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54b9a4ec1e
Previously we would crash the process immediately when a promise violation was found during a syscall. This is error prone, as we don't unwind the stack. This means that in certain cases we can leak resources, like an OwnPtr / RefPtr tracked on the stack. Or even leak a lock acquired in a ScopeLockLocker. To remedy this situation we move the promise violation handling to the syscall handler, right before we return to user space. This allows the code to follow the normal unwind path, and grantees there is no longer any cleanup that needs to occur. The Process::require_promise() and Process::require_no_promises() functions were modified to return ErrorOr<void> so we enforce that the errors are always propagated by the caller.
28 lines
821 B
C++
28 lines
821 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/FileSystem/OpenFileDescription.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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// NOTE: The length is passed by pointer because off_t is 64bit,
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// hence it can't be passed by register on 32bit platforms.
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ErrorOr<FlatPtr> Process::sys$ftruncate(int fd, Userspace<off_t const*> userspace_length)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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TRY(require_promise(Pledge::stdio));
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auto length = TRY(copy_typed_from_user(userspace_length));
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if (length < 0)
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return EINVAL;
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auto description = TRY(fds().open_file_description(fd));
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if (!description->is_writable())
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return EBADF;
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TRY(description->truncate(static_cast<u64>(length)));
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return 0;
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}
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}
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