PATCH (again) Re: termcap bug on Linux

["Bart Schaefer" <schaefer@candle.brasslantern.com>]

I wrote earlier:
}
} I'm going to commit 14516 as it is, and then look at this a bit more.

OK, here's a patch for consideration.  This factors out the tgetflag()
stuff into a new function ztgetflag(), which believes tgetflag() only
when it returns -1 [no such cap] or != 0 ["yes"].  Otherwise it searches
the boolcodes for the cap name and returns 0 ["no"] only if it finds
the name there; the fallback is to return -1.

The end result is that this consistently treats "known" flag cap names
as either true or false, even if they don't actually appear in the term
definition, and will consistently treat "unknown" cap names as "no such
capability".  An "unknown" cap that is set to true is still at the mercy
of tgetflag(), but I don't see any way to work around that at all -- and
we do want to yield true for any previously-unknown capability that may
come along and be set.

"Consistently" here means on a particular installation -- it might be
that zsh on an ncurses 4.2 system does not agree with zsh on an ncurses
5.2 system even given identical term defs.

If we don't want to trust the -1 return from tgetflag() at all, ever,
just remove the `break' from the -1 case in ztgetflag().

diff -u zsh-forge/current/Src/Modules/termcap.c zsh-4.0/Src/Modules/termcap.c
--- zsh-forge/current/Src/Modules/termcap.c	Wed May 30 08:30:41 2001
+++ zsh-4.0/Src/Modules/termcap.c	Wed May 30 10:47:34 2001
@@ -67,6 +67,38 @@
 
 static Param termcap_pm;
 
+#ifndef HAVE_BOOLCODES
+static char *boolcodes[] = {
+    "bw", "am", "ut", "cc", "xs", "YA", "YF", "YB", "xt", "xn", "eo",
+    "gn", "hc", "HC", "km", "YC", "hs", "hl", "in", "YG", "da", "db",
+    "mi", "ms", "nx", "xb", "NP", "ND", "NR", "os", "5i", "YD", "YE",
+    "es", "hz", "ul", "xo", NULL};
+#endif
+
+/**/
+static int
+ztgetflag(char *s)
+{
+    char **b;
+
+    /* ncurses can tell if an existing boolean capability is *
+     * off, but other curses variants can't, so we fudge it. *
+     * This feature of ncurses appears to have gone away as  *
+     * of NCURSES_MAJOR_VERSION == 5, so don't rely on it.   */
+    switch (tgetflag(s)) {
+    case -1:
+	break;
+    case 0:
+	for (b = (char **)boolcodes; *b; ++b)
+	    if (s[0] == (*b)[0] && s[1] == (*b)[1])
+		return 0;
+	break;
+    default:
+	return 1;
+    }
+    return -1;
+}
+
 /* echotc: output a termcap */
 
 /**/
@@ -86,16 +118,8 @@
 	printf("%d\n", num);
 	return 0;
     }
-    /* if the specified termcap is boolean, and set, say so  *
-     * ncurses can tell if an existing boolean capability is *
-     * off so in this case we print "no".                    */
-#if !defined(NCURSES_VERSION) || !defined(COLOR_PAIR)
-    if (tgetflag(s) > 0) {
-	puts("yes");
-	return (0);
-    }
-#else /* NCURSES_VERSION && COLOR_PAIR */
-    switch (tgetflag(s)) {
+    /* if the specified termcap is boolean, and set, say so  */
+    switch (ztgetflag(s)) {
     case -1:
 	break;
     case 0:
@@ -105,7 +129,6 @@
 	puts("yes");
 	return 0;
     }
-#endif /* NCURSES_VERSION && COLOR_PAIR */
     /* get a string-type capability */
     u = buf;
     t = tgetstr(s, &u);
@@ -232,14 +255,7 @@
 	pm->flags |= PM_INTEGER;
 	return (HashNode) pm;
     }
-#if !defined(NCURSES_VERSION) || !defined(COLOR_PAIR)
-    if ((num = tgetflag(name)) > 0) {
-	pm->u.str = dupstring("yes");
-	pm->flags |= PM_SCALAR;
-	return (HashNode) pm;
-    }
-#else /* NCURSES_VERSION && COLOR_PAIR */
-    switch (tgetflag(name)) {
+    switch (ztgetflag(name)) {
     case -1:
 	break;
     case 0:
@@ -251,7 +267,6 @@
 	pm->flags |= PM_SCALAR;
 	return (HashNode) pm;
     }
-#endif /* NCURSES_VERSION && COLOR_PAIR */
     if ((tcstr = tgetstr(name, &u)) != NULL && tcstr != (char *)-1)
     {
 	pm->u.str = dupstring(tcstr);
@@ -274,14 +289,6 @@
     int num;
     char **capcode, *tcstr, buf[2048], *u;
 
-#ifndef HAVE_BOOLCODES
-    static char *boolcodes[] = {
-	"bw", "am", "ut", "cc", "xs", "YA", "YF", "YB", "xt", "xn", "eo",
-	"gn", "hc", "HC", "km", "YC", "hs", "hl", "in", "YG", "da", "db",
-	"mi", "ms", "nx", "xb", "NP", "ND", "NR", "os", "5i", "YD", "YE",
-	"es", "hz", "ul", "xo", NULL};
-#endif
-
 #ifndef HAVE_NUMCODES
     static char *numcodes[] = {
 	"co", "it", "lh", "lw", "li", "lm", "sg", "ma", "Co", "pa", "MW",
@@ -344,7 +351,7 @@
 
     pm->flags = PM_READONLY | PM_SCALAR;
     for (capcode = (char **)boolcodes; *capcode; capcode++) {
-	if ((num = tgetflag(*capcode)) != -1) {
+	if ((num = ztgetflag(*capcode)) != -1) {
 	    pm->u.str = num ? dupstring("yes") : dupstring("no");
 	    pm->nam = dupstring(*capcode);
 	    func((HashNode) pm, flags);

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

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net