1 #!/usr/local/plan9/bin/rc
2 
3 # the venti configuration is stored at the 248kB offset in the first index
4 # partition and extends for at most 8 kB.
5 
6 rfork e
7 fn usage {
8 	echo 'usage: venti/conf [-w] /dev/sdC0/v.arenas' >[1=2]
9 	exit usage
10 }
11 
12 wflag=no
13 while(! ~ $#* 0 && ~ $1 -* && ! ~ $1 --){
14 	switch($1){
15 	case -w
16 		wflag=yes
17 	case *
18 		usage
19 	}
20 	shift
21 }
22 if(~ $1 --)
23 	shift
24 
25 if(~ $wflag no && ! ~ $#* 1)
26 	usage
27 if(~ $wflag yes && ! ~ $#* 1 2)
28 	usage
29 
30 disk=$1
31 if(! 9 test -f $disk){
32 	echo 'unknown disk' $1 >[1=2]
33 	exit nodisk
34 }
35 
36 fn sigexit {
37 	#rm -f /tmp/venticonf.$pid
38 }
39 
40 if(~ $wflag yes){
41 	{echo venti config; cat $2} >/tmp/venticonf.$pid || exit oops
42 	if(! 9 test -s /tmp/venticonf.$pid){
43 		echo 'config is empty; will not install' >[1=2]
44 		exit emptyconfig
45 	}
46 	if(9 test `{9 ls -l /tmp/venticonf.$pid | awk '{print $6}'} -gt 8192){
47 		echo 'config is too long; max is a little less than eight kilobytes' >[1=2]
48 		exit toolong
49 	}
50 	9 dd -quiet 1 -bs 1024 -count 8 -if $disk -iseek 248 \
51 		>/tmp/_venticonf.old || exit backup
52 	9 dd -quiet 1 -count 2 </dev/zero >> /tmp/venticonf.$pid || exit dd
53 	9 dd -quiet 1 -bs 1024 -count 8 -if /tmp/venticonf.$pid \
54 		-of $disk -trunc 0 -oseek 248 || exit dd2
55 	exit 0
56 }
57 
58 9 dd -quiet 1 -bs 1024 -count 8 -if $disk -iseek 248 |
59 	zerotrunc >/tmp/venticonf.$pid
60 
61 if(! cmp <{sed 1q /tmp/venticonf.$pid} <{echo venti config}){
62 	echo 'config has bad header' >[1=2]
63 	exit badconfig
64 }
65 
66 sed 1d /tmp/venticonf.$pid
67 exit ''