Add pwait utility, which waits for any process to terminate.

This is similar to the Solaris utility of the same name.

Some use cases:
* rc.subr's wait_for_pids
* interactive use, e.g. to shut down the computer when some task is done
  even if the task is already running

Discussed on:	hackers@

4 files changed, 229 insertions, 0 deletions

diff --git a/bin/Makefile b/bin/Makefile
index 7491be9..3114e67 100644
--- a/bin/Makefile
+++ b/bin/Makefile
@@ -27,6 +27,7 @@ SUBDIR= cat \
 	pax \
 	pkill \
 	ps \
+	pwait \
 	pwd \
 	${_rcp} \
 	realpath \
diff --git a/bin/pwait/Makefile b/bin/pwait/Makefile
new file mode 100644
index 0000000..cdf322e
--- /dev/null
+++ b/bin/pwait/Makefile
@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+PROG=	pwait
+
+.include <bsd.prog.mk>
diff --git a/bin/pwait/pwait.1 b/bin/pwait/pwait.1
new file mode 100644
index 0000000..132d83c
--- /dev/null
+++ b/bin/pwait/pwait.1
@@ -0,0 +1,78 @@
+.\"
+.\" Copyright (c) 2004-2009, Jilles Tjoelker
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with
+.\" or without modification, are permitted provided that the
+.\" following conditions are met:
+.\"
+.\" 1. Redistributions of source code must retain the above
+.\"    copyright notice, this list of conditions and the
+.\"    following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the
+.\"    above copyright notice, this list of conditions and
+.\"    the following disclaimer in the documentation and/or
+.\"    other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+.\" CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
+.\" WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+.\" PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+.\" COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY
+.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+.\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+.\" USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+.\" OF SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd November 1, 2009
+.Os
+.Dt PWAIT 1
+.Sh NAME
+.Nm pwait
+.Nd wait for processes to terminate
+.Sh SYNOPSIS
+.Nm
+.Op Fl v
+.Ar pid
+\&...
+.Sh DESCRIPTION
+The
+.Nm
+utility will wait until each of the given processes has terminated. 
+.Pp
+The following option is available:
+.Bl -tag -width indent
+.It Fl v
+Print the exit status when each process terminates.
+.El
+.Sh DIAGNOSTICS
+.Pp
+The
+.Nm
+utility returns 0 on success, and >0 if an error occurs.
+.Pp
+Invalid pids elicit a warning message but are otherwise ignored.
+.Sh SEE ALSO
+.Xr kill 1 ,
+.Xr pkill 1 ,
+.Xr ps 1 ,
+.Xr wait 1 ,
+.Xr kqueue 2
+.Sh NOTES
+.Nm
+is not a substitute for the
+.Xr wait 1
+builtin
+as it will not clean up any zombies or state in the parent process.
+.Sh HISTORY
+A
+.Nm
+command first appeared in SunOS 5.8.
diff --git a/bin/pwait/pwait.c b/bin/pwait/pwait.c
new file mode 100644
index 0000000..26cf1bd
--- /dev/null
+++ b/bin/pwait/pwait.c
@@ -0,0 +1,145 @@
+/*-
+ * Copyright (c) 2004-2009, Jilles Tjoelker
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with
+ * or without modification, are permitted provided that the
+ * following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above
+ *    copyright notice, this list of conditions and the
+ *    following disclaimer.
+ * 2. Redistributions in binary form must reproduce the
+ *    above copyright notice, this list of conditions and
+ *    the following disclaimer in the documentation and/or
+ *    other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/event.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static void
+usage(void)
+{
+
+	fprintf(stderr, "usage: pwait [-v] pid ...\n");
+	exit(EX_USAGE);
+}
+
+/*
+ * pwait - wait for processes to terminate
+ */
+int
+main(int argc, char *argv[])
+{
+	int kq;
+	struct kevent *e;
+	int verbose = 0;
+	int opt, nleft, n, i, duplicate, status;
+	long pid;
+	char *s, *end;
+
+	while ((opt = getopt(argc, argv, "v")) != -1) {
+		switch (opt) {
+		case 'v':
+			verbose = 1;
+			break;
+		default:
+			usage();
+			/* NOTREACHED */
+		}
+	}
+
+	argc -= optind;
+	argv += optind;
+
+	if (argc == 0)
+		usage();
+
+	kq = kqueue();
+	if (kq == -1)
+		err(1, "kqueue");
+
+	e = malloc(argc * sizeof(struct kevent));
+	if (e == NULL)
+		err(1, "malloc");
+	nleft = 0;
+	for (n = 0; n < argc; n++) {
+		s = argv[n];
+		if (!strncmp(s, "/proc/", 6)) /* Undocumented Solaris compat */
+			s += 6;
+		errno = 0;
+		pid = strtol(s, &end, 10);
+		if (pid < 0 || *end != '\0' || errno != 0) {
+			warnx("%s: bad process id", s);
+			continue;
+		}
+		duplicate = 0;
+		for (i = 0; i < nleft; i++)
+			if (e[i].ident == (uintptr_t)pid)
+				duplicate = 1;
+		if (!duplicate) {
+			EV_SET(e + nleft, pid, EVFILT_PROC, EV_ADD, NOTE_EXIT,
+			    0, NULL);
+			if (kevent(kq, e + nleft, 1, NULL, 0, NULL) == -1)
+				warn("%ld", pid);
+			else
+				nleft++;
+		}
+	}
+
+	while (nleft > 0) {
+		n = kevent(kq, NULL, 0, e, nleft, NULL);
+		if (n == -1)
+			err(1, "kevent");
+		if (verbose)
+			for (i = 0; i < n; i++) {
+				status = e[i].data;
+				if (WIFEXITED(status))
+					printf("%ld: exited with status %d.\n",
+					    (long)e[i].ident,
+					    WEXITSTATUS(status));
+				else if (WIFSIGNALED(status))
+					printf("%ld: killed by signal %d.\n",
+					    (long)e[i].ident,
+					    WTERMSIG(status));
+				else
+					printf("%ld: terminated.\n",
+					    (long)e[i].ident);
+			}
+		nleft -= n;
+	}
+
+	return 0;
+}