1 files changed, 324 insertions, 0 deletions
diff --git a/hal/gonk/GonkDiskSpaceWatcher.cpp b/hal/gonk/GonkDiskSpaceWatcher.cpp
new file mode 100644
index 0000000000..cdc48ef89a
--- /dev/null
+++ b/hal/gonk/GonkDiskSpaceWatcher.cpp
@@ -0,0 +1,324 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Hal.h"
+#include <sys/syscall.h>
+#include <sys/vfs.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "base/message_loop.h"
+#include "base/task.h"
+#include "DiskSpaceWatcher.h"
+#include "fanotify.h"
+#include "nsIObserverService.h"
+#include "nsIDiskSpaceWatcher.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+#include "mozilla/ModuleUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+
+using namespace mozilla;
+
+namespace mozilla { namespace hal_impl { class GonkDiskSpaceWatcher; } }
+
+using namespace mozilla::hal_impl;
+
+namespace mozilla {
+namespace hal_impl {
+
+// NOTE: this should be unnecessary once we no longer support ICS.
+#ifndef __NR_fanotify_init
+#if defined(__ARM_EABI__)
+#define __NR_fanotify_init 367
+#define __NR_fanotify_mark 368
+#elif defined(__i386__)
+#define __NR_fanotify_init 338
+#define __NR_fanotify_mark 339
+#else
+#error "Unhandled architecture"
+#endif
+#endif
+
+// fanotify_init and fanotify_mark functions are syscalls.
+// The user space bits are not part of bionic so we add them here
+// as well as fanotify.h
+int fanotify_init (unsigned int flags, unsigned int event_f_flags)
+{
+  return syscall(__NR_fanotify_init, flags, event_f_flags);
+}
+
+// Add, remove, or modify an fanotify mark on a filesystem object.
+int fanotify_mark (int fanotify_fd, unsigned int flags,
+                   uint64_t mask, int dfd, const char *pathname)
+{
+
+  // On 32 bits platforms we have to convert the 64 bits mask into
+  // two 32 bits ints.
+  if (sizeof(void *) == 4) {
+    union {
+      uint64_t _64;
+      uint32_t _32[2];
+    } _mask;
+    _mask._64 = mask;
+    return syscall(__NR_fanotify_mark, fanotify_fd, flags,
+		   _mask._32[0], _mask._32[1], dfd, pathname);
+  }
+
+  return syscall(__NR_fanotify_mark, fanotify_fd, flags, mask, dfd, pathname);
+}
+
+class GonkDiskSpaceWatcher final : public MessageLoopForIO::Watcher
+{
+public:
+  GonkDiskSpaceWatcher();
+  ~GonkDiskSpaceWatcher() {};
+
+  virtual void OnFileCanReadWithoutBlocking(int aFd);
+
+  // We should never write to the fanotify fd.
+  virtual void OnFileCanWriteWithoutBlocking(int aFd)
+  {
+    MOZ_CRASH("Must not write to fanotify fd");
+  }
+
+  void DoStart();
+  void DoStop();
+
+private:
+  void NotifyUpdate();
+
+  uint64_t mLowThreshold;
+  uint64_t mHighThreshold;
+  TimeDuration mTimeout;
+  TimeStamp  mLastTimestamp;
+  uint64_t mLastFreeSpace;
+  uint32_t mSizeDelta;
+
+  bool mIsDiskFull;
+  uint64_t mFreeSpace;
+
+  int mFd;
+  MessageLoopForIO::FileDescriptorWatcher mReadWatcher;
+};
+
+static GonkDiskSpaceWatcher* gHalDiskSpaceWatcher = nullptr;
+
+#define WATCHER_PREF_LOW        "disk_space_watcher.low_threshold"
+#define WATCHER_PREF_HIGH       "disk_space_watcher.high_threshold"
+#define WATCHER_PREF_TIMEOUT    "disk_space_watcher.timeout"
+#define WATCHER_PREF_SIZE_DELTA "disk_space_watcher.size_delta"
+
+static const char kWatchedPath[] = "/data";
+
+// Helper class to dispatch calls to xpcom on the main thread.
+class DiskSpaceNotifier : public Runnable
+{
+public:
+  DiskSpaceNotifier(const bool aIsDiskFull, const uint64_t aFreeSpace) :
+    mIsDiskFull(aIsDiskFull),
+    mFreeSpace(aFreeSpace) {}
+
+  NS_IMETHOD Run() override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    DiskSpaceWatcher::UpdateState(mIsDiskFull, mFreeSpace);
+    return NS_OK;
+  }
+
+private:
+  bool mIsDiskFull;
+  uint64_t mFreeSpace;
+};
+
+// Helper runnable to delete the watcher on the main thread.
+class DiskSpaceCleaner : public Runnable
+{
+public:
+  NS_IMETHOD Run() override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    if (gHalDiskSpaceWatcher) {
+      delete gHalDiskSpaceWatcher;
+      gHalDiskSpaceWatcher = nullptr;
+    }
+    return NS_OK;
+  }
+};
+
+GonkDiskSpaceWatcher::GonkDiskSpaceWatcher() :
+  mLastFreeSpace(UINT64_MAX),
+  mIsDiskFull(false),
+  mFreeSpace(UINT64_MAX),
+  mFd(-1)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(gHalDiskSpaceWatcher == nullptr);
+
+  // Default values: 5MB for low threshold, 10MB for high threshold, and
+  // a timeout of 5 seconds.
+  mLowThreshold = Preferences::GetInt(WATCHER_PREF_LOW, 5) * 1024 * 1024;
+  mHighThreshold = Preferences::GetInt(WATCHER_PREF_HIGH, 10) * 1024 * 1024;
+  mTimeout = TimeDuration::FromSeconds(Preferences::GetInt(WATCHER_PREF_TIMEOUT, 5));
+  mSizeDelta = Preferences::GetInt(WATCHER_PREF_SIZE_DELTA, 1) * 1024 * 1024;
+}
+
+void
+GonkDiskSpaceWatcher::DoStart()
+{
+  NS_ASSERTION(XRE_GetIOMessageLoop() == MessageLoopForIO::current(),
+               "Not on the correct message loop");
+
+  mFd = fanotify_init(FAN_CLASS_NOTIF, FAN_CLOEXEC | O_LARGEFILE);
+  if (mFd == -1) {
+    if (errno == ENOSYS) {
+      // Don't change these printf_stderr since we need these logs even
+      // in opt builds.
+      printf_stderr("Warning: No fanotify support in this device's kernel.\n");
+#if ANDROID_VERSION >= 19
+      MOZ_CRASH("Fanotify support must be enabled in the kernel.");
+#endif
+    } else {
+      printf_stderr("Error calling fanotify_init()");
+    }
+    return;
+  }
+
+  if (fanotify_mark(mFd, FAN_MARK_ADD | FAN_MARK_MOUNT, FAN_CLOSE,
+                    0, kWatchedPath) < 0) {
+    NS_WARNING("Error calling fanotify_mark");
+    close(mFd);
+    mFd = -1;
+    return;
+  }
+
+  if (!MessageLoopForIO::current()->WatchFileDescriptor(
+    mFd, /* persistent = */ true,
+    MessageLoopForIO::WATCH_READ,
+    &mReadWatcher, gHalDiskSpaceWatcher)) {
+      NS_WARNING("Unable to watch fanotify fd.");
+      close(mFd);
+      mFd = -1;
+  }
+}
+
+void
+GonkDiskSpaceWatcher::DoStop()
+{
+  NS_ASSERTION(XRE_GetIOMessageLoop() == MessageLoopForIO::current(),
+               "Not on the correct message loop");
+
+  if (mFd != -1) {
+    mReadWatcher.StopWatchingFileDescriptor();
+    fanotify_mark(mFd, FAN_MARK_FLUSH, 0, 0, kWatchedPath);
+    close(mFd);
+    mFd = -1;
+  }
+
+  // Dispatch the cleanup to the main thread.
+  nsCOMPtr<nsIRunnable> runnable = new DiskSpaceCleaner();
+  NS_DispatchToMainThread(runnable);
+}
+
+// We are called off the main thread, so we proxy first to the main thread
+// before calling the xpcom object.
+void
+GonkDiskSpaceWatcher::NotifyUpdate()
+{
+  mLastTimestamp = TimeStamp::Now();
+  mLastFreeSpace = mFreeSpace;
+
+  nsCOMPtr<nsIRunnable> runnable =
+    new DiskSpaceNotifier(mIsDiskFull, mFreeSpace);
+  NS_DispatchToMainThread(runnable);
+}
+
+void
+GonkDiskSpaceWatcher::OnFileCanReadWithoutBlocking(int aFd)
+{
+  struct fanotify_event_metadata* fem = nullptr;
+  char buf[4096];
+  struct statfs sfs;
+  int32_t len, rc;
+
+  do {
+    len = read(aFd, buf, sizeof(buf));
+  } while(len == -1 && errno == EINTR);
+
+  // Bail out if the file is busy.
+  if (len < 0 && errno == ETXTBSY) {
+    return;
+  }
+
+  // We should get an exact multiple of fanotify_event_metadata
+  if (len <= 0 || (len % FAN_EVENT_METADATA_LEN != 0)) {
+    MOZ_CRASH("About to crash: fanotify_event_metadata read error.");
+  }
+
+  fem = reinterpret_cast<fanotify_event_metadata *>(buf);
+
+  while (FAN_EVENT_OK(fem, len)) {
+    rc = fstatfs(fem->fd, &sfs);
+    if (rc < 0) {
+      NS_WARNING("Unable to stat fan_notify fd");
+    } else {
+      bool firstRun = mFreeSpace == UINT64_MAX;
+      mFreeSpace = sfs.f_bavail * sfs.f_bsize;
+      // We change from full <-> free depending on the free space and the
+      // low and high thresholds.
+      // Once we are in 'full' mode we send updates for all size changes with
+      // a minimum of time between messages or when we cross a size change
+      // threshold.
+      if (firstRun) {
+        mIsDiskFull = mFreeSpace <= mLowThreshold;
+        // Always notify the current state at first run.
+        NotifyUpdate();
+      } else if (!mIsDiskFull && (mFreeSpace <= mLowThreshold)) {
+        mIsDiskFull = true;
+        NotifyUpdate();
+      } else if (mIsDiskFull && (mFreeSpace > mHighThreshold)) {
+        mIsDiskFull = false;
+        NotifyUpdate();
+      } else if (mIsDiskFull) {
+        if (mTimeout < TimeStamp::Now() - mLastTimestamp ||
+            mSizeDelta < llabs(mFreeSpace - mLastFreeSpace)) {
+          NotifyUpdate();
+        }
+      }
+    }
+    close(fem->fd);
+    fem = FAN_EVENT_NEXT(fem, len);
+  }
+}
+
+void
+StartDiskSpaceWatcher()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Bail out if called several times.
+  if (gHalDiskSpaceWatcher != nullptr) {
+    return;
+  }
+
+  gHalDiskSpaceWatcher = new GonkDiskSpaceWatcher();
+
+  XRE_GetIOMessageLoop()->PostTask(
+    NewNonOwningRunnableMethod(gHalDiskSpaceWatcher, &GonkDiskSpaceWatcher::DoStart));
+}
+
+void
+StopDiskSpaceWatcher()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!gHalDiskSpaceWatcher) {
+    return;
+  }
+
+  XRE_GetIOMessageLoop()->PostTask(
+    NewNonOwningRunnableMethod(gHalDiskSpaceWatcher, &GonkDiskSpaceWatcher::DoStop));
+}
+
+} // namespace hal_impl
+} // namespace mozilla