Add OTA stress test script

Test: python3 ota_stress_test.py ota.zip
Change-Id: I313768945e2c2f98c950f283c7c860d334b99f08
diff --git a/scripts/ota_stress_test.py b/scripts/ota_stress_test.py
new file mode 100644
index 0000000..55aa4b1
--- /dev/null
+++ b/scripts/ota_stress_test.py
@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""Repeatedly install an A/B update to an Android device over adb."""
+
+import argparse
+import sys
+from pathlib import Path
+import subprocess
+import signal
+
+
+def CleanupLoopDevices():
+  # b/184716804 clean up unused loop devices
+  subprocess.check_call(["adb", "shell", "su", "0", "losetup", '-D'])
+
+
+def CancelOTA():
+  subprocess.call(["adb", "shell", "su", "0",
+                  "update_engine_client", "--cancel"])
+
+
+def PerformOTAThenPause(otafile: Path, update_device_script: Path):
+  python = sys.executable
+  ota_cmd = [python, str(update_device_script), str(otafile),
+             "--no-postinstall", "--no-slot-switch"]
+  p = subprocess.Popen(ota_cmd)
+  pid = p.pid
+  try:
+    ret = p.wait(10)
+    if ret is not None and ret != 0:
+      raise RuntimeError("OTA failed to apply")
+    if ret == 0:
+      print("OTA finished early? Surprise.")
+      return
+  except subprocess.TimeoutExpired:
+    pass
+  print(f"Killing {pid}")
+  subprocess.check_call(["pkill", "-INT", "-P", str(pid)])
+  p.send_signal(signal.SIGINT)
+  p.wait()
+
+
+def PerformTest(otafile: Path, resumes: int, timeout: int):
+  """Install an OTA to device, raising exceptions on failure
+
+  Args:
+    otafile: Path to the ota.zip to install
+
+  Return:
+    None if no error, if there's an error exception will be thrown
+  """
+  assert otafile.exists()
+  print("Applying", otafile)
+  script_dir = Path(__file__).parent.absolute()
+  update_device_script = script_dir / "update_device.py"
+  assert update_device_script.exists()
+  print(update_device_script)
+  python = sys.executable
+
+  for i in range(resumes):
+    print("Pause/Resume for the", i+1, "th time")
+    PerformOTAThenPause(otafile, update_device_script)
+  CancelOTA()
+  CleanupLoopDevices()
+
+  ota_cmd = [python, str(update_device_script),
+             str(otafile), "--no-postinstall"]
+  print("Finishing OTA Update", ota_cmd)
+  output = subprocess.check_output(
+      ota_cmd, stderr=subprocess.STDOUT, timeout=timeout).decode()
+  print(output)
+  if "onPayloadApplicationComplete(ErrorCode::kSuccess" not in output:
+    raise RuntimeError("Failed to finish OTA")
+  subprocess.call(
+      ["adb", "shell", "su", "0", "update_engine_client", "--cancel"])
+  subprocess.check_call(
+      ["adb", "shell", "su", "0", "update_engine_client", "--reset_status"])
+  CleanupLoopDevices()
+
+
+def main():
+  parser = argparse.ArgumentParser(
+      description='Android A/B OTA stress test helper.')
+  parser.add_argument('otafile', metavar='PAYLOAD', type=Path,
+                      help='the OTA package file (a .zip file) or raw payload \
+                      if device uses Omaha.')
+  parser.add_argument('-n', "--iterations", type=int, default=10,
+                      metavar='ITERATIONS',
+                      help='The number of iterations to run the stress test, or\
+                       -1 to keep running until CTRL+C')
+  parser.add_argument('-r', "--resumes", type=int, default=5, metavar='RESUMES',
+                      help='The number of iterations to pause the update when \
+                        installing')
+  parser.add_argument('-t', "--timeout", type=int, default=60*60,
+                      metavar='TIMEOUTS',
+                      help='Timeout, in seconds, when waiting for OTA to \
+                        finish')
+  args = parser.parse_args()
+  print(args)
+  n = args.iterations
+  while n != 0:
+    PerformTest(args.otafile, args.resumes, args.timeout)
+    n -= 1
+
+
+if __name__ == "__main__":
+  main()