allow fshalt to power off the system

Reference: /n/atom/patch/applied2013/fshalth
Date: Tue Oct 22 10:54:31 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /rc/bin/fshalt	Tue Oct 22 10:54:08 2013
+++ /rc/bin/fshalt	Tue Oct 22 10:54:08 2013
@@ -1,17 +1,19 @@
 #!/bin/rc
-# fshalt [-r] - sync (flush) and, if possible, halt all file servers
-#	and optionally reboot
+# fshalt [-rh] - sync (flush) and, if possible, halt all file servers
+#	and optionally reboot or hard halt
 rfork nes
 kerncopy=()
-reboot=no
-switch ($#*) {
-case 0
-case 1
-	reboot=yes
-case *
-	echo usage: $0 '[-r]' >[1=2]
+flagfmt='r,h'
+args='kern' 
+if(! ifs=() eval `{aux/getflags $*} || ! ~ $#* 0 1){
+	aux/usage
 	exit usage
 }
+if(~ $#flagh 1 && {~ $#flagr 1 || ~ $#* 1}){
+	aux/usage
+	exit usage
+}
+kern=$*
 
 path=(/bin)
 builtin cd /
@@ -32,7 +34,8 @@
 }
 
 fn isbootable {
-	test -e $1 && ~ `{file $1} *' plan 9 boot image'
+	test -e $1 && ~ `'' {file $1} *' plan 9 boot image' \
+		*' plan 9 executable'* *ELF*' executable'
 }
 fn usekernel {
 	kerncopy=kern
@@ -40,9 +43,10 @@
 }
 
 # make a copy of the right kernel
-if (~ $reboot yes) {
-	kern=`{echo $terminal |
-		sed 's;^([^ ]+) .*/([^/]+)$;/n/boot/'$cputype'/9\2;'}
+if (~ $#flagr 1) {
+	if (~ $#kern 0)
+		kern=`{echo $terminal |
+			sed 's;^([^ ]+) .*/([^/ ]+).*$;/n/boot/'$cputype'/9\2;'}
 	if (isbootable $kern)
 		usekernel $kern
 	if not {
@@ -136,8 +140,10 @@
 	echo
 	echo done halting
 
-	if (~ $reboot yes)
+	if (~ $#flagr 1)
 		echo reboot $kerncopy >'#c/reboot'
+	if(~ $#flagh 1)
+		echo power off > '#α/acpictl'
 }
 
 x
--- /sys/man/8/fshalt	Tue Oct 22 10:54:09 2013
+++ /sys/man/8/fshalt	Tue Oct 22 10:54:10 2013
@@ -4,7 +4,7 @@
 .SH SYNOPSIS
 .B fshalt
 [
-.B -r
+.B -rh
 ] [
 .I new-kernel
 ]
@@ -23,6 +23,9 @@
 and
 .IR kfs
 servers.
+If given
+.BR -h ,
+the machine will be powered down, if possible.
 If given
 .BR -r ,
 .I fshalt