optget(3): Fix crash on unexpected long option value (re: 9fcd023)

@dnewhall reports:
> Found this while testing a very long optstring that had a typo.
>
> For the following snippet of code in opttest.ksh:
>
>	optstring="f(file)"
>	while getopts "$optstring" opt
>	do
>	    print -- "$opt: $OPTARG"
>	done
>
> If you accidentally add a parameter using =, you get a
> segmentation fault:
>
>	$ opttest.ksh --file=foo
>	Segmentation fault (core dumped)
>
> Obviously, calling with --file foo doesn't break it.
>
> (The correct optstring was supposed to be "f:(file)", which works.)

The bug is worse; the crash is also triggered for a correct options
string, when an option-argument is given for a long option that
doesn't expect one. For example, set --default=foo, ksh
--posix=foo, /opt/ast/bin/cp --preserve=foo all crash.

Analysis: In the referenced commit I incorrectly assumed that
nothing ever calles optnumber() with a third argument of NULL (int
*e, a pointer through which to pass back the value of errno before
restoring it), so that commit removed the check for e==NULL from
optget.c:4145. However, in optget.c:5242, there is an optnumber()
call I overlooked that does pass a third argument of NULL.

src/lib/libast/misc/optget.c: optnum():
- Restore the check for non-NULL e before dereferencing e.

Resolves: #794

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.
 
+2024-11-14:
+
+- Fixed a crash in option parsing upon encountering an option value to a
+  long option that doesn't accept one (e.g., 'set --state=foo' crashed).
+  Bug introduced on 2024-08-01.
+
 2024-11-02:
 
 - Fixed: assigning to TMOUT in a virtual subshell was rendering further

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	"1.1.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2024-11-03"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2024-11-14"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2024 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

src/cmd/ksh93/tests/builtins.sh

@@ -1729,5 +1729,24 @@ case $? in
 *)	err_exit "broken test" ;;
 esac
 
+# ======
+# https://github.com/ksh93/ksh/issues/794
+
+exp=$'issue794: --file: value not expected\n?: '
+got=$(set +x; { "$SHELL" -c '
+	optstring="f(file)"
+	while getopts "$optstring" opt
+	do
+	    print -- "$opt: $OPTARG"
+	done
+' issue794 --file=foo; } 2>&1)
+[[ e=$? -eq 0 && $got == "$exp" ]] || err_exit "crash on unexpected option value" \
+	"(expected status 0, $(printf %q "$exp");" \
+	"got status $e$( ((e>128)) && print -n /SIG && kill -l "$e"), $(printf %q "$got"))"
+
+got=$(set +x; { (ulimit -c 0; set --state=foo); } 2>&1)
+let "(e=$?) == 2" || err_exit "crash on unexpected option value" \
+	"(got status $e$( ((e>128)) && print -n /SIG && kill -l "$e"), $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))

src/cmd/ksh93/tests/libcmd.sh

@@ -905,5 +905,15 @@ if builtin getconf 2> /dev/null; then
 	[[ $exp == "$got" ]] || err_exit "'getconf -n' doesn't match names correctly" \
 		"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 fi
+
+# ======
+# https://github.com/ksh93/ksh/issues/794
+
+if builtin cp 2>/dev/null; then
+	got=$(set +x; { (ulimit -c 0; cp --preserve=foo); } 2>&1)
+	let "(e=$?) == 2" || err_exit "crash on unexpected option value" \
+		"(got status $e$( ((e>128)) && print -n /SIG && kill -l "$e"), $(printf %q "$got"))"
+fi
+
 # ======
 exit $((Errors<125?Errors:125))

src/lib/libast/misc/optget.c

@@ -4122,8 +4122,6 @@ optusage(const char* opts)
  * i.e., it looks octal but isn't, to meet
  * POSIX Utility Argument Syntax -- use
  * 0x.* or <base>#* for alternate bases
- *
- * NOTE: none of the pointer arguments may be NULL
  */
 
 static intmax_t     
@@ -4142,7 +4140,8 @@ optnumber(const char* s, char** t, int* e)
 		errno = 0;
 		n = strtonll(s, t, &lastbase, 0);
 	}
-	*e = errno;
+	if (e)
+		*e = errno;
 	errno = oerrno;
 	return n;
 }