fuchsia: Add QEMU and helper script to start/stop instance

This is mostly intended to be used for waterfall/trybots.
Fuchsia-on-metal isn't available as a Swarming dimension, so in order to
run tests, use QEMU-with-KVM on the host. It might also be useful for
local development for those without a Fuchsia hardware device.

Bug: crashpad:196, crashpad:212
Change-Id: I88170bc95bd532676b787b50a94f7fa3c69b1ac7
Reviewed-on: https://chromium-review.googlesource.com/822523
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>

.gitignore

@@ -12,6 +12,7 @@
 /out
 /third_party/fuchsia/.cipd
 /third_party/fuchsia/clang
+/third_party/fuchsia/qemu
 /third_party/fuchsia/sdk
 /third_party/gtest/gtest
 /third_party/gyp/gyp

DEPS

@@ -145,6 +145,36 @@ hooks = [
       '-log-level', 'info',
     ],
   },
+  {
+    # Same rationale for using "install" rather than "ensure" as for clang
+    # packages. https://crbug.com/789364.
+    'name': 'fuchsia_qemu_mac',
+    'pattern': '.',
+    'condition': 'checkout_fuchsia and host_os == "mac"',
+    'action': [
+      'cipd',
+      'install',
+      'fuchsia/qemu/mac-amd64',
+      'latest',
+      '-root', 'crashpad/third_party/fuchsia/qemu/mac-amd64',
+      '-log-level', 'info',
+    ],
+  },
+  {
+    # Same rationale for using "install" rather than "ensure" as for clang
+    # packages. https://crbug.com/789364.
+    'name': 'fuchsia_qemu_linux',
+    'pattern': '.',
+    'condition': 'checkout_fuchsia and host_os == "linux"',
+    'action': [
+      'cipd',
+      'install',
+      'fuchsia/qemu/linux-amd64',
+      'latest',
+      '-root', 'crashpad/third_party/fuchsia/qemu/linux-amd64',
+      '-log-level', 'info',
+    ],
+  },
   {
     # The SDK is keyed to the host system because it contains build tools.
     # Currently, linux-amd64 is the only SDK published (see

build/run_fuchsia_qemu.py

@@ -0,0 +1,119 @@
+#!/usr/bin/env python
+
+# Copyright 2017 The Crashpad Authors. All rights reserved.
+#
+# 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.
+
+"""Helper script to [re]start or stop a helper Fuchsia QEMU instance to be used
+for running tests without a device.
+"""
+
+from __future__ import print_function
+
+import getpass
+import os
+import random
+import signal
+import subprocess
+import sys
+import tempfile
+
+try:
+  from subprocess import DEVNULL
+except ImportError:
+  DEVNULL = open(os.devnull, 'r+b')
+
+CRASHPAD_ROOT = os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                             os.pardir)
+
+
+def _Stop(pid_file):
+  if os.path.isfile(pid_file):
+    with open(pid_file, 'rb') as f:
+      pid = int(f.read().strip())
+    try:
+      os.kill(pid, signal.SIGTERM)
+    except:
+      print('Unable to kill pid %d, continuing' % pid, file=sys.stderr)
+    os.unlink(pid_file)
+
+
+def _CheckForTun():
+  """Check for networking. TODO(scottmg): Currently, this is Linux-specific.
+  """
+  returncode = subprocess.call(
+      ['tunctl', '-b', '-u', getpass.getuser(), '-t', 'qemu'],
+      stdout=DEVNULL, stderr=DEVNULL)
+  if returncode != 0:
+    print('To use QEMU with networking on Linux, configure TUN/TAP. See:',
+          file=sys.stderr)
+    print('  https://fuchsia.googlesource.com/magenta/+/HEAD/docs/qemu.md#enabling-networking-under-qemu-x86_64-only',
+          file=sys.stderr)
+    return 2
+  return 0
+
+
+def _Start(pid_file):
+  tun_result = _CheckForTun()
+  if tun_result != 0:
+    return tun_result
+
+  arch = 'mac-amd64' if sys.platform == 'darwin' else 'linux-amd64'
+  fuchsia_dir = os.path.join(CRASHPAD_ROOT, 'third_party', 'fuchsia')
+  qemu_path = os.path.join(fuchsia_dir, 'qemu', arch, 'bin',
+                           'qemu-system-x86_64')
+  kernel_data_dir = os.path.join(fuchsia_dir, 'sdk', arch, 'target', 'x86_64')
+  kernel_path = os.path.join(kernel_data_dir, 'zircon.bin')
+  initrd_path = os.path.join(kernel_data_dir, 'bootdata.bin')
+
+  mac_tail = ':'.join('%02x' % random.randint(0, 255) for x in range(3))
+
+  # These arguments are from the Fuchsia repo in zircon/scripts/run-zircon.
+  popen = subprocess.Popen([
+    qemu_path,
+    '-m', '2048',
+    '-nographic',
+    '-kernel', kernel_path,
+    '-initrd', initrd_path,
+    '-smp', '4',
+    '-serial', 'stdio',
+    '-monitor', 'none',
+    '-machine', 'q35',
+    '-cpu', 'host,migratable=no',
+    '-enable-kvm',
+    '-netdev', 'type=tap,ifname=qemu,script=no,downscript=no,id=net0',
+    '-device', 'e1000,netdev=net0,mac=52:54:00:' + mac_tail,
+    '-append', 'TERM=dumb',
+  ], stdin=DEVNULL, stdout=DEVNULL, stderr=DEVNULL)
+
+  with open(pid_file, 'wb') as f:
+    f.write('%d\n' % popen.pid)
+
+
+def main(args):
+  if len(args) != 1 or args[0] not in ('start', 'stop'):
+    print('usage: run_fuchsia_qemu.py start|stop', file=sys.stderr)
+    return 1
+
+  command = args[0]
+
+  pid_file = os.path.join(tempfile.gettempdir(), 'crashpad_fuchsia_qemu_pid')
+  _Stop(pid_file)
+  if command == 'start':
+    _Start(pid_file)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv[1:]))