1 files changed, 251 insertions, 0 deletions
diff --git a/onlineupdate/source/update/updater/automounter_gonk.cxx b/onlineupdate/source/update/updater/automounter_gonk.cxx
new file mode 100644
index 000000000000..3dff2a1337a1
--- /dev/null
+++ b/onlineupdate/source/update/updater/automounter_gonk.cxx
@@ -0,0 +1,251 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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 <android/log.h>
+#include <cutils/android_reboot.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/reboot.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "automounter_gonk.h"
+#include "updatedefines.h"
+#include "updatelogging.h"
+
+#define LOG_TAG "GonkAutoMounter"
+
+#define GONK_LOG(level, format, ...) \
+  LOG((LOG_TAG ": " format "\n", ##__VA_ARGS__)); \
+  __android_log_print(level, LOG_TAG, format, ##__VA_ARGS__)
+
+#define LOGI(format, ...) GONK_LOG(ANDROID_LOG_INFO, format, ##__VA_ARGS__)
+#define LOGE(format, ...) GONK_LOG(ANDROID_LOG_ERROR, format, ##__VA_ARGS__)
+
+const char *kGonkMountsPath = "/proc/mounts";
+const char *kGonkSystemPath = "/system";
+
+GonkAutoMounter::GonkAutoMounter() : mDevice(nullptr), mAccess(Unknown)
+{
+  if (!RemountSystem(ReadWrite)) {
+    LOGE("Could not remount %s as read-write.", kGonkSystemPath);
+  }
+}
+
+GonkAutoMounter::~GonkAutoMounter()
+{
+  bool result = RemountSystem(ReadOnly);
+  free(mDevice);
+
+  if (!result) {
+    // Don't take any chances when remounting as read-only fails, just reboot.
+    Reboot();
+  }
+}
+
+void
+GonkAutoMounter::Reboot()
+{
+  // The android_reboot wrapper provides more safety, doing fancier read-only
+  // remounting and attempting to sync() the filesystem first. If this fails
+  // our only hope is to force a reboot directly without these protections.
+  // For more, see system/core/libcutils/android_reboot.c
+  LOGE("Could not remount %s as read-only, forcing a system reboot.",
+       kGonkSystemPath);
+  LogFlush();
+
+  if (android_reboot(ANDROID_RB_RESTART, 0, nullptr) != 0) {
+    LOGE("Safe system reboot failed, attempting to force");
+    LogFlush();
+
+    if (reboot(RB_AUTOBOOT) != 0) {
+      LOGE("CRITICAL: Failed to force restart");
+    }
+  }
+}
+
+static const char *
+MountAccessToString(MountAccess access)
+{
+  switch (access) {
+    case ReadOnly: return "read-only";
+    case ReadWrite: return "read-write";
+    default: return "unknown";
+  }
+}
+
+bool
+GonkAutoMounter::RemountSystem(MountAccess access)
+{
+  if (!UpdateMountStatus()) {
+    return false;
+  }
+
+  if (mAccess == access) {
+    return true;
+  }
+
+  unsigned long flags = MS_REMOUNT;
+  if (access == ReadOnly) {
+    flags |= MS_RDONLY;
+    // Give the system a chance to flush file buffers
+    sync();
+  }
+
+  if (!MountSystem(flags)) {
+    return false;
+  }
+
+  // Check status again to verify /system has been properly remounted
+  if (!UpdateMountStatus()) {
+    return false;
+  }
+
+  if (mAccess != access) {
+    LOGE("Updated mount status %s should be %s",
+         MountAccessToString(mAccess),
+         MountAccessToString(access));
+    return false;
+  }
+
+  return true;
+}
+
+bool
+GonkAutoMounter::UpdateMountStatus()
+{
+  FILE *mountsFile = NS_tfopen(kGonkMountsPath, "r");
+
+  if (mountsFile == nullptr) {
+    LOGE("Error opening %s: %s", kGonkMountsPath, strerror(errno));
+    return false;
+  }
+
+  // /proc/mounts returns a 0 size from fstat, so we use the same
+  // pre-allocated buffer size that ADB does here
+  const int mountsMaxSize = 4096;
+  char mountData[mountsMaxSize];
+  size_t read = fread(mountData, 1, mountsMaxSize - 1, mountsFile);
+  mountData[read + 1] = '\0';
+
+  if (ferror(mountsFile)) {
+    LOGE("Error reading %s, %s", kGonkMountsPath, strerror(errno));
+    fclose(mountsFile);
+    return false;
+  }
+
+  char *token, *tokenContext;
+  bool foundSystem = false;
+
+  for (token = strtok_r(mountData, "\n", &tokenContext);
+       token;
+       token = strtok_r(nullptr, "\n", &tokenContext))
+  {
+    if (ProcessMount(token)) {
+      foundSystem = true;
+      break;
+    }
+  }
+
+  fclose(mountsFile);
+
+  if (!foundSystem) {
+    LOGE("Couldn't find %s mount in %s", kGonkSystemPath, kGonkMountsPath);
+  }
+  return foundSystem;
+}
+
+bool
+GonkAutoMounter::ProcessMount(const char *mount)
+{
+  const int strSize = 256;
+  char mountDev[strSize];
+  char mountDir[strSize];
+  char mountAccess[strSize];
+
+  int rv = sscanf(mount, "%255s %255s %*s %255s %*d %*d\n",
+                  mountDev, mountDir, mountAccess);
+  mountDev[strSize - 1] = '\0';
+  mountDir[strSize - 1] = '\0';
+  mountAccess[strSize - 1] = '\0';
+
+  if (rv != 3) {
+    return false;
+  }
+
+  if (strcmp(kGonkSystemPath, mountDir) != 0) {
+    return false;
+  }
+
+  free(mDevice);
+  mDevice = strdup(mountDev);
+  mAccess = Unknown;
+
+  char *option, *optionContext;
+  for (option = strtok_r(mountAccess, ",", &optionContext);
+       option;
+       option = strtok_r(nullptr, ",", &optionContext))
+  {
+    if (strcmp("ro", option) == 0) {
+      mAccess = ReadOnly;
+      break;
+    } else if (strcmp("rw", option) == 0) {
+      mAccess = ReadWrite;
+      break;
+    }
+  }
+
+  return true;
+}
+
+/*
+ * Mark the given block device as read-write or read-only, using the BLKROSET
+ * ioctl.
+ */
+static void SetBlockReadWriteStatus(const char *blockdev, bool setReadOnly) {
+  int fd;
+  int roMode = setReadOnly ? 1 : 0;
+
+  fd = open(blockdev, O_RDONLY);
+  if (fd < 0) {
+    return;
+  }
+
+  if (ioctl(fd, BLKROSET, &roMode) == -1) {
+    LOGE("Error setting read-only mode on %s to %s: %s", blockdev,
+         setReadOnly ? "true": "false", strerror(errno));
+  }
+  close(fd);
+}
+
+
+bool
+GonkAutoMounter::MountSystem(unsigned long flags)
+{
+  if (!mDevice) {
+    LOGE("No device was found for %s", kGonkSystemPath);
+    return false;
+  }
+
+  // Without setting the block device ro mode to false, we get a permission
+  // denied error while trying to remount it in read-write.
+  SetBlockReadWriteStatus(mDevice, (flags & MS_RDONLY));
+
+  const char *readOnly = flags & MS_RDONLY ? "read-only" : "read-write";
+  int result = mount(mDevice, kGonkSystemPath, "none", flags, nullptr);
+
+  if (result != 0) {
+    LOGE("Error mounting %s as %s: %s", kGonkSystemPath, readOnly,
+         strerror(errno));
+    return false;
+  }
+
+  LOGI("Mounted %s partition as %s", kGonkSystemPath, readOnly);
+  return true;
+}