PATCH: poll() support in zle

[Peter Stephenson <pws@xxxxxxx>]

This makes poll() available as an alternative to select() in zle.  It's
the preferred alternative since this is what some system documentation
suggests.

Two special uses of select() haven't been converted since they are only
used in rare circumstances; they might even be on systems we don't
properly support any more.

There is one extra feature that if poll() reports HUP, ERR or NVAL
in the returned events this is passed on to a function listening using
`zle -F'.  I haven't documented this, however, since I haven't been able
to test it.

zselect() should get the same treatment at some point, in which case it
would be more sensible to call it zpoll which is a more meaningful name.

Index: Src/Zle/zle_main.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/zle_main.c,v
retrieving revision 1.23
diff -u -r1.23 zle_main.c
--- Src/Zle/zle_main.c	21 May 2002 11:10:17 -0000	1.23
+++ Src/Zle/zle_main.c	5 Jun 2002 15:10:34 -0000
@@ -30,6 +30,13 @@
 #include "zle.mdh"
 #include "zle_main.pro"
 
+#ifdef HAVE_POLL_H
+# include <poll.h>
+#endif
+#if defined(HAVE_POLL) && !defined(POLLIN) && !defined(POLLNORM)
+# undef HAVE_POLL
+#endif
+
 /* != 0 if in a shell function called from completion, such that read -[cl]  *
  * will work (i.e., the line is metafied, and the above word arrays are OK). */
 
@@ -340,11 +347,13 @@
 {
     long exp100ths;
     int ret;
-#ifdef HAVE_SELECT
+#ifndef HAVE_POLL
+# ifdef HAVE_SELECT
     fd_set foofd;
-#else
-# ifdef HAS_TIO
+# else
+#  ifdef HAS_TIO
     struct ttyinfo ti;
+#  endif
 # endif
 #endif
 
@@ -364,18 +373,45 @@
 	    exp100ths = 500;
 	else
 	    exp100ths = keytimeout;
-#ifdef HAVE_SELECT
+#if defined(HAVE_SELECT) || defined(HAVE_POLL)
 	if (!keytmout || exp100ths) {
+	    int i, errtry = 0, selret;
+# ifdef HAVE_POLL
+	    int poll_timeout;
+	    int nfds = keytmout ? 1 : 1 + nwatch;
+	    /* First pollfd is SHTTY, following are the nwatch fds */
+	    struct pollfd *fds = zalloc(sizeof(struct pollfd) * nfds);
+	    if (exp100ths)
+		poll_timeout = exp100ths * 10;
+	    else
+		poll_timeout = -1;
+
+	    fds[0].fd = SHTTY;
+	    /*
+	     * POLLIN, POLLIN, POLLIN,
+	     * Keep those fd's POLLIN...
+	     */
+	    fds[0].events = POLLIN;
+	    if (!keytmout) {
+		for (i = 0; i < nwatch; i++) {
+		    fds[i+1].fd = watch_fds[i];
+		    fds[i+1].events = POLLIN;
+		}
+	    }
+# else
+	    int fdmax = SHTTY;
 	    struct timeval *tvptr = NULL;
 	    struct timeval expire_tv;
-	    int i, fdmax = SHTTY, errtry = 0;
 	    if (exp100ths) {
 		expire_tv.tv_sec = exp100ths / 100;
 		expire_tv.tv_usec = (exp100ths % 100) * 10000L;
 		tvptr = &expire_tv;
 	    }
+# endif
 	    do {
-		int selret;
+# ifdef HAVE_POLL
+		selret = poll(fds, errtry ? 1 : nfds, poll_timeout);
+# else
 		FD_ZERO(&foofd);
 		FD_SET(SHTTY, &foofd);
 		if (!keytmout && !errtry) {
@@ -388,11 +424,12 @@
 		}
 		selret = select(fdmax+1, (SELECT_ARG_2_T) & foofd,
 				NULL, NULL, tvptr);
+# endif
 		/*
 		 * Make sure a user interrupt gets passed on straight away.
 		 */
 		if (selret < 0 && errflag)
-		    return selret;
+		    break;
 		/*
 		 * Try to avoid errors on our special fd's from
 		 * messing up reads from the terminal.  Try first
@@ -404,9 +441,10 @@
 		}
 		if (selret == 0) {
 		    /* Special value -2 signals nothing ready */
-		    return -2;
-		} else if (selret < 0)
-		    return selret;
+		    selret = -2;
+		}
+		if (selret < 0)
+		    break;
 		if (!keytmout && nwatch) {
 		    /*
 		     * Copy the details of the watch fds in case the
@@ -418,7 +456,13 @@
 		    char **lwatch_funcs = zarrdup(watch_funcs);
 		    memcpy(lwatch_fds, watch_fds, lnwatch*sizeof(int));
 		    for (i = 0; i < lnwatch; i++) {
-			if (FD_ISSET(lwatch_fds[i], &foofd)) {
+			if (
+# ifdef HAVE_POLL
+			    (fds[i+1].revents & POLLIN)
+# else
+			    FD_ISSET(lwatch_fds[i], &foofd)
+# endif
+			    ) {
 			    /* Handle the fd. */
 			    LinkList funcargs = znewlinklist();
 			    zaddlinknode(funcargs, ztrdup(lwatch_funcs[i]));
@@ -427,6 +471,21 @@
 				convbase(buf, lwatch_fds[i], 10);
 				zaddlinknode(funcargs, ztrdup(buf));
 			    }
+# ifdef HAVE_POLL
+#  ifdef POLLERR
+			    if (fds[i+1].revents & POLLERR)
+				zaddlinknode(funcargs, ztrdup("err"));
+#  endif
+#  ifdef POLLHUP
+			    if (fds[i+1].revents & POLLHUP)
+				zaddlinknode(funcargs, ztrdup("hup"));
+#  endif
+#  ifdef POLLNVAL
+			    if (fds[i+1].revents & POLLNVAL)
+				zaddlinknode(funcargs, ztrdup("nval"));
+#  endif
+# endif
+
 
 			    callhookfunc(lwatch_funcs[i], funcargs);
 			    if (errflag) {
@@ -447,7 +506,18 @@
 		    zfree(lwatch_fds, lnwatch*sizeof(int));
 		    freearray(lwatch_funcs);
 		}
-	    } while (!FD_ISSET(SHTTY, &foofd));
+	    } while (!
+# ifdef HAVE_POLL
+		     (fds[0].revents & POLLIN)
+# else
+		     FD_ISSET(SHTTY, &foofd)
+# endif
+		);
+# ifdef HAVE_POLL
+	    zfree(fds, sizeof(struct pollfd) * nfds);
+# endif
+	    if (selret < 0)
+		return selret;
 	}
 #else
 # ifdef HAS_TIO
@@ -571,10 +641,13 @@
     int old_errno = errno;
     int tmout = getiparam("TMOUT");
 
-#ifdef HAVE_SELECT
+#if defined(HAVE_SELECT) || defined(HAVE_POLL)
     long costmult;
+# ifdef HAVE_POLL
+# else
     struct timeval tv;
     fd_set foofd;
+# endif
 
     baud = getiparam("BAUD");
     costmult = (baud) ? 3840000L / baud : 0;
@@ -620,8 +693,10 @@
 
     zlereadflags = flags;
     histline = curhist;
-#ifdef HAVE_SELECT
+#ifndef HAVE_POLL
+# ifdef HAVE_SELECT
     FD_ZERO(&foofd);
+# endif
 #endif
     undoing = 1;
     line = (unsigned char *)zalloc((linesz = 256) + 2);
@@ -683,7 +758,20 @@
 	    errflag = 1;
 	    break;
 	}
-#ifdef HAVE_SELECT
+#ifdef HAVE_POLL
+	if (baud && !(lastcmd & ZLE_MENUCMP)) {
+	    struct pollfd pfd;
+	    int to = cost * costmult / 1000; /* milliseconds */
+
+	    if (to > 500)
+		to = 500;
+	    pfd.fd = SHTTY;
+	    pfd.events = POLLIN;
+	    if (!kungetct && poll(&pfd, 1, to) <= 0)
+		zrefresh();
+	} else
+#else
+# ifdef HAVE_SELECT
 	if (baud && !(lastcmd & ZLE_MENUCMP)) {
 	    FD_SET(SHTTY, &foofd);
 	    tv.tv_sec = 0;
@@ -693,6 +781,7 @@
 				    NULL, NULL, &tv) <= 0)
 		zrefresh();
 	} else
+# endif
 #endif
 	    if (!kungetct)
 		zrefresh();
Index: Doc/Zsh/zle.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/zle.yo,v
retrieving revision 1.18
diff -u -r1.18 zle.yo
--- Doc/Zsh/zle.yo	21 May 2002 11:10:17 -0000	1.18
+++ Doc/Zsh/zle.yo	5 Jun 2002 15:10:34 -0000
@@ -413,8 +413,8 @@
 command line) will start as usual with the `tt(main)' keymap selected.
 )
 item(tt(-F) [ tt(-L) ] [ var(fd) [ var(handler) ] ])(
-Only available if your system support the `select' system call; most
-modern systems do.
+Only available if your system supports one of the `poll' or `select' system
+calls; most modern systems do.
 
 Installs var(handler) (the name of a shell function) to handle input from
 file descriptor var(fd).  When zle is attempting to read data, it will

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


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