Disallow >;word and <>;word for 'redirect' (re: 7b59fb80, 7b82c338)

The >;word and <>;word redirection operators cannot be used with
the 'exec' builtin, but the 'redirect' builtin (which used to be
an alias of 'command exec') permitted them. However, they do not
have the documented effect of the added ';'. So this commit blocks
those operators for 'redirect' as they are blocked for 'exec'.

It also tweaks redirect's error message if a non-redirection
argument is encountered.

src/cmd/ksh93/sh/parse.c: simple():
- Set the lexp->inexec flag for SYSREDIR (redirect) as well as
  SYSEXEC (exec). This flag is checked for in sh_lex() (lex.c) to
  throw a syntax error if one of these two operators is used.

src/cmd/ksh93/sh.1, src/cmd/ksh93/data/builtins.c:
- Documentation tweaks.

src/cmd/ksh93/sh/xec.c, src/cmd/ksh93/bltins/misc.c:
- When 'redirect' gives an 'incorrect syntax' (e_badsyntax) error
  message, include the first word that was found not to be a valid
  redirection. This is simply the first argument, as redirections
  are removed from the arguments list.

src/cmd/ksh93/tests/io.sh:
- Update test to reflect new error message format.

src/cmd/ksh93/bltins/misc.c

@@ -110,7 +110,7 @@ int    b_exec(int argc,char *argv[], Shbltin_t *context)
 	if(error_info.errors)
 		errormsg(SH_DICT,ERROR_usage(2),"%s",optusage((char*)0));
 	if(*argv[0]=='r' && argv[opt_info.index])  /* 'redirect' supports no args */
-		errormsg(SH_DICT,ERROR_exit(2),e_badsyntax);
+		errormsg(SH_DICT,ERROR_exit(2),"%s: %s",e_badsyntax,argv[opt_info.index]);
 	argv += opt_info.index;
 	if(!*argv)
 		return(0);

src/cmd/ksh93/data/builtins.c

@@ -598,7 +598,7 @@ const char sh_optexec[] =
 "[+?Because \bexec\b is a special built-in command, any failure will cause the "
 	"script or command line that invokes it to be aborted. This can be "
 	"prevented by invoking \bexec\b from the \bcommand\b utility.]"
-"[+SEE ALSO?\bcommand\b(1), \beval\b(1), \bredirect(1)\b]"
+"[+SEE ALSO?\bcommand\b(1), \beval\b(1), \bredirect\b(1)]"
 ;
 
 const char sh_optexit[] =
@@ -1447,7 +1447,7 @@ const char sh_optreadonly[] =
 ;
 
 const char sh_optredirect[] =
-"[-1c?\n@(#)$Id: redirect (ksh 93u+m) 2020-08-08 $\n]"
+"[-1c?\n@(#)$Id: redirect (ksh 93u+m) 2021-02-06 $\n]"
 "[--catalog?" SH_DICT "]"
 "[+NAME?redirect - open/close and duplicate file descriptors]"
 "[+DESCRIPTION?This command only accepts input/output redirections. "
@@ -1455,9 +1455,10 @@ const char sh_optredirect[] =
 	"to \b9\b using the standard redirection mechanism available to all "
 	"commands, with the difference that the effect persists past the "
 	"execution of the \bredirect\b command.]"
-"[+?Any file descriptor numbers greater than \b2\b that are opened with this "
+"[+?When invoking another program, file descriptors greater than \b2\b that "
-	"mechanism are closed when invoking another program, unless "
+	"were opened with this mechanism are only passed on if they are "
-	"explicitly redirected to themselves as part of that invocation.]"
+	"explicitly redirected to themselves as part of the invocation "
+	"(e.g. \b4>&4\b) or if the \bposix\b option is set.]"
 "[+?\bredirect\b cannot be invoked from a restricted shell to create "
 	"files or to open a file for writing or appending.]"
 "\n"

src/cmd/ksh93/sh.1

@@ -3403,7 +3403,9 @@ otherwise, delete the temporary file.
 .BI >; word
 cannot be used with the
 .IR exec
-built-in.
+and
+.IR redirect
+built-ins.
 .TP
 .BI >> word
 Use file
@@ -3428,7 +3430,9 @@ is truncated to the offset at command completion.
 .BI <>; word
 cannot be used with the
 .IR exec
-built-in.
+and
+.IR redirect
+built-ins.
 .TP
 \f3<<\fP\*(OK\f3\-\fP\*(CK\f2word\fP
 The shell input is read up to a line that is the same as
@@ -6854,11 +6858,11 @@ section above),
 with the difference that the effect persists past the execution of the
 .B redirect
 command.
-Any file descriptor numbers greater than
+When invoking another program, file descriptors greater than
 .B 2
-that are opened with this mechanism are closed when invoking another program,
+that were opened with this mechanism are only passed on if they are explicitly
-unless they are explicitly redirected to themselves as part of that invocation
+redirected to themselves as part of the invocation (e.g. \fB4>&4\fR)
-(e.g. \fB4>&4\fR) or the \fBposix\fR shell option is active.
+or if the \fBposix\fR option is set.
 .TP
 \(dg \f3return\fP \*(OK \f2n\^\fP \*(CK
 Causes a shell

src/cmd/ksh93/sh/parse.c

@@ -1459,7 +1459,7 @@ static Shnode_t *simple(Lex_t *lexp,int flag, struct ionod *io)
 					}
 					else if(np==SYSCOMMAND && !sh_isoption(SH_POSIX))
 						cmdarg++;
-					else if(np==SYSEXEC)
+					else if(np==SYSEXEC || np==SYSREDIR)
 						lexp->inexec = 1;
 					else if(np->nvalue.bfp==(Nambfp_f)b_getopts)
 						opt_get |= FOPTGET;

src/cmd/ksh93/sh/xec.c

@@ -1277,7 +1277,8 @@ int sh_exec(register const Shnode_t *t, int flags)
 								if(!com[1])
 									type = 2;
 								else
-									errormsg(SH_DICT,ERROR_exit(2),"redirect: %s",e_badsyntax);
+									errormsg(SH_DICT, ERROR_exit(2), "%s: %s: %s",
+										 SYSREDIR->nvname, e_badsyntax, com[1]);
 							else
 								type = (execflg && !shp->subshell && !shp->st.trapcom[0]);
 							shp->redir0 = 1;

src/cmd/ksh93/tests/io.sh

@@ -528,7 +528,7 @@ actual=$(redirect 2>&- 3>&2; echo ok)
 [[ $actual == ok ]] || err_exit "redirection error in 'redirect' causes exit"
 
 # Test that 'redirect' does not accept non-redir args
-expect=$'*: redirect: incorrect syntax\n status = 2'
+expect=$'*: redirect: incorrect syntax: /dev/null/foo\n status = 2'
 actual=$( (redirect /dev/null/foo) 2>&1; echo " status = $?" );
 [[ $actual == $expect ]] || err_exit 'redirect command accepts non-redirection argument' \
 	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"