From: Christian Goeschel Ndjomouo <cgoesc2@wgu.edu>
Date: Thu, 23 Apr 2026 01:01:43 +0000 (-0400)
Subject: tests: (helpers) simple tool to create a child process
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=de4e565ba60a7fac32ceee306a462a796ed259b1;p=thirdparty%2Futil-linux.git

tests: (helpers) simple tool to create a child process

This basic helper program can be used to create a child process
to test process attribute inheritances between parent and
child processes, e.g. real-time scheduling attributes with chrt(1)
or utilization clamp settings with uclampset(1), where options
like --reset-on-fork need to be tested.

Signed-off-by: Christian Goeschel Ndjomouo <cgoesc2@wgu.edu>
---

diff --git a/meson.build b/meson.build
index 48070b741..0e5248da2 100644
--- a/meson.build
+++ b/meson.build
@@ -4006,6 +4006,16 @@ if not is_disabler(exe)
   exes += exe
 endif
 
+exe = executable(
+  'test_child_create',
+  'tests/helpers/test_child_create.c',
+  include_directories : includes,
+  link_with : lib_common,
+  build_by_default: program_tests)
+if not is_disabler(exe)
+  exes += exe
+endif
+
 ############################################################
 
 if conf.get('HAVE_OPENAT').to_string() == '1'
diff --git a/tests/commands.sh b/tests/commands.sh
index e68d0b3e3..07a147382 100644
--- a/tests/commands.sh
+++ b/tests/commands.sh
@@ -5,6 +5,7 @@ TS_TESTUSER=${TS_TESTUSER:-"nobody"}
 TS_HELPER_BOILERPLATE="${ts_helpersdir}test_boilerplate"
 TS_HELPER_BYTESWAP="${ts_helpersdir}test_byteswap"
 TS_HELPER_CANONICALIZE="${ts_helpersdir}test_canonicalize"
+TS_HELPER_CHILD_CREATE="${ts_helpersdir}test_child_create"
 TS_HELPER_COLORS="${ts_helpersdir}test_colors"
 TS_HELPER_CONFIGS="${ts_helpersdir}test_configs"
 TS_HELPER_CPUSET="${ts_helpersdir}test_cpuset"
diff --git a/tests/helpers/Makemodule.am b/tests/helpers/Makemodule.am
index 1e02e68a7..d374c0db1 100644
--- a/tests/helpers/Makemodule.am
+++ b/tests/helpers/Makemodule.am
@@ -63,3 +63,7 @@ endif
 
 check_PROGRAMS += test_open_twice
 test_open_twice_SOURCES = tests/helpers/test_open_twice.c
+
+check_PROGRAMS += test_child_create
+test_child_create_SOURCES = tests/helpers/test_child_create.c
+test_child_create_LDADD = $(LDADD) libcommon.la
diff --git a/tests/helpers/test_child_create.c b/tests/helpers/test_child_create.c
new file mode 100644
index 000000000..1e06659e0
--- /dev/null
+++ b/tests/helpers/test_child_create.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2026 Christian Goeschel Ndjomouo <cgoesc2@wgu.edu>
+ *
+ * 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, see <https://gnu.org/licenses/>.
+ */
+
+#include <sys/prctl.h>
+#include <stdint.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <err.h>
+#include <getopt.h>
+#include <errno.h>
+#include "strutils.h"
+
+#define DEFAULT_CHILD_SLEEP_SEC 2
+#define DEFAULT_FORK_DELAY_SEC 1
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+	printf("%s [options] <sleep time>\n\n", program_invocation_short_name);
+	fputs("Options:\n", stdout);
+	fputs(" -d, --delay <sec>  delay (in seconds) before forking\n", stdout);
+	fputs(" -h, --help         show this usage information\n", stdout);
+
+	exit(EXIT_SUCCESS);
+}
+
+int main(int argc, char **argv)
+{
+	int c, status, rc = 0;
+	uint16_t sleep_time = DEFAULT_CHILD_SLEEP_SEC;
+	uint16_t fork_delay = DEFAULT_FORK_DELAY_SEC;
+	pid_t pid = 0;
+
+	static const struct option longopts[] = {
+		{ "delay",       1, NULL, 'd' },
+		{ "help",       0, NULL, 'h' },
+		{ NULL, 0, NULL, 0 },
+	};
+
+	while((c = getopt_long(argc, argv, "hd:", longopts, NULL)) != -1) {
+		switch(c) {
+		case 'd':
+			fork_delay = strtou16_or_err(optarg, "invalid --delay argument");
+			break;
+		case 'h':
+			usage();
+			break;
+		default:
+			err(EXIT_FAILURE, "try --help");
+		}
+	}
+
+	if (argc - optind > 1)
+		errx(EXIT_FAILURE, "too many arguments");
+
+	if (optind < argc)
+		sleep_time = strtou16_or_err(argv[optind], "invalid <sleep time> argument");
+
+
+	printf("Parent PID: %d\n", getpid());
+	fflush(stdout);
+
+	sleep(fork_delay);
+
+	errno = 0;
+	pid = fork();
+	switch (pid) {
+	case -1:
+		err(EXIT_FAILURE, "failed to create child process");
+	case 0:
+		errno = 0;
+		rc = prctl(PR_SET_PDEATHSIG, SIGTERM);
+		if (rc < 0)
+			err(EXIT_FAILURE, "prctl() failed");
+
+		sleep(sleep_time);
+		return EXIT_SUCCESS;
+	default:
+		printf("Child PID: %d\n", pid);
+		fflush(stdout);
+
+		errno = 0;
+		rc = waitpid(pid, &status, 0);
+		if (rc < 0 && errno != ECHILD) {
+			err(EXIT_FAILURE, "waitpid() failed for child process %d", pid);
+		}
+	}
+	return EXIT_SUCCESS;
+}