1.  NCCRUNE was too large by sizeof(Reclass.end)/sizeof(Rune).
use enum of NSPANS in <regexp.h> to size Reclass.spans
and NCCLASS to size Reprog.class.

could use nelem(yyclassp->spans) and nelem(classp->class)
instead, but that seems a tad confusing.

2.  a too-large character class didn't compile correctly and did not
yield an error.  error out if character class is too large.

3.  use NSPANS=128 and not NSPANS=64/2.

Notes:
Fri Jul 23 16:13:10 EDT 2010 geoff
    done at bit differently, partly to avoid adding new symbols
    to <regexp.h>.


Reference: /n/sources/patch/applied/regexpclass
Date: Tue Dec  1 02:40:23 CET 2009
Signed-off-by: quanstro@quanstro.net
Reviewed-by: geoff

--- /sys/include/regexp.h	Tue Dec  1 02:17:39 2009
+++ /sys/include/regexp.h	Tue Dec  1 02:17:38 2009
@@ -1,6 +1,11 @@
 #pragma	src	"/sys/src/libregexp"
 #pragma	lib	"libregexp.a"
 
+enum {
+	NSPANS	= 128,		/* max rune ranges per character class */
+	NCLASS	= 16,		/* max character classes per program */
+};
+
 typedef struct Resub		Resub;
 typedef struct Reclass		Reclass;
 typedef struct Reinst		Reinst;
@@ -27,7 +32,7 @@
  */
 struct Reclass{
 	Rune	*end;
-	Rune	spans[64];
+	Rune	spans[NSPANS*2];
 };
 
 /*
@@ -52,7 +57,7 @@
  */
 struct Reprog{
 	Reinst	*startinst;	/* start pc */
-	Reclass	class[16];	/* .data */
+	Reclass	class[NCLASS];	/* .data */
 	Reinst	firstinst[5];	/* .text */
 };
 
--- /sys/src/libregexp/regcomp.h	Tue Dec  1 02:17:46 2009
+++ /sys/src/libregexp/regcomp.h	Tue Dec  1 02:17:44 2009
@@ -8,13 +8,6 @@
 	Resub	m[NSUBEXP];
 };
 
-/* max character classes per program */
-Reprog	RePrOg;
-#define	NCLASS	(sizeof(RePrOg.class)/sizeof(Reclass))
-
-/* max rune ranges per character class */
-#define NCCRUNE	(sizeof(Reclass)/sizeof(Rune))
-
 /*
  * Actions and Tokens (Reinst types)
  *
--- /sys/src/libregexp/regcomp.c	Tue Dec  1 02:17:54 2009
+++ /sys/src/libregexp/regcomp.c	Tue Dec  1 02:17:52 2009
@@ -387,7 +387,7 @@
 bldcclass(void)
 {
 	int type;
-	Rune r[NCCRUNE];
+	Rune r[NSPANS*2];
 	Rune *p, *ep, *np;
 	Rune rune;
 	int quoted;
@@ -408,7 +408,11 @@
 	}
 
 	/* parse class into a set of spans */
-	for(; ep<&r[NCCRUNE];){
+	for(;;){
+		if(ep == r + nelem(r)){
+			rcerror("class too large");
+			return 0;
+		}
 		if(rune == 0){
 			rcerror("malformed '[]'");
 			return 0;