Fix octal number arguments in printf integer arithmetic

Bug 1: POSIX requires numbers used as arguments for all the %d,
%u... in printf to be interpreted as in the C language, so
	printf '%d\n' 010
should output 8 when the posix option is on. However, it outputs 10.

This bug was introduced as a side effect of a change introduced in
the 2012-02-07 version of ksh 93u+m, which caused the recognition
of leading-zero numbers as octal in arithmetic expressions to be
disabled outside ((...)) and $((...)). However, POSIX requires
leading-zero octal numbers to be recognised for printf, too.

The change in question introduced a sh.arith flag that is set while
we're processing a POSIX arithmetic expression, i.e., one that
recognises leading-zero octal numbers.
Bug 2: Said flag is not reset in a command substitution used within
an arithmetic expression. A command substitution should be a
completely new context, so the following should both output 10:

$ ksh -c 'integer x; x=010; echo $x'
10            # ok; it's outside ((…)) so octals are not recognised
$ ksh -c 'echo $(( $(integer x; x=010; echo $x) ))'
8             # bad; $(comsub) should create new non-((…)) context

src/cmd/ksh93/bltins/print.c: extend():
- For the u, d, i, o, x, and X conversion modifiers, set the POSIX
  arithmetic context flag before calling sh_strnum() to convert the
  argument. This fixes bug 1.

src/cmd/ksh93/sh/subshell.c: sh_subshell():
- When invoking a command substitution, save and unset the POSIX
  arithmetic context flag. Restore it at the end. This fixes bug 2.

Reported-by: @stephane-chazelas
Resolves: https://github.com/ksh93/ksh/issues/326

NEWS

@@ -3,6 +3,18 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-09-13:
+
+- Fixed a bug introduced in 93u+ 2012-02-07 that caused the 'printf' builtin
+  (and its 'print -f' equivalent) to fail to recognise integer arguments with a
+  leading zero as octal numbers. For example, 'printf "%d\n" 010' now once
+  again outputs '8' instead of '10'.
+
+- Disable the POSIX arithmetic context while running a command substitution
+  invoked from within an arithmetic expression. This fixes a bug that caused
+  integer arguments with a leading zero to be incorrectly interpreted as octal
+  numbers in non-POSIX arithmetic contexts within such command substitutions.
+
 2021-09-12:
 
 - When invoking a script without an interpreter/hashbang path on Linux and

src/cmd/ksh93/COMPATIBILITY

@@ -151,6 +151,11 @@ For more details, see the NEWS file and for complete details, see the git log.
 	correctly negates another '!', e.g., [[ ! ! 1 -eq 1 ]] now returns
 	0/true. Note that this has always been the case for 'test'/'['.
 
+28.	In the 'printf' builtin (and the 'print -f' equivalent), numeric
+	arguments with a leading zero are now once again recognized as octal
+	numbers as in ksh93 versions before 2012-02-07, and as POSIX requires.
+	For example, 'printf "%d\n" 010' now once again outputs '8'.
+
 ____________________________________________________________________________
 
 		KSH-93 VS. KSH-88

src/cmd/ksh93/bltins/print.c

@@ -882,7 +882,9 @@ static int extend(Sfio_t* sp, void* v, Sffmt_t* fe)
 				}
 				break;
 			default:
+				shp->inarith = 1;	/* POSIX compliance: recognize octal constants, e.g. printf '%d\n' 010 */
 				d = sh_strnum(argp,&lastchar,0);
+				shp->inarith = 0;
 				if(d<longmin)
 				{
 					errormsg(SH_DICT,ERROR_warn(0),e_overflow,argp);

src/cmd/ksh93/data/builtins.c

@@ -1193,7 +1193,7 @@ const char sh_optprint[] =
 ;
 
 const char sh_optprintf[] =
-"[-1c?\n@(#)$Id: printf (ksh 93u+m) 2020-08-10 $\n]"
+"[-1c?\n@(#)$Id: printf (ksh 93u+m) 2021-09-13 $\n]"
 "[--catalog?" SH_DICT "]"
 "[+NAME?printf - write formatted output]"
 "[+DESCRIPTION?\bprintf\b writes each \astring\a operand to "

src/cmd/ksh93/include/defs.h

@@ -204,7 +204,7 @@ struct shared
 	char		used_pos;	/* used positional parameter */\
 	char		universe; \
 	char		winch; \
-	char		inarith; 	/* set when in ((...)) */ \
+	char		inarith; 	/* set when in POSIX arith context, i.e. leading zero = octal, e.g. in ((...)) */ \
 	short		arithrecursion;	/* current arithmetic recursion level */ \
 	char		indebug; 	/* set when in debug trap */ \
 	unsigned char	ignsig;		/* ignored signal in subshell */ \

src/cmd/ksh93/include/version.h

@@ -21,7 +21,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-beta.2"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2021-09-12"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-09-13"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2021 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

src/cmd/ksh93/sh/subshell.c

@@ -470,6 +470,7 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 	struct rand *rp;		/* current $RANDOM discipline function data */
 	unsigned int save_rand_seed;	/* parent shell $RANDOM seed */
 	int save_rand_last;		/* last random number from $RANDOM in parent shell */
+	char save_inarith;		/* flag indicating POSIX arithmetic context */
 	memset((char*)sp, 0, sizeof(*sp));
 	sfsync(shp->outpool);
 	sh_sigcheck(shp);
@@ -591,6 +592,9 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 	{
 		if(comsub)
 		{
+			/* a comsub within an arithmetic expression must not itself be in an arithmetic context */
+			save_inarith = shp->inarith;
+			shp->inarith = 0;
 			/* disable job control */
 			shp->spid = 0;
 			sp->jobcontrol = job.jobcontrol;
@@ -734,6 +738,8 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 			sh_close(sp->tmpfd);
 		}
 		shp->fdstatus[1] = sp->fdstatus;
+		/* restore POSIX arithmetic context flag */
+		shp->inarith = save_inarith;
 	}
 	if(!shp->subshare)
 	{

src/cmd/ksh93/tests/arith.sh

@@ -876,5 +876,27 @@ then
 fi
 unset got
 
+# ======
+# https://github.com/ksh93/ksh/issues/326
+for m in u d i o x X
+do
+	case $m in
+	o)	exp="10;21;32;" ;;
+	x)	exp="8;11;1a;" ;;
+	X)	exp="8;11;1A;" ;;
+	*)	exp="8;17;26;" ;;
+	esac
+	got=${ printf "%$m;" 010 021 032; }
+	[[ $got == "$exp" ]] || err_exit "printf %$m does not recognize octal arguments" \
+		"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+done
+
+# https://github.com/ksh93/ksh/issues/326#issuecomment-917707463
+exp=18
+got=$(( $(integer x; x=010; echo $x) + 010 ))
+#		       ^^^ decimal     ^^^ octal
+[[ $got == "$exp" ]] || err_exit 'Integer with leading zero incorrectly interpreted as octal in non-POSIX arith context' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))