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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.
*/
#include "libdm/loop_control.h"
#include <fcntl.h>
#include <linux/loop.h>
#include <stdint.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <unistd.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
namespace android {
namespace dm {
LoopControl::LoopControl() : control_fd_(-1) {
control_fd_.reset(TEMP_FAILURE_RETRY(open(kLoopControlDevice, O_RDWR | O_CLOEXEC)));
if (control_fd_ < 0) {
PLOG(ERROR) << "Failed to open loop-control";
}
}
bool LoopControl::Attach(int file_fd, std::string* loopdev) const {
if (!FindFreeLoopDevice(loopdev)) {
LOG(ERROR) << "Failed to attach, no free loop devices";
return false;
}
android::base::unique_fd loop_fd(TEMP_FAILURE_RETRY(open(loopdev->c_str(), O_RDWR | O_CLOEXEC)));
if (loop_fd < 0) {
PLOG(ERROR) << "Failed to open: " << *loopdev;
return false;
}
int rc = ioctl(loop_fd, LOOP_SET_FD, file_fd);
if (rc < 0) {
PLOG(ERROR) << "Failed LOOP_SET_FD";
return false;
}
return true;
}
bool LoopControl::Detach(const std::string& loopdev) const {
if (loopdev.empty()) {
LOG(ERROR) << "Must provide a loop device";
return false;
}
android::base::unique_fd loop_fd(TEMP_FAILURE_RETRY(open(loopdev.c_str(), O_RDWR | O_CLOEXEC)));
if (loop_fd < 0) {
PLOG(ERROR) << "Failed to open: " << loopdev;
return false;
}
int rc = ioctl(loop_fd, LOOP_CLR_FD, 0);
if (rc) {
PLOG(ERROR) << "Failed LOOP_CLR_FD for '" << loopdev << "'";
return false;
}
return true;
}
bool LoopControl::FindFreeLoopDevice(std::string* loopdev) const {
int rc = ioctl(control_fd_, LOOP_CTL_GET_FREE);
if (rc < 0) {
PLOG(ERROR) << "Failed to get free loop device";
return false;
}
// Ueventd on android creates all loop devices as /dev/block/loopX
// The total number of available devices is determined by 'loop.max_part'
// kernel command line argument.
*loopdev = ::android::base::StringPrintf("/dev/block/loop%d", rc);
return true;
}
LoopDevice::LoopDevice(int fd, bool auto_close) : fd_(fd), owns_fd_(auto_close) {
Init();
}
LoopDevice::LoopDevice(const std::string& path) : fd_(-1), owns_fd_(true) {
fd_.reset(open(path.c_str(), O_RDWR | O_CLOEXEC));
if (fd_ < -1) {
PLOG(ERROR) << "open failed for " << path;
return;
}
Init();
}
LoopDevice::~LoopDevice() {
if (valid()) {
control_.Detach(device_);
}
if (!owns_fd_) {
(void)fd_.release();
}
}
void LoopDevice::Init() {
control_.Attach(fd_, &device_);
}
} // namespace dm
} // namespace android
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