tests: verify the auxstr of unshare(2) when --namespace=switch is given

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

Author: masatake

tests/gen_tests.in

@@ -1173,6 +1173,7 @@ umovestr_cached_adjacent	+umovestr_cached.test 3
 unlink	-a24
 unlinkat	-a35
 unshare	-a11
+unshare-report-ns-id	-a11	-e trace=unshare -e namespace=switch
 userfaultfd	-a15
 ustat	-a33
 utime	-a16

tests/pure_executables.list

@@ -835,6 +835,7 @@ uname
 unlink
 unlinkat
 unshare
+unshare-report-ns-id
 userfaultfd
 ustat
 utime

tests/unshare-report-ns-id.c

@@ -0,0 +1,71 @@
+/*
+ * Check appending auxstr of unshare(2) when --namespace=switch is given
+ *
+ * This is derrived from unshare.c.
+ *
+ * Copyright (c) 2024 The strace developers.
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "tests.h"
+#include "scno.h"
+
+#include <limits.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int
+main(void)
+{
+	static const kernel_ulong_t bogus_flags =
+		(kernel_ulong_t) 0xbadc0ded0000000fULL;
+
+	static struct {
+		kernel_ulong_t val;
+		const char *str;
+		const char *fnames[8];
+	} unshare_flags[] = {
+		{ ARG_STR(0), { NULL } },
+		{ 0x10000000, "CLONE_NEWUSER", { "user", NULL } },
+		{ 0x00020000, "CLONE_NEWNS", { "mnt", NULL } },
+		{ 0x00000080|0x00020000|0x02000000|0x04000000|0x08000000|0x20000000|0x40000000,
+		  "CLONE_NEWTIME|CLONE_NEWNS|CLONE_NEWCGROUP"
+		  "|CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWPID"
+		  "|CLONE_NEWNET", { "cgroup", "ipc", "mnt", "net", "pid", "time", "uts", NULL } },
+	};
+
+	long rc = syscall(__NR_unshare, bogus_flags);
+	printf("unshare(%#llx /* CLONE_??? */) = %s\n",
+	       (unsigned long long) bogus_flags, sprintrc(rc));
+
+	if (chdir("/proc/self/ns") != 0)
+		perror_msg_and_skip("chdir");
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(unshare_flags); ++i) {
+		rc = syscall(__NR_unshare, unshare_flags[i].val);
+		printf("unshare(%s) = %s%s",
+		       unshare_flags[i].str, sprintrc(rc), rc == 0? "": "\n");
+
+		if (rc == 0) {
+			unsigned int j;
+			for (j = 0; unshare_flags[i].fnames[j]; j++) {
+				char buf[PATH_MAX + 1];
+				int n = readlink(unshare_flags[i].fnames[j], buf, sizeof(buf));
+				if (n < 0 || (size_t)n >= sizeof(buf))
+					perror_msg_and_skip("readlink");
+				buf[n] = '\0';
+				if (j == 0)
+					printf(" (%s", buf);
+				else
+					printf(", %s", buf);
+			}
+			printf("%s", j == 0? "\n": ")\n");
+		}
+	}
+
+	puts("+++ exited with 0 +++");
+
+	return 0;
+}