132 lines
3.3 KiB
C
132 lines
3.3 KiB
C
// poll.h
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// poll using select
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#ifndef _FAKE_POLL_H
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#define _FAKE_POLL_H
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#include <limits.h>
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#define FD_SETSIZE OPEN_MAX
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#include <sys/types.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include <stdlib.h>
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typedef struct pollfd {
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int fd; /* file desc to poll */
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short events; /* events of interest on fd */
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short revents; /* events that occurred on fd */
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} pollfd_t;
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// poll flags
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#define POLLIN 0x0001
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#define POLLOUT 0x0004
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#define POLLERR 0x0008
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// synonyms
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#define POLLNORM POLLIN
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#define POLLPRI POLLIN
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#define POLLRDNORM POLLIN
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#define POLLRDBAND POLLIN
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#define POLLWRNORM POLLOUT
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#define POLLWRBAND POLLOUT
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// ignored
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#define POLLHUP 0x0010
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#define POLLNVAL 0x0020
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inline int poll(struct pollfd *pollSet, int pollCount, int pollTimeout)
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{
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struct timeval tv;
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struct timeval *tvp;
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fd_set readFDs, writeFDs, exceptFDs;
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fd_set *readp, *writep, *exceptp;
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struct pollfd *pollEnd, *p;
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int selected;
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int result;
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int maxFD;
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if (!pollSet) {
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pollEnd = NULL;
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readp = NULL;
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writep = NULL;
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exceptp = NULL;
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maxFD = 0;
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}
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else {
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pollEnd = pollSet + pollCount;
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readp = &readFDs;
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writep = &writeFDs;
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exceptp = &exceptFDs;
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FD_ZERO(readp);
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FD_ZERO(writep);
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FD_ZERO(exceptp);
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// Find the biggest fd in the poll set
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maxFD = 0;
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for (p = pollSet; p < pollEnd; p++) {
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if (p->fd > maxFD) maxFD = p->fd;
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}
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// Transcribe flags from the poll set to the fd sets
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for (p = pollSet; p < pollEnd; p++) {
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if (p->events & POLLIN) FD_SET(p->fd, readp);
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if (p->events & POLLOUT) FD_SET(p->fd, writep);
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if (p->events != 0) FD_SET(p->fd, exceptp);
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// POLLERR is never set coming in; poll() always reports errors.
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// But don't report if we're not listening to anything at all.
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}
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}
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// poll timeout is in milliseconds. Convert to struct timeval.
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// poll timeout == -1 : wait forever : select timeout of NULL
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// poll timeout == 0 : return immediately : select timeout of zero
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if (pollTimeout >= 0) {
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tv.tv_sec = pollTimeout / 1000;
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tv.tv_usec = (pollTimeout % 1000) * 1000;
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tvp = &tv;
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} else {
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tvp = NULL;
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}
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selected = select(maxFD+1, readp, writep, exceptp, tvp);
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if (selected < 0) {
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// Error during select
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result = -1;
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}
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else if (selected > 0) {
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// Select found something
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// Transcribe result from fd sets to poll set.
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// Also count the number of selected fds. poll returns the
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// number of ready fds; select returns the number of bits set.
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int polled = 0;
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for (p = pollSet; p < pollEnd; p++) {
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p->revents = 0;
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if (FD_ISSET(p->fd, readp)) p->revents |= POLLIN;
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if (FD_ISSET(p->fd, writep)) p->revents |= POLLOUT;
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if (FD_ISSET(p->fd, exceptp)) p->revents |= POLLERR;
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if (p->revents) polled++;
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}
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result = polled;
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}
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else {
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// selected == 0, select timed out before anything happened
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// Clear all result bits and return zero.
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for (p = pollSet; p < pollEnd; p++) {
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p->revents = 0;
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}
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result = 0;
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}
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return result;
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}
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#undef FD_SETSIZE
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#endif
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