tests: verify the auxstr of clone3(2) with -e namespace=new option

* tests/gen_tests.in (clone3-report-ns-id): New test.
* tests/pure_executables.list: Add clone3-report-ns-id.
* tests/clone3-report-ns-id.c: New fle.
* tests/.gitignore: Add clone3-report-ns-id.

Changes in v3 (Suggested by Dmitry V. Levin <[email protected]>):
* Don't wait for the child process exiting in the parent process.

Signed-off-by: Masatake YAMATO <[email protected]>

Author: masatake

tests/.gitignore

@@ -72,6 +72,7 @@ clone3
 clone3-Xabbrev
 clone3-Xraw
 clone3-Xverbose
+clone3-report-ns-id
 clone3-success
 clone3-success-Xabbrev
 clone3-success-Xraw

tests/clone3-report-ns-id.c

@@ -0,0 +1,42 @@
+/*
+ * Check appending auxstr of clone3(2) when --namespace=switchTo is given
+ *
+ * Copyright (c) 2024 The strace developers.
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "tests.h"
+#include "xmalloc.h"
+
+#include <limits.h>
+#include <linux/sched.h>
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "scno.h"
+
+int
+main(void)
+{
+	struct clone_args arg = { .flags = CLONE_NEWUSER };
+	int pid = syscall(__NR_clone3, &arg, sizeof(arg));
+	if (pid < 0)
+		perror_msg_and_fail("clone3");
+	if (pid > 0) {
+		printf("clone3({flags=CLONE_NEWUSER, exit_signal=0, stack=NULL, stack_size=0}"
+		       ", %zu) = %s ", sizeof(arg), sprintrc(pid));
+
+		char userns[PATH_MAX + 1];
+		char *fname = xasprintf("/proc/%d/ns/user", pid);
+		int rc = readlink(fname, userns, sizeof(userns));
+		if ((size_t) rc >= sizeof(userns))
+			perror_msg_and_fail("readlink");
+		userns[rc] = '\0';
+		printf("(%s)\n", userns);
+		puts("+++ exited with 0 +++");
+	}
+	return 0;
+}

tests/gen_tests.in

@@ -66,6 +66,7 @@ clone3-success-Xabbrev	-einject=clone3:retval=42 -etrace=clone3 -a16 -Xabbrev
 clone3-success-Xraw	-einject=clone3:retval=42 -etrace=clone3 -a16 -Xraw
 clone3-success-Xverbose	-einject=clone3:retval=42 -etrace=clone3 -a16 -Xverbose
 clone_parent +clone_ptrace.test
+clone3-report-ns-id	-etrace=clone3 -a35 -e namespace=new
 clone_parent--quiet-exit +clone_ptrace.test --quiet=exit,personality
 clone_parent-q +clone_ptrace.test -q
 clone_parent-qq +clone_ptrace.test -qq

tests/pure_executables.list

@@ -44,6 +44,7 @@ clone3
 clone3-Xabbrev
 clone3-Xraw
 clone3-Xverbose
+clone3-report-ns-id
 copy_file_range
 creat
 delete_module