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use strict;
use File::Temp qw(tempdir);
our @sshOpts = split ' ', ($ENV{"NIX_SSHOPTS"} or "");
push @sshOpts, "-x";
my $sshStarted = 0;
my $sshHost;
# Open a master SSH connection to `host', unless there already is a
# running master connection (as determined by `-O check').
sub openSSHConnection {
my ($host) = @_;
die if $sshStarted;
$sshHost = $host;
return 1 if system("ssh $sshHost @sshOpts -O check 2> /dev/null") == 0;
my $tmpDir = tempdir("nix-ssh.XXXXXX", CLEANUP => 1, TMPDIR => 1)
or die "cannot create a temporary directory";
push @sshOpts, "-S", "$tmpDir/control";
# Start the master. We can't use the `-f' flag (fork into
# background after establishing the connection) because then the
# child continues to run if we are killed. So instead make SSH
# print "started" when it has established the connection, and wait
# until we see that.
open SSHPIPE, "ssh $sshHost @sshOpts -M -N -o LocalCommand='echo started' -o PermitLocalCommand=yes |" or die;
while (<SSHPIPE>) {
chomp;
if ($_ eq "started") {
$sshStarted = 1;
return 1;
}
}
return 0;
}
# Tell the master SSH client to exit.
sub closeSSHConnection {
if ($sshStarted) {
system("ssh $sshHost @sshOpts -O exit 2> /dev/null") == 0
or warn "unable to stop SSH master: $?";
}
}
END { my $saved = $?; closeSSHConnection; $? = $saved; }
return 1;
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