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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "EmulatedVolume.h"
     18 #include "Utils.h"
     19 
     20 #include <android-base/stringprintf.h>
     21 #include <android-base/logging.h>
     22 #include <cutils/fs.h>
     23 #include <private/android_filesystem_config.h>
     24 #include <utils/Timers.h>
     25 
     26 #include <fcntl.h>
     27 #include <stdlib.h>
     28 #include <sys/mount.h>
     29 #include <sys/stat.h>
     30 #include <sys/types.h>
     31 #include <sys/sysmacros.h>
     32 #include <sys/wait.h>
     33 
     34 using android::base::StringPrintf;
     35 
     36 namespace android {
     37 namespace vold {
     38 
     39 static const char* kFusePath = "/system/bin/sdcard";
     40 
     41 EmulatedVolume::EmulatedVolume(const std::string& rawPath) :
     42         VolumeBase(Type::kEmulated), mFusePid(0) {
     43     setId("emulated");
     44     mRawPath = rawPath;
     45     mLabel = "emulated";
     46 }
     47 
     48 EmulatedVolume::EmulatedVolume(const std::string& rawPath, dev_t device,
     49         const std::string& fsUuid) : VolumeBase(Type::kEmulated), mFusePid(0) {
     50     setId(StringPrintf("emulated:%u,%u", major(device), minor(device)));
     51     mRawPath = rawPath;
     52     mLabel = fsUuid;
     53 }
     54 
     55 EmulatedVolume::~EmulatedVolume() {
     56 }
     57 
     58 status_t EmulatedVolume::doMount() {
     59     // We could have migrated storage to an adopted private volume, so always
     60     // call primary storage "emulated" to avoid media rescans.
     61     std::string label = mLabel;
     62     if (getMountFlags() & MountFlags::kPrimary) {
     63         label = "emulated";
     64     }
     65 
     66     mFuseDefault = StringPrintf("/mnt/runtime/default/%s", label.c_str());
     67     mFuseRead = StringPrintf("/mnt/runtime/read/%s", label.c_str());
     68     mFuseWrite = StringPrintf("/mnt/runtime/write/%s", label.c_str());
     69 
     70     setInternalPath(mRawPath);
     71     setPath(StringPrintf("/storage/%s", label.c_str()));
     72 
     73     if (fs_prepare_dir(mFuseDefault.c_str(), 0700, AID_ROOT, AID_ROOT) ||
     74             fs_prepare_dir(mFuseRead.c_str(), 0700, AID_ROOT, AID_ROOT) ||
     75             fs_prepare_dir(mFuseWrite.c_str(), 0700, AID_ROOT, AID_ROOT)) {
     76         PLOG(ERROR) << getId() << " failed to create mount points";
     77         return -errno;
     78     }
     79 
     80     dev_t before = GetDevice(mFuseWrite);
     81 
     82     if (!(mFusePid = fork())) {
     83         if (execl(kFusePath, kFusePath,
     84                 "-u", "1023", // AID_MEDIA_RW
     85                 "-g", "1023", // AID_MEDIA_RW
     86                 "-m",
     87                 "-w",
     88                 "-G",
     89                 "-i",
     90                 mRawPath.c_str(),
     91                 label.c_str(),
     92                 NULL)) {
     93             PLOG(ERROR) << "Failed to exec";
     94         }
     95 
     96         LOG(ERROR) << "FUSE exiting";
     97         _exit(1);
     98     }
     99 
    100     if (mFusePid == -1) {
    101         PLOG(ERROR) << getId() << " failed to fork";
    102         return -errno;
    103     }
    104 
    105     nsecs_t start = systemTime(SYSTEM_TIME_BOOTTIME);
    106     while (before == GetDevice(mFuseWrite)) {
    107         LOG(VERBOSE) << "Waiting for FUSE to spin up...";
    108         usleep(50000); // 50ms
    109 
    110         nsecs_t now = systemTime(SYSTEM_TIME_BOOTTIME);
    111         if (nanoseconds_to_milliseconds(now - start) > 5000) {
    112             LOG(WARNING) << "Timed out while waiting for FUSE to spin up";
    113             return -ETIMEDOUT;
    114         }
    115     }
    116     /* sdcardfs will have exited already. FUSE will still be running */
    117     if (TEMP_FAILURE_RETRY(waitpid(mFusePid, nullptr, WNOHANG)) == mFusePid)
    118         mFusePid = 0;
    119 
    120     return OK;
    121 }
    122 
    123 status_t EmulatedVolume::doUnmount() {
    124     // Unmount the storage before we kill the FUSE process. If we kill
    125     // the FUSE process first, most file system operations will return
    126     // ENOTCONN until the unmount completes. This is an exotic and unusual
    127     // error code and might cause broken behaviour in applications.
    128     KillProcessesUsingPath(getPath());
    129     ForceUnmount(mFuseDefault);
    130     ForceUnmount(mFuseRead);
    131     ForceUnmount(mFuseWrite);
    132 
    133     if (mFusePid > 0) {
    134         kill(mFusePid, SIGTERM);
    135         TEMP_FAILURE_RETRY(waitpid(mFusePid, nullptr, 0));
    136         mFusePid = 0;
    137     }
    138 
    139     rmdir(mFuseDefault.c_str());
    140     rmdir(mFuseRead.c_str());
    141     rmdir(mFuseWrite.c_str());
    142 
    143     mFuseDefault.clear();
    144     mFuseRead.clear();
    145     mFuseWrite.clear();
    146 
    147     return OK;
    148 }
    149 
    150 }  // namespace vold
    151 }  // namespace android
    152