/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "libdm/loop_control.h"
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#include <fcntl.h>
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#include <linux/loop.h>
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#include <stdint.h>
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#include <sys/ioctl.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include <android-base/unique_fd.h>
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namespace android {
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namespace dm {
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LoopControl::LoopControl() : control_fd_(-1) {
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control_fd_.reset(TEMP_FAILURE_RETRY(open(kLoopControlDevice, O_RDWR | O_CLOEXEC)));
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if (control_fd_ < 0) {
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PLOG(ERROR) << "Failed to open loop-control";
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}
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}
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bool LoopControl::Attach(int file_fd, std::string* loopdev) const {
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if (!FindFreeLoopDevice(loopdev)) {
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LOG(ERROR) << "Failed to attach, no free loop devices";
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return false;
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}
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android::base::unique_fd loop_fd(TEMP_FAILURE_RETRY(open(loopdev->c_str(), O_RDWR | O_CLOEXEC)));
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if (loop_fd < 0) {
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PLOG(ERROR) << "Failed to open: " << *loopdev;
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return false;
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}
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int rc = ioctl(loop_fd, LOOP_SET_FD, file_fd);
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if (rc < 0) {
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PLOG(ERROR) << "Failed LOOP_SET_FD";
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return false;
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}
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return true;
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}
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bool LoopControl::Detach(const std::string& loopdev) const {
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if (loopdev.empty()) {
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LOG(ERROR) << "Must provide a loop device";
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return false;
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}
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android::base::unique_fd loop_fd(TEMP_FAILURE_RETRY(open(loopdev.c_str(), O_RDWR | O_CLOEXEC)));
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if (loop_fd < 0) {
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PLOG(ERROR) << "Failed to open: " << loopdev;
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return false;
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}
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int rc = ioctl(loop_fd, LOOP_CLR_FD, 0);
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if (rc) {
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PLOG(ERROR) << "Failed LOOP_CLR_FD for '" << loopdev << "'";
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return false;
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}
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return true;
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}
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bool LoopControl::FindFreeLoopDevice(std::string* loopdev) const {
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int rc = ioctl(control_fd_, LOOP_CTL_GET_FREE);
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if (rc < 0) {
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PLOG(ERROR) << "Failed to get free loop device";
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return false;
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}
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// Ueventd on android creates all loop devices as /dev/block/loopX
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// The total number of available devices is determined by 'loop.max_part'
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// kernel command line argument.
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*loopdev = ::android::base::StringPrintf("/dev/block/loop%d", rc);
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return true;
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}
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LoopDevice::LoopDevice(int fd, bool auto_close) : fd_(fd), owns_fd_(auto_close) {
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Init();
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}
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LoopDevice::LoopDevice(const std::string& path) : fd_(-1), owns_fd_(true) {
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fd_.reset(open(path.c_str(), O_RDWR | O_CLOEXEC));
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if (fd_ < -1) {
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PLOG(ERROR) << "open failed for " << path;
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return;
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}
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Init();
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}
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LoopDevice::~LoopDevice() {
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if (valid()) {
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control_.Detach(device_);
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}
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if (!owns_fd_) {
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(void)fd_.release();
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}
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}
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void LoopDevice::Init() {
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control_.Attach(fd_, &device_);
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}
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} // namespace dm
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} // namespace android
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