[RFC,1/1] support/testing/tests/package/test_criu.py: new runtime test

diff --git a/DEVELOPERS b/DEVELOPERS
index d6e6a98202..7220e66af3 100644
--- a/DEVELOPERS
+++ b/DEVELOPERS
@@ -1723,6 +1723,8 @@  F:	support/testing/tests/package/test_acpica/
 F:	support/testing/tests/package/test_brotli.py
 F:	support/testing/tests/package/test_bzip2.py
 F:	support/testing/tests/package/test_compressor_base.py
+F:	support/testing/tests/package/test_criu.py
+F:	support/testing/tests/package/test_criu/
 F:	support/testing/tests/package/test_ddrescue.py
 F:	support/testing/tests/package/test_ddrescue/
 F:	support/testing/tests/package/test_dos2unix.py
diff --git a/support/testing/tests/package/test_criu.py b/support/testing/tests/package/test_criu.py
new file mode 100644
index 0000000000..af2def85e1
--- /dev/null
+++ b/support/testing/tests/package/test_criu.py
@@ -0,0 +1,127 @@ 
+import os
+import time
+
+import infra.basetest
+
+
+class TestCriu(infra.basetest.BRTest):
+    # Criu needs to recompile a Kernel, to enable
+    # CONFIG_CHECKPOINT_RESTORE=y
+    config = \
+        """
+        BR2_aarch64=y
+        BR2_TOOLCHAIN_EXTERNAL=y
+        BR2_TARGET_GENERIC_GETTY_PORT="ttyAMA0"
+        BR2_LINUX_KERNEL=y
+        BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+        BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.1.53"
+        BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+        BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/aarch64-virt/linux.config"
+        BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="{}"
+        BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+        BR2_PACKAGE_CRIU=y
+        BR2_PACKAGE_HOST_PYTHON3=y
+        BR2_ROOTFS_OVERLAY="{}"
+        BR2_TARGET_ROOTFS_CPIO=y
+        BR2_TARGET_ROOTFS_CPIO_GZIP=y
+        # BR2_TARGET_ROOTFS_TAR is not set
+        """.format(
+            infra.filepath("tests/package/test_criu/linux-criu.fragment"),
+            infra.filepath("tests/package/test_criu/rootfs-overlay")
+        )
+    # Define constants for the test
+    test_script_name = "criu-loop.sh"
+    test_script_path = f"/root/{test_script_name}"
+    test_flag_file = "/tmp/wait-flag"
+    test_log = "/tmp/criu-loop.log"
+    pidof_cmd = f"pidof {test_script_name}"
+    checkpoint_dir = "/root/checkpoint"
+    tail1_log_cmd = f"tail -1 {test_log}"
+    expected_log_end = "Done"
+
+    def assert_script_is_running(self):
+        # We check our script is running if the command "pidof"
+        # succeed to find a valid PID.
+        self.assertRunOk(self.pidof_cmd)
+
+    def assert_script_is_not_running(self):
+        # Conversely, the "pidof" command will fail if it cannot find
+        # a valid PID for our script.
+        _, exit_code = self.emulator.run(self.pidof_cmd)
+        self.assertNotEqual(exit_code, 0)
+
+    def test_run(self):
+        img = os.path.join(self.builddir, "images", "rootfs.cpio.gz")
+        kern = os.path.join(self.builddir, "images", "Image")
+        self.emulator.boot(arch="aarch64",
+                           kernel=kern,
+                           kernel_cmdline=["console=ttyAMA0"],
+                           options=["-M", "virt",
+                                    "-cpu", "cortex-a57",
+                                    "-m", "256M",
+                                    "-initrd", img])
+        self.emulator.login()
+
+        # We check the program can execute.
+        self.assertRunOk("criu --version")
+
+        # We run the "criu check" command, which validates the kernel
+        # supports the needed features. We also add verbose logs for
+        # easier debugging.
+        self.assertRunOk("criu check -v")
+
+        # We start our test script, in a new session. Note: to make
+        # sure this test will be reliable in different execution speed
+        # conditions, the script implement a simple synchronization
+        # mechanism by creating a flag file and wait for it to be
+        # removed by this test controller.
+        cmd = f"setsid {self.test_script_path}"
+        cmd += f" < /dev/null &> {self.test_log} &"
+        self.assertRunOk(cmd)
+
+        # Let the script make few loops, then create and wait on its
+        # flag file.
+        time.sleep(3)
+
+        # Our script is supposed to be running.
+        self.assert_script_is_running()
+
+        # We dump the process tree with criu.
+        self.assertRunOk(f"mkdir -p {self.checkpoint_dir}")
+        cmd = f"criu dump -D {self.checkpoint_dir} -t $({self.pidof_cmd})"
+        self.assertRunOk(cmd)
+
+        # We check some criu image files were created.
+        self.assertRunOk(f"ls -1 --color=never {self.checkpoint_dir}/*.img")
+
+        # Our script is no longer supposed to be running (it was
+        # supposed to be stopped bu criu during the dump).
+        self.assert_script_is_not_running()
+
+        # We expect the last line of the log to NOT be "Done" yet.
+        output, exit_code = self.emulator.run(self.tail1_log_cmd)
+        self.assertEqual(exit_code, 0)
+        self.assertNotEqual(output[0], self.expected_log_end)
+
+        # We restore the process image.
+        self.assertRunOk(f"criu restore -d -D {self.checkpoint_dir}")
+
+        # Our script is supposed to be running again.
+        self.assert_script_is_running()
+
+        # We remove our test flag, to let our script to end its loop
+        # (this flag was created by the test script, while we were
+        # waiting earlier).
+        self.assertRunOk(f"rm {self.test_flag_file}")
+
+        # We wait for the script to finish its loop.
+        time.sleep(5)
+
+        # Our script is supposed to have reached its end, and
+        # exited. The script is no longer supposed to be running.
+        self.assert_script_is_not_running()
+
+        # We expect the last line of the log to be the end message.
+        output, exit_code = self.emulator.run(self.tail1_log_cmd)
+        self.assertEqual(exit_code, 0)
+        self.assertEqual(output[0], self.expected_log_end)
diff --git a/support/testing/tests/package/test_criu/linux-criu.fragment b/support/testing/tests/package/test_criu/linux-criu.fragment
new file mode 100644
index 0000000000..c554a09cec
--- /dev/null
+++ b/support/testing/tests/package/test_criu/linux-criu.fragment
@@ -0,0 +1 @@ 
+CONFIG_CHECKPOINT_RESTORE=y
diff --git a/support/testing/tests/package/test_criu/rootfs-overlay/root/criu-loop.sh b/support/testing/tests/package/test_criu/rootfs-overlay/root/criu-loop.sh
new file mode 100755
index 0000000000..6a1f72b442
--- /dev/null
+++ b/support/testing/tests/package/test_criu/rootfs-overlay/root/criu-loop.sh
@@ -0,0 +1,15 @@ 
+#! /bin/sh
+set -eu
+echo "Start"
+for LOOP in $(seq 6) ; do
+    echo "Loop $LOOP"
+    if [ "$LOOP" -eq 3 ] ; then
+        touch /tmp/wait-flag
+    fi
+    while [ -e /tmp/wait-flag ] ; do
+        sleep 1
+        echo "Waiting..."
+    done
+    sleep 1
+done
+echo "Done"