[v1.1] Add ;;& control operator to 'case' statement

@tungstengmd asks:
> would ;;& a la bash be a good addition for case statements ?
> instead of just falling through like a ;& it tests any subsequent
> case and falls through upon a match

To add this, we need three things:
1. The lexer (lex.c) needs to learn to recognise ;;& as a symbol.
2. The parser (parse.c) needs to recognise that symbol and flag it
   up in 'case' pattern nodes (struct regnod).
3. The executor (xec.c) needs to actually have the functionality.

src/cmd/ksh93/include/shlex.h,
src/cmd/ksh93/sh/lex.c:
- sh_lex():
    - Add FALLMATCHSYM which is a repeated (SYMREP) ';' with a
      trailing ampersand (SYMAMP).
    - Recognise a trailing & after a SYMREP symbol and addthe
      SYMAMP bit if found. Any repeated S_OP character (see
      lexstates.c) can now be combined with a trailing & to make a
      symbol, but for now we're only using this for FALLMATCHSYM.
    - Set lex.incase flag also in case of FALLMATCHSYM.
- fmttoken():
    - Support SYMAMP in combination with SYMREP to generate
      repeated operators with trailing & for error messages. This
      is for "syntax error: `;;&' unexpected" and the like.

src/cmd/ksh93/sh/parse.c:
- syncase():
    - The regflag member of struct regnod is 1 for ;&. Add a new
      value 2 for ;;& by increasing it twice in that case.
    - Refactor a little for legibility using a switch statement.
      This avoids the need to duplicate the recursive syncase call.
- inout():
    - A side effect of the lex.c changes was that >>&foo and <<&foo
      were no longer detected as a syntax error. To fix this in a
      future-proof manner, check for unhandled SYM* bits in the
      token and throw a syntax error if there are any.

src/cmd/ksh93/sh/xec.c: sh_exec(): case TSW:
- Implementing the functionality requires just a couple of tweaks
  here. Detect ;& by checking for regflag==1 instead of nonzero.
  Avoid breaking the outer loop if regflag is neither 0 nor 1, so
  the pattern matching walk will resume upon encountering ;;&.

src/cmd/ksh93/sh/deparse.c: p_switch():
- Add support for ";;&" when generating code from a parse tree.

Resolves: #847

Author: McDutchie

ANNOUNCE

@@ -29,6 +29,10 @@ New command line editor features:
 
 New shell language features:
 
+- The 'case' compound command now supports the ;;& control operator as on
+  bash 4.0+. The ;;& operator falls through like ;& but executes the next
+  matching list instead of simply executing the next list.
+
 - The appending redirection operator &>>FILE is now available. It is a
   shorthand for: >>FILE 2>&1
 

NEWS

@@ -2,6 +2,12 @@ This documents significant changes in the dev branch of ksh 93u+m.
 For full details, see the git log at: https://github.com/ksh93/ksh
 Uppercase BUG_* IDs are shell bug IDs as used by the Modernish shell library.
 
+2025-04-29:
+
+- [v1.1] The 'case' compound command now supports the ;;& control operator
+  as on bash 4.0+. The ;;& operator falls through like ;& but executes the
+  next matching list instead of simply executing the next list.
+
 2025-04-27:
 
 - [v1.1] The emacs mode now accepts a numeric repeat parameter for ordinary

src/cmd/ksh93/include/shlex.h

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2011 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2024 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2025 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -133,6 +133,7 @@ typedef struct  _shlex_
 #define IOMOV0SYM	(SYMAMP|'<')
 #define IOMOV1SYM	(SYMAMP|'>')
 #define FALLTHRUSYM	(SYMAMP|';')
+#define FALLMATCHSYM	(SYMREP|SYMAMP|';')
 #define COOPSYM		(SYMAMP|'|')
 #define IORDWRSYM	(SYMGT|'<')
 #define IORDWRSYMT	(SYMSEMI|'<')

src/cmd/ksh93/include/version.h

@@ -18,7 +18,7 @@
 #include <ast_release.h>
 #include "git.h"
 
-#define SH_RELEASE_DATE	"2025-04-27"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2025-04-29"	/* must be in this format for $((.sh.version)) */
 /*
  * This comment keeps SH_RELEASE_DATE a few lines away from SH_RELEASE_SVER to avoid
  * merge conflicts when cherry-picking dev branch commits onto a release branch.

src/cmd/ksh93/sh.1

@@ -443,6 +443,15 @@ If
 is used in place of
 .B ;;
 the next subsequent list, if any,  is executed.
+If
+.B ;;&
+is used in place of
+.B ;;
+the subsequent list whose
+.I pattern\^
+matches
+.IR word ,
+if any, is executed.
 .TP
 \f3if\fP \f2list\^\fP \f3;then\fP \f2list\^\fP \*(OK \
 \f3;elif\fP \f2list\^\fP \f3;then\fP \f2list\^\fP \*(CK .\|.\|. \

src/cmd/ksh93/sh/deparse.c

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2011 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2024 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2025 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -597,7 +597,9 @@ static void p_switch(const struct regnod *reg)
 	if(reg->regcom)
 		p_tree(reg->regcom,0);
 	level++;
-	if(reg->regflag)
+	if(reg->regflag > 1)
+		p_keyword(";;&",END);
+	else if(reg->regflag)
 		p_keyword(";&",END);
 	else
 		p_keyword(";;",END);

src/cmd/ksh93/sh/lex.c

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2012 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2024 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2025 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -509,6 +509,12 @@ int sh_lex(Lex_t* lp)
 							return r;
 						}
 						c |= SYMREP;
+						/* Check for repeated operator character plus &, like ;;& (FALLMATCHSYM) */
+						fcgetc();
+						if(fcpeek(0)=='&')
+							c |= SYMAMP;
+						else
+							fcseek(-1);
 						/* Here document redirection operator '<<' */
 						if(c==IODOCSYM)
 							lp->lexd.docword = 1;
@@ -578,7 +584,7 @@ int sh_lex(Lex_t* lp)
 					if(n)
 					{
 						fcseek(1);
-						lp->lex.incase = (c==BREAKCASESYM || c==FALLTHRUSYM);
+						lp->lex.incase = (c==BREAKCASESYM || c==FALLTHRUSYM || c==FALLMATCHSYM);
 					}
 					else
 					{
@@ -2070,7 +2076,11 @@ static char	*fmttoken(Lex_t *lp, int sym)
 	stkfreeze(sh.stk,0);
 	sfputc(sh.stk,sym);
 	if(sym&SYMREP)
+	{
 		sfputc(sh.stk,sym);
+		if(sym&SYMAMP)
+			sfputc(sh.stk,'&');
+	}
 	else
 	{
 		switch(sym&SYMMASK)

src/cmd/ksh93/sh/parse.c

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2012 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2024 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2025 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -707,15 +707,18 @@ static struct regnod*	syncase(Lex_t *lexp,int esym)
 			sh_syntax(lexp,0);
 	}
 	r->regcom=sh_cmd(lexp,0,SH_NL|SH_EMPTY|SH_SEMI);
-	if((tok=lexp->token)==BREAKCASESYM)
-		r->regnxt=syncase(lexp,esym);
-	else if(tok==FALLTHRUSYM)
+	switch (tok = lexp->token)
 	{
+	case FALLMATCHSYM:	/* ;;& */
+		r->regflag++;
+		/* FALLTHROUGH */
+	case FALLTHRUSYM:	/* ;& */
 		r->regflag++;
+		/* FALLTHROUGH */
+	case BREAKCASESYM:	/* ;; */
 		r->regnxt=syncase(lexp,esym);
-	}
-	else
-	{
+		break;
+	default:
 		if(tok!=esym && tok!=EOFSYM)
 			sh_syntax(lexp,0);
 		r->regnxt=0;
@@ -1687,6 +1690,8 @@ static struct ionod	*inout(Lex_t *lexp,struct ionod *lastio,int flag)
 			else if(n>0)
 				fcseek(-1);
 		}
+		else if((token&UCHAR_MAX)!=token)  /* unhandled SYM* bits */
+			sh_syntax(lexp,0);
 		break;
 
 	    case '>':
@@ -1706,6 +1711,8 @@ static struct ionod	*inout(Lex_t *lexp,struct ionod *lastio,int flag)
 			iof |= IOLSEEK;
 		else if((token&SYMSEMI) == SYMSEMI)
 			iof |= IOREWRITE;
+		else if((token&UCHAR_MAX)!=token)  /* unhandled SYM* bits */
+			sh_syntax(lexp,0);
 		break;
 
 	    default:

src/cmd/ksh93/sh/xec.c

@@ -2221,10 +2221,11 @@ int sh_exec(const Shnode_t *t, int flags)
 						s = rex->argval;
 					if(raw && strcmp(r,s)==0 || !raw && strmatch(r,s))
 					{
-						do
+						do				/* execute; keep going while ;& */
 							sh_exec(t->reg.regcom, t->reg.regflag ? eflag : flags);
-						while(t->reg.regflag && (t = (Shnode_t*)t->reg.regnxt));
-						t=0;
+						while(t->reg.regflag==1 && (t = (Shnode_t*)t->reg.regnxt));
+						if(t && t->reg.regflag==0)	/* if not end or ;;& */
+							t = 0;			/* break outer loop */
 						break;
 					}
 					else

src/cmd/ksh93/tests/case.sh

@@ -2,7 +2,7 @@
 #                                                                      #
 #               This software is part of the ast package               #
 #          Copyright (c) 1982-2011 AT&T Intellectual Property          #
-#          Copyright (c) 2020-2024 Contributors to ksh 93u+m           #
+#          Copyright (c) 2020-2025 Contributors to ksh 93u+m           #
 #                      and is licensed under the                       #
 #                 Eclipse Public License, Version 2.0                  #
 #                                                                      #
@@ -195,5 +195,29 @@ got=$(set +x; eval '
 [[ $got == "$exp" ]] || err_exit "spurious syntax error in case with extended expression" \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
+# ======
+# ;;& -- fall through to next matching pattern -- new as of 93u+m/1.1
+got=
+case ${.sh.version} in
+*93u+m/1.[!0]* | *93u+m/[!1].* | 93u+m/?[!.]* )
+	eval '
+		case foo.txt in
+		foo*)	got+=yes1 ;;&
+		bar*)	got+=no1 ;;
+		*.txt)	got+=yes2 ;&
+		*.asc)	got+=yes3 ;;&
+		*.jpg)	got+=no2 ;;
+		*.gif)	got+=no3 ;;
+		*.tx*)	got+=yes4 ;;
+		*)	got+=no4 ;;
+		esac
+	'
+	exp=yes1yes2yes3yes4
+	[[ $got == "$exp" ]] || err_exit ";;& case operator" \
+		"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+	;;
+*)	warning ";;& operator supported as of 93u+m/1.1 but we're on ${.sh.version} -- skipping test"
+esac
+
 # ======
 exit $((Errors<125?Errors:125))