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