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https://github.com/RGBCube/serenity
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b56646e293
There's no reason for this to use a spinlock. Instead, let's allow threads to block if someone else is using the descriptor table.
56 lines
1.8 KiB
C++
56 lines
1.8 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/FileSystem/FIFO.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$pipe(int pipefd[2], int flags)
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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 open_count = fds().with_shared([](auto& fds) { return fds.open_count(); });
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if (open_count + 2 > OpenFileDescriptions::max_open())
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return EMFILE;
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// Reject flags other than O_CLOEXEC, O_NONBLOCK
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if ((flags & (O_CLOEXEC | O_NONBLOCK)) != flags)
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return EINVAL;
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u32 fd_flags = (flags & O_CLOEXEC) ? FD_CLOEXEC : 0;
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auto fifo = TRY(FIFO::try_create(uid()));
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ScopedDescriptionAllocation reader_fd_allocation;
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ScopedDescriptionAllocation writer_fd_allocation;
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TRY(m_fds.with_exclusive([&](auto& fds) -> ErrorOr<void> {
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reader_fd_allocation = TRY(fds.allocate());
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writer_fd_allocation = TRY(fds.allocate());
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return {};
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}));
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auto reader_description = TRY(fifo->open_direction(FIFO::Direction::Reader));
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auto writer_description = TRY(fifo->open_direction(FIFO::Direction::Writer));
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reader_description->set_readable(true);
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writer_description->set_writable(true);
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if (flags & O_NONBLOCK) {
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reader_description->set_blocking(false);
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writer_description->set_blocking(false);
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}
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TRY(m_fds.with_exclusive([&](auto& fds) -> ErrorOr<void> {
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fds[reader_fd_allocation.fd].set(move(reader_description), fd_flags);
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fds[writer_fd_allocation.fd].set(move(writer_description), fd_flags);
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return {};
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}));
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TRY(copy_to_user(&pipefd[0], &reader_fd_allocation.fd));
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TRY(copy_to_user(&pipefd[1], &writer_fd_allocation.fd));
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return 0;
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}
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}
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