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/* Postfix master - signal processing
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/* int master_gotsighup;
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/* int master_gotsigchld;
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/* int master_sigsetup()
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/* This module implements the master process signal handling interface.
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/* master_gotsighup (master_gotsigchld) is set to SIGHUP (SIGCHLD)
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/* when the process receives a hangup (child death) signal.
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/* master_sigsetup() enables processing of hangup and child death signals.
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/* Receipt of SIGINT, SIGQUIT, SIGSEGV, SIGILL, or SIGTERM
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/* is interpreted as a request for termination. Child processes are
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/* notified of the master\'s demise by sending them a SIGTERM signal.
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/* Need a way to register cleanup actions.
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/* The Secure Mailer license must be distributed with this software.
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/* IBM T.J. Watson Research
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/* Yorktown Heights, NY 10598, USA
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/* System libraries. */
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/* Utility library. */
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#include <posix_signals.h>
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/* Application-specific. */
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#include <sys/syscall.h>
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#ifndef USE_SIG_RETURN
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int master_sig_pipe[2];
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#define SIG_PIPE_WRITE_FD master_sig_pipe[1]
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#define SIG_PIPE_READ_FD master_sig_pipe[0]
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int master_gotsigchld;
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/* master_sighup - register arrival of hangup signal */
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static void master_sighup(int sig)
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* WARNING WARNING WARNING.
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* This code runs at unpredictable moments, as a signal handler. Don't put
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* any code here other than for setting a global flag.
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master_gotsighup = sig;
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/* master_sigchld - register arrival of child death signal */
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static void master_sigchld(int sig, int code, struct sigcontext * scp)
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* WARNING WARNING WARNING.
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* This code runs at unpredictable moments, as a signal handler. Don't put
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* any code here other than for setting a global flag, or code that is
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* intended to be run within a signal handler.
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master_gotsigchld = sig;
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if (scp != NULL && scp->sc_syscall == SYS_select) {
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scp->sc_syscall_action = SIG_RETURN;
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} else if (scp != NULL) {
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scp->sc_syscall_action = SIG_RESTART;
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/* master_sigchld - force wakeup from select() */
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static void master_sigchld(int unused_sig)
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int saved_errno = errno;
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* WARNING WARNING WARNING.
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* This code runs at unpredictable moments, as a signal handler. Don't put
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* any code here other than for setting a global flag, or code that is
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* intended to be run within a signal handler. Restore errno in case we
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* are interrupting the epilog of a failed system call.
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if (write(SIG_PIPE_WRITE_FD, "", 1) != 1)
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msg_warn("write to SIG_PIPE_WRITE_FD failed: %m");
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/* master_sig_event - called upon return from select() */
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static void master_sig_event(int unused_event, char *unused_context)
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while (read(SIG_PIPE_READ_FD, c, 1) > 0)
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master_gotsigchld = 1;
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static void master_sigchld(int sig)
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* WARNING WARNING WARNING.
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* This code runs at unpredictable moments, as a signal handler. Don't put
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* any code here other than for setting a global flag.
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master_gotsigchld = sig;
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/* master_sigdeath - die, women and children first */
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static void master_sigdeath(int sig)
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char *myname = "master_sigdeath";
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struct sigaction action;
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pid_t pid = getpid();
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* XXX We're running from a signal handler, and really should not call
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* any msg() routines at all, but it would be even worse to silently
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* terminate without informing the sysadmin.
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msg_info("terminating on signal %d", sig);
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* Terminate all processes in our process group, except ourselves.
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sigemptyset(&action.sa_mask);
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action.sa_handler = SIG_IGN;
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if (sigaction(SIGTERM, &action, (struct sigaction *) 0) < 0)
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msg_fatal("%s: sigaction: %m", myname);
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if (kill(-pid, SIGTERM) < 0)
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msg_fatal("%s: kill process group: %m", myname);
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* Deliver the signal to ourselves and clean up. XXX We're running as a
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* signal handler and really should not be doing complicated things...
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sigemptyset(&action.sa_mask);
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action.sa_handler = SIG_DFL;
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if (sigaction(sig, &action, (struct sigaction *) 0) < 0)
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msg_fatal("%s: sigaction: %m", myname);
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if (kill(pid, sig) < 0)
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msg_fatal("%s: kill myself: %m", myname);
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/* master_sigsetup - set up signal handlers */
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void master_sigsetup(void)
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char *myname = "master_sigsetup";
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struct sigaction action;
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static int sigs[] = {
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SIGINT, SIGQUIT, SIGILL, SIGBUS, SIGSEGV, SIGTERM,
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sigemptyset(&action.sa_mask);
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* Prepare to kill our children when we receive any of the above signals.
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action.sa_handler = master_sigdeath;
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for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
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if (sigaction(sigs[i], &action, (struct sigaction *) 0) < 0)
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msg_fatal("%s: sigaction(%d): %m", myname, sigs[i]);
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if (pipe(master_sig_pipe))
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msg_fatal("pipe: %m");
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non_blocking(SIG_PIPE_WRITE_FD, NON_BLOCKING);
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non_blocking(SIG_PIPE_READ_FD, NON_BLOCKING);
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close_on_exec(SIG_PIPE_WRITE_FD, CLOSE_ON_EXEC);
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close_on_exec(SIG_PIPE_READ_FD, CLOSE_ON_EXEC);
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event_enable_read(SIG_PIPE_READ_FD, master_sig_event, (char *) 0);
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* Intercept SIGHUP (re-read config file) and SIGCHLD (child exit).
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action.sa_flags |= SA_RESTART;
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action.sa_handler = master_sighup;
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if (sigaction(SIGHUP, &action, (struct sigaction *) 0) < 0)
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msg_fatal("%s: sigaction(%d): %m", myname, SIGHUP);
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action.sa_flags |= SA_NOCLDSTOP;
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action.sa_handler = master_sigchld;
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if (sigaction(SIGCHLD, &action, (struct sigaction *) 0) < 0)
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msg_fatal("%s: sigaction(%d): %m", myname, SIGCHLD);
added
removed
src/master/master_sig.c
