From 2f9fde5ac8a14ba6be7c5ec2ef95735fd94ec73c Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Wed, 28 Aug 2024 21:55:33 -0400
Subject: auto-restart ECHOSEND

---
 src/twopane.bash | 72 +++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 51 insertions(+), 21 deletions(-)

(limited to 'src')

diff --git a/src/twopane.bash b/src/twopane.bash
index fe61dc2..990035d 100755
--- a/src/twopane.bash
+++ b/src/twopane.bash
@@ -280,6 +280,16 @@ send()
         printf '%s\n' "$*" >&${TOP_PANE_OUT?Internal error}
 }
 
+check_restart_sink()
+{
+        (( $# > 0 )) || set -- SINK
+        declare -n sinkfd="$1"
+        declare -n pid="${!sinkfd}_PID"
+        [ "$pid" ] || return
+        kill -0 "$pid" &>/dev/null ||
+        start_sink_process "${!sinkfd}"
+}
+
 tty_forward()
 {
         printf '%d\n' "$BASHPID" > "$TWOPANE"/tty_forward.pid
@@ -305,7 +315,7 @@ TOP_PANE()
         esac
 }
 
-magic_fifo()
+magic_fifo_sink()
 {
         # Some bash magic from superuser.com.
         # Use two PIDs instead of one inode to make fifo.  (Not just
@@ -323,46 +333,63 @@ magic_fifo()
         quiet_bg "${@:2}" <&"$fd_in"
 }
 
-ordinary_fifo()
+# This function serves to replace bash's builtin >() syntax.  That
+# syntax does not allow the asynchronous command to be subject to
+# interactive job control.  The actual bash implementation of >() uses a
+# /proc/fd/ trick on Linux to avoid mkfifo.
+fifo_sink()
 {
+        (( $# > 0 )) || set -- SINK
+        (( $# > 1 )) || set -- "$1" "$1"
         declare -n fd_out="$1"
-        local fifo
-        fifo=$TWOPANE/sink_${!fd}.fifo
-        mkfifo "$fifo"
+        local fifo fd_in
+        fifo=${TWOPANE:-$TMP}/sink_${!fd_out}.$$.fifo
+        mkfifo "$fifo" || return
+
         exec {fd_out}<>"$fifo"
+        fd_in=$fd_out
         rm "$fifo"
-        quiet_bg "${@:2}" <&"$fd_out"
+        quiet_bg "${@:2}" <&"$fd_in" {fd_in}<&-
+        return
 }
 
 connect_sink()
 {
         (( $# > 0 )) || set -- SINK
-        declare -n fd="$1"
-        declare -n pid="${!fd}_PID"
+        (( $# > 1 )) || set -- "$1" "$1"
+        declare -n sinkfd="$1"
+        declare -n pid="${!sinkfd}_PID"
+        declare -n sinkstartcmd="${!sinkfd}_start_command"
+        sinkstartcmd=$(printf '%q\n' "${@:2}")
         if [ "$pid" ]
         then
-                i "sink already running: ${!fd}"
-                return
-        fi
-        i "sink starting: ${!fd}"
-
-        if false && mountpoint -q /proc
-        then
-                magic_fifo fd "${@:2}"
+                i "sink already running: ${!sinkfd}"
         else
-                ordinary_fifo fd "${@:2}"
+                start_sink_process "${!sinkfd}"
         fi
+}
+
+start_sink_process()
+{
+        (( $# > 0 )) || set -- SINK
+        declare -n sinkfd="$1"
+        declare -n sinkstartcmd="${!sinkfd}_start_command"
+        declare -a cmd
+        cmd=($sinkstartcmd)
+        (( ${#cmd[@]} > 0 )) || return
+        i "sink starting: ${!sinkfd}"
+        fifo_sink "${!sinkfd}" "${cmd[@]}"
         pid=$!
 }
 
 disconnect_sink()
 {
         (( $# > 0 )) || set -- SINK
-        declare -n fd="$1"
+        declare -n sinkfd="$1"
         [ "$fd" ] || return
-        declare -n pid="${!fd}_PID"
-        i "sink stopping: ${!fd}"
-        exec {fd}>&-
+        declare -n pid="${!sinkfd}_PID"
+        i "sink stopping: ${!sinkfd}"
+        exec {sinkfd}>&-
         kill $pid 2>/dev/null
         unset fd pid
 }
@@ -466,6 +493,8 @@ killpgrp()
 
 prompt_command()
 {
+        check_restart_sink ECHOSEND
+
         [ "$TOP_EXIT" = 'restart' ] || return 0
 
         if [ "$SIG" = INT ]
@@ -514,6 +543,7 @@ our_bashrc_main()
         trap 'SIGINT' INT
         trap '! [ "$DEBUG" ] || read -p "Exit> "; quit' EXIT
         export PS1="$BOT_TITLE\\\$ "
+        export PS4='+ \t$LINENO\t '
 }
 
 save_file bashrc <<.
-- 
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