Luna/kernel/src/sys/poll.cpp
apio 6f3ed70363
kernel+libluna: Avoid scrubbing when the memory is going to be overwritten anyway
This is the case for objects with constructors and temporary memory which is filled afterwards.
2023-08-27 20:48:33 +02:00

77 lines
2.1 KiB
C++

#include "Log.h"
#include "Pledge.h"
#include "fs/VFS.h"
#include "memory/MemoryManager.h"
#include "sys/Syscall.h"
#include "thread/Scheduler.h"
#include <bits/poll.h>
Result<u64> sys_poll(Registers*, SyscallArgs args)
{
struct pollfd* fds = (struct pollfd*)args[0];
nfds_t nfds = (nfds_t)args[1];
int timeout = (int)args[2];
struct pollfd* kfds = (struct pollfd*)TRY(malloc_impl(nfds * sizeof(pollfd), false, false));
auto guard = make_scope_guard([kfds] { free_impl(kfds); });
if (!MemoryManager::copy_from_user(fds, kfds, nfds * sizeof(pollfd))) return err(EFAULT);
auto* current = Scheduler::current();
TRY(check_pledge(current, Promise::p_stdio));
Vector<SharedPtr<VFS::Inode>> inodes;
TRY(inodes.try_reserve(nfds));
for (nfds_t i = 0; i < nfds; i++)
{
int fd = kfds[i].fd;
auto maybe_inode = current->resolve_fd(fd);
if (maybe_inode.has_error())
{
kwarnln("poll: fd %lu (%d) is not valid, storing POLLNVAL", i, fd);
kfds[i].revents |= POLLNVAL;
TRY(inodes.try_append({}));
}
else
TRY(inodes.try_append(maybe_inode.release_value()->description->inode));
}
bool infinite = timeout < 0;
nfds_t fds_with_events;
do {
fds_with_events = 0;
for (nfds_t i = 0; i < nfds; i++)
{
auto& inode = inodes[i];
if (!inode) continue;
if (kfds[i].events & POLLIN && !inode->will_block_if_read())
{
fds_with_events++;
kfds[i].revents |= POLLIN;
}
}
if (!fds_with_events && (timeout > 0 || infinite))
{
kernel_sleep(10);
timeout -= (10 - (int)current->sleep_ticks_left);
if (current->interrupted)
{
guard.deactivate();
free_impl(kfds);
return err(EINTR);
}
continue;
}
break;
} while (1);
MemoryManager::copy_to_user(fds, kfds, nfds * sizeof(pollfd));
return fds_with_events;
}