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