[LTP] [PATCH 4/6] Add ioctl_pidfd02 test

[Andrea Cervesato]

From: Andrea Cervesato <andrea.cervesato@suse.com>

Check if the ioctl() function allows retrieval of a child's exit code
using PIDFD_INFO_EXIT from a process that is isolated from the child.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                                |  1 +
 testcases/kernel/syscalls/ioctl/.gitignore      |  1 +
 testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c | 62 +++++++++++++++++++++++++
 3 files changed, 64 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index 7f6312ce5fa241a778d8dda7f8ee9edd0a8800e6..23f335846663d62a39e6de3a8f6948c1b0acf8a5 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -613,6 +613,7 @@ ioctl_ficlonerange02 ioctl_ficlonerange02
 ioctl_fiemap01 ioctl_fiemap01
 
 ioctl_pidfd01 ioctl_pidfd01
+ioctl_pidfd02 ioctl_pidfd02
 
 inotify_init1_01 inotify_init1_01
 inotify_init1_02 inotify_init1_02
diff --git a/testcases/kernel/syscalls/ioctl/.gitignore b/testcases/kernel/syscalls/ioctl/.gitignore
index aa952c1a7bae0ae2dbb04de0595f10d508b6759a..1c81c2bed8db952af0c93fb1ce5bfbad82794b60 100644
--- a/testcases/kernel/syscalls/ioctl/.gitignore
+++ b/testcases/kernel/syscalls/ioctl/.gitignore
@@ -30,3 +30,4 @@
 /ioctl_ficlonerange02
 /ioctl_fiemap01
 /ioctl_pidfd01
+/ioctl_pidfd02
diff --git a/testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c b/testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c
new file mode 100644
index 0000000000000000000000000000000000000000..82dd8c359938cdc7bf69cc2fd6afc90ce2a95290
--- /dev/null
+++ b/testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2025 Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * Check if the ioctl() function allows retrieval of a child's exit code
+ * using PIDFD_INFO_EXIT from a process that is isolated from the child.
+ */
+
+#include "tst_test.h"
+#include "lapi/pidfd.h"
+#include "lapi/sched.h"
+
+static struct tst_clone_args *args;
+static struct pidfd_info *info;
+
+static void run(void)
+{
+	int status;
+	int pidfd = 0;
+	pid_t pid_child;
+
+	memset(args, 0, sizeof(struct tst_clone_args));
+
+	args->flags = CLONE_PIDFD | CLONE_NEWUSER | CLONE_NEWPID;
+	args->pidfd = (uint64_t)&pidfd;
+	args->exit_signal = SIGCHLD;
+
+	pid_child = SAFE_CLONE(args);
+	if (!pid_child) {
+		TST_CHECKPOINT_WAIT(0);
+		exit(100);
+	}
+
+	/* child is not reaped, so ioctl() will pass */
+	info->mask = 0;
+	SAFE_IOCTL(pidfd, PIDFD_GET_INFO, info);
+
+	TST_CHECKPOINT_WAKE(0);
+	SAFE_WAITPID(pid_child, &status, 0);
+
+	/* child is now reaped, so we can ask for the exit status */
+	info->mask = PIDFD_INFO_EXIT;
+	SAFE_IOCTL(pidfd, PIDFD_GET_INFO, info);
+
+	TST_EXP_EQ_LI(info->mask & PIDFD_INFO_EXIT, PIDFD_INFO_EXIT);
+	TST_EXP_EQ_LI(WIFEXITED(info->exit_code), WIFEXITED(status));
+	TST_EXP_EQ_LI(WEXITSTATUS(info->exit_code), WEXITSTATUS(status));
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.forks_child = 1,
+	.needs_checkpoints = 1,
+	.min_kver = "6.15",
+	.bufs = (struct tst_buffers []) {
+		{&args, .size = sizeof(*args)},
+		{&info, .size = sizeof(*info)},
+		{}
+	}
+};

-- 
2.50.0