michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim:set ts=2 sw=2 sts=2 et cindent: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include <android/log.h>
michael@0: #include <cutils/android_reboot.h>
michael@0: #include <errno.h>
michael@0: #include <stdlib.h>
michael@0: #include <sys/mount.h>
michael@0: #include <sys/reboot.h>
michael@0: #include <sys/types.h>
michael@0: #include <unistd.h>
michael@0: 
michael@0: #include "automounter_gonk.h"
michael@0: #include "updatedefines.h"
michael@0: #include "updatelogging.h"
michael@0: 
michael@0: #define LOG_TAG "GonkAutoMounter"
michael@0: 
michael@0: #define GONK_LOG(level, format, ...) \
michael@0:   LOG((LOG_TAG ": " format "\n", ##__VA_ARGS__)); \
michael@0:   __android_log_print(level, LOG_TAG, format, ##__VA_ARGS__)
michael@0: 
michael@0: #define LOGI(format, ...) GONK_LOG(ANDROID_LOG_INFO, format, ##__VA_ARGS__)
michael@0: #define LOGE(format, ...) GONK_LOG(ANDROID_LOG_ERROR, format, ##__VA_ARGS__)
michael@0: 
michael@0: const char *kGonkMountsPath = "/proc/mounts";
michael@0: const char *kGonkSystemPath = "/system";
michael@0: 
michael@0: GonkAutoMounter::GonkAutoMounter() : mDevice(nullptr), mAccess(Unknown)
michael@0: {
michael@0:   if (!RemountSystem(ReadWrite)) {
michael@0:     LOGE("Could not remount %s as read-write.", kGonkSystemPath);
michael@0:   }
michael@0: }
michael@0: 
michael@0: GonkAutoMounter::~GonkAutoMounter()
michael@0: {
michael@0:   bool result = RemountSystem(ReadOnly);
michael@0:   free(mDevice);
michael@0: 
michael@0:   if (!result) {
michael@0:     // Don't take any chances when remounting as read-only fails, just reboot.
michael@0:     Reboot();
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: GonkAutoMounter::Reboot()
michael@0: {
michael@0:   // The android_reboot wrapper provides more safety, doing fancier read-only
michael@0:   // remounting and attempting to sync() the filesystem first. If this fails
michael@0:   // our only hope is to force a reboot directly without these protections.
michael@0:   // For more, see system/core/libcutils/android_reboot.c
michael@0:   LOGE("Could not remount %s as read-only, forcing a system reboot.",
michael@0:        kGonkSystemPath);
michael@0:   LogFlush();
michael@0: 
michael@0:   if (android_reboot(ANDROID_RB_RESTART, 0, nullptr) != 0) {
michael@0:     LOGE("Safe system reboot failed, attempting to force");
michael@0:     LogFlush();
michael@0: 
michael@0:     if (reboot(RB_AUTOBOOT) != 0) {
michael@0:       LOGE("CRITICAL: Failed to force restart");
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: static const char *
michael@0: MountAccessToString(MountAccess access)
michael@0: {
michael@0:   switch (access) {
michael@0:     case ReadOnly: return "read-only";
michael@0:     case ReadWrite: return "read-write";
michael@0:     default: return "unknown";
michael@0:   }
michael@0: }
michael@0: 
michael@0: bool
michael@0: GonkAutoMounter::RemountSystem(MountAccess access)
michael@0: {
michael@0:   if (!UpdateMountStatus()) {
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   if (mAccess == access) {
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   unsigned long flags = MS_REMOUNT;
michael@0:   if (access == ReadOnly) {
michael@0:     flags |= MS_RDONLY;
michael@0:     // Give the system a chance to flush file buffers
michael@0:     sync();
michael@0:   }
michael@0: 
michael@0:   if (!MountSystem(flags)) {
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   // Check status again to verify /system has been properly remounted
michael@0:   if (!UpdateMountStatus()) {
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   if (mAccess != access) {
michael@0:     LOGE("Updated mount status %s should be %s",
michael@0:          MountAccessToString(mAccess),
michael@0:          MountAccessToString(access));
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool
michael@0: GonkAutoMounter::UpdateMountStatus()
michael@0: {
michael@0:   FILE *mountsFile = NS_tfopen(kGonkMountsPath, "r");
michael@0: 
michael@0:   if (mountsFile == nullptr) {
michael@0:     LOGE("Error opening %s: %s", kGonkMountsPath, strerror(errno));
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   // /proc/mounts returns a 0 size from fstat, so we use the same
michael@0:   // pre-allocated buffer size that ADB does here
michael@0:   const int mountsMaxSize = 4096;
michael@0:   char mountData[mountsMaxSize];
michael@0:   size_t read = fread(mountData, 1, mountsMaxSize - 1, mountsFile);
michael@0:   mountData[read + 1] = '\0';
michael@0: 
michael@0:   if (ferror(mountsFile)) {
michael@0:     LOGE("Error reading %s, %s", kGonkMountsPath, strerror(errno));
michael@0:     fclose(mountsFile);
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   char *token, *tokenContext;
michael@0:   bool foundSystem = false;
michael@0: 
michael@0:   for (token = strtok_r(mountData, "\n", &tokenContext);
michael@0:        token;
michael@0:        token = strtok_r(nullptr, "\n", &tokenContext))
michael@0:   {
michael@0:     if (ProcessMount(token)) {
michael@0:       foundSystem = true;
michael@0:       break;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   fclose(mountsFile);
michael@0: 
michael@0:   if (!foundSystem) {
michael@0:     LOGE("Couldn't find %s mount in %s", kGonkSystemPath, kGonkMountsPath);
michael@0:   }
michael@0:   return foundSystem;
michael@0: }
michael@0: 
michael@0: bool
michael@0: GonkAutoMounter::ProcessMount(const char *mount)
michael@0: {
michael@0:   const int strSize = 256;
michael@0:   char mountDev[strSize];
michael@0:   char mountDir[strSize];
michael@0:   char mountAccess[strSize];
michael@0: 
michael@0:   int rv = sscanf(mount, "%255s %255s %*s %255s %*d %*d\n",
michael@0:                   mountDev, mountDir, mountAccess);
michael@0:   mountDev[strSize - 1] = '\0';
michael@0:   mountDir[strSize - 1] = '\0';
michael@0:   mountAccess[strSize - 1] = '\0';
michael@0: 
michael@0:   if (rv != 3) {
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   if (strcmp(kGonkSystemPath, mountDir) != 0) {
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   free(mDevice);
michael@0:   mDevice = strdup(mountDev);
michael@0:   mAccess = Unknown;
michael@0: 
michael@0:   char *option, *optionContext;
michael@0:   for (option = strtok_r(mountAccess, ",", &optionContext);
michael@0:        option;
michael@0:        option = strtok_r(nullptr, ",", &optionContext))
michael@0:   {
michael@0:     if (strcmp("ro", option) == 0) {
michael@0:       mAccess = ReadOnly;
michael@0:       break;
michael@0:     } else if (strcmp("rw", option) == 0) {
michael@0:       mAccess = ReadWrite;
michael@0:       break;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool
michael@0: GonkAutoMounter::MountSystem(unsigned long flags)
michael@0: {
michael@0:   if (!mDevice) {
michael@0:     LOGE("No device was found for %s", kGonkSystemPath);
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   const char *readOnly = flags & MS_RDONLY ? "read-only" : "read-write";
michael@0:   int result = mount(mDevice, kGonkSystemPath, "none", flags, nullptr);
michael@0: 
michael@0:   if (result != 0) {
michael@0:     LOGE("Error mounting %s as %s: %s", kGonkSystemPath, readOnly,
michael@0:          strerror(errno));
michael@0:     return false;
michael@0:   }
michael@0: 
michael@0:   LOGI("Mounted %s partition as %s", kGonkSystemPath, readOnly);
michael@0:   return true;
michael@0: }