From 37e9061c0f8caa953b5a0adb1a3c4329930ac749 Mon Sep 17 00:00:00 2001
From: Sean Whitton <spwhitton@spwhitton.name>
Date: Tue, 17 Jan 2023 10:15:34 -0700
Subject: emacsclient wrapper: get_listener: find the youngest process

---
 bin/emacsclient | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

(limited to 'bin/emacsclient')

diff --git a/bin/emacsclient b/bin/emacsclient
index c29a86ee..82d05976 100755
--- a/bin/emacsclient
+++ b/bin/emacsclient
@@ -64,7 +64,7 @@ defer () {
 
 [ -n "$BASH_VERSION" ] \
     || { command -v bash >/dev/null && exec bash "$0" "$@" || defer "$@"; }
-for cmd in flock inotifywait perl pwdx ss; do
+for cmd in flock inotifywait pwdx ss; do
     command -v $cmd >/dev/null || defer "$@"
 done
 
@@ -80,9 +80,19 @@ server-file:,display:,parent-id:,timeout:,tramp:" -- "$@")
 eval set -- "$getopt"
 
 get_listener () {
-    local socket="$1"
-    local listener=$(ss -plx src "$socket" \
-	| perl -wne'$tmp = $_; END { $tmp =~ /pid=(\d+)/ and print $1 }')
+    local socket=$1 listener= listener_age= rematch_listener= rematch_age=
+    # Find the youngest process listening on a socket of this name.
+    while read -r line; do
+	[[ $line =~ ,pid=([[:digit:]]+), ]] || continue
+	rematch_listener=${BASH_REMATCH[1]}
+	rematch_age="$(ps h -o etimes $rematch_listener)"
+	[[ $rematch_age =~ ^[[:blank:]]*[[:digit:]]+[[:blank:]]*$ ]] \
+	    || fail "couldn't find age of process $rematch_listener"
+	if [ -z "$listener" ] || [ $rematch_age -lt $listener_age ]; then
+	    listener=$rematch_listener
+	    listener_age=$rematch_age
+	fi
+    done < <(ss -plx src "$socket")
     if [ -z "$listener" -a -e "$socket" ]; then
 	# Nothing is listening: remove dangling socket.
 	rm "$socket"
-- 
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