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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;
KResultOr<FlatPtr> Process::sys$select(Userspace<const Syscall::SC_select_params*> user_params)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
REQUIRE_PROMISE(stdio);
auto params = TRY(copy_typed_from_user(user_params));
if (params.nfds < 0)
return EINVAL;
Thread::BlockTimeout timeout;
if (params.timeout) {
auto timeout_time = TRY(copy_time_from_user(params.timeout));
timeout = Thread::BlockTimeout(false, &timeout_time);
}
auto current_thread = Thread::current();
u32 previous_signal_mask = 0;
if (params.sigmask) {
sigset_t sigmask_copy;
TRY(copy_from_user(&sigmask_copy, params.sigmask));
previous_signal_mask = current_thread->update_signal_mask(sigmask_copy);
}
ScopeGuard rollback_signal_mask([&]() {
if (params.sigmask)
current_thread->update_signal_mask(previous_signal_mask);
});
fd_set fds_read, fds_write, fds_except;
size_t bytes_used = ceil_div(params.nfds, 8);
if (bytes_used > sizeof(fds_read))
return EINVAL;
if (params.readfds)
TRY(copy_from_user(&fds_read, params.readfds, bytes_used));
if (params.writefds)
TRY(copy_from_user(&fds_write, params.writefds, bytes_used));
if (params.exceptfds)
TRY(copy_from_user(&fds_except, params.exceptfds, bytes_used));
Thread::SelectBlocker::FDVector fds_info;
Vector<int, FD_SETSIZE> selected_fds;
for (int fd = 0; fd < params.nfds; fd++) {
auto block_flags = BlockFlags::None;
if (params.readfds && FD_ISSET(fd, &fds_read))
block_flags |= BlockFlags::Read;
if (params.writefds && FD_ISSET(fd, &fds_write))
block_flags |= BlockFlags::Write;
if (params.exceptfds && FD_ISSET(fd, &fds_except))
block_flags |= BlockFlags::Exception;
if (block_flags == BlockFlags::None)
continue;
auto description = TRY(fds().file_description(fd));
if (!fds_info.try_append({ move(description), block_flags }))
return ENOMEM;
if (!selected_fds.try_append(fd))
return ENOMEM;
}
if constexpr (IO_DEBUG || POLL_SELECT_DEBUG)
dbgln("selecting on {} fds, timeout={}", fds_info.size(), params.timeout);
if (current_thread->block<Thread::SelectBlocker>(timeout, fds_info).was_interrupted()) {
dbgln_if(POLL_SELECT_DEBUG, "select was interrupted");
return EINTR;
}
if (params.readfds)
FD_ZERO(&fds_read);
if (params.writefds)
FD_ZERO(&fds_write);
if (params.exceptfds)
FD_ZERO(&fds_except);
int marked_fd_count = 0;
for (size_t i = 0; i < fds_info.size(); i++) {
auto& fd_entry = fds_info[i];
if (fd_entry.unblocked_flags == BlockFlags::None)
continue;
if (params.readfds && has_flag(fd_entry.unblocked_flags, BlockFlags::Read)) {
FD_SET(selected_fds[i], &fds_read);
marked_fd_count++;
}
if (params.writefds && has_flag(fd_entry.unblocked_flags, BlockFlags::Write)) {
FD_SET(selected_fds[i], &fds_write);
marked_fd_count++;
}
if (params.exceptfds && has_any_flag(fd_entry.unblocked_flags, BlockFlags::Exception)) {
FD_SET(selected_fds[i], &fds_except);
marked_fd_count++;
}
}
if (params.readfds)
TRY(copy_to_user(params.readfds, &fds_read, bytes_used));
if (params.writefds)
TRY(copy_to_user(params.writefds, &fds_write, bytes_used));
if (params.exceptfds)
TRY(copy_to_user(params.exceptfds, &fds_except, bytes_used));
return marked_fd_count;
}
KResultOr<FlatPtr> Process::sys$poll(Userspace<const Syscall::SC_poll_params*> user_params)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
REQUIRE_PROMISE(stdio);
auto params = TRY(copy_typed_from_user(user_params));
if (params.nfds >= fds().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;
if (!fds_copy.try_resize(params.nfds))
return ENOMEM;
TRY(copy_from_user(fds_copy.data(), ¶ms.fds[0], nfds_checked.value()));
}
Thread::SelectBlocker::FDVector fds_info;
for (size_t i = 0; i < params.nfds; i++) {
auto& pfd = fds_copy[i];
auto description = TRY(fds().file_description(pfd.fd));
BlockFlags block_flags = BlockFlags::Exception; // 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 (!fds_info.try_append({ move(description), block_flags }))
return ENOMEM;
}
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_any_flag(fds_entry.unblocked_flags, BlockFlags::Exception)) {
if (has_flag(fds_entry.unblocked_flags, BlockFlags::ReadHangUp))
pfd.revents |= POLLRDHUP;
if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteError))
pfd.revents |= POLLERR;
if (has_flag(fds_entry.unblocked_flags, BlockFlags::WriteHangUp))
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::Write)) {
VERIFY(pfd.events & POLLOUT);
pfd.revents |= POLLOUT;
}
}
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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