85 lines
2.3 KiB
C++
85 lines
2.3 KiB
C++
/* poll.cc. Implements poll(2) via usage of select(2) call.
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Copyright 2000 Cygnus Solutions.
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This file is part of Cygwin.
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This software is a copyrighted work licensed under the terms of the
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Cygwin license. Please consult the file "CYGWIN_LICENSE" for
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details. */
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#include "winsup.h"
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#include <sys/poll.h>
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#include <errno.h>
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#include "fhandler.h"
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#include "dtable.h"
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#include "cygerrno.h"
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extern "C"
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int
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poll (struct pollfd *fds, unsigned int nfds, int timeout)
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{
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int max_fd = 0;
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fd_set *open_fds, *read_fds, *write_fds, *except_fds;
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struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
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for (unsigned int i = 0; i < nfds; ++i)
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if (fds[i].fd > max_fd)
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max_fd = fds[i].fd;
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size_t fds_size = howmany(max_fd + 1, NFDBITS) * sizeof (fd_mask);
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open_fds = (fd_set *) alloca (fds_size);
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read_fds = (fd_set *) alloca (fds_size);
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write_fds = (fd_set *) alloca (fds_size);
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except_fds = (fd_set *) alloca (fds_size);
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if (!open_fds || !read_fds || !write_fds || !except_fds)
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{
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set_errno (ENOMEM);
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return -1;
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}
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memset (open_fds, 0, fds_size);
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memset (read_fds, 0, fds_size);
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memset (write_fds, 0, fds_size);
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memset (except_fds, 0, fds_size);
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for (unsigned int i = 0; i < nfds; ++i)
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if (!fdtab.not_open (fds[i].fd))
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{
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FD_SET (fds[i].fd, open_fds);
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if (fds[i].events & POLLIN)
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FD_SET (fds[i].fd, read_fds);
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if (fds[i].events & POLLOUT)
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FD_SET (fds[i].fd, write_fds);
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if (fds[i].events & POLLPRI)
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FD_SET (fds[i].fd, except_fds);
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}
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int ret = cygwin_select (max_fd + 1, read_fds, write_fds, except_fds,
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timeout < 0 ? NULL : &tv);
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for (unsigned int i = 0; i < nfds; ++i)
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{
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if (!FD_ISSET (fds[i].fd, open_fds))
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fds[i].revents = POLLNVAL;
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else if (fdtab.not_open(fds[i].fd))
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fds[i].revents = POLLHUP;
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else if (ret < 0)
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fds[i].revents = POLLERR;
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else
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{
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fds[i].revents = 0;
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if (FD_ISSET (fds[i].fd, read_fds))
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fds[i].revents |= POLLIN;
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if (FD_ISSET (fds[i].fd, write_fds))
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fds[i].revents |= POLLOUT;
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if (FD_ISSET (fds[i].fd, except_fds))
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fds[i].revents |= POLLPRI;
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}
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}
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return ret;
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}
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