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https://github.com/SerenityOS/serenity
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5dcf03ad9a
This device is a block device that allows a user to effectively treat an Inode as a block device. The static construction method is given an OpenFileDescription reference but validates that: - The description has a valid custody (so it's not some arbitrary file). Failing this requirement will yield EINVAL. - The description custody points to an Inode which is a regular file, as we only support (seekable) regular files. Failing this requirement will yield ENOTSUP. LoopDevice can be used to mount a regular file on the filesystem like other supported types of (physical) block devices.
87 lines
2.8 KiB
C++
87 lines
2.8 KiB
C++
/*
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* Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/Ioctl.h>
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#include <Kernel/Devices/DeviceManagement.h>
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#include <Kernel/Devices/Generic/DeviceControlDevice.h>
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#include <Kernel/Devices/Loop/LoopDevice.h>
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#include <Kernel/Library/StdLib.h>
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namespace Kernel {
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UNMAP_AFTER_INIT NonnullLockRefPtr<DeviceControlDevice> DeviceControlDevice::must_create()
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{
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auto device_control_device_or_error = DeviceManagement::try_create_device<DeviceControlDevice>();
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// FIXME: Find a way to propagate errors
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VERIFY(!device_control_device_or_error.is_error());
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return device_control_device_or_error.release_value();
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}
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bool DeviceControlDevice::can_read(OpenFileDescription const&, u64) const
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{
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return DeviceManagement::the().event_queue({}).with([](auto& queue) -> bool {
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return !queue.is_empty();
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});
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}
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UNMAP_AFTER_INIT DeviceControlDevice::DeviceControlDevice()
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: CharacterDevice(2, 10)
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{
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}
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UNMAP_AFTER_INIT DeviceControlDevice::~DeviceControlDevice() = default;
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ErrorOr<size_t> DeviceControlDevice::read(OpenFileDescription&, u64 offset, UserOrKernelBuffer& buffer, size_t size)
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{
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if (offset != 0)
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return Error::from_errno(EINVAL);
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if ((size % sizeof(DeviceEvent)) != 0)
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return Error::from_errno(EOVERFLOW);
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return DeviceManagement::the().event_queue({}).with([&](auto& queue) -> ErrorOr<size_t> {
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size_t nread = 0;
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for (size_t event_index = 0; event_index < (size / sizeof(DeviceEvent)); event_index++) {
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if (queue.is_empty())
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break;
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auto event = queue.dequeue();
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TRY(buffer.write(&event, nread, sizeof(DeviceEvent)));
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nread += sizeof(DeviceEvent);
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}
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return nread;
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});
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}
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ErrorOr<void> DeviceControlDevice::ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg)
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{
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switch (request) {
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case DEVCTL_CREATE_LOOP_DEVICE: {
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unsigned fd { 0 };
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TRY(copy_from_user(&fd, static_ptr_cast<unsigned*>(arg)));
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auto file_description = TRY(Process::current().open_file_description(fd));
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auto device = TRY(LoopDevice::create_with_file_description(file_description));
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unsigned index = device->index();
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return copy_to_user(static_ptr_cast<unsigned*>(arg), &index);
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}
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case DEVCTL_DESTROY_LOOP_DEVICE: {
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unsigned index { 0 };
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TRY(copy_from_user(&index, static_ptr_cast<unsigned*>(arg)));
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return LoopDevice::all_instances().with([index](auto& list) -> ErrorOr<void> {
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for (auto& device : list) {
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if (device.index() == index) {
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device.remove({});
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return {};
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}
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}
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return Error::from_errno(ENODEV);
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});
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}
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default:
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return Error::from_errno(EINVAL);
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};
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}
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}
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