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01b79910b3
The compiler can re-order the structure (class) members if that's necessary, so if we make Process to inherit from ProcFSExposedComponent, even if the declaration is to inherit first from ProcessBase, then from ProcFSExposedComponent and last from Weakable<Process>, the members of class ProcFSExposedComponent (including the Ref-counted parts) are the first members of the Process class. This problem made it impossible to safely use the current toggling method with the write-protection bit on the ProcessBase members, so instead of inheriting from it, we make its members the last ones in the Process class so we can safely locate and modify the corresponding page write protection bit of these values. We make sure that the Process class doesn't expand beyond 8192 bytes and the protected values are always aligned on a page boundary.
22 lines
454 B
C++
22 lines
454 B
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Process.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$umask(mode_t mask)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(stdio);
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auto old_mask = m_protected_values.umask;
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ProtectedDataMutationScope scope { *this };
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m_protected_values.umask = mask & 0777;
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return old_mask;
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}
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}
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