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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ScopeGuard.h>
#include <AK/Time.h>
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/Process.h>
namespace Kernel {
using BlockFlags = Thread::FileBlocker::BlockFlags;
ErrorOr<FlatPtr> Process::sys$poll(Userspace<Syscall::SC_poll_params const*> user_params)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
TRY(require_promise(Pledge::stdio));
auto params = TRY(copy_typed_from_user(user_params));
if (params.nfds >= OpenFileDescriptions::max_open())
return ENOBUFS;
Thread::BlockTimeout timeout;
if (params.timeout) {
auto timeout_time = TRY(copy_time_from_user(params.timeout));
timeout = Thread::BlockTimeout(false, &timeout_time);
}
sigset_t sigmask = {};
if (params.sigmask)
TRY(copy_from_user(&sigmask, params.sigmask));
Vector<pollfd, FD_SETSIZE> fds_copy;
if (params.nfds > 0) {
Checked<size_t> nfds_checked = sizeof(pollfd);
nfds_checked *= params.nfds;
if (nfds_checked.has_overflow())
return EFAULT;
TRY(fds_copy.try_resize(params.nfds));
TRY(copy_from_user(fds_copy.data(), ¶ms.fds[0], nfds_checked.value()));
}
Thread::SelectBlocker::FDVector fds_info;
TRY(fds_info.try_ensure_capacity(params.nfds));
TRY(m_fds.with_shared([&](auto& fds) -> ErrorOr<void> {
for (size_t i = 0; i < params.nfds; i++) {
auto& pfd = fds_copy[i];
RefPtr<OpenFileDescription> description;
auto description_or_error = fds.open_file_description(pfd.fd);
if (!description_or_error.is_error())
description = description_or_error.release_value();
BlockFlags block_flags = BlockFlags::WriteError | BlockFlags::WriteHangUp; // always want POLLERR, POLLHUP, POLLNVAL
if (pfd.events & POLLIN)
block_flags |= BlockFlags::Read;
if (pfd.events & POLLOUT)
block_flags |= BlockFlags::Write;
if (pfd.events & POLLPRI)
block_flags |= BlockFlags::ReadPriority;
if (pfd.events & POLLWRBAND)
block_flags |= BlockFlags::WritePriority;
if (pfd.events & POLLRDHUP)
block_flags |= BlockFlags::ReadHangUp;
fds_info.unchecked_append({ move(description), block_flags });
}
return {};
}));
auto* current_thread = Thread::current();
u32 previous_signal_mask = 0;
if (params.sigmask)
previous_signal_mask = current_thread->update_signal_mask(sigmask);
ScopeGuard rollback_signal_mask([&]() {
if (params.sigmask)
current_thread->update_signal_mask(previous_signal_mask);
});
if constexpr (IO_DEBUG || POLL_SELECT_DEBUG)
dbgln("polling on {} fds, timeout={}", fds_info.size(), params.timeout);
if (current_thread->block<Thread::SelectBlocker>(timeout, fds_info).was_interrupted())
return EINTR;
int fds_with_revents = 0;
for (unsigned i = 0; i < params.nfds; ++i) {
auto& pfd = fds_copy[i];
auto& fds_entry = fds_info[i];
pfd.revents = 0;
if (fds_entry.unblocked_flags == BlockFlags::None)
continue;
if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteHangUp))
pfd.revents |= POLLHUP;
if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteError) || !fds_entry.description) {
if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteError))
pfd.revents |= POLLERR;
if (!fds_entry.description)
pfd.revents |= POLLNVAL;
} else {
if (has_flag(fds_entry.unblocked_flags, BlockFlags::Read)) {
VERIFY(pfd.events & POLLIN);
pfd.revents |= POLLIN;
}
if (has_flag(fds_entry.unblocked_flags, BlockFlags::ReadPriority)) {
VERIFY(pfd.events & POLLPRI);
pfd.revents |= POLLPRI;
}
if (!has_flag(fds_entry.unblocked_flags, BlockFlags::WriteHangUp) && has_flag(fds_entry.unblocked_flags, BlockFlags::Write)) {
VERIFY(pfd.events & POLLOUT);
pfd.revents |= POLLOUT;
}
if (has_flag(fds_entry.unblocked_flags, BlockFlags::WritePriority)) {
VERIFY(pfd.events & POLLWRBAND);
pfd.revents |= POLLWRBAND;
}
if (has_flag(fds_entry.unblocked_flags, BlockFlags::ReadHangUp)) {
VERIFY(pfd.events & POLLRDHUP);
pfd.revents |= POLLRDHUP;
}
}
if (pfd.revents)
fds_with_revents++;
}
if (params.nfds > 0)
TRY(copy_to_user(¶ms.fds[0], fds_copy.data(), params.nfds * sizeof(pollfd)));
return fds_with_revents;
}
}
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