Attachment 168466 Details for Bug 208188 – waitx2.c demonstrate the multiple / identical wait4() results.

waitx2.c demonstrate the multiple / identical wait4() results.

waitx2.c (text/x-csrc), 3.26 KB, created by joss.upton on 2016-03-21 20:38:30 UTC

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Creator: joss.upton

Created: 2016-03-21 20:38:30 UTC

Size: 3.26 KB

patch

obsolete

>
>#include <sys/types.h>
>#include <sys/ptrace.h>
>#include <sys/wait.h>
>#include <sys/time.h>
>#include <sys/socket.h>
>#include <signal.h>
>#include <err.h>
>#include <stdio.h>
>#include <fcntl.h>
>#include <unistd.h>
>#include <errno.h>
>
>volatile int done;
>
>#define NWAITLOG 10
>volatile int logindex;
>struct wait_log {
>	int wl_status;
>	pid_t wl_pid;
>} waitlog[NWAITLOG];
>
>void run_child(int *);
>void alarm_handler(int);
>void child_handler(int);
>
>int
>main(int argc, char *argv[]) {
>	pid_t pid;
>	int socks[2], i;
>	struct sigaction sa;
>	sigset_t sset;
>	struct itimerval itimer;
>	
>	if (socketpair(AF_LOCAL, SOCK_STREAM, PF_UNSPEC, socks) == -1)
>		err(1, "socketpair");
>	
>	pid = fork();
>	if (pid == 0)
>		run_child(socks);
>
>	if (close(socks[1]) == -1)
>		err(1, "close-socket");
>
>	sa.sa_flags = SA_RESTART;
>	sigemptyset(&sa.sa_mask);
>	sigaddset(&sa.sa_mask, SIGCHLD);
>	sigaddset(&sa.sa_mask, SIGALRM);
>	sa.sa_handler = child_handler;
>	if (sigaction(SIGCHLD, &sa, NULL) == -1)
>		err(1, "sigaction-child");
>
>	sa.sa_flags = SA_RESTART;
>	sigemptyset(&sa.sa_mask);
>	sigaddset(&sa.sa_mask, SIGCHLD);
>	sigaddset(&sa.sa_mask, SIGALRM);
>	sa.sa_handler = alarm_handler;
>	if (sigaction(SIGALRM, &sa, NULL) == -1)
>		err(1, "sigaction-child");
>
>	sigemptyset(&sset);
>	sigaddset(&sset, SIGCHLD);
>	sigaddset(&sset, SIGALRM);
>	if (sigprocmask(SIG_BLOCK, &sset, NULL) == -1)
>		err(1, "sigprocmask(block)");
>
>	itimer.it_interval.tv_sec = itimer.it_value.tv_sec = 5;
>	itimer.it_interval.tv_usec = itimer.it_value.tv_usec = 0;
>	if (setitimer(ITIMER_REAL, &itimer, NULL) == -1)
>		err(1, "setitimer");
>
>	done = 0;
>	logindex = 0;
>	close(socks[0]);
>	sigemptyset(&sset);
>	for (;;) {
>		sigsuspend(&sset);
>		if (done)
>			break;
>	}
>
>	for (i = 0; i < logindex; i++) {
>		printf("%d: pid=%d", i, waitlog[i].wl_pid);
>		if (WIFEXITED(waitlog[i].wl_status))
>			printf(" exited(%d)",
>			       WEXITSTATUS(waitlog[i].wl_status));
>		if (WIFSIGNALED(waitlog[i].wl_status))
>			printf(" signaled(%d)",
>			       WTERMSIG(waitlog[i].wl_status));
>		if (WIFSTOPPED(waitlog[i].wl_status))
>			printf(" stopped(%d)", WSTOPSIG(waitlog[i].wl_status));
>		if (WCOREDUMP(waitlog[i].wl_status))
>			printf(" core-dump");
>		printf("\n");
>	}
>}
>
>void
>alarm_handler() {
>	done = 1;
>}
>
>void
>child_handler() {
>	pid_t pid;
>	int sts, i;
>
>	for (;;) {
>		pid = wait4(-1, &sts, WNOHANG, NULL);
>		if (pid == 0 || (pid == -1 && errno == ECHILD))
>			break;
>		if (pid == -1)
>			err(1, "wait4");
>		if (logindex >= NWAITLOG)
>			errx(1, "waitlog full");
>
>		if (WIFSTOPPED(sts) && WSTOPSIG(sts) == SIGTRAP) {
>			ptrace(PT_CONTINUE, pid, (caddr_t)1, 0);
>		}
>		
>		i = logindex++;
>		waitlog[i].wl_status = sts;
>		waitlog[i].wl_pid = pid;
>	}
>}
>
>void
>run_child(int socks[2]) {
>	ssize_t r;
>	int fd;
>	char c;
>
>	if (close(socks[0]) == -1)
>		err(1, "close-socket");
>
>	r = read(socks[1], &c, sizeof(c));
>	if (r == -1)
>		err(1, "read");
>	if (r != 0)
>		errx(1, "unexpected read");
>
>	if (close(socks[1]) == -1)
>		err(1, "close-socket");
>
>	if (ptrace(PT_TRACE_ME, getpid(), 0, 0) == -1)
>		err(1, "ptrace-trace-me");
>
>	fd = open("/dev/null", O_RDWR, 0);
>	if (fd == -1)
>		err(1, "/dev/null");
>	if (dup2(fd, 0) < 0)
>		err(1, "dup2-stdin");
>	if (dup2(fd, 1) < 0)
>		err(1, "dup2-stdout");
>	if (dup2(fd, 2) < 0)
>		err(1, "dup2-stderr");
>	if (fd > 2 && close(fd) < 0)
>		err(1, "close /dev/null");
>
>	execl("/bin/cat", "cat", NULL);
>	err(1, "execv");
>}

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