-nolisten tcp"
XAUTHPROTO=.
LOCKDIR=
XVFB_RUN_TMPDIR=
XVFBPID=

DEFCOLUMNS=$(stty size 2>/dev/null | awk '{print $2}') || true
case "$DEFCOLUMNS" in
    *[!0-9]*|'') DEFCOLUMNS=80 ;;
esac

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

error() {
    message "error: $*" >&2
}

usage() {
    [ -n "$*" ] && message "usage error: $*"
    cat <<EOF_USAGE
Usage: $PROGNAME [OPTION ...] COMMAND
Run COMMAND in a virtual X server environment.

Defaults differ from Debian xvfb-run:
  --auto-servernum is enabled by default
  --server-args defaults to "$XVFBARGS"
  ASAN_OPTIONS gets detect_leaks=0 for COMMAND

Options:
-a        --auto-servernum          try to get a free server number, starting at --server-num [default]
          --no-auto-servernum       use exactly --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
-h        --help                    display this usage message and exit
-n NUM    --server-num=NUM          first/exact server number to use (default: $SERVERNUM)
          --max-server-num=NUM      highest server number to try in auto mode (default: $MAX_SERVERNUM)
-l        --listen-tcp              enable TCP port listening in Xvfb
-p PROTO  --xauth-protocol=PROTO    X authority protocol name to use (default: xauth default)
-s ARGS   --server-args=ARGS        arguments to pass to Xvfb (default: "$XVFBARGS")
-w DELAY  --wait=DELAY              seconds to wait for Xvfb to start when xdpyinfo is unavailable (default: $STARTWAIT)
EOF_USAGE
}

cleanup() {
    status=$?

    if [ -n "$XVFBPID" ]; then
        kill "$XVFBPID" >/dev/null 2>&1 || true
        wait "$XVFBPID" >/dev/null 2>&1 || true
    fi

    if [ -n "$AUTHFILE" ]; then
        XAUTHORITY=$AUTHFILE xauth remove ":$SERVERNUM" >"$ERRORFILE" 2>&1 || true
    fi

    [ -n "$XVFB_RUN_TMPDIR" ] && rm -rf "$XVFB_RUN_TMPDIR" || true
    [ -n "$LOCKDIR" ] && rmdir "$LOCKDIR" >/dev/null 2>&1 || true

    exit "$status"
}

is_display_busy() {
    n=$1

    # Xorg/Xvfb convention: lock file plus socket. Check both because stale
    # lock files and still-existing sockets can happen independently.
    [ -e "/tmp/.X$n-lock" ] && return 0
    [ -e "/tmp/.X11-unix/X$n" ] && return 0

    return 1
}

claim_display() {
    n=$1
    lock="${TMPDIR:-/tmp}/$PROGNAME-display-$n.lock"

    # mkdir is atomic on local filesystems and avoids the race in classic
    # xvfb-run -a, where many jobs can pick the same currently-free display.
    if mkdir "$lock" 2>/dev/null; then
        LOCKDIR=$lock
        SERVERNUM=$n
        # Helpful for manual cleanup/debugging. Not used as synchronization.
        echo "$$" > "$LOCKDIR/pid" 2>/dev/null || true
        return 0
    fi

    # Older versions of this script claimed displays from a command substitution,
    # which left lock directories behind because LOCKDIR was set in a subshell.
    # Recover those stale claims, but never touch a lock owned by a live process.
    if [ -f "$lock/pid" ]; then
        oldpid=$(cat "$lock/pid" 2>/dev/null || true)
        case "$oldpid" in
            *[!0-9]*|'') oldpid= ;;
        esac
        if [ -z "$oldpid" ] || ! kill -0 "$oldpid" >/dev/null 2>&1; then
            rm -f "$lock/pid" 2>/dev/null || true
            rmdir "$lock" 2>/dev/null || true
            if mkdir "$lock" 2>/dev/null; then
                LOCKDIR=$lock
                SERVERNUM=$n
                echo "$$" > "$LOCKDIR/pid" 2>/dev/null || true
                return 0
            fi
        fi
    fi

    return 1
}

find_and_claim_display() {
    i=$SERVERNUM
    while [ "$i" -le "$MAX_SERVERNUM" ]; do
        if ! is_display_busy "$i" && claim_display "$i"; then
            return 0
        fi
        i=$((i + 1))
    done
    return 1
}

wait_for_xvfb() {
    if command -v xdpyinfo >/dev/null 2>&1; then
        i=0
        # Poll for up to about 10 seconds. Avoid requiring sleep fractions.
        while [ "$i" -lt 100 ]; do
            DISPLAY=:$SERVERNUM XAUTHORITY=$AUTHFILE xdpyinfo >/dev/null 2>&1 && return 0
            kill -0 "$XVFBPID" >/dev/null 2>&1 || return 1
            sleep 0.1 2>/dev/null || sleep 1
            i=$((i + 1))
        done
        return 1
    fi

    sleep "$STARTWAIT"
    kill -0 "$XVFBPID" >/dev/null 2>&1
}

ARGS=$(getopt --options +ae:f:hn:lp:s:w: \
    --long auto-servernum,no-auto-servernum,error-file:,auth-file:,help,server-num:,max-server-num:,listen-tcp,xauth-protocol:,server-args:,wait: \
    --name "$PROGNAME" -- "$@")
GETOPT_STATUS=$?

if [ "$GETOPT_STATUS" -ne 0 ]; then
    error "internal error; getopt exited with status $GETOPT_STATUS"
    exit 6
fi

eval set -- "$ARGS"

SHOWHELP=
while :; do
    case "$1" in
        -a|--auto-servernum) AUTO_SERVERNUM=yes ;;
        --no-auto-servernum) AUTO_SERVERNUM=no ;;
        -e|--error-file) ERRORFILE=$2; shift ;;
        -f|--auth-file) AUTHFILE=$2; shift ;;
        -h|--help) SHOWHELP=yes ;;
        -n|--server-num) SERVERNUM=$2; shift ;;
        --max-server-num) MAX_SERVERNUM=$2; shift ;;
        -l|--listen-tcp) LISTENTCP= ;;
        -p|--xauth-protocol) XAUTHPROTO=$2; shift ;;
        -s|--server-args) XVFBARGS=$2; shift ;;
        -w|--wait) STARTWAIT=$2; shift ;;
        --) shift; break ;;
        *) error "internal error; getopt permitted '$1' unexpectedly"; exit 6 ;;
    esac
    shift
done

if [ "$SHOWHELP" ]; then
    usage
    exit 0
fi

if [ "$#" -eq 0 ]; then
    usage "need a command to run" >&2
    exit 2
fi

case "$SERVERNUM:$MAX_SERVERNUM" in
    *[!0-9:]*|:*|*:)
        error "server numbers must be numeric"
        exit 2
        ;;
esac

if ! command -v xauth >/dev/null 2>&1; then
    error "xauth command not found"
    exit 3
fi

if ! command -v Xvfb >/dev/null 2>&1; then
    error "Xvfb command not found"
    exit 3
fi

if [ "$AUTO_SERVERNUM" = yes ]; then
    START_SERVERNUM=$SERVERNUM
    if ! find_and_claim_display; then
        error "could not find a free X display between $START_SERVERNUM and $MAX_SERVERNUM"
        exit 4
    fi
else
    if is_display_busy "$SERVERNUM"; then
        error "display :$SERVERNUM is already busy"
        exit 4
    fi
    if ! claim_display "$SERVERNUM"; then
        error "display :$SERVERNUM is already claimed by another $PROGNAME process"
        exit 4
    fi
fi

trap cleanup EXIT INT TERM HUP

if [ -z "$AUTHFILE" ]; then
    XVFB_RUN_TMPDIR=$(mktemp -d "${TMPDIR:-/tmp}/$PROGNAME.XXXXXXXX") || {
        error "could not create temporary directory"
        exit 4
    }
    AUTHFILE=$(mktemp "$XVFB_RUN_TMPDIR/Xauthority.XXXXXXXX") || {
        error "could not create Xauthority file"
        exit 4
    }
fi

MCOOKIE=$(mcookie)
XAUTHORITY=$AUTHFILE xauth add ":$SERVERNUM" "$XAUTHPROTO" "$MCOOKIE" >"$ERRORFILE" 2>&1

# shellcheck disable=SC2086 # XVFBARGS and LISTENTCP intentionally split like xvfb-run.
Xvfb ":$SERVERNUM" $XVFBARGS $LISTENTCP -auth "$AUTHFILE" >"$ERRORFILE" 2>&1 &
XVFBPID=$!

if ! wait_for_xvfb; then
    error "Xvfb failed to start on display :$SERVERNUM; see $ERRORFILE"
    exit 1
fi

set +e
ASAN_OPTIONS="${ASAN_OPTIONS:+$ASAN_OPTIONS:}detect_leaks=0" \
DISPLAY=:$SERVERNUM \
XAUTHORITY=$AUTHFILE \
"$@"
RETVAL=$?
set -e

exit "$RETVAL"