mirror of
https://github.com/SerenityOS/serenity.git
synced 2026-11-09 17:52:31 -10:00
Sönke Holz
688bf2d7f7
`offset` is in bytes, not blocks. Previously, if `BlockBasedFileSystem::read_block()` attempted to read at a byte offset that is equal to the block count, `nread` would be 0, so it wouldn't read any data. This led to a crash because `BlockBasedFileSystem::read_block()` asserts that the returned byte count is equal to the number of bytes it requested. The same bug also applies to the `write()` function. If `read()` or `write()` was called with an offset that is larger than the block count, the first parameter to the `min()` call would underflow to a large value, leading it to always use the second argument.
87 lines
3.4 KiB
C++
87 lines
3.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <[email protected]>
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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/MajorNumberAllocation.h>
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#include <Kernel/Debug.h>
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#include <Kernel/Devices/Device.h>
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#include <Kernel/Devices/Storage/StorageDevice.h>
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#include <Kernel/Devices/Storage/StorageDevicePartition.h>
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#include <Kernel/FileSystem/OpenFileDescription.h>
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namespace Kernel {
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ErrorOr<NonnullRefPtr<StorageDevicePartition>> StorageDevicePartition::create(StorageDevice& device, MinorNumber minor_number, Partition::DiskPartitionMetadata metadata)
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{
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return TRY(Device::try_create_device<StorageDevicePartition>(device, minor_number, metadata));
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}
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StorageDevicePartition::StorageDevicePartition(StorageDevice& device, MinorNumber minor_number, Partition::DiskPartitionMetadata metadata)
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: BlockDevice(MajorAllocation::BlockDeviceFamily::StoragePartition, minor_number, device.block_size())
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, m_device(device)
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, m_metadata(metadata)
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{
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}
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StorageDevicePartition::~StorageDevicePartition() = default;
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Partition::DiskPartitionMetadata const& StorageDevicePartition::metadata() const
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{
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return m_metadata;
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}
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void StorageDevicePartition::start_request(AsyncBlockDeviceRequest& request)
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{
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auto device = m_device.strong_ref();
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if (!device)
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request.complete(AsyncBlockDeviceRequest::RequestResult::Failure);
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auto sub_request_or_error = device->try_make_request<AsyncBlockDeviceRequest>(request.request_type(),
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request.block_index() + m_metadata.start_block(), request.block_count(), request.buffer(), request.buffer_size());
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if (sub_request_or_error.is_error())
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TODO();
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request.add_sub_request(sub_request_or_error.release_value());
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}
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ErrorOr<size_t> StorageDevicePartition::read(OpenFileDescription& fd, u64 offset, UserOrKernelBuffer& outbuf, size_t len)
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{
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auto device = m_device.strong_ref();
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if (!device)
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return Error::from_errno(EIO);
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size_t total_block_count = m_metadata.end_block() - m_metadata.start_block() + 1;
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// NOTE: The last available offset is actually just after the last addressable block.
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if (offset >= total_block_count * block_size())
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return 0;
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size_t nread = min(static_cast<size_t>(total_block_count * block_size() - offset), len);
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u64 adjust = m_metadata.start_block() * block_size();
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dbgln_if(OFFD_DEBUG, "StorageDevicePartition::read offset={}, adjust={}, len={}", fd.offset(), adjust, nread);
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return device->read(fd, offset + adjust, outbuf, nread);
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}
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ErrorOr<size_t> StorageDevicePartition::write(OpenFileDescription& fd, u64 offset, UserOrKernelBuffer const& inbuf, size_t len)
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{
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auto device = m_device.strong_ref();
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if (!device)
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return Error::from_errno(EIO);
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size_t total_block_count = m_metadata.end_block() - m_metadata.start_block() + 1;
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// NOTE: The last available offset is actually just after the last addressable block.
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if (offset >= total_block_count * block_size())
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return Error::from_errno(ENOSPC);
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size_t nwrite = min(static_cast<size_t>(total_block_count * block_size() - offset), len);
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u64 adjust = m_metadata.start_block() * block_size();
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dbgln_if(OFFD_DEBUG, "StorageDevicePartition::write offset={}, adjust={}, len={}", offset, adjust, nwrite);
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return device->write(fd, offset + adjust, inbuf, nwrite);
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}
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StringView StorageDevicePartition::class_name() const
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{
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return "StorageDevicePartition"sv;
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}
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}
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