1 files changed, 255 insertions, 0 deletions
diff --git a/misc-utils/waitpid.c b/misc-utils/waitpid.c
new file mode 100644
index 0000000..b01a2f0
--- /dev/null
+++ b/misc-utils/waitpid.c
@@ -0,0 +1,255 @@
+/*
+ * waitpid(1) - wait for process termination
+ *
+ * Copyright (C) 2022 Thomas Weißschuh <thomas@t-8ch.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <sys/epoll.h>
+#include <sys/timerfd.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <getopt.h>
+
+#include "pidfd-utils.h"
+#include "c.h"
+#include "nls.h"
+#include "xalloc.h"
+#include "strutils.h"
+#include "exitcodes.h"
+#include "timeutils.h"
+#include "optutils.h"
+
+#define EXIT_TIMEOUT_EXPIRED 3
+
+#define TIMEOUT_SOCKET_IDX UINT64_MAX
+
+#define err_nosys(exitcode, ...) \
+	err(errno == ENOSYS ? EXIT_NOTSUPP : exitcode, __VA_ARGS__)
+
+static bool verbose = false;
+static struct timespec timeout;
+static bool allow_exited = false;
+static size_t count;
+
+static pid_t *parse_pids(size_t n_strings, char * const *strings)
+{
+	pid_t *pids = xcalloc(n_strings, sizeof(*pids));
+
+	for (size_t i = 0; i < n_strings; i++)
+		pids[i] = strtopid_or_err(strings[i], _("failed to parse pid"));
+
+	return pids;
+}
+
+static int *open_pidfds(size_t n_pids, pid_t *pids)
+{
+	int *pidfds = xcalloc(n_pids, sizeof(*pidfds));
+
+	for (size_t i = 0; i < n_pids; i++) {
+		pidfds[i] = pidfd_open(pids[i], 0);
+		if (pidfds[i] == -1) {
+			if (allow_exited && errno == ESRCH) {
+				warnx(_("PID %d has exited, skipping"), pids[i]);
+				continue;
+			}
+			err_nosys(EXIT_FAILURE, _("could not open pid %u"), pids[i]);
+		}
+	}
+
+	return pidfds;
+}
+
+static int open_timeoutfd(void)
+{
+	int fd;
+	struct itimerspec timer = {};
+
+	if (!timeout.tv_sec && !timeout.tv_nsec)
+		return -1;
+
+	timer.it_value = timeout;
+
+	fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);
+	if (fd == -1)
+		err_nosys(EXIT_FAILURE, _("could not create timerfd"));
+
+	if (timerfd_settime(fd, 0, &timer, NULL))
+		err_nosys(EXIT_FAILURE, _("could not set timer"));
+
+	return fd;
+
+}
+
+static size_t add_listeners(int epll, size_t n_pids, int * const pidfds, int timeoutfd)
+{
+	size_t skipped = 0;
+	struct epoll_event evt = {
+		.events = EPOLLIN,
+	};
+
+	if (timeoutfd != -1) {
+		evt.data.u64 = TIMEOUT_SOCKET_IDX;
+		if (epoll_ctl(epll, EPOLL_CTL_ADD, timeoutfd, &evt))
+			err_nosys(EXIT_FAILURE, _("could not add timerfd"));
+	}
+
+	for (size_t i = 0; i < n_pids; i++) {
+		if (pidfds[i] == -1) {
+			skipped++;
+			continue;
+		}
+		evt.data.u64 = i;
+		if (epoll_ctl(epll, EPOLL_CTL_ADD, pidfds[i], &evt))
+			err_nosys(EXIT_FAILURE, _("could not add listener"));
+	}
+
+	return n_pids - skipped;
+}
+
+static void wait_for_exits(int epll, size_t active_pids, pid_t * const pids,
+			   int * const pidfds)
+{
+	while (active_pids) {
+		struct epoll_event evt;
+		int ret, fd;
+
+		ret = epoll_wait(epll, &evt, 1, -1);
+		if (ret == -1) {
+			if (errno == EINTR)
+				continue;
+			else
+				err_nosys(EXIT_FAILURE, _("failure during wait"));
+		}
+		if (evt.data.u64 == TIMEOUT_SOCKET_IDX) {
+			if (verbose)
+				printf(_("Timeout expired\n"));
+			exit(EXIT_TIMEOUT_EXPIRED);
+		}
+		if (verbose)
+			printf(_("PID %d finished\n"), pids[evt.data.u64]);
+		assert((size_t) ret <= active_pids);
+		fd = pidfds[evt.data.u64];
+		epoll_ctl(epll, EPOLL_CTL_DEL, fd, NULL);
+		active_pids -= ret;
+	}
+}
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+	FILE *out = stdout;
+
+	fputs(USAGE_HEADER, out);
+	fprintf(out, _(" %s [options] pid...\n"), program_invocation_short_name);
+
+	fputs(USAGE_OPTIONS, out);
+	fputs(_(" -v, --verbose           be more verbose\n"), out);
+	fputs(_(" -t, --timeout=<timeout> wait at most timeout seconds\n"), out);
+	fputs(_(" -e, --exited            allow exited PIDs\n"), out);
+	fputs(_(" -c, --count=<count>     number of process exits to wait for\n"), out);
+
+	fputs(USAGE_SEPARATOR, out);
+	fprintf(out, USAGE_HELP_OPTIONS(25));
+
+	fprintf(out, USAGE_MAN_TAIL("waitpid(1)"));
+
+	exit(EXIT_SUCCESS);
+}
+
+static int parse_options(int argc, char **argv)
+{
+	int c;
+	static const struct option longopts[] = {
+		{ "verbose", no_argument,       NULL, 'v' },
+		{ "timeout", required_argument, NULL, 't' },
+		{ "exited",  no_argument,       NULL, 'e' },
+		{ "count",   required_argument, NULL, 'c' },
+		{ "version", no_argument,       NULL, 'V' },
+		{ "help",    no_argument,       NULL, 'h' },
+		{ 0 }
+	};
+	static const ul_excl_t excl[] = {       /* rows and cols in ASCII order */
+		{ 'c', 'e' },
+		{ 0 }
+	};
+	int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
+
+	while ((c = getopt_long (argc, argv, "vVht:c:e", longopts, NULL)) != -1) {
+
+		err_exclusive_options(c, longopts, excl, excl_st);
+
+		switch (c) {
+		case 'v':
+			verbose = true;
+			break;
+		case 't':
+			strtotimespec_or_err(optarg, &timeout,
+					     _("Could not parse timeout"));
+			break;
+		case 'e':
+			allow_exited = true;
+			break;
+		case 'c':
+			count = str2num_or_err(optarg, 10, _("Invalid count"),
+					       1, INT64_MAX);
+			break;
+		case 'V':
+			print_version(EXIT_SUCCESS);
+		case 'h':
+			usage();
+		default:
+			errtryhelp(EXIT_FAILURE);
+		}
+	}
+
+	return optind;
+}
+
+int main(int argc, char **argv)
+{
+	int pid_idx, epoll, timeoutfd, *pidfds;
+	size_t n_pids, active_pids;
+
+	setlocale(LC_ALL, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+
+	pid_idx = parse_options(argc, argv);
+	n_pids = argc - pid_idx;
+	if (!n_pids)
+		errx(EXIT_FAILURE, _("no PIDs specified"));
+
+	if (count && count > n_pids)
+		errx(EXIT_FAILURE,
+		     _("can't want for %zu of %zu PIDs"), count, n_pids);
+
+	pid_t *pids = parse_pids(argc - pid_idx, argv + pid_idx);
+
+	pidfds = open_pidfds(n_pids, pids);
+	timeoutfd = open_timeoutfd();
+	epoll = epoll_create(n_pids);
+	if (epoll == -1)
+		err_nosys(EXIT_FAILURE, _("could not create epoll"));
+
+	active_pids = add_listeners(epoll, n_pids, pidfds, timeoutfd);
+	if (count)
+		active_pids = min(active_pids, count);
+	wait_for_exits(epoll, active_pids, pids, pidfds);
+}