arc: Abort booting ARC if the device is critically low on disk space.

components/arc/arc_bridge_bootstrap.cc

Index: components/arc/arc_bridge_bootstrap.cc
diff --git a/components/arc/arc_bridge_bootstrap.cc b/components/arc/arc_bridge_bootstrap.cc
index c9cafb21c37bc8eb7d66cd01da3edb1689bedc96..652bb68a6d606cece70c964b9e84ca6bdaa2e24b 100644
--- a/components/arc/arc_bridge_bootstrap.cc
+++ b/components/arc/arc_bridge_bootstrap.cc
@@ -21,6 +21,7 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/threading/worker_pool.h"
 #include "chromeos/cryptohome/cryptohome_parameters.h"
+#include "chromeos/dbus/cryptohome_client.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/session_manager_client.h"
@@ -42,6 +43,8 @@ const base::FilePath::CharType kArcBridgeSocketPath[] =
 
 const char kArcBridgeSocketGroup[] = "arc-bridge";
 
+const uint64_t kCriticalDiskFreeBytes = 64 << 20;  // 64MB
+
 // This is called when StopArcInstance D-Bus method completes. Since we have the
 // ArcInstanceStopped() callback and are notified if StartArcInstance fails, we
 // don't need to do anything when StopArcInstance completes.
@@ -65,6 +68,8 @@ class ArcBridgeBootstrapImpl : public ArcBridgeBootstrap,
   //
   // STOPPED
   //   Start() ->
+  // DISK_SPACE_CHECKING
+  //   CheckDiskSpace() -> OnDiskSpaceChecked() ->
   // SOCKET_CREATING
   //   CreateSocket() -> OnSocketCreated() ->
   // STARTING
@@ -85,7 +90,7 @@ class ArcBridgeBootstrapImpl : public ArcBridgeBootstrap,
   // When the instance crashes while it was ready, it will be stopped:
   //   READY -> STOPPING -> STOPPED
   // and then restarted:
-  //   STOPPED -> SOCKET_CREATING -> ... -> READY).
+  //   STOPPED -> DISK_SPACE_CHECKING -> ... -> READY).
   //
   // Note: Order of constants below matters. Please make sure to sort them
   // in chronological order.
@@ -93,6 +98,9 @@ class ArcBridgeBootstrapImpl : public ArcBridgeBootstrap,
     // ARC is not currently running.
     STOPPED,
 
+    // Checking the disk space.
+    DISK_SPACE_CHECKING,
+
     // An UNIX socket is being created.
     SOCKET_CREATING,
 
@@ -121,6 +129,10 @@ class ArcBridgeBootstrapImpl : public ArcBridgeBootstrap,
   // functions when they encounter an error during boot.
   void AbortBoot(ArcBridgeService::StopReason reason);
 
+  // Called after checking the device disk space.
+  void OnDiskSpaceChecked(chromeos::DBusMethodCallStatus call_status,
+                          uint64_t disk_free_bytes);
+
   // Creates the UNIX socket on the bootstrap thread and then processes its
   // file descriptor.
   static base::ScopedFD CreateSocket();
@@ -180,6 +192,29 @@ void ArcBridgeBootstrapImpl::Start() {
     return;
   }
   stop_reason_ = ArcBridgeService::StopReason::SHUTDOWN;
+  // TODO(crbug.com/628124): Move disk space checking logic to session_manager
+  // to avoid extra D-Bus method call cost.
+  SetState(State::DISK_SPACE_CHECKING);
+  chromeos::CryptohomeClient* cryptohome_client =
+      chromeos::DBusThreadManager::Get()->GetCryptohomeClient();
+  cryptohome_client->GetFreeDiskSpace(base::Bind(
+      &ArcBridgeBootstrapImpl::OnDiskSpaceChecked, weak_factory_.GetWeakPtr()));
+}
+
+void ArcBridgeBootstrapImpl::OnDiskSpaceChecked(
+    chromeos::DBusMethodCallStatus call_status,
+    uint64_t disk_free_bytes) {
+  DCHECK(thread_checker_.CalledOnValidThread());

[hidehiko, 2016/07/14 14:10:26]

Could you check if Stop() is called between start() and OnDiscSpaceChecked()?
If so, please not to continue the bootstrap procedure.

cf) OnSocketCreated().

[Shuhei Takahashi, 2016/07/15 06:06:09]

Done.

+  if (call_status != chromeos::DBUS_METHOD_CALL_SUCCESS) {
+    LOG(ERROR) << "ARC: Failed to check free disk space.";
+    AbortBoot(ArcBridgeService::StopReason::GENERIC_BOOT_FAILURE);
+    return;
+  }
+  if (disk_free_bytes < kCriticalDiskFreeBytes) {
+    LOG(ERROR) << "ARC: The device is too low on disk space to start ARC";
+    AbortBoot(ArcBridgeService::StopReason::LOW_DISK_SPACE);
+    return;
+  }
   SetState(State::SOCKET_CREATING);
   base::PostTaskAndReplyWithResult(
       base::WorkerPool::GetTaskRunner(true).get(), FROM_HERE,