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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 
     25 #include <fcntl.h>
     26 #include <stdlib.h>
     27 #include <sys/mount.h>
     28 #include <sys/stat.h>
     29 #include <sys/types.h>
     30 #include <sys/wait.h>
     31 
     32 using android::base::StringPrintf;
     33 
     34 namespace android {
     35 namespace vold {
     36 
     37 static const char* kFusePath = "/system/bin/sdcard";
     38 
     39 EmulatedVolume::EmulatedVolume(const std::string& rawPath) :
     40         VolumeBase(Type::kEmulated), mFusePid(0) {
     41     setId("emulated");
     42     mRawPath = rawPath;
     43     mLabel = "emulated";
     44 }
     45 
     46 EmulatedVolume::EmulatedVolume(const std::string& rawPath, dev_t device,
     47         const std::string& fsUuid) : VolumeBase(Type::kEmulated), mFusePid(0) {
     48     setId(StringPrintf("emulated:%u,%u", major(device), minor(device)));
     49     mRawPath = rawPath;
     50     mLabel = fsUuid;
     51 }
     52 
     53 EmulatedVolume::~EmulatedVolume() {
     54 }
     55 
     56 status_t EmulatedVolume::doMount() {
     57     // We could have migrated storage to an adopted private volume, so always
     58     // call primary storage "emulated" to avoid media rescans.
     59     std::string label = mLabel;
     60     if (getMountFlags() & MountFlags::kPrimary) {
     61         label = "emulated";
     62     }
     63 
     64     mFuseDefault = StringPrintf("/mnt/runtime/default/%s", label.c_str());
     65     mFuseRead = StringPrintf("/mnt/runtime/read/%s", label.c_str());
     66     mFuseWrite = StringPrintf("/mnt/runtime/write/%s", label.c_str());
     67 
     68     setInternalPath(mRawPath);
     69     setPath(StringPrintf("/storage/%s", label.c_str()));
     70 
     71     if (fs_prepare_dir(mFuseDefault.c_str(), 0700, AID_ROOT, AID_ROOT) ||
     72             fs_prepare_dir(mFuseRead.c_str(), 0700, AID_ROOT, AID_ROOT) ||
     73             fs_prepare_dir(mFuseWrite.c_str(), 0700, AID_ROOT, AID_ROOT)) {
     74         PLOG(ERROR) << getId() << " failed to create mount points";
     75         return -errno;
     76     }
     77 
     78     dev_t before = GetDevice(mFuseWrite);
     79 
     80     if (!(mFusePid = fork())) {
     81         if (execl(kFusePath, kFusePath,
     82                 "-u", "1023", // AID_MEDIA_RW
     83                 "-g", "1023", // AID_MEDIA_RW
     84                 "-m",
     85                 "-w",
     86                 mRawPath.c_str(),
     87                 label.c_str(),
     88                 NULL)) {
     89             PLOG(ERROR) << "Failed to exec";
     90         }
     91 
     92         LOG(ERROR) << "FUSE exiting";
     93         _exit(1);
     94     }
     95 
     96     if (mFusePid == -1) {
     97         PLOG(ERROR) << getId() << " failed to fork";
     98         return -errno;
     99     }
    100 
    101     while (before == GetDevice(mFuseWrite)) {
    102         LOG(VERBOSE) << "Waiting for FUSE to spin up...";
    103         usleep(50000); // 50ms
    104     }
    105 
    106     return OK;
    107 }
    108 
    109 status_t EmulatedVolume::doUnmount() {
    110     // Unmount the storage before we kill the FUSE process. If we kill
    111     // the FUSE process first, most file system operations will return
    112     // ENOTCONN until the unmount completes. This is an exotic and unusual
    113     // error code and might cause broken behaviour in applications.
    114     KillProcessesUsingPath(getPath());
    115     ForceUnmount(mFuseDefault);
    116     ForceUnmount(mFuseRead);
    117     ForceUnmount(mFuseWrite);
    118 
    119     if (mFusePid > 0) {
    120         kill(mFusePid, SIGTERM);
    121         TEMP_FAILURE_RETRY(waitpid(mFusePid, nullptr, 0));
    122         mFusePid = 0;
    123     }
    124 
    125     rmdir(mFuseDefault.c_str());
    126     rmdir(mFuseRead.c_str());
    127     rmdir(mFuseWrite.c_str());
    128 
    129     mFuseDefault.clear();
    130     mFuseRead.clear();
    131     mFuseWrite.clear();
    132 
    133     return OK;
    134 }
    135 
    136 }  // namespace vold
    137 }  // namespace android
    138