ref: 79fbfbff48c19e11c60317797e7b9f2903e69a37
dir: /rc/bin/srvssh/
#!/bin/rc
# Serve Unix u9fs over SSH
#
# Basically, try each of the following until you find one that works:
#
# srvssh unix
# srvssh -r unix
# srvssh -R unix
# srvssh -r -s unix
# srvssh -R -s unix
#
# and then never look back. Note that "srvssh unix" should always
# work. It's just that if you're talking with certain sshd's, you'll get
# hit by Nagle's algorithm and need to explore the other flags.
# When using ssh to start u9fs, the only way to turn off
# Nagle's algorithm (which kills the performance of RPC-based
# protocols like 9P) is to allocate a pseudo-terminal. The
# command ssh -Rmp attempts to allocate a pseudo-terminal and
# then put it in a transparent mode. Especially when
# connected to older SSH daemons, the connection ends up not
# quite transparent. To get around this, we explicity set the tty
# mode on the command line as well. The hope is that -Rmp makes
# the connection transparent enough for the Tversion, and the stty
# command will do the rest. If -Rmp doesn't make the connection
# transparent enough for the Tversion (but the stty commands do
# make the connection fully transparent) then add "-s 5" to the srv
# command to tell it to wait 5 seconds before sending the Tversion.
# That should be enough time for the stty to take effect.
rfork e
fn usage {
echo 'usage: srvssh [-R] [-r] [-s] [-u u9fspath] system [srvname [mtpt]]' >[1=2]
exit usage
}
rawhack=''
sleephack=()
u9fspath=u9fs
rawflags=''
while(~ $1 -*){
switch($1){
case -r
rawflags='-Rmp'
shift
case -R
rawflags='-Rmp'
rawhack=('stty raw -echo '';''')
shift
case -s
sleephack=(-s 5)
shift
case -u
shift
u9fspath=$1
shift
case -u*
u9fspath=`{echo $1 | sed s/-u//}
shift
case *
usage
}
}
if(! ~ $#* 1 2 3)
usage
switch($#*){
case 1
srv=$1
mtpt=/n/$1
case 2
srv=$2
mtpt=/n/$1
case 3
srv=$2
mtpt=$3
}
x=(srv $sleephack -e \
'ssh '$rawflags' '$1' '$rawhack' '$u9fspath' -na none -u ''$''USER -l ''$''HOME/u9fs.log' \
$srv $mtpt)
$x
# Sometimes /srv/whatever can be a closed pipe, in which case
# srv will have been killed for writing to it, without a chance to
# defend itself. Rerun it in this case.
ss=$status
if(~ $ss *'write on closed pipe'*){
rm -f /srv/$srv
$x
ss=$status
}
if(! ~ $ss '')
echo srvssh: $ss >[1=2]
exit $ss