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#!/usr/bin/perl
eval 'exec /usr/bin/perl -S $0 ${1+"$@"}'
if $running_under_some_shell;
require 'sys/ipc.ph';
require 'sys/msg.ph';
$| = 1;
$mode = shift;
die "usage: ipcmsg {r|s}\n" unless $mode =~ /^[rs]$/;
$signal = ($mode eq "s");
$id = semget(0x1234, 1, ($signal ? 0 : &IPC_CREAT) | 0644);
die "Can't get semaphore: $!\n" unless defined($id);
print "semaphore id: $id\n";
if ($signal) {
while (<STDIN>) {
print "Signalling\n";
unless (semop($id, pack("sss", 0, 1, 0))) {
die "Can't signal semaphore: $!\n";
}
}
}
else {
$SIG{'INT'} = $SIG{'QUIT'} = "leave";
for (;;) {
unless (semop($id, pack("sss", 0, -1, 0))) {
die "Can't wait for semaphore: $!\n";
}
print "Unblocked\n";
}
}
&leave;
sub leave {
if (!$signal) {
$x = semctl($id, 0, &IPC_RMID, 0);
if (!defined($x) || $x < 0) {
die "Can't remove semaphore: $!\n";
}
}
exit;
}
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