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https://github.com/RGBCube/serenity
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04221a7533
We really don't want callers of this function to accidentally change the jail, or even worse - remove the Process from an attached jail. To ensure this never happens, we can just declare this method as const so nobody can mutate it this way.
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
/*
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* Copyright (c) 2022, 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/FileSystem/SysFS/Subsystems/Kernel/GlobalInformation.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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ErrorOr<size_t> SysFSGlobalInformation::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, OpenFileDescription* description) const
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{
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dbgln_if(SYSFS_DEBUG, "SysFSGlobalInformation @ {}: read_bytes offset: {} count: {}", name(), offset, count);
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VERIFY(offset >= 0);
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VERIFY(buffer.user_or_kernel_ptr());
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if (!description)
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return Error::from_errno(EIO);
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MutexLocker locker(m_refresh_lock);
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if (!description->data()) {
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dbgln("SysFSGlobalInformation: Do not have cached data!");
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return Error::from_errno(EIO);
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}
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auto& typed_cached_data = static_cast<SysFSInodeData&>(*description->data());
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auto& data_buffer = typed_cached_data.buffer;
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if (!data_buffer || (size_t)offset >= data_buffer->size())
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return 0;
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ssize_t nread = min(static_cast<off_t>(data_buffer->size() - offset), static_cast<off_t>(count));
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TRY(buffer.write(data_buffer->data() + offset, nread));
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return nread;
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}
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SysFSGlobalInformation::SysFSGlobalInformation(SysFSDirectory const& parent_directory)
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: SysFSComponent(parent_directory)
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{
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}
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ErrorOr<void> SysFSGlobalInformation::refresh_data(OpenFileDescription& description) const
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{
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MutexLocker lock(m_refresh_lock);
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auto& cached_data = description.data();
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if (!cached_data) {
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cached_data = adopt_own_if_nonnull(new (nothrow) SysFSInodeData);
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if (!cached_data)
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return ENOMEM;
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}
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auto builder = TRY(KBufferBuilder::try_create());
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TRY(Process::current().jail().with([&](auto const& my_jail) -> ErrorOr<void> {
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if (my_jail && !is_readable_by_jailed_processes())
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return Error::from_errno(EPERM);
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return {};
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}));
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TRY(const_cast<SysFSGlobalInformation&>(*this).try_generate(builder));
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auto& typed_cached_data = static_cast<SysFSInodeData&>(*cached_data);
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typed_cached_data.buffer = builder.build();
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if (!typed_cached_data.buffer)
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return ENOMEM;
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return {};
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}
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}
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