/*++ /* NAME /* timed_wait 3 /* SUMMARY /* wait operations with timeout /* SYNOPSIS /* #include <timed_wait.h> /* /* int timed_waitpid(pid, statusp, options, time_limit) /* pid_t pid; /* WAIT_STATUS_T *statusp; /* int options; /* int time_limit; /* DESCRIPTION /* \fItimed_waitpid\fR() waits at most \fItime_limit\fR seconds /* for process termination. /* /* Arguments: /* .IP "pid, statusp, options" /* The process ID, status pointer and options passed to waitpid(3). /* .IP time_limit /* The time in seconds that timed_waitpid() will wait. /* This must be a number > 0. /* DIAGNOSTICS /* Panic: interface violation. /* /* When the time limit is exceeded, the result is -1 and errno /* is set to ETIMEDOUT. Otherwise, the result value is the result /* from the underlying waitpid() routine. /* BUGS /* If there were a \fIportable\fR way to select() on process status /* information, these routines would not have to use a steenkeeng /* alarm() timer and signal() handler. /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include <sys_defs.h> #include <sys/wait.h> #include <unistd.h> #include <signal.h> #include <errno.h> /* Utility library. */ #include <msg.h> #include <posix_signals.h> #include <timed_wait.h> /* Application-specific. */ static int timed_wait_expired; /* timed_wait_alarm - timeout handler */ static void timed_wait_alarm(int unused_sig) { /* * WARNING WARNING WARNING. * * This code runs at unpredictable moments, as a signal handler. This code * is here only so that we can break out of waitpid(). Don't put any code * here other than for setting a global flag. */ timed_wait_expired = 1; } /* timed_waitpid - waitpid with time limit */ int timed_waitpid(pid_t pid, WAIT_STATUS_T *statusp, int options, int time_limit) { const char *myname = "timed_waitpid"; struct sigaction action; struct sigaction old_action; int time_left; int wpid; /* * Sanity checks. */ if (time_limit <= 0) msg_panic("%s: bad time limit: %d", myname, time_limit); /* * Set up a timer. */ sigemptyset(&action.sa_mask); action.sa_flags = 0; action.sa_handler = timed_wait_alarm; if (sigaction(SIGALRM, &action, &old_action) < 0) msg_fatal("%s: sigaction(SIGALRM): %m", myname); timed_wait_expired = 0; time_left = alarm(time_limit); /* * Wait for only a limited amount of time. */ if ((wpid = waitpid(pid, statusp, options)) < 0 && timed_wait_expired) errno = ETIMEDOUT; /* * Cleanup. */ alarm(0); if (sigaction(SIGALRM, &old_action, (struct sigaction *) 0) < 0) msg_fatal("%s: sigaction(SIGALRM): %m", myname); if (time_left) alarm(time_left); return (wpid); }