Fuchsia: Explicitly check that all file dependencies exist.

Wrap file path references with "EnsureFileExists()" which acts as a
simple identity function, except for invalid paths for which it
raises IOErrors.

Bug: 837200
Change-Id: Ie718cd5517415b375ed3bf5d5112d59b32074c04
Reviewed-on: https://chromium-review.googlesource.com/1037778Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555137}

build/fuchsia/common.py

@@ -8,3 +8,11 @@ DIR_SOURCE_ROOT = os.path.abspath(
     os.path.join(os.path.dirname(__file__), os.pardir, os.pardir))
 SDK_ROOT = os.path.join(DIR_SOURCE_ROOT, 'third_party', 'fuchsia-sdk', 'sdk')
 
+def EnsurePathExists(path):
+  """Checks that the file |path| exists on the filesystem and returns the path
+  if it does, raising an exception otherwise."""
+
+  if not os.path.exists(path):
+    raise IOError('Missing file: ' + path)
+
+  return path

build/fuchsia/device_target.py

@@ -5,7 +5,6 @@
 """Implements commands for running and interacting with Fuchsia on devices."""
 
 import boot_data
-import common
 import logging
 import os
 import subprocess
@@ -13,6 +12,8 @@ import target
 import time
 import uuid
 
+from common import SDK_ROOT, EnsurePathExists
+
 CONNECT_RETRY_COUNT = 20
 CONNECT_RETRY_WAIT_SECS = 1
 
@@ -34,7 +35,8 @@ class DeviceTarget(target.Target):
     self._new_instance = True
 
     if self._auto:
-      self._ssh_config_path = boot_data.GetSSHConfigPath(output_dir)
+      self._ssh_config_path = EnsurePathExists(
+          boot_data.GetSSHConfigPath(output_dir))
     else:
       self._ssh_config_path = os.path.expanduser(ssh_config)
       self._host = host
@@ -46,7 +48,7 @@ class DeviceTarget(target.Target):
     """Returns the IP address and port of a Fuchsia instance discovered on
     the local area network."""
 
-    netaddr_path = os.path.join(common.SDK_ROOT, 'tools', 'netaddr')
+    netaddr_path = os.path.join(SDK_ROOT, 'tools', 'netaddr')
     command = [netaddr_path, '--fuchsia', '--nowait', node_name]
     logging.debug(' '.join(command))
     proc = subprocess.Popen(command,
@@ -69,25 +71,25 @@ class DeviceTarget(target.Target):
 
       logging.info('Netbooting Fuchsia. ' +
                    'Please ensure that your device is in bootloader mode.')
-      bootserver_path = os.path.join(common.SDK_ROOT, 'tools', 'bootserver')
-      data_fvm_path = boot_data.ConfigureDataFVM(self._output_dir,
-                                                 boot_data.FVM_TYPE_SPARSE)
-      bootserver_command = [bootserver_path,
-                            '-1',
-                            '--efi',
-                            boot_data.GetTargetFile(self._GetTargetSdkArch(),
-                                                    'local.esp.blk'),
-                            '--fvm',
-                            boot_data.GetTargetFile(self._GetTargetSdkArch(),
-                                                    'fvm.sparse.blk'),
-                            '--fvm',
-                            data_fvm_path,
-                            boot_data.GetTargetFile(self._GetTargetSdkArch(),
-                                                    'zircon.bin'),
-                            boot_data.GetTargetFile(self._GetTargetSdkArch(),
-                                                    'bootdata-blob.bin'),
-                            '--'] + \
-                            boot_data.GetKernelArgs(self._output_dir)
+      bootserver_path = os.path.join(SDK_ROOT, 'tools', 'bootserver')
+      bootserver_command = [
+          bootserver_path,
+          '-1',
+          '--efi',
+          EnsurePathExists(boot_data.GetTargetFile(self._GetTargetSdkArch(),
+                                                   'local.esp.blk')),
+          '--fvm',
+          EnsurePathExists(boot_data.GetTargetFile(self._GetTargetSdkArch(),
+                                                   'fvm.sparse.blk')),
+          '--fvm',
+          EnsurePathExists(
+              boot_data.ConfigureDataFVM(self._output_dir,
+                                         boot_data.FVM_TYPE_SPARSE)),
+          EnsurePathExists(boot_data.GetTargetFile(self._GetTargetSdkArch(),
+                                                   'zircon.bin')),
+          EnsurePathExists(boot_data.GetTargetFile(self._GetTargetSdkArch(),
+                                                   'bootdata-blob.bin')),
+          '--'] + boot_data.GetKernelArgs(self._output_dir)
       logging.debug(' '.join(bootserver_command))
       subprocess.check_call(bootserver_command)
 

build/fuchsia/qemu_target.py

@@ -5,7 +5,6 @@
 """Implements commands for running and interacting with Fuchsia on QEMU."""
 
 import boot_data
-import common
 import logging
 import target
 import os
@@ -14,6 +13,8 @@ import socket
 import subprocess
 import time
 
+from common import SDK_ROOT, EnsurePathExists
+
 
 # Virtual networking configuration data for QEMU.
 GUEST_NET = '192.168.3.0/24'
@@ -51,9 +52,8 @@ class QemuTarget(target.Target):
       self.Shutdown()
 
   def Start(self):
-    qemu_path = os.path.join(
-        common.SDK_ROOT, 'qemu', 'bin',
-        'qemu-system-' + self._GetTargetSdkArch())
+    qemu_path = os.path.join(SDK_ROOT, 'qemu', 'bin',
+                             'qemu-system-' + self._GetTargetSdkArch())
     kernel_args = boot_data.GetKernelArgs(self._output_dir)
 
     # TERM=dumb tells the guest OS to not emit ANSI commands that trigger
@@ -67,20 +67,24 @@ class QemuTarget(target.Target):
     qemu_command = [qemu_path,
         '-m', str(self._ram_size_mb),
         '-nographic',
-        '-kernel', boot_data.GetTargetFile(self._GetTargetSdkArch(),
-                                           'zircon.bin'),
-        '-initrd', boot_data.GetTargetFile(self._GetTargetSdkArch(),
-                                           'bootdata-blob.bin'),
+        '-kernel', EnsurePathExists(
+            boot_data.GetTargetFile(self._GetTargetSdkArch(),
+                                    'zircon.bin')),
+        '-initrd', EnsurePathExists(
+            boot_data.GetTargetFile(self._GetTargetSdkArch(),
+                                    'bootdata-blob.bin')),
         '-smp', '4',
 
         # Attach the blobstore and data volumes. Use snapshot mode to discard
         # any changes.
         '-snapshot',
         '-drive', 'file=%s,format=qcow2,if=none,id=data,snapshot=on' %
-            os.path.join(self._output_dir, 'fvm.blk.qcow2'),
+                    EnsurePathExists(os.path.join(self._output_dir,
+                                                  'fvm.blk.qcow2')),
         '-drive', 'file=%s,format=qcow2,if=none,id=blobstore,snapshot=on' %
-            boot_data.ConfigureDataFVM(self._output_dir,
-                                       boot_data.FVM_TYPE_QCOW),
+            EnsurePathExists(
+                boot_data.ConfigureDataFVM(self._output_dir,
+                                           boot_data.FVM_TYPE_QCOW)),
         '-device', 'virtio-blk-pci,drive=data',
         '-device', 'virtio-blk-pci,drive=blobstore',