kernel/poll.c


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#include <fs/vfs.h>
#include <halts.h>
#include <interrupts.h>
#include <lib/list.h>
#include <poll.h>
#include <sched/scheduler.h>

int poll(struct pollfd *fds, size_t nfds, int timeout) {
  (void)timeout;
  int rc = 0;

  disable_interrupts();

  struct list *read_list = &get_current_task()->read_list;
  struct list *write_list = &get_current_task()->write_list;
  struct list *disconnect_list = &get_current_task()->disconnect_list;
  for (size_t i = 0; i < nfds; i++) {
    if (fds[i].fd < 0)
      continue;
    vfs_fd_t *f = get_vfs_fd(fds[i].fd);
    if (NULL == f) {
      continue;
    }

    if (fds[i].events & POLLIN) {
      list_add(read_list, f->inode);
    }
    if (fds[i].events & POLLOUT) {
      list_add(write_list, f->inode);
    }
    if (fds[i].events & POLLHUP) {
      list_add(disconnect_list, f->inode);
    }
  }

  switch_task();
  disable_interrupts();

  list_reset(read_list);
  list_reset(write_list);
  list_reset(disconnect_list);

  for (size_t i = 0; i < nfds; i++) {
    if (0 > fds[i].fd) {
      fds[i].revents = 0;
      continue;
    }
    vfs_fd_t *f = get_vfs_fd(fds[i].fd);
    if (!f) {
      if (fds[i].events & POLLHUP)
        fds[i].revents |= POLLHUP;
    } else {
      if (f->inode->has_data && fds[i].events & POLLIN)
        fds[i].revents |= POLLIN;
      if (f->inode->can_write && fds[i].events & POLLOUT)
        fds[i].revents |= POLLOUT;
      if (!(f->inode->is_open) && fds[i].events & POLLHUP)
        fds[i].revents |= POLLHUP;
      if (fds[i].revents)
        rc++;
    }
  }
  enable_interrupts();
  return rc;
}