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a8765fa673
Theoretically the append should never fail as we have in-line storage of FD_SETSIZE, which should always be enough. However I'm planning on removing the non-try variants of AK::Vector when compiling in kernel mode in the future, so this will need to go eventually. I suppose it also protects against some unforeseen bug where we we can append more than FD_SETSIZE items.
242 lines
8.0 KiB
C++
242 lines
8.0 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 <AK/ScopeGuard.h>
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#include <AK/Time.h>
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#include <Kernel/Debug.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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using BlockFlags = Thread::FileBlocker::BlockFlags;
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KResultOr<int> Process::sys$select(Userspace<const Syscall::SC_select_params*> user_params)
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{
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REQUIRE_PROMISE(stdio);
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Syscall::SC_select_params params {};
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if (!copy_from_user(¶ms, user_params))
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return EFAULT;
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if (params.nfds < 0)
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return EINVAL;
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Thread::BlockTimeout timeout;
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if (params.timeout) {
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Optional<Time> timeout_time = copy_time_from_user(params.timeout);
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if (!timeout_time.has_value())
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return EFAULT;
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timeout = Thread::BlockTimeout(false, &timeout_time.value());
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}
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auto current_thread = Thread::current();
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u32 previous_signal_mask = 0;
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if (params.sigmask) {
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sigset_t sigmask_copy;
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if (!copy_from_user(&sigmask_copy, params.sigmask))
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return EFAULT;
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previous_signal_mask = current_thread->update_signal_mask(sigmask_copy);
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}
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ScopeGuard rollback_signal_mask([&]() {
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if (params.sigmask)
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current_thread->update_signal_mask(previous_signal_mask);
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});
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fd_set fds_read, fds_write, fds_except;
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size_t bytes_used = ceil_div(params.nfds, 8);
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if (bytes_used > sizeof(fds_read))
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return EINVAL;
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if (params.readfds && !copy_from_user(&fds_read, params.readfds, bytes_used))
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return EFAULT;
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if (params.writefds && !copy_from_user(&fds_write, params.writefds, bytes_used))
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return EFAULT;
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if (params.exceptfds && !copy_from_user(&fds_except, params.exceptfds, bytes_used))
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return EFAULT;
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Thread::SelectBlocker::FDVector fds_info;
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Vector<int, FD_SETSIZE> fds;
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for (int fd = 0; fd < params.nfds; fd++) {
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auto block_flags = BlockFlags::None;
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if (params.readfds && FD_ISSET(fd, &fds_read))
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block_flags |= BlockFlags::Read;
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if (params.writefds && FD_ISSET(fd, &fds_write))
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block_flags |= BlockFlags::Write;
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if (params.exceptfds && FD_ISSET(fd, &fds_except))
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block_flags |= BlockFlags::Exception;
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if (block_flags == BlockFlags::None)
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continue;
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auto description = file_description(fd);
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if (!description) {
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dbgln("sys$select: Bad fd number {}", fd);
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return EBADF;
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}
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if (!fds_info.try_append({ description.release_nonnull(), block_flags }))
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return ENOMEM;
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if (!fds.try_append(fd))
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return ENOMEM;
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}
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if constexpr (IO_DEBUG || POLL_SELECT_DEBUG)
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dbgln("selecting on {} fds, timeout={}", fds_info.size(), params.timeout);
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if (current_thread->block<Thread::SelectBlocker>(timeout, fds_info).was_interrupted()) {
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dbgln_if(POLL_SELECT_DEBUG, "select was interrupted");
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return EINTR;
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}
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if (params.readfds)
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FD_ZERO(&fds_read);
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if (params.writefds)
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FD_ZERO(&fds_write);
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if (params.exceptfds)
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FD_ZERO(&fds_except);
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int marked_fd_count = 0;
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for (size_t i = 0; i < fds_info.size(); i++) {
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auto& fd_entry = fds_info[i];
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if (fd_entry.unblocked_flags == BlockFlags::None)
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continue;
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if (params.readfds && has_flag(fd_entry.unblocked_flags, BlockFlags::Read)) {
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FD_SET(fds[i], &fds_read);
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marked_fd_count++;
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}
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if (params.writefds && has_flag(fd_entry.unblocked_flags, BlockFlags::Write)) {
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FD_SET(fds[i], &fds_write);
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marked_fd_count++;
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}
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if (params.exceptfds && has_flag(fd_entry.unblocked_flags, BlockFlags::Exception)) {
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FD_SET(fds[i], &fds_except);
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marked_fd_count++;
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}
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}
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if (params.readfds && !copy_to_user(params.readfds, &fds_read, bytes_used))
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return EFAULT;
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if (params.writefds && !copy_to_user(params.writefds, &fds_write, bytes_used))
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return EFAULT;
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if (params.exceptfds && !copy_to_user(params.exceptfds, &fds_except, bytes_used))
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return EFAULT;
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return marked_fd_count;
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}
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KResultOr<int> Process::sys$poll(Userspace<const Syscall::SC_poll_params*> user_params)
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{
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REQUIRE_PROMISE(stdio);
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Syscall::SC_poll_params params;
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if (!copy_from_user(¶ms, user_params))
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return EFAULT;
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if (params.nfds >= m_max_open_file_descriptors)
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return ENOBUFS;
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Thread::BlockTimeout timeout;
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if (params.timeout) {
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auto timeout_time = copy_time_from_user(params.timeout);
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if (!timeout_time.has_value())
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return EFAULT;
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timeout = Thread::BlockTimeout(false, &timeout_time.value());
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}
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sigset_t sigmask = {};
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if (params.sigmask && !copy_from_user(&sigmask, params.sigmask))
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return EFAULT;
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Vector<pollfd> fds_copy;
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if (params.nfds > 0) {
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Checked nfds_checked = sizeof(pollfd);
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nfds_checked *= params.nfds;
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if (nfds_checked.has_overflow())
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return EFAULT;
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if (!fds_copy.try_resize(params.nfds))
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return ENOMEM;
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if (!copy_from_user(fds_copy.data(), ¶ms.fds[0], nfds_checked.value()))
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return EFAULT;
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}
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Thread::SelectBlocker::FDVector fds_info;
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for (size_t i = 0; i < params.nfds; i++) {
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auto& pfd = fds_copy[i];
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auto description = file_description(pfd.fd);
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if (!description) {
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dbgln("sys$poll: Bad fd number {}", pfd.fd);
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return EBADF;
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}
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BlockFlags block_flags = BlockFlags::Exception; // always want POLLERR, POLLHUP, POLLNVAL
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if (pfd.events & POLLIN)
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block_flags |= BlockFlags::Read;
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if (pfd.events & POLLOUT)
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block_flags |= BlockFlags::Write;
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if (pfd.events & POLLPRI)
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block_flags |= BlockFlags::ReadPriority;
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if (!fds_info.try_append({ description.release_nonnull(), block_flags }))
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return ENOMEM;
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}
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auto current_thread = Thread::current();
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u32 previous_signal_mask = 0;
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if (params.sigmask)
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previous_signal_mask = current_thread->update_signal_mask(sigmask);
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ScopeGuard rollback_signal_mask([&]() {
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if (params.sigmask)
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current_thread->update_signal_mask(previous_signal_mask);
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});
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if constexpr (IO_DEBUG || POLL_SELECT_DEBUG)
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dbgln("polling on {} fds, timeout={}", fds_info.size(), params.timeout);
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if (current_thread->block<Thread::SelectBlocker>(timeout, fds_info).was_interrupted())
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return EINTR;
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int fds_with_revents = 0;
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for (unsigned i = 0; i < params.nfds; ++i) {
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auto& pfd = fds_copy[i];
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auto& fds_entry = fds_info[i];
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pfd.revents = 0;
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if (fds_entry.unblocked_flags == BlockFlags::None)
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continue;
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::Exception)) {
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::ReadHangUp))
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pfd.revents |= POLLRDHUP;
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteError))
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pfd.revents |= POLLERR;
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteHangUp))
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pfd.revents |= POLLNVAL;
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} else {
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::Read)) {
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VERIFY(pfd.events & POLLIN);
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pfd.revents |= POLLIN;
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}
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::ReadPriority)) {
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VERIFY(pfd.events & POLLPRI);
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pfd.revents |= POLLPRI;
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}
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if (has_flag(fds_entry.unblocked_flags, BlockFlags::Write)) {
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VERIFY(pfd.events & POLLOUT);
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pfd.revents |= POLLOUT;
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}
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}
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if (pfd.revents)
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fds_with_revents++;
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}
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if (params.nfds > 0 && !copy_to_user(¶ms.fds[0], fds_copy.data(), params.nfds * sizeof(pollfd)))
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return EFAULT;
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return fds_with_revents;
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}
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}
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