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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.
55 lines
1.5 KiB
C++
55 lines
1.5 KiB
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/Debug.h>
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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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ErrorOr<FlatPtr> Process::sys$fcntl(int fd, int cmd, u32 arg)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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TRY(require_promise(Pledge::stdio));
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dbgln_if(IO_DEBUG, "sys$fcntl: fd={}, cmd={}, arg={}", fd, cmd, arg);
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auto description = TRY(fds().open_file_description(fd));
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// NOTE: The FD flags are not shared between OpenFileDescription objects.
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// This means that dup() doesn't copy the FD_CLOEXEC flag!
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switch (cmd) {
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case F_DUPFD: {
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int arg_fd = (int)arg;
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if (arg_fd < 0)
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return EINVAL;
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auto fd_allocation = TRY(m_fds.allocate(arg_fd));
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m_fds[fd_allocation.fd].set(*description);
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return fd_allocation.fd;
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}
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case F_GETFD:
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return m_fds[fd].flags();
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case F_SETFD:
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m_fds[fd].set_flags(arg);
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break;
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case F_GETFL:
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return description->file_flags();
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case F_SETFL:
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description->set_file_flags(arg);
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break;
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case F_ISTTY:
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return description->is_tty();
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case F_GETLK:
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TRY(description->get_flock(Userspace<flock*>(arg)));
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return 0;
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case F_SETLK:
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TRY(description->apply_flock(Process::current(), Userspace<const flock*>(arg)));
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return 0;
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default:
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return EINVAL;
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}
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return 0;
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}
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}
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