PATCH: Why ask when you know the answer?

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxxxxxxxxx>]

This patch separates the FIONREAD test for typeahead from getquery() into
its own function, which I've called noquery() because it returns non-zero
when typeahead would cause getquery() to return 'n'.

I've then made a separate call to noquery() from spckword(), to avoid the
annoying prompt-and-beep when one e.g. cut'n'pastes a multi-line function
definition into an xterm.  It's called again from getquery() itself, of
course, after the prompt is printed, but spckword() now simply doesn't
prompt or call getquery() at all if it can't possibly succeed.

Does anyone see a problem with this?  The only thing that worries me is
that previously attachtty();setcbreak();ioctl(FIONREAD);sttyinfo() were
called, but now it's ioctl();attachtty();setcbreak();ioctl();sttyinfo()
instead.  I'm not sure about attachtty(), but the ioctl() may cause the
behavior to change on systems where setcbreak() causes typeahead to be
lost -- although I think that may actually be an improvement.  If there
is no problem, then perhaps the setcbreak() should be moved to after the
call to noquery() even within getquery()?

I didn't change checkrmall() or bin_read(); since files will actually not
be removed if there's typeahead at checkrmall(), the appearance of the
prompt conveys useful information about what happened, and in the case of
bin_read() it might be confusing to call "read 'var?prompt'" yet not see
the prompt.

Index: Src/utils.c
===================================================================
@@ -1313,31 +1313,39 @@
 
 /**/
 int
-getquery(char *valid_chars, int purge)
+noquery(int purge)
 {
-    int c, d;
-    int isem = !strcmp(term, "emacs");
+    int c, val = 0;
 
 #ifdef FIONREAD
-    int val = 0;
+    ioctl(SHTTY, FIONREAD, (char *)&val);
+    if (purge) {
+	while(val--)
+	    read(SHTTY, &c, 1);
+    }
 #endif
 
+    return val;
+}
+
+/**/
+int
+getquery(char *valid_chars, int purge)
+{
+    int c, d;
+    int isem = !strcmp(term, "emacs");
+
     attachtty(mypgrp);
     if (!isem)
 	setcbreak();
 
-#ifdef FIONREAD
-    ioctl(SHTTY, FIONREAD, (char *)&val);
-    if(purge) {
-	while(val--)
-	    read(SHTTY, &c, 1);
-    } else if (val) {
+    if (noquery(purge)) {
 	if (!isem)
 	    settyinfo(&shttyinfo);
 	write(SHTTY, "n\n", 2);
 	return 'n';
     }
-#endif
+
     while ((c = read1char()) >= 0) {
 	if (c == 'Y' || c == '\t')
 	    c = 'y';
@@ -1494,13 +1502,17 @@
 	    *guess = *best = ztokens[ic - Pound];
 	}
 	if (ask) {
-	    char *pptbuf;
-	    pptbuf = promptexpand(sprompt, 0, best, guess);
-	    zputs(pptbuf, shout);
-	    free(pptbuf);
-	    fflush(shout);
-	    zbeep();
-	    x = getquery("nyae ", 0);
+	    if (noquery(0)) {
+		x = 'n';
+	    } else {
+		char *pptbuf;
+		pptbuf = promptexpand(sprompt, 0, best, guess);
+		zputs(pptbuf, shout);
+		free(pptbuf);
+		fflush(shout);
+		zbeep();
+		x = getquery("nyae ", 0);
+	    }
 	} else
 	    x = 'y';
 	if (x == 'y' || x == ' ') {

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com