From 382982ac00d81d9f71f1dbfeb670e544a6e56a55 Mon Sep 17 00:00:00 2001
From: Philippe Benard <phi.debian@gmail.com>
Date: Sat, 7 Jun 2025 19:21:57 +0200
Subject: [PATCH] bug-666:

TLDR;
- src/cmd/ksh93/include/shlex.h
  Implement yet another lex state funcalias, set to 1 when function
  keyword is an alias expansion.
- src/cmd/ksh93/sh/lex.c
  Allow alias expansion on word following a 'function ' expansion.
- src/cmd/ksh93/tests/alias.sh
  Update alias.sh to catch alias x='function ' failure.

Explanations:
Alias allows aliases to be chained while expanded alias value has a trailing
space.

Assuming
alias 'x=function ' y=f

Parsing
x y { echo :\); }

x is a simple cmd, a check for alias is done and is successfull we got
'function '
The parser then then enter funct() for parsing a function, the nex
token fetch is not a simple cmd anymore, no check for alias will be
done, next token is then y and become the function name.

To fix this, when expanding to 'function ' we need to setup a lexer
state, I called it funcalias in shlex.c, it is then set to 1 in
sh_lex()
When funct() parse y { ... the funcalias==1 allows a check for alias,
we then get the 'f' expansion and reset funcalias.
At this point other alias expansion are permitted, though hard to
follow.

$ alias 'x=function ' y=f z='{ ' t='echo ' u='AA '  v='}'
$ x y z t u v
$ f
AA
---
 src/cmd/ksh93/include/shlex.h |  1 +
 src/cmd/ksh93/sh/lex.c        | 36 ++++++++++++++++++++++++++++++++++-
 src/cmd/ksh93/tests/alias.sh  |  6 ++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/cmd/ksh93/include/shlex.h b/src/cmd/ksh93/include/shlex.h
index 0894a732f88f..e2eba00564a0 100644
--- a/src/cmd/ksh93/include/shlex.h
+++ b/src/cmd/ksh93/include/shlex.h
@@ -56,6 +56,7 @@ struct _shlex_pvt_lexdata_
 	char		warn;
 	char		message;
 	char		arith;
+	char		funcalias; /* bug-666: Phi: */
 	char 		*first;
 	int		level;
 	int		lastc;
diff --git a/src/cmd/ksh93/sh/lex.c b/src/cmd/ksh93/sh/lex.c
index 643fda58c444..ca2870562a48 100644
--- a/src/cmd/ksh93/sh/lex.c
+++ b/src/cmd/ksh93/sh/lex.c
@@ -1481,6 +1481,14 @@ int sh_lex(Lex_t* lp)
 		}
 	}
 	c = 0;
+	/*
+	 * bug-666: Phi:
+	 * 
+	 */
+	if(lp->lexd.funcalias==1)
+	{ goto check_alias;
+	}
+
 	if(!lp->lex.skipword)
 	{
 		if(n>1 && lp->lex.reservok==1 && mode==ST_NAME &&
@@ -1519,6 +1527,8 @@ int sh_lex(Lex_t* lp)
 		{
 			/* check for aliases */
 			Namval_t* np;
+
+		check_alias: /* bug-666: Phi: */
 			if(!lp->lex.incase && !assignment && fcpeek(0)!=LPAREN &&
 				(np=nv_search(state,sh.alias_tree,0))
 				&& !nv_isattr(np,NV_NOEXPAND)
@@ -1526,11 +1536,35 @@ int sh_lex(Lex_t* lp)
 				&& (!sh_isstate(SH_NOALIAS) || nv_isattr(np,NV_NOFREE))
 				&& (state=nv_getval(np)))
 			{
+				int t; /* bug-666: Phi: */
 				setupalias(lp,state,np);
 				nv_onattr(np,NV_NOEXPAND);
 				lp->lex.reservok = 1;
 				lp->assignok |= lp->lex.reservok;
-				return sh_lex(lp);
+				/*
+				 * bug-666: Phi: Check if we just expanded
+				 * "function " (i.e trailig space), if so we
+				 * got to set lp->lexd.funcalias=1;
+				 * so that next funct() will have a chance to
+				 * expand next word. The original return
+				 * below is replaced with the funcalias
+				 * setup
+				 */
+				/* return sh_lex(lp);  */
+				if(lp->lexd.funcalias==1)
+				{
+					lp->lexd.funcalias++;
+				}
+				t=sh_lex(lp);
+				if(strcmp(state,"function ")==0)
+				{
+					lp->lexd.funcalias=1;
+				}
+				else
+				{
+					lp->lexd.funcalias=0;
+				}
+				return t;
 			}
 		}
 		lp->lex.reservok = 0;
diff --git a/src/cmd/ksh93/tests/alias.sh b/src/cmd/ksh93/tests/alias.sh
index a349485fd449..1b27f65a0da5 100755
--- a/src/cmd/ksh93/tests/alias.sh
+++ b/src/cmd/ksh93/tests/alias.sh
@@ -319,5 +319,11 @@ chmod +x bad_func  # bug only triggered if file is executable
 (FPATH=$PWD; alias -t bad_func 2>/dev/null; typeset -f bad_func >/dev/null)
 (($? > 0)) || err_exit "'hash'/'alias -t' autoloads function"
 
+# bug-666: Phi:
+alias 'x=function ' y=f z='{ ' t='echo ' u='AA '  v='}'
+x y z t u v
+got=$(f)
+[ "$got" = 'AA' ] || err_exit "alias x='function ' not working"
+
 # ======
 exit $((Errors<125?Errors:125))