Revert "[v1.0] Remove experimental .getn discipline"

This reverts commit 42fc5c4c0d.
It somehow caused the following reproducer to fail. Reason unknown.

  typeset -i x
  function x.set { :; }
  x[0]=0
  unset x
  typeset -p x

Expected output: none

Actual output:

  typeset -a -i x=()

The 'x' variable fails to be unset.

With the .get and .getn discipline functions instead of .set, the
above reproducer still fails even after the revert, but that always
has failed, back to at least 93u+ 2012-08-01.

This is yet more evidence that discipline functions are a mess.
But a proper cleanup will require a lot of time and very thorough
testing, so it will have to wait until some future release.

src/cmd/ksh93/tests/variables.sh:
- In addition to the revert, add the above reproducer as a
  regression test for the .set, .unset and .append disciplines.

src/cmd/ksh93/data/variables.c

@@ -104,7 +104,7 @@ const struct shtable2 shtab_variables[] =
 	"",	0,					(char*)0
 };
 
-const char *nv_discnames[] = { "get", "set", "append", "unset", 0 };
+const char *nv_discnames[] = { "get", "set", "append", "unset", "getn", 0 };
 
 #if SHOPT_STATS
 const Shtable_t shtab_stats[] =

src/cmd/ksh93/include/version.h

@@ -18,7 +18,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.3-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2022-08-16"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2022-08-18"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2022 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

src/cmd/ksh93/sh/nvdisc.c

@@ -151,15 +151,16 @@ void nv_putv(Namval_t *np, const char *value, int flags, register Namfun_t *nfp)
 	}
 }
 
-#define	LOOKUP		0
+#define	LOOKUPS		0
 #define	ASSIGN		1
 #define	APPEND		2
 #define	UNASSIGN	3
+#define	LOOKUPN		4
 
 struct	vardisc
 {
 	Namfun_t	fun;
-	Namval_t	*disc[4];
+	Namval_t	*disc[5];
 };
 
 struct blocked
@@ -286,8 +287,8 @@ static void	assign(Namval_t *np,const char* val,int flags,Namfun_t *handle)
 		savelex = *lexp;
 		sh_lexopen(lexp, 0);   /* needs full init (0), not what it calls reinit (1) */
 		block(bp,type);
-		if(bflag = (type==APPEND && !isblocked(bp,LOOKUP)))
-			block(bp,LOOKUP);
+		if(bflag = (type==APPEND && !isblocked(bp,LOOKUPS)))
+			block(bp,LOOKUPS);
 		sh_pushcontext(&checkpoint, 1);
 		jmpval = sigsetjmp(checkpoint.buff, 0);
 		if(!jmpval)
@@ -297,7 +298,7 @@ static void	assign(Namval_t *np,const char* val,int flags,Namfun_t *handle)
 			sh_iorestore(checkpoint.topfd, jmpval);
 		unblock(bp,type);
 		if(bflag)
-			unblock(bp,LOOKUP);
+			unblock(bp,LOOKUPS);
 		if(!vp->disc[type])
 			chktfree(np,vp);
 		*lexp = savelex;
@@ -374,15 +375,15 @@ done:
  * This function executes a lookup disc and then performs
  * the lookup on the given node <np>
  */
-static char*	lookup(Namval_t *np, Namfun_t *handle)
+static char*	lookup(Namval_t *np, int type, Sfdouble_t *dp,Namfun_t *handle)
 {
 	register struct vardisc	*vp = (struct vardisc*)handle;
 	struct blocked		block, *bp = block_info(np, &block);
-	register Namval_t	*nq = vp->disc[LOOKUP];
+	register Namval_t	*nq = vp->disc[type];
 	register char		*cp=0;
 	Namval_t		node;
 	union Value		*up = np->nvalue.up;
-	if(nq && !isblocked(bp,LOOKUP))
+	if(nq && !isblocked(bp,type))
 	{
 		struct checkpt	checkpoint;
 		int		jmpval;
@@ -397,7 +398,12 @@ static char*	lookup(Namval_t *np, Namfun_t *handle)
 			nv_onattr(SH_VALNOD,NV_NOFREE);
 			_nv_unset(SH_VALNOD,0);
 		}
-		block(bp,LOOKUP);
+		if(type==LOOKUPN)
+		{
+			nv_onattr(SH_VALNOD,NV_DOUBLE|NV_INTEGER);
+			nv_setsize(SH_VALNOD,10);
+		}
+		block(bp,type);
 		block(bp, UNASSIGN);   /* make sure nv_setdisc doesn't invalidate 'vp' by freeing it */
 		sh_pushcontext(&checkpoint, 1);
 		jmpval = sigsetjmp(checkpoint.buff, 0);
@@ -407,10 +413,15 @@ static char*	lookup(Namval_t *np, Namfun_t *handle)
 		if(sh.topfd != checkpoint.topfd)
 			sh_iorestore(checkpoint.topfd, jmpval);
 		unblock(bp,UNASSIGN);
-		unblock(bp,LOOKUP);
-		if(!vp->disc[LOOKUP])
+		unblock(bp,type);
+		if(!vp->disc[type])
 			chktfree(np,vp);
-		if(cp = nv_getval(SH_VALNOD))
+		if(type==LOOKUPN)
+		{
+			cp = (char*)(SH_VALNOD->nvalue.cp);
+			*dp = nv_getnum(SH_VALNOD);
+		}
+		else if(cp = nv_getval(SH_VALNOD))
 			cp = stkcopy(stkstd,cp);
 		_nv_unset(SH_VALNOD,NV_RDONLY);
 		if(!nv_isnull(&node))
@@ -424,7 +435,12 @@ static char*	lookup(Namval_t *np, Namfun_t *handle)
 	if(nv_isarray(np))
 		np->nvalue.up = up;
 	if(!cp)
-		cp = nv_getv(np,handle);
+	{
+		if(type==LOOKUPS)
+			cp = nv_getv(np,handle);
+		else
+			*dp = nv_getn(np,handle);
+	}
 	if(bp== &block)
 		block_done(bp);
 	if(nq && nq->nvalue.rp && nq->nvalue.rp->running==1)
@@ -435,6 +451,19 @@ static char*	lookup(Namval_t *np, Namfun_t *handle)
 	return(cp);
 }
 
+static char*	lookups(Namval_t *np, Namfun_t *handle)
+{
+	return(lookup(np,LOOKUPS,(Sfdouble_t*)0,handle));
+}
+
+static Sfdouble_t lookupn(Namval_t *np, Namfun_t *handle)
+{
+	Sfdouble_t	d;
+	lookup(np,LOOKUPN, &d ,handle);
+	return(d);
+}
+
+
 /*
  * Set disc on given <event> to <action>
  * If action==np, the current disc is returned
@@ -531,7 +560,10 @@ char *nv_setdisc(register Namval_t* np,register const char *event,Namval_t *acti
 	else if(action)
 	{
 		Namdisc_t *dp = (Namdisc_t*)vp->fun.disc;
-		dp->getval = lookup;
+		if(type==LOOKUPS)
+			dp->getval = lookups;
+		else if(type==LOOKUPN)
+			dp->getnum = lookupn;
 		vp->disc[type] = action;
 	}
 	else

src/cmd/ksh93/tests/variables.sh

@@ -1381,6 +1381,14 @@ got=$("$SHELL" -c $'foo=baz; foo+=_foo "$SHELL" -c \'print $foo\'; print $foo')
 [[ $exp == "$got" ]] || err_exit "using the += operator for invocation-local assignments changes variables outside of the invocation-local scope" \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
+# ======
+# Crash when setting attribute after getn (numeric get) discipline
+# https://github.com/ksh93/ksh/issues/435#issuecomment-1148813866
+got=$("$SHELL" -c 'foo.getn() { .sh.value=2.3*4.5; }; typeset -F2 foo; typeset -p foo' 2>&1)
+exp='typeset -F 2 foo=10.35'
+[[ $got == "$exp" ]] || err_exit "Setting attribute after setting getn discipline fails" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 # As of 2022-07-12, the current scope is restored after changing .sh.level in a DEBUG trap
 exp=$'a: 2 CHILD\nb: 1 PARENT\nc: 2 CHILD\nd: 1 PARENT'
@@ -1435,5 +1443,22 @@ got=$var1
 unset var1 var2
 [[ $got == one ]] || err_exit ".sh.value not restored after second .get discipline call (got $(printf %q "$got"))"
 
+# ======
+# TODO: this is known to fail with a .get or .getn discipline function
+for disc in set append unset
+do
+	for type in i F E
+	do
+		got=$(eval "
+			typeset -$type x
+			function x.$disc { :; }
+			x[0]=0
+			unset x
+			typeset -p x
+		")
+		[[ -z $got ]] || err_exit "-$type array with .$disc discipline fails to be unset (got $(printf %q "$got"))"
+	done
+done
+
 # ======
 exit $((Errors<125?Errors:125))