path: root/bin/emacsclient

#!/bin/bash

# Copyright (C) 2022  Sean Whitton
#
# 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 for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.



# emacsclient(1) wrapper to handle updating the environment of existing
# daemons and choosing between installed and in-tree builds of Emacs.

min_arg=0
may_start=true
want_update=false
want_installed=false
want_eval=false
want_version=false
devel_running=false
installed_running=false
pass_to_gdbmacs=false
status=
daemon_name=
gdbmacs=
args=
xdg="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
socket_dir="$xdg/emacs/"
locks_dir="$xdg/spw_emacsclient/"

get_listener () {
    local socket="$1"
    local listener=$(ss -Hplx src "$socket" \
			 | perl -wne'/pid=(\d+)/ and print $1')
    if [ -z "$listener" -a -e "$socket" ]; then
	# Nothing is listening: remove dangling socket.
	rm "$socket"
    else
	echo "$listener"
    fi
}

maybe_notify () {
    echo >&2 "$1"
    [ -n "$XDG_RUNTIME_DIR" ] \
	&& notify-send --urgency=low --expire-time=10000 "$1"
}

spw_flock () {
    mkdir -p "$locks_dir"
    eval "exec $1<>${locks_dir}$2"
    if ! flock --wait 15 "$1"; then
	maybe_notify "couldn't lock starting Emacs daemon named $2"
	exit 1
    fi
}

die_wedged () {
    maybe_notify "in-tree Emacs appears to be wedged"
    # Only exit non-zero if we were expected to start the daemon.
    ! $may_start; exit
}

egrep_negate () {
    echo -n "^([^${1:0:1}]"
    for (( i=1; i < ${#1}; i++ )); do
	echo -n "|(${1:0:$i}([^${1:$i:1}]|$))"
    done
    echo -n "|($1.+))"
}

for arg do
    shift
    case "$arg" in
	'--spw/installed')               want_installed=true	 ;;
	'--spw/no-start')                may_start=false	 ;;
	'--spw/update-environment')      want_update=true	 ;;
	'-V'|'--version')                want_version=true	 ;;&
	'-e'|'--eval')                   want_eval=true          ;;&
	'-s'|'--socket-name') min_arg=2; daemon_name="$1"        ;;&
	'-s'?*)               min_arg=1; daemon_name="${arg:2}"  ;;&
	'--socket-name='?*)   min_arg=1; daemon_name="${arg:14}" ;;&
	*) set -- "$@" "$arg" ;;
    esac
done

devel_emacs="$HOME/src/emacs/src/emacs"
devel_emacsclient="$HOME/src/emacs/lib-src/emacsclient"

installed_emacs=$(command -v emacs)
installed_emacsclient=$(PATH=$(echo "$PATH" \
				   | sed -e "s#$HOME/src/dotfiles/bin:##") \
			    command -v emacsclient)

command -v ss >/dev/null || exec "$installed_emacsclient" -a "" "$@"

$want_version || spw_flock 3 "${daemon_name:-server}"

socket="$socket_dir${daemon_name:-server}"
listener="$(get_listener $socket)"
if [ -n "$listener" ]; then
    case "$(ps h -o exe $listener | sed -e 's/ (deleted)$//')" in
	"$devel_emacs")                 devel_running=true     ;;
	"$(realpath $installed_emacs)") installed_running=true ;;
	*) echo >&2 "Unknown Emacs listening on $socket"; exit 1  ;;
    esac
fi

# ---- Special case for primary session that's always under gdb
if [ -z "$daemon_name" ] && $devel_running && $want_installed; then
    inotifywait -qq -e delete "$socket" &
    inotifywait=$!
    kill "$listener"

    # Detach gdb so that Emacs can handle the SIGTERM.  We also have to quit
    # gdb so that `spw/gdbmacs-attach' doesn't look at `gdb-inferior-status'.
    [ -n "${gdbmacs:=$(get_listener ${socket_dir}gdbmacs)}" ] \
	&& "$installed_emacsclient" -sgdbmacs \
				    --eval '(gdb-wait-for-pending
				             (lambda ()
					       (gud-basic-call "detach")
					       (gdb-wait-for-pending
				                (lambda ()
					          (gud-basic-call "quit")))))'

    wait $inotifywait
    devel_running=false
fi
# ---- End special case for primary session that's always under gdb

[ -z "$listener" ] && ! $may_start && exit 0

# We check whether there is something which looks like the installed Emacs
# running because we do not want the in-tree emacsclient to try to connect to
# that, and we check whether there is a build in progress and no running
# daemon, as we don't want to start a new daemon until the build is finished.
# The idea is that I can always hit C-i e without worrying about builds.
if ! $want_installed && ! $installed_running \
	&& [ -e "$HOME/src/emacs/admin/flagfile.melete" \
		-a -x "$HOME/src/emacs/lib-src/emacsclient" \
		-a -d "/usr/share/emacs-snapshot/site-lisp/elpa" ] \
	&& ! ( ! $devel_running && ps h -o pid -C make \
		       | xargs pwdx 2>/dev/null \
		       | grep -q "$HOME/src/emacs" ); then
    emacs="$devel_emacs"
    emacsclient="$devel_emacsclient"

    # ---- Two special cases for primary session that's always under gdb
    if [ -z "$daemon_name" ] && ! $want_version; then
	spw_flock 4 gdbmacs
	# If devel Emacs is stopped or gdbmacs can't start it, ask gdbmacs to
	# handle the request: it's probs. C-i e or editing a file via EDITOR.

	[ -n "${gdbmacs:=$(get_listener ${socket_dir}gdbmacs)}" ] \
	    && status=$("$installed_emacsclient" \
			    -sgdbmacs \
			    --eval \
			    '(and (boundp '"'"'gud-comint-buffer)
				  (get-buffer-process gud-comint-buffer)
				  (string= "signal-received"
					   gdb-inferior-status))')

	if [ "$status" = t ]; then
	    if $want_eval || $want_update; then
		die_wedged
	    else
		pass_to_gdbmacs=true
	    fi
	elif [ -z "$listener" ]; then
	    # inotifywait(1) in Debian "bullseye" doesn't have --include.
	    inotifywait -qq -e create "${socket_dir}" \
			--exclude "$(egrep_negate ${socket_dir}server)" &
	    inotifywait=$!

	    if "$installed_emacsclient" \
		   -a '' -sgdbmacs \
		   --eval '(spw/gdbmacs-attach)' 3>&- 4>&-; then
		wait $inotifywait
		listener=true
	    elif $want_eval || $want_update; then
		kill $inotifywait
		die_wedged
	    else
		kill $inotifywait
		pass_to_gdbmacs=true
	    fi
	fi

	if $pass_to_gdbmacs; then
	    emacs="$installed_emacs"
	    emacsclient="$installed_emacsclient"
	    socket="${socket_dir}gdbmacs"
	    listener="$gdbmacs"
	    set -- "$@" -sgdbmacs
	fi
	exec 4>&-
    fi
    # ---- End two special cases for primary session that's always under gdb
else
    emacs="$installed_emacs"
    emacsclient="$installed_emacsclient"
fi

# Update Emacs daemon environment vars for a new interactive session.  This
# allows us to have the Emacs daemon survive restarts of the graphical desktop
# environment, and to update Emacs on a remote host when there is a new
# forwarded SSH agent socket.  See 'upenv' in .bash_defns.
if $want_update && [ -n "$listener" ]; then
    for var in DISPLAY WAYLAND_DISPLAY \
		       XAUTHORITY WINDOWID \
		       XDG_SESSION_TYPE XDG_CURRENT_DESKTOP \
		       SWAYSOCK I3SOCK \
		       SSH_ASKPASS SSH_CONNECTION \
		       SSH_AUTH_SOCK SSH_AGENT_PID; do
	eval isset=\${$var+x}
	if [ "$isset" = "x" ]; then
	    eval val=\$$var
	    args="$args"' "'$var'" "'$val'"'
	fi
    done
    [ -n "$args" ] \
	&& "$emacsclient" -s"${daemon_name:-server}" \
			  --eval "(spw/update-environment$args))"
fi

maybe_hold_lock () {
    # Hold on to the lock until daemon has started up.
    $want_version || [ -n "$listener" ] \
	|| inotifywait -qq -e create "${socket_dir}" \
		       --exclude "$(egrep_negate $socket)" &
}

# emacsclient(1) requires an argument.  As a special case, if there are no
# arguments except -s/--socket-name, and no daemon is running, just start one.
# And if there were no arguments but we were requested just to update env
# vars, exit peacefully.
if [ "$#" -eq "$min_arg" -a -z "$listener" ]; then
    maybe_hold_lock
    exec "$emacs" --daemon"${daemon_name:+=$daemon_name}" 3>&-
elif ! ( [ "$#" -eq "$min_arg" ] && $want_update ); then
    maybe_hold_lock
    exec "$emacsclient" -a "" "$@" 3>&-
fi