From 7287ebb84338db042f47bc91b7c2f075ab8a94ed Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 9 Jun 2012 19:00:52 +0100
Subject: [PATCH] works again

---
 applet.tcl | 57 ++++++++++++++++++++++++++++++++++++++----
 example    | 72 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 118 insertions(+), 11 deletions(-)

diff --git a/applet.tcl b/applet.tcl
index 1a75f14..8440092 100644
--- a/applet.tcl
+++ b/applet.tcl
@@ -20,11 +20,16 @@
 #    which should examine b and do something appropriate.
 #    
 
+proc manyset {list args} {
+    foreach val $list var $args {
+        upvar 1 $var my
+        set my $val
+    }
+}
 
 
+package require Tclx
 package require tktray
-#load /home/ian/things/Systray/tktray-1.3.8/libtktray1.3.8.so
-
 
 wm withdraw .
 
@@ -60,7 +65,7 @@ proc msel {} {
     set posted 0
 }
 
-proc innerwindow-event {why} {
+proc innerwindow-resetup-required {why} {
     global innerwindow_after
 puts "IW-EVENT $why"
     if {[info exists innerwindow_after]} return
@@ -73,6 +78,8 @@ proc innerwindow-resetup {} {
 
 puts RESETUP
 
+    innerwindow-destroying
+
     catch { destroy .i.i.c }
     if {![winfo exists .i.i]} return
     destroy [frame .i.i.make-exist]
@@ -93,7 +100,7 @@ puts RESETUP
 #	set inner_lastw $w
 #	set inner_lasth $h
 #	innerwindow-ph-dummy configure -width $w -height 2
-	innerwindow [winfo id .i.i.b.c]
+	innerwindow-ready
 #    }
 }
 
@@ -107,7 +114,7 @@ proc setupinnerwindow {w} {
 
     destroy [frame .i.make-exist]
     destroy [frame .i.i.make-exist]
-    bind .i <<IconConfigure>> { innerwindow-event "%w" }
+    bind .i <<IconConfigure>> { innerwindow-resetup-required IconConfigure }
 }
 
 bind .i <ButtonPress> { pressed %b %X %Y }
@@ -167,3 +174,43 @@ proc tooltip_show {x y} {
 proc setimage {image} {
     .i configure -image $image
 }
+
+proc fork-then {ondeath inchild} {
+    global children errorCode errorInfo
+    foreach f {stdout stderr} {
+	if {[catch { flush $f } emsg]} {
+	    catch { bgerror $emsg }
+	}
+    }
+    set pid [fork]
+    if {!$pid} { 
+	if {[catch { 
+	    uplevel 1 $inchild
+	} emsg]} {
+	    puts stderr "CHILD ERROR $emsg\n$errorCode\n$errorInfo\n"
+	}
+	kill KILL [id process]
+    }
+    set children($pid) $ondeath
+    return $pid
+}
+
+proc chld-handler {} {
+    global children
+    while 1 {
+	if {[catch { set got [wait -nohang] }]} break
+	if {![llength $got]} break
+	manyset $got pid how how2
+	if {[info exists children($pid)]} {
+	    set l $children($pid)
+	    unset children($pid)
+	    if {[catch {
+		uplevel #0 [concat [list $l] $how $how2]
+	    } emsg]} {
+		catch { bgerror $emsg }
+	    }
+	}
+    }	
+}
+
+signal -restart trap CHLD { after idle chld-handler }
diff --git a/example b/example
index 4a6a16a..3b45d0b 100755
--- a/example
+++ b/example
@@ -16,13 +16,73 @@ image create bitmap ims -file gs_s.xbm
 setuptooltip
 settooltip "line\nanother"
 
-proc innerwindow {id} {
-    puts IICONFIG
-    puts "IC $id"
+fconfigure stdout -buffering line
 
-    .i.i.b configure -background darkblue -bd 1
-exec /home/ian/things/Chiark-utils/chiark-utils.git/cprogs/xacpi-simple \
-	-into $id &
+set status none
+
+proc innerwindow-destroying {} {
+    global status
+    puts "DESTROYING $status"
+    switch -exact $status {
+	none { }
+	old { }
+	default { kill $status; set status old }
+    }
+}
+
+proc innerwindow-ready {} {
+    global status
+    puts "READY $status"
+    switch -exact $status {
+	none {
+	    run-child
+	}
+	old {
+	    # wait for it to die
+	}
+	default {
+	    error "unexpected state $status"
+	}
+    }
+    puts "READY-done $status"
+}
+
+set ratelimit 0
+
+proc run-child {} {
+    global status ratelimit
+
+    puts "RUN-CHILD $status"
+    set now [clock seconds]
+    lappend ratelimit $now
+    while {[lindex $ratelimit 0] < {$now - 10}} {
+	set ratelimit [lrange $ratelimit 1 end]
+    }
+    if {[llength $ratelimit] > 10} {
+	puts stderr "crashing repeatedly, quitting $ratelimit"
+	exit 127
+    }
+
+    set status none
+    set status [fork-then child-died {
+	execl xacpi-simple [list -into [winfo id .i.i.b.c]]
+    }]
+    puts "FORKED $status"
+}
+
+proc child-died {how how2} {
+    puts "DIED $how $how2"
+    global status
+    switch -exact $status {
+	old {
+	    set status none
+	    run-child
+	}
+	default {
+	    set status none
+	    innerwindow-resetup-required "child died"
+	}
+    }
 }
 
 setupinnerwindow 40
-- 
2.30.2