Per suggestion and patch from Ken Staton, emulates poll using

select for older 2.0 kernels where poll is missing.

libc/sysdeps/linux/common/poll.c

@@ -0,0 +1,192 @@
+/* Copyright (C) 1994,1996,1997,1998,1999,2001,2002
+   Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <alloca.h>
+#include <sys/poll.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/param.h>
+#include <unistd.h>
+
+/* Poll the file descriptors described by the NFDS structures starting at
+   FDS.  If TIMEOUT is nonzero and not -1, allow TIMEOUT milliseconds for
+   an event to occur; if TIMEOUT is -1, block until an event occurs.
+   Returns the number of file descriptors with events, zero if timed out,
+   or -1 for errors.  */
+
+int poll(struct pollfd *fds, nfds_t nfds, int timeout)
+{
+    static int max_fd_size;
+    struct timeval tv;
+    fd_set *rset, *wset, *xset;
+    struct pollfd *f;
+    int ready;
+    int maxfd = 0;
+    int bytes;
+
+    if (!max_fd_size)
+	max_fd_size = getdtablesize ();
+
+    bytes = howmany (max_fd_size, __NFDBITS);
+    rset = alloca (bytes);
+    wset = alloca (bytes);
+    xset = alloca (bytes);
+
+    /* We can't call FD_ZERO, since FD_ZERO only works with sets
+       of exactly __FD_SETSIZE size.  */
+    bzero (rset, bytes);
+    bzero (wset, bytes);
+    bzero (xset, bytes);
+
+    for (f = fds; f < &fds[nfds]; ++f)
+    {
+	f->revents = 0;
+	if (f->fd >= 0)
+	{
+	    if (f->fd >= max_fd_size)
+	    {
+		/* The user provides a file descriptor number which is higher
+		   than the maximum we got from the `getdtablesize' call.
+		   Maybe this is ok so enlarge the arrays.  */
+		fd_set *nrset, *nwset, *nxset;
+		int nbytes;
+
+		max_fd_size = roundup (f->fd, __NFDBITS);
+		nbytes = howmany (max_fd_size, __NFDBITS);
+
+		nrset = alloca (nbytes);
+		nwset = alloca (nbytes);
+		nxset = alloca (nbytes);
+
+		bzero ((char *) nrset + bytes, nbytes - bytes);
+		bzero ((char *) nwset + bytes, nbytes - bytes);
+		bzero ((char *) nxset + bytes, nbytes - bytes);
+
+		rset = memcpy (nrset, rset, bytes);
+		wset = memcpy (nwset, wset, bytes);
+		xset = memcpy (nxset, xset, bytes);
+
+		bytes = nbytes;
+	    }
+
+	    if (f->events & POLLIN)
+		FD_SET (f->fd, rset);
+	    if (f->events & POLLOUT)
+		FD_SET (f->fd, wset);
+	    if (f->events & POLLPRI)
+		FD_SET (f->fd, xset);
+	    if (f->fd > maxfd && (f->events & (POLLIN|POLLOUT|POLLPRI)))
+		maxfd = f->fd;
+	}
+    }
+
+    tv.tv_sec = timeout / 1000;
+    tv.tv_usec = (timeout % 1000) * 1000;
+
+    while (1)
+    {
+	ready = select (maxfd + 1, rset, wset, xset,
+		timeout == -1 ? NULL : &tv);
+
+	/* It might be that one or more of the file descriptors is invalid.
+	   We now try to find and mark them and then try again.  */
+	if (ready == -1 && errno == EBADF)
+	{
+	    fd_set *sngl_rset = alloca (bytes);
+	    fd_set *sngl_wset = alloca (bytes);
+	    fd_set *sngl_xset = alloca (bytes);
+	    struct timeval sngl_tv;
+
+	    /* Clear the original set.  */
+	    bzero (rset, bytes);
+	    bzero (wset, bytes);
+	    bzero (xset, bytes);
+
+	    /* This means we don't wait for input.  */
+	    sngl_tv.tv_sec = 0;
+	    sngl_tv.tv_usec = 0;
+
+	    maxfd = -1;
+
+	    /* Reset the return value.  */
+	    ready = 0;
+
+	    for (f = fds; f < &fds[nfds]; ++f)
+		if (f->fd != -1 && (f->events & (POLLIN|POLLOUT|POLLPRI))
+			&& (f->revents & POLLNVAL) == 0)
+		{
+		    int n;
+
+		    bzero (sngl_rset, bytes);
+		    bzero (sngl_wset, bytes);
+		    bzero (sngl_xset, bytes);
+
+		    if (f->events & POLLIN)
+			FD_SET (f->fd, sngl_rset);
+		    if (f->events & POLLOUT)
+			FD_SET (f->fd, sngl_wset);
+		    if (f->events & POLLPRI)
+			FD_SET (f->fd, sngl_xset);
+
+		    n = select (f->fd + 1, sngl_rset, sngl_wset, sngl_xset,
+			    &sngl_tv);
+		    if (n != -1)
+		    {
+			/* This descriptor is ok.  */
+			if (f->events & POLLIN)
+			    FD_SET (f->fd, rset);
+			if (f->events & POLLOUT)
+			    FD_SET (f->fd, wset);
+			if (f->events & POLLPRI)
+			    FD_SET (f->fd, xset);
+			if (f->fd > maxfd)
+			    maxfd = f->fd;
+			if (n > 0)
+			    /* Count it as being available.  */
+			    ++ready;
+		    }
+		    else if (errno == EBADF)
+			f->revents |= POLLNVAL;
+		}
+	    /* Try again.  */
+	    continue;
+	}
+
+	break;
+    }
+
+    if (ready > 0)
+	for (f = fds; f < &fds[nfds]; ++f)
+	{
+	    if (f->fd >= 0)
+	    {
+		if (FD_ISSET (f->fd, rset))
+		    f->revents |= POLLIN;
+		if (FD_ISSET (f->fd, wset))
+		    f->revents |= POLLOUT;
+		if (FD_ISSET (f->fd, xset))
+		    f->revents |= POLLPRI;
+	    }
+	}
+
+    return ready;
+}
+

libc/sysdeps/linux/common/syscalls.c

@@ -1721,9 +1721,12 @@ int getresuid (uid_t *ruid, uid_t *euid, uid_t *suid)
 #endif	
 
 //#define __NR_poll                     168
-#if defined(L_poll) && defined(__NR_poll) /* uClinux 2.0 doesn't have poll */
+#if defined(L_poll) && defined(__NR_poll)
 #include <sys/poll.h>
 _syscall3(int, poll, struct pollfd *, fds, unsigned long int, nfds, int, timeout);
+#else
+/* uClinux 2.0 doesn't have poll, emulate it using select */
+#include "poll.c"
 #endif
 
 //#define __NR_nfsservctl               169