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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "apexd"
#include "apexd_private.h"
#include <sys/mount.h>
#include <sys/stat.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
#include "string_log.h"
using android::base::ErrnoError;
using android::base::Result;
namespace android {
namespace apex {
namespace apexd_private {
Result<void> BindMount(const std::string& target, const std::string& source) {
LOG(VERBOSE) << "Creating bind-mount for " << target << " for " << source;
// Ensure the directory exists, try to unmount.
{
bool exists;
bool is_dir;
{
struct stat buf;
if (stat(target.c_str(), &buf) != 0) {
if (errno == ENOENT) {
exists = false;
is_dir = false;
} else {
PLOG(ERROR) << "Could not stat target directory " << target;
// Still attempt to bind-mount.
exists = true;
is_dir = true;
}
} else {
exists = true;
is_dir = S_ISDIR(buf.st_mode);
}
}
// Ensure that it is a folder.
if (exists && !is_dir) {
LOG(WARNING) << target << " is not a directory, attempting to fix";
if (unlink(target.c_str()) != 0) {
PLOG(ERROR) << "Failed to unlink " << target;
// Try mkdir, anyways.
}
exists = false;
}
// And create it if necessary.
if (!exists) {
LOG(VERBOSE) << "Creating mountpoint " << target;
if (mkdir(target.c_str(), kMkdirMode) != 0) {
return ErrnoError() << "Could not create mountpoint " << target;
}
};
// Unmount any active bind-mount.
if (exists) {
int rc = umount2(target.c_str(), UMOUNT_NOFOLLOW);
if (rc != 0 && errno != EINVAL) {
// Log error but ignore.
PLOG(ERROR) << "Could not unmount " << target;
}
}
}
LOG(VERBOSE) << "Bind-mounting " << source << " to " << target;
if (mount(source.c_str(), target.c_str(), nullptr, MS_BIND, nullptr) == 0) {
return {};
}
return ErrnoError() << "Could not bind-mount " << source << " to " << target;
}
} // namespace apexd_private
} // namespace apex
} // namespace android
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