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..5379cbd5dd56b4b587b28e9552eda5b119bd9c88 100644
--- a/components/arc/arc_bridge_bootstrap.cc
+++ b/components/arc/arc_bridge_bootstrap.cc
@@ -16,6 +16,7 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/posix/eintr_wrapper.h"
+#include "base/sys_info.h"
 #include "base/task_runner_util.h"
 #include "base/threading/thread_checker.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -42,6 +43,10 @@ const base::FilePath::CharType kArcBridgeSocketPath[] =
 
 const char kArcBridgeSocketGroup[] = "arc-bridge";
 
+const base::FilePath::CharType kDiskCheckPath[] = "/home";
+
+const int64_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 +70,8 @@ class ArcBridgeBootstrapImpl : public ArcBridgeBootstrap,
   //
   // STOPPED
   //   Start() ->
+  // DISK_SPACE_CHECKING
+  //   CheckDiskSpace() -> OnDiskSpaceChecked() ->
   // SOCKET_CREATING
   //   CreateSocket() -> OnSocketCreated() ->
   // STARTING
@@ -85,7 +92,7 @@ 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 +100,9 @@ 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 +131,10 @@ class ArcBridgeBootstrapImpl : public ArcBridgeBootstrap,
   // functions when they encounter an error during boot.
   void AbortBoot(ArcBridgeService::StopReason reason);
 
+  // Checks the device disk space.
+  static int64_t CheckDiskSpace();

[hidehiko, 2016/07/15 14:47:25]

Optional: how about "GetFreeDiskSpace()"?
"Check" is sometimes used for a function like a validation function, but yours
looks a kind of getter?

An alternative is just using base::Bind

PostTaskAndReplyWithResult(
    ....
    base::Bind(AmountOfFreeDiskSpace, FilePath(kDiskCheckPath)),
    ...);

Up to you.

[Shuhei Takahashi, 2016/07/19 04:38:00]

Good point that we can just bind to AmountOfFreeDiskSpace! Changed accordingly.

+  void OnDiskSpaceChecked(int64_t disk_free_bytes);
+
   // Creates the UNIX socket on the bootstrap thread and then processes its
   // file descriptor.
   static base::ScopedFD CreateSocket();
@@ -180,6 +194,35 @@ void ArcBridgeBootstrapImpl::Start() {
     return;
   }
   stop_reason_ = ArcBridgeService::StopReason::SHUTDOWN;
+  // TODO(crbug.com/628124): Move disk space checking logic to session_manager.
+  SetState(State::DISK_SPACE_CHECKING);
+  base::PostTaskAndReplyWithResult(
+      base::WorkerPool::GetTaskRunner(true).get(), FROM_HERE,
+      base::Bind(&ArcBridgeBootstrapImpl::CheckDiskSpace),
+      base::Bind(&ArcBridgeBootstrapImpl::OnDiskSpaceChecked,
+                 weak_factory_.GetWeakPtr()));
+}
+
+// static
+int64_t ArcBridgeBootstrapImpl::CheckDiskSpace() {
+  return base::SysInfo::AmountOfFreeDiskSpace(base::FilePath(kDiskCheckPath));
+}
+
+void ArcBridgeBootstrapImpl::OnDiskSpaceChecked(int64_t disk_free_bytes) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (state_ != State::DISK_SPACE_CHECKING) {
+    VLOG(1) << "Stop() called while checking disk space";
+    return;
+  }
+  if (disk_free_bytes < 0) {
+    LOG(ERROR) << "ARC: Failed to get free disk space";
+    AbortBoot(ArcBridgeService::StopReason::GENERIC_BOOT_FAILURE);
+    return;
+  } else if (disk_free_bytes < kCriticalDiskFreeBytes) {

[hidehiko, 2016/07/15 14:47:25]

  return;
}
if (...) {
  :
  return;
}

to standardize the style in this file?

[Shuhei Takahashi, 2016/07/19 04:38:00]

Done.

+    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,