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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/ScopedValueRollback.h>
#include <AK/Time.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
namespace Kernel {
int Process::sys$select(const Syscall::SC_select_params* params)
{
REQUIRE_PROMISE(stdio);
// FIXME: Return -EINVAL if timeout is invalid.
if (!validate_read_typed(params))
return -EFAULT;
SmapDisabler disabler;
int nfds = params->nfds;
fd_set* readfds = params->readfds;
fd_set* writefds = params->writefds;
fd_set* exceptfds = params->exceptfds;
const timespec* timeout = params->timeout;
const sigset_t* sigmask = params->sigmask;
if (writefds && !validate_write_typed(writefds))
return -EFAULT;
if (readfds && !validate_write_typed(readfds))
return -EFAULT;
if (exceptfds && !validate_write_typed(exceptfds))
return -EFAULT;
if (timeout && !validate_read_typed(timeout))
return -EFAULT;
if (sigmask && !validate_read_typed(sigmask))
return -EFAULT;
if (nfds < 0)
return -EINVAL;
timespec computed_timeout;
bool select_has_timeout = false;
if (timeout && (timeout->tv_sec || timeout->tv_nsec)) {
timespec ts_since_boot;
timeval_to_timespec(Scheduler::time_since_boot(), ts_since_boot);
timespec_add(ts_since_boot, *timeout, computed_timeout);
select_has_timeout = true;
}
auto current_thread = Thread::current();
ScopedValueRollback scoped_sigmask(current_thread->m_signal_mask);
if (sigmask)
current_thread->m_signal_mask = *sigmask;
Thread::SelectBlocker::FDVector rfds;
Thread::SelectBlocker::FDVector wfds;
Thread::SelectBlocker::FDVector efds;
auto transfer_fds = [&](auto* fds, auto& vector) -> int {
vector.clear_with_capacity();
if (!fds)
return 0;
for (int fd = 0; fd < nfds; ++fd) {
if (FD_ISSET(fd, fds)) {
if (!file_description(fd)) {
dbg() << "sys$select: Bad fd number " << fd;
return -EBADF;
}
vector.append(fd);
}
}
return 0;
};
if (int error = transfer_fds(writefds, wfds))
return error;
if (int error = transfer_fds(readfds, rfds))
return error;
if (int error = transfer_fds(exceptfds, efds))
return error;
#if defined(DEBUG_IO) || defined(DEBUG_POLL_SELECT)
dbg() << "selecting on (read:" << rfds.size() << ", write:" << wfds.size() << "), timeout=" << timeout;
#endif
if (!timeout || select_has_timeout) {
if (current_thread->block<Thread::SelectBlocker>(select_has_timeout ? &computed_timeout : nullptr, rfds, wfds, efds).was_interrupted())
return -EINTR;
// While we blocked, the process lock was dropped. This gave other threads
// the opportunity to mess with the memory. For example, it could free the
// region, and map it to a region to which it has no write permissions.
// Therefore, we need to re-validate all pointers.
if (writefds && !validate_write_typed(writefds))
return -EFAULT;
if (readfds && !validate_write_typed(readfds))
return -EFAULT;
// See the fixme below.
if (exceptfds && !validate_write_typed(exceptfds))
return -EFAULT;
}
int marked_fd_count = 0;
auto mark_fds = [&](auto* fds, auto& vector, auto should_mark) {
if (!fds)
return;
FD_ZERO(fds);
for (int fd : vector) {
if (auto description = file_description(fd); description && should_mark(*description)) {
FD_SET(fd, fds);
++marked_fd_count;
}
}
};
mark_fds(readfds, rfds, [](auto& description) { return description.can_read(); });
mark_fds(writefds, wfds, [](auto& description) { return description.can_write(); });
// FIXME: We should also mark exceptfds as appropriate.
return marked_fd_count;
}
int Process::sys$poll(Userspace<const Syscall::SC_poll_params*> user_params)
{
REQUIRE_PROMISE(stdio);
// FIXME: Return -EINVAL if timeout is invalid.
Syscall::SC_poll_params params;
if (!validate_read_and_copy_typed(¶ms, user_params))
return -EFAULT;
SmapDisabler disabler;
pollfd* fds = params.fds;
unsigned nfds = params.nfds;
if (fds && !validate_read_typed(fds, nfds))
return -EFAULT;
timespec timeout = {};
if (params.timeout && !validate_read_and_copy_typed(&timeout, params.timeout))
return -EFAULT;
sigset_t sigmask = {};
if (params.sigmask && !validate_read_and_copy_typed(&sigmask, params.sigmask))
return -EFAULT;
Thread::SelectBlocker::FDVector rfds;
Thread::SelectBlocker::FDVector wfds;
for (unsigned i = 0; i < nfds; ++i) {
if (fds[i].events & POLLIN)
rfds.append(fds[i].fd);
if (fds[i].events & POLLOUT)
wfds.append(fds[i].fd);
}
timespec actual_timeout;
bool has_timeout = false;
if (params.timeout && (timeout.tv_sec || timeout.tv_nsec)) {
timespec ts_since_boot;
timeval_to_timespec(Scheduler::time_since_boot(), ts_since_boot);
timespec_add(ts_since_boot, timeout, actual_timeout);
has_timeout = true;
}
auto current_thread = Thread::current();
ScopedValueRollback scoped_sigmask(current_thread->m_signal_mask);
if (params.sigmask)
current_thread->m_signal_mask = sigmask;
#if defined(DEBUG_IO) || defined(DEBUG_POLL_SELECT)
dbg() << "polling on (read:" << rfds.size() << ", write:" << wfds.size() << "), timeout=" << timeout;
#endif
if (!params.timeout || has_timeout) {
if (current_thread->block<Thread::SelectBlocker>(has_timeout ? &actual_timeout : nullptr, rfds, wfds, Thread::SelectBlocker::FDVector()).was_interrupted())
return -EINTR;
}
// Validate we can still write after waking up.
if (fds && !validate_write_typed(fds, nfds))
return -EFAULT;
int fds_with_revents = 0;
for (unsigned i = 0; i < nfds; ++i) {
auto description = file_description(fds[i].fd);
if (!description) {
fds[i].revents = POLLNVAL;
continue;
}
fds[i].revents = 0;
if (fds[i].events & POLLIN && description->can_read())
fds[i].revents |= POLLIN;
if (fds[i].events & POLLOUT && description->can_write())
fds[i].revents |= POLLOUT;
if (fds[i].revents)
++fds_with_revents;
}
return fds_with_revents;
}
}
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