From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Thu, 2 Mar 2023 21:06:31 +0000 (+0000)
Subject: waitpid: allow to only wait for a specific number of process exits
X-Git-Tag: v2.39-rc1~16^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f0e793a3d9083aa5d8bfe1ec27ce107f2df6780f;p=thirdparty%2Futil-linux.git

waitpid: allow to only wait for a specific number of process exits

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---

diff --git a/bash-completion/waitpid b/bash-completion/waitpid
index 67601bb8f7..60ea275afc 100644
--- a/bash-completion/waitpid
+++ b/bash-completion/waitpid
@@ -9,6 +9,9 @@ _waitpid_module()
 			COMPREPLY=( $(compgen -W "seconds" -- $cur) )
 			return 0
 			;;
+		'-c'|'--count')
+			return 0
+			;;
 		'-h'|'--help'|'-V'|'--version')
 			return 0
 			;;
@@ -18,6 +21,7 @@ _waitpid_module()
 			OPTS="--verbose
 				--timeout
 				--exited
+				--count
 				--help
 				--version"
 			COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) )
diff --git a/misc-utils/waitpid.1.adoc b/misc-utils/waitpid.1.adoc
index ea9a7cf5c3..e0dae517ed 100644
--- a/misc-utils/waitpid.1.adoc
+++ b/misc-utils/waitpid.1.adoc
@@ -32,6 +32,9 @@ Maximum wait time.
 *-e*, *--exited*::
 Don't error on already exited PIDs.
 
+*-c*, *--count* _count_::
+Number of process exits to wait for.
+
 include::man-common/help-version.adoc[]
 
 == EXIT STATUS
diff --git a/misc-utils/waitpid.c b/misc-utils/waitpid.c
index f7c5d4166e..871a36949e 100644
--- a/misc-utils/waitpid.c
+++ b/misc-utils/waitpid.c
@@ -46,6 +46,7 @@
 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)
 {
@@ -161,6 +162,7 @@ static void __attribute__((__noreturn__)) usage(void)
 	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));
@@ -177,12 +179,13 @@ static int parse_options(int argc, char **argv)
 		{ "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 }
 	};
 
-	while ((c = getopt_long (argc, argv, "vVht:e", longopts, NULL)) != -1) {
+	while ((c = getopt_long (argc, argv, "vVht:c:e", longopts, NULL)) != -1) {
 		switch (c) {
 		case 'v':
 			verbose = true;
@@ -194,6 +197,10 @@ static int parse_options(int argc, char **argv)
 		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':
@@ -203,6 +210,10 @@ static int parse_options(int argc, char **argv)
 		}
 	}
 
+	if (allow_exited && count)
+		errx(EXIT_FAILURE,
+		     _("-e/--exited and -c/--count are incompatible"));
+
 	return optind;
 }
 
@@ -220,6 +231,10 @@ int main(int argc, char **argv)
 	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);
@@ -229,5 +244,7 @@ int main(int argc, char **argv)
 		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);
 }
diff --git a/tests/expected/misc/waitpid-count b/tests/expected/misc/waitpid-count
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/tests/expected/misc/waitpid-count
@@ -0,0 +1 @@
+1
diff --git a/tests/expected/misc/waitpid-count.err b/tests/expected/misc/waitpid-count.err
new file mode 100644
index 0000000000..573541ac97
--- /dev/null
+++ b/tests/expected/misc/waitpid-count.err
@@ -0,0 +1 @@
+0
diff --git a/tests/ts/misc/waitpid b/tests/ts/misc/waitpid
index 599bb47da3..ae5ab6f928 100755
--- a/tests/ts/misc/waitpid
+++ b/tests/ts/misc/waitpid
@@ -48,4 +48,12 @@ ts_init_subtest exited
 echo $? >> "$TS_ERRLOG"
 ts_finalize_subtest
 
+ts_init_subtest count
+(sleep 0.2; echo 1 >> "$TS_OUTPUT") &
+BG1="$!"
+
+"$TS_CMD_WAITPID" -c 1 1 "$BG1" >> "$TS_OUTPUT" 2>> "$TS_ERRLOG"
+echo $? >> "$TS_ERRLOG"
+ts_finalize_subtest
+
 ts_finalize