Merge "Fully unmount existing storage in Zygote." into mnc-dev

#include <sys/mount.h>

#include <linux/fs.h>

#include <list>

#include <string>

#include <fcntl.h>

#include <grp.h>

#include <inttypes.h>

#include <mntent.h>

#include <paths.h>

#include <signal.h>

#include <stdlib.h>

  }

}

static int UnmountTree(const char* path) {

    size_t path_len = strlen(path);

    FILE* fp = setmntent("/proc/mounts", "r");

    if (fp == NULL) {

        ALOGE("Error opening /proc/mounts: %s", strerror(errno));

        return -errno;

    }

    // Some volumes can be stacked on each other, so force unmount in

    // reverse order to give us the best chance of success.

    std::list<std::string> toUnmount;

    mntent* mentry;

    while ((mentry = getmntent(fp)) != NULL) {

        if (strncmp(mentry->mnt_dir, path, path_len) == 0) {

            toUnmount.push_front(std::string(mentry->mnt_dir));

        }

    }

    endmntent(fp);

    for (auto path : toUnmount) {

        if (umount2(path.c_str(), MNT_DETACH)) {

            ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno));

        }

    }

    return 0;

}

// Create a private mount namespace and bind mount appropriate emulated

// storage for the given user.

static bool MountEmulatedStorage(uid_t uid, jint mount_mode,

    }

    // Unmount storage provided by root namespace and mount requested view

    umount2("/storage", MNT_FORCE);

    UnmountTree("/storage");

    String8 storageSource;

    if (mount_mode == MOUNT_EXTERNAL_DEFAULT) {

        return false;

    }

    // Mount user-specific symlink helpers into place

    // Mount user-specific symlink helper into place

    userid_t user_id = multiuser_get_user_id(uid);

    const String8 userSource(String8::format("/mnt/user/%d", user_id));

    if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) {