Add support for saving VM state when a test fails.

bin/cros_run_vm_test

 #!/bin/bash
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Runs a given test case under a VM.
 
 . "$(dirname $0)/../common.sh"
 . "$(dirname $0)/../lib/cros_vm_lib.sh"
 . "$(dirname "$0")/../lib/cros_vm_constants.sh"
 
 MAX_RETRIES=3
 
 get_default_board
 
 DEFINE_string board "$DEFAULT_BOARD" \
     "The board for which you built autotest." b
 DEFINE_string image_path "" "Full path of the VM image"
 DEFINE_string results_dir_root "" "alternate root results directory"
+DEFINE_boolean save_vm_state ${FLAGS_FALSE} \
+    "Save the state of the VM when a test fails"
+DEFINE_string save_vm_state_file ${DEFAULT_QEMU_COW_IMAGE} \
+    "Name of file to save VM state into if test fails"
 DEFINE_string test_case "" "Name of the test case to run"
 DEFINE_boolean use_emerged ${FLAGS_FALSE} \
     "Force use of emerged autotest packages"
 DEFINE_string verify_chrome_version "" \
     "Verify that this chrome version matches that on vm."
 
 set -e
 
 # Returns normally if the given $1 is a valid chrome version.
 chrome_version_is_valid() {
@@ skipping 16 matching lines @@
 
 if [ -n "${FLAGS_test_case}" ]; then
   warn "Use of --test_case=<test> is being deprecated.  Just pass test names \
 as separate command line arguments."
 fi
 
 if [ -z "${FLAGS_test_case}" ] && [ -z "${FLAGS_ARGV}" ]; then
   die "You must specify a test case."
 fi
 
+if [ ${FLAGS_save_vm_state} -eq ${FLAGS_TRUE} ] &&
+   [ ${FLAGS_snapshot} -eq ${FLAGS_TRUE} ]; then
+  die "You cannot set both --snapshot and --save_vm_state."
+fi
+
+if [ ${FLAGS_save_vm_state} -eq ${FLAGS_TRUE} ] &&
+   [ -z ${FLAGS_save_vm_state_file} ]; then
+  die "You must specify a save_vm_state_file."
+fi
+
 USE_EMERGED=
 if [[ ${FLAGS_use_emerged} -eq ${FLAGS_TRUE} ]]; then
   USE_EMERGED="--use_emerged"
 fi
 
 tests=( )
 [ -n "${FLAGS_test_case}" ] && tests=( "${FLAGS_test_case}" )
 for test in ${FLAGS_ARGV}; do
   tests=( "${tests[@]}" "$(remove_quotes "${test}")" )
 done
 
+# Create a copy-on-write qcow2 file that is based off the default QEMU image
+# so that we can save state information into it.
+if [ ${FLAGS_save_vm_state} -eq ${FLAGS_TRUE} ]; then
+  QEMU_COW_IMAGE="$(${SCRIPTS_DIR}/get_latest_image.sh \
+      --board=${FLAGS_board})/${FLAGS_save_vm_state_file}"
+  qemu-img create -f qcow2 -b ${LATEST_IMAGE} ${QEMU_COW_IMAGE}
+  FLAGS_image_path=${QEMU_COW_IMAGE}
+fi
+
 trap stop_kvm EXIT
 start_kvm "${FLAGS_image_path}"
 info "Checking for ssh access to virtual machine."
 retry_until_ssh ${MAX_RETRIES}
 
 if [ -n "${FLAGS_verify_chrome_version}" ]; then
   info "Verifying version of Chrome matches what we expect."
   if chrome_version_is_valid "${FLAGS_verify_chrome_version}"; then
     chrome_version_on_vm=$("$(dirname $0)/cros_get_chrome_version" \
         --remote=127.0.0.1 \
         --ssh_port=${FLAGS_ssh_port})
     [[ ${chrome_version_on_vm} == ${FLAGS_verify_chrome_version} ]] || \
         die "Chrome version mismatch.  VM reported ${chrome_version_on_vm}"
   else
     warn "${FLAGS_verify_chrome_version} is not a valid Chrome version"
   fi
 fi
 
 "$(dirname $0)"/../run_remote_tests.sh \
     --board=${FLAGS_board} \
     --ssh_port=${FLAGS_ssh_port} \
     --remote=127.0.0.1 \
     --results_dir_root="${FLAGS_results_dir_root}" \
     ${USE_EMERGED} \
     "${tests[@]}"