ftests: Add a test for cgroup_attach_task_pid()

Add a functional test for cgroup_attach_task_pid().

-----------------------------------------------------------------
Test Results:
	Run Date:                          Jan 04 21:06:16
	Passed:                                  1 test(s)
	Skipped:                                 0 test(s)
	Failed:                                  0 test(s)
-----------------------------------------------------------------
Timing Results:
	Test                                   Time (sec)
	-------------------------------------------------
	setup                                        0.00
	053-sudo-cgroup_attach_task_pid.py           2.06
	teardown                                     0.00
	-------------------------------------------------
	Total Run Time                               2.06

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>

diff --git a/tests/ftests/053-sudo-cgroup_attach_task_pid.py b/tests/ftests/053-sudo-cgroup_attach_task_pid.py
new file mode 100755 (executable)
index 0000000..36f184b
--- /dev/null
+++ b/tests/ftests/053-sudo-cgroup_attach_task_pid.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: LGPL-2.1-only
+#
+# Attach a task to a cgroup via cgroup_attach_task_pid()
+#
+# Copyright (c) 2023 Oracle and/or its affiliates.
+# Author: Tom Hromatka <tom.hromatka@oracle.com>
+#
+
+from cgroup import Cgroup as CgroupCli
+from libcgroup import Cgroup, Version
+from cgroup import CgroupVersion
+import ftests
+import consts
+import sys
+import os
+
+CGNAME = '052cgattachcg'
+
+# Which controller isn't all that important, but it is important that we
+# have a cgroup v2 controller
+CONTROLLER = 'cpu'
+
+
+def prereqs(config):
+    if config.args.container:
+        result = consts.TEST_SKIPPED
+        cause = 'This test cannot be run within a container'
+        return result, cause
+
+    if CgroupVersion.get_version(CONTROLLER) != CgroupVersion.CGROUP_V2:
+        result = consts.TEST_SKIPPED
+        cause = 'This test requires cgroup v2'
+        return result, cause
+
+    result = consts.TEST_PASSED
+    cause = None
+
+    return result, cause
+
+
+def setup(config):
+    cg = Cgroup(CGNAME, Version.CGROUP_V2)
+    cg.add_controller(CONTROLLER)
+    cg.create()
+
+
+def test(config):
+    result = consts.TEST_PASSED
+    cause = None
+
+    child_pid = config.process.create_process(config)
+
+    cg = Cgroup(CGNAME, Version.CGROUP_V2)
+    cg.get()
+    cg.attach(int(child_pid))
+
+    found = False
+    pids = CgroupCli.get_pids_in_cgroup(config, CGNAME, CONTROLLER)
+    for pid in pids.splitlines():
+        if pid == child_pid:
+            # our process was successfully added to the cgroup
+            found = True
+
+    if not found:
+        result = consts.TEST_FAILED
+        cause = 'Could not find pid {} in cgroup {}'.format(child_pid, CGNAME)
+        return result, cause
+
+    # now let's attach the child process to the root cgroup and ensure we no longer
+    # are in CGNAME
+    cg.attach(pid=int(child_pid), root_cgroup=True)
+
+    found = False
+    pids = CgroupCli.get_pids_in_cgroup(config, CGNAME, CONTROLLER)
+    for pid in pids.splitlines():
+        if pid == child_pid:
+            # our process was successfully added to the cgroup
+            found = True
+
+    if found:
+        result = consts.TEST_FAILED
+        cause = 'pid {} was erroneously found in cgroup {}'.format(child_pid, CGNAME)
+
+    return result, cause
+
+
+def teardown(config, result):
+    cg = Cgroup(CGNAME, Version.CGROUP_V2)
+    try:
+        cg.delete()
+    except RuntimeError:
+        pass
+
+    return consts.TEST_PASSED, None
+
+
+def main(config):
+    [result, cause] = prereqs(config)
+    if result != consts.TEST_PASSED:
+        return [result, cause]
+
+    try:
+        result = consts.TEST_FAILED
+        setup(config)
+        [result, cause] = test(config)
+    finally:
+        teardown(config, result)
+
+    return [result, cause]
+
+
+if __name__ == '__main__':
+    config = ftests.parse_args()
+    # this test was invoked directly.  run only it
+    config.args.num = int(os.path.basename(__file__).split('-')[0])
+    sys.exit(ftests.main(config))
+
+# vim: set et ts=4 sw=4: