Adding upstream version 5.0.upstream/5.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1661 insertions, 0 deletions

diff --git a/expr.c b/expr.c
new file mode 100644
index 0000000..9edc8d9
--- /dev/null
+++ b/expr.c
@@ -0,0 +1,1661 @@
+/* expr.c -- arithmetic expression evaluation. */
+
+/* Copyright (C) 1990-2015 Free Software Foundation, Inc.
+
+   This file is part of GNU Bash, the Bourne Again SHell.
+
+   Bash is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   Bash is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with Bash.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ All arithmetic is done as intmax_t integers with no checking for overflow
+ (though division by 0 is caught and flagged as an error).
+
+ The following operators are handled, grouped into a set of levels in
+ order of decreasing precedence.
+
+	"id++", "id--"		[post-increment and post-decrement]
+	"-", "+"		[(unary operators)]
+	"++id", "--id"		[pre-increment and pre-decrement]
+	"!", "~"
+	"**"			[(exponentiation)]
+	"*", "/", "%"
+	"+", "-"
+	"<<", ">>"
+	"<=", ">=", "<", ">"
+	"==", "!="
+	"&"
+	"^"
+	"|"
+	"&&"
+	"||"
+	"expr ? expr : expr"
+	"=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="
+	,			[comma]
+
+ (Note that most of these operators have special meaning to bash, and an
+ entire expression should be quoted, e.g. "a=$a+1" or "a=a+1" to ensure
+ that it is passed intact to the evaluator when using `let'.  When using
+ the $[] or $(( )) forms, the text between the `[' and `]' or `((' and `))'
+ is treated as if in double quotes.)
+
+ Sub-expressions within parentheses have a precedence level greater than
+ all of the above levels and are evaluated first.  Within a single prece-
+ dence group, evaluation is left-to-right, except for the arithmetic
+ assignment operator (`='), which is evaluated right-to-left (as in C).
+
+ The expression evaluator returns the value of the expression (assignment
+ statements have as a value what is returned by the RHS).  The `let'
+ builtin, on the other hand, returns 0 if the last expression evaluates to
+ a non-zero, and 1 otherwise.
+
+ Implementation is a recursive-descent parser.
+
+ Chet Ramey
+ chet@po.cwru.edu
+*/
+
+#include "config.h"
+
+#include <stdio.h>
+#include "bashansi.h"
+
+#if defined (HAVE_UNISTD_H)
+#  ifdef _MINIX
+#    include <sys/types.h>
+#  endif
+#  include <unistd.h>
+#endif
+
+#include "chartypes.h"
+#include "bashintl.h"
+
+#include "shell.h"
+#include "arrayfunc.h"
+#include "execute_cmd.h"
+#include "flags.h"
+#include "subst.h"
+#include "typemax.h"		/* INTMAX_MAX, INTMAX_MIN */
+
+/* Because of the $((...)) construct, expressions may include newlines.
+   Here is a macro which accepts newlines, tabs and spaces as whitespace. */
+#define cr_whitespace(c) (whitespace(c) || ((c) == '\n'))
+
+/* Size be which the expression stack grows when necessary. */
+#define EXPR_STACK_GROW_SIZE 10
+
+/* Maximum amount of recursion allowed.  This prevents a non-integer
+   variable such as "num=num+2" from infinitely adding to itself when
+   "let num=num+2" is given. */
+#define MAX_EXPR_RECURSION_LEVEL 1024
+
+/* The Tokens.  Singing "The Lion Sleeps Tonight". */
+
+#define EQEQ	1	/* "==" */
+#define NEQ	2	/* "!=" */
+#define LEQ	3	/* "<=" */
+#define GEQ	4	/* ">=" */
+#define STR	5	/* string */
+#define NUM	6	/* number */
+#define LAND	7	/* "&&" Logical AND */
+#define LOR	8	/* "||" Logical OR */
+#define LSH	9	/* "<<" Left SHift */
+#define RSH    10	/* ">>" Right SHift */
+#define OP_ASSIGN 11	/* op= expassign as in Posix.2 */
+#define COND	12	/* exp1 ? exp2 : exp3 */
+#define POWER	13	/* exp1**exp2 */
+#define PREINC	14	/* ++var */
+#define PREDEC	15	/* --var */
+#define POSTINC	16	/* var++ */
+#define POSTDEC	17	/* var-- */
+#define EQ	'='
+#define GT	'>'
+#define LT	'<'
+#define PLUS	'+'
+#define MINUS	'-'
+#define MUL	'*'
+#define DIV	'/'
+#define MOD	'%'
+#define NOT	'!'
+#define LPAR	'('
+#define RPAR	')'
+#define BAND	'&'	/* Bitwise AND */
+#define BOR	'|'	/* Bitwise OR. */
+#define BXOR	'^'	/* Bitwise eXclusive OR. */
+#define BNOT	'~'	/* Bitwise NOT; Two's complement. */
+#define QUES	'?'
+#define COL	':'
+#define COMMA	','
+
+/* This should be the function corresponding to the operator with the
+   highest precedence. */
+#define EXP_HIGHEST	expcomma
+
+#ifndef MAX_INT_LEN
+#  define MAX_INT_LEN 32
+#endif
+
+struct lvalue
+{
+  char *tokstr;		/* possibly-rewritten lvalue if not NULL */
+  intmax_t tokval;	/* expression evaluated value */
+  SHELL_VAR *tokvar;	/* variable described by array or var reference */
+  intmax_t ind;		/* array index if not -1 */
+};
+
+/* A structure defining a single expression context. */
+typedef struct {
+  int curtok, lasttok;
+  char *expression, *tp, *lasttp;
+  intmax_t tokval;
+  char *tokstr;
+  int noeval;
+  struct lvalue lval;
+} EXPR_CONTEXT;
+
+static char	*expression;	/* The current expression */
+static char	*tp;		/* token lexical position */
+static char	*lasttp;	/* pointer to last token position */
+static int	curtok;		/* the current token */
+static int	lasttok;	/* the previous token */
+static int	assigntok;	/* the OP in OP= */
+static char	*tokstr;	/* current token string */
+static intmax_t	tokval;		/* current token value */
+static int	noeval;		/* set to 1 if no assignment to be done */
+static procenv_t evalbuf;
+
+/* set to 1 if the expression has already been run through word expansion */
+static int	already_expanded;
+
+static struct lvalue curlval = {0, 0, 0, -1};
+static struct lvalue lastlval = {0, 0, 0, -1};
+
+static int	_is_arithop __P((int));
+static void	readtok __P((void));	/* lexical analyzer */
+
+static void	init_lvalue __P((struct lvalue *));
+static struct lvalue *alloc_lvalue __P((void));
+static void	free_lvalue __P((struct lvalue *));
+
+static intmax_t	expr_streval __P((char *, int, struct lvalue *));
+static intmax_t	strlong __P((char *));
+static void	evalerror __P((const char *));
+
+static void	pushexp __P((void));
+static void	popexp __P((void));
+static void	expr_unwind __P((void));
+static void	expr_bind_variable __P((char *, char *));
+#if defined (ARRAY_VARS)
+static void	expr_bind_array_element __P((char *, arrayind_t, char *));
+#endif
+
+static intmax_t subexpr __P((char *));
+
+static intmax_t	expcomma __P((void));
+static intmax_t expassign __P((void));
+static intmax_t	expcond __P((void));
+static intmax_t explor __P((void));
+static intmax_t expland __P((void));
+static intmax_t	expbor __P((void));
+static intmax_t	expbxor __P((void));
+static intmax_t	expband __P((void));
+static intmax_t exp5 __P((void));
+static intmax_t exp4 __P((void));
+static intmax_t expshift __P((void));
+static intmax_t exp3 __P((void));
+static intmax_t expmuldiv __P((void));
+static intmax_t	exppower __P((void));
+static intmax_t exp1 __P((void));
+static intmax_t exp0 __P((void));
+
+/* Global var which contains the stack of expression contexts. */
+static EXPR_CONTEXT **expr_stack;
+static int expr_depth;		   /* Location in the stack. */
+static int expr_stack_size;	   /* Number of slots already allocated. */
+
+#if defined (ARRAY_VARS)
+extern const char * const bash_badsub_errmsg;
+#endif
+
+#define SAVETOK(X) \
+  do { \
+    (X)->curtok = curtok; \
+    (X)->lasttok = lasttok; \
+    (X)->tp = tp; \
+    (X)->lasttp = lasttp; \
+    (X)->tokval = tokval; \
+    (X)->tokstr = tokstr; \
+    (X)->noeval = noeval; \
+    (X)->lval = curlval; \
+  } while (0)
+
+#define RESTORETOK(X) \
+  do { \
+    curtok = (X)->curtok; \
+    lasttok = (X)->lasttok; \
+    tp = (X)->tp; \
+    lasttp = (X)->lasttp; \
+    tokval = (X)->tokval; \
+    tokstr = (X)->tokstr; \
+    noeval = (X)->noeval; \
+    curlval = (X)->lval; \
+  } while (0)
+
+/* Push and save away the contents of the globals describing the
+   current expression context. */
+static void
+pushexp ()
+{
+  EXPR_CONTEXT *context;
+
+  if (expr_depth >= MAX_EXPR_RECURSION_LEVEL)
+    evalerror (_("expression recursion level exceeded"));
+
+  if (expr_depth >= expr_stack_size)
+    {
+      expr_stack_size += EXPR_STACK_GROW_SIZE;
+      expr_stack = (EXPR_CONTEXT **)xrealloc (expr_stack, expr_stack_size * sizeof (EXPR_CONTEXT *));
+    }
+
+  context = (EXPR_CONTEXT *)xmalloc (sizeof (EXPR_CONTEXT));
+
+  context->expression = expression;
+  SAVETOK(context);
+
+  expr_stack[expr_depth++] = context;
+}
+
+/* Pop the the contents of the expression context stack into the
+   globals describing the current expression context. */
+static void
+popexp ()
+{
+  EXPR_CONTEXT *context;
+
+  if (expr_depth <= 0)
+    {
+      /* See the comment at the top of evalexp() for an explanation of why
+	 this is done. */
+      expression = lasttp = 0;
+      evalerror (_("recursion stack underflow"));
+    }
+
+  context = expr_stack[--expr_depth];
+
+  expression = context->expression;
+  RESTORETOK (context);
+
+  free (context);
+}
+
+static void
+expr_unwind ()
+{
+  while (--expr_depth > 0)
+    {
+      if (expr_stack[expr_depth]->tokstr)
+	free (expr_stack[expr_depth]->tokstr);
+
+      if (expr_stack[expr_depth]->expression)
+	free (expr_stack[expr_depth]->expression);
+
+      free (expr_stack[expr_depth]);
+    }
+  if (expr_depth == 0)
+    free (expr_stack[expr_depth]);	/* free the allocated EXPR_CONTEXT */
+
+  noeval = 0;	/* XXX */
+}
+
+static void
+expr_bind_variable (lhs, rhs)
+     char *lhs, *rhs;
+{
+  SHELL_VAR *v;
+  int aflags;
+
+  if (lhs == 0 || *lhs == 0)
+    return;		/* XXX */
+
+#if defined (ARRAY_VARS)
+  aflags = (assoc_expand_once && already_expanded) ? ASS_NOEXPAND : 0;
+#else
+  aflags = 0;
+#endif
+  v = bind_int_variable (lhs, rhs, aflags);
+  if (v && (readonly_p (v) || noassign_p (v)))
+    sh_longjmp (evalbuf, 1);	/* variable assignment error */
+  stupidly_hack_special_variables (lhs);
+}
+
+#if defined (ARRAY_VARS)
+/* This is similar to the logic in arrayfunc.c:valid_array_subscript when
+   you pass VA_NOEXPAND. */
+static int
+expr_skipsubscript (vp, cp)
+     char *vp, *cp;
+{
+  int flags, isassoc;
+  SHELL_VAR *entry;
+
+  isassoc = 0;
+  entry = 0;
+  if (assoc_expand_once & already_expanded)
+    {
+      *cp = '\0';
+      isassoc = legal_identifier (vp) && (entry = find_variable (vp)) && assoc_p (entry);
+      *cp = '[';	/* ] */
+    }
+  flags = (isassoc && assoc_expand_once && already_expanded) ? VA_NOEXPAND : 0;
+  return (skipsubscript (cp, 0, flags));
+}
+
+/* Rewrite tok, which is of the form vname[expression], to vname[ind], where
+   IND is the already-calculated value of expression. */
+static void
+expr_bind_array_element (tok, ind, rhs)
+     char *tok;
+     arrayind_t ind;
+     char *rhs;
+{
+  char *lhs, *vname;
+  size_t llen;
+  char ibuf[INT_STRLEN_BOUND (arrayind_t) + 1], *istr;
+
+  istr = fmtumax (ind, 10, ibuf, sizeof (ibuf), 0);
+  vname = array_variable_name (tok, 0, (char **)NULL, (int *)NULL);
+
+  llen = strlen (vname) + sizeof (ibuf) + 3;
+  lhs = xmalloc (llen);
+
+  sprintf (lhs, "%s[%s]", vname, istr);		/* XXX */
+  
+/*itrace("expr_bind_array_element: %s=%s", lhs, rhs);*/
+  expr_bind_variable (lhs, rhs);
+  free (vname);
+  free (lhs);
+}
+#endif /* ARRAY_VARS */
+
+/* Evaluate EXPR, and return the arithmetic result.  If VALIDP is
+   non-null, a zero is stored into the location to which it points
+   if the expression is invalid, non-zero otherwise.  If a non-zero
+   value is returned in *VALIDP, the return value of evalexp() may
+   be used.
+
+   The `while' loop after the longjmp is caught relies on the above
+   implementation of pushexp and popexp leaving in expr_stack[0] the
+   values that the variables had when the program started.  That is,
+   the first things saved are the initial values of the variables that
+   were assigned at program startup or by the compiler.  Therefore, it is
+   safe to let the loop terminate when expr_depth == 0, without freeing up
+   any of the expr_depth[0] stuff. */
+intmax_t
+evalexp (expr, flags, validp)
+     char *expr;
+     int flags;
+     int *validp;
+{
+  intmax_t val;
+  int c;
+  procenv_t oevalbuf;
+
+  val = 0;
+  noeval = 0;
+  already_expanded = (flags&EXP_EXPANDED);
+
+  FASTCOPY (evalbuf, oevalbuf, sizeof (evalbuf));
+
+  c = setjmp_nosigs (evalbuf);
+
+  if (c)
+    {
+      FREE (tokstr);
+      FREE (expression);
+      tokstr = expression = (char *)NULL;
+
+      expr_unwind ();
+      expr_depth = 0;	/* XXX - make sure */
+
+      /* We copy in case we've called evalexp recursively */
+      FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf));
+
+      if (validp)
+	*validp = 0;
+      return (0);
+    }
+
+  val = subexpr (expr);
+
+  if (validp)
+    *validp = 1;
+
+  FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf));
+
+  return (val);
+}
+
+static intmax_t
+subexpr (expr)
+     char *expr;
+{
+  intmax_t val;
+  char *p;
+
+  for (p = expr; p && *p && cr_whitespace (*p); p++)
+    ;
+
+  if (p == NULL || *p == '\0')
+    return (0);
+
+  pushexp ();
+  expression = savestring (expr);
+  tp = expression;
+
+  curtok = lasttok = 0;
+  tokstr = (char *)NULL;
+  tokval = 0;
+  init_lvalue (&curlval);
+  lastlval = curlval;
+
+  readtok ();
+
+  val = EXP_HIGHEST ();
+
+  if (curtok != 0)
+    evalerror (_("syntax error in expression"));
+
+  FREE (tokstr);
+  FREE (expression);
+
+  popexp ();
+
+  return val;
+}
+
+static intmax_t
+expcomma ()
+{
+  register intmax_t value;
+
+  value = expassign ();
+  while (curtok == COMMA)
+    {
+      readtok ();
+      value = expassign ();
+    }
+
+  return value;
+}
+  
+static intmax_t
+expassign ()
+{
+  register intmax_t value;
+  char *lhs, *rhs;
+  arrayind_t lind;
+#if defined (HAVE_IMAXDIV)
+  imaxdiv_t idiv;
+#endif
+
+  value = expcond ();
+  if (curtok == EQ || curtok == OP_ASSIGN)
+    {
+      int special, op;
+      intmax_t lvalue;
+
+      special = curtok == OP_ASSIGN;
+
+      if (lasttok != STR)
+	evalerror (_("attempted assignment to non-variable"));
+
+      if (special)
+	{
+	  op = assigntok;		/* a OP= b */
+	  lvalue = value;
+	}
+
+      if (tokstr == 0)
+	evalerror (_("syntax error in variable assignment"));
+
+      /* XXX - watch out for pointer aliasing issues here */
+      lhs = savestring (tokstr);
+      /* save ind in case rhs is string var and evaluation overwrites it */
+      lind = curlval.ind;
+      readtok ();
+      value = expassign ();
+
+      if (special)
+	{
+	  if ((op == DIV || op == MOD) && value == 0)
+	    {
+	      if (noeval == 0)
+		evalerror (_("division by 0"));
+	      else
+	        value = 1;
+	    }
+
+	  switch (op)
+	    {
+	    case MUL:
+	      lvalue *= value;
+	      break;
+	    case DIV:
+	    case MOD:
+	      if (lvalue == INTMAX_MIN && value == -1)
+		lvalue = (op == DIV) ? INTMAX_MIN : 0;
+	      else
+#if HAVE_IMAXDIV
+		{
+		  idiv = imaxdiv (lvalue, value);
+		  lvalue = (op == DIV) ? idiv.quot : idiv.rem;
+		}
+#else
+	        lvalue = (op == DIV) ? lvalue / value : lvalue % value;
+#endif
+	      break;
+	    case PLUS:
+	      lvalue += value;
+	      break;
+	    case MINUS:
+	      lvalue -= value;
+	      break;
+	    case LSH:
+	      lvalue <<= value;
+	      break;
+	    case RSH:
+	      lvalue >>= value;
+	      break;
+	    case BAND:
+	      lvalue &= value;
+	      break;
+	    case BOR:
+	      lvalue |= value;
+	      break;
+	    case BXOR:
+	      lvalue ^= value;
+	      break;
+	    default:
+	      free (lhs);
+	      evalerror (_("bug: bad expassign token"));
+	      break;
+	    }
+	  value = lvalue;
+	}
+
+      rhs = itos (value);
+      if (noeval == 0)
+	{
+#if defined (ARRAY_VARS)
+	  if (lind != -1)
+	    expr_bind_array_element (lhs, lind, rhs);
+	  else
+#endif
+	    expr_bind_variable (lhs, rhs);
+	}
+      if (curlval.tokstr && curlval.tokstr == tokstr)
+	init_lvalue (&curlval);
+
+      free (rhs);
+      free (lhs);
+      FREE (tokstr);
+      tokstr = (char *)NULL;		/* For freeing on errors. */
+    }
+
+  return (value);
+}
+
+/* Conditional expression (expr?expr:expr) */
+static intmax_t
+expcond ()
+{
+  intmax_t cval, val1, val2, rval;
+  int set_noeval;
+
+  set_noeval = 0;
+  rval = cval = explor ();
+  if (curtok == QUES)		/* found conditional expr */
+    {
+      if (cval == 0)
+	{
+	  set_noeval = 1;
+	  noeval++;
+	}
+
+      readtok ();
+      if (curtok == 0 || curtok == COL)
+	evalerror (_("expression expected"));
+
+      val1 = EXP_HIGHEST ();
+
+      if (set_noeval)
+	noeval--;
+      if (curtok != COL)
+	evalerror (_("`:' expected for conditional expression"));
+
+      set_noeval = 0;
+      if (cval)
+ 	{
+ 	  set_noeval = 1;
+	  noeval++;
+ 	}
+
+      readtok ();
+      if (curtok == 0)
+	evalerror (_("expression expected"));
+      val2 = expcond ();
+
+      if (set_noeval)
+	noeval--;
+      rval = cval ? val1 : val2;
+      lasttok = COND;
+    }
+  return rval;
+}
+
+/* Logical OR. */
+static intmax_t
+explor ()
+{
+  register intmax_t val1, val2;
+  int set_noeval;
+
+  val1 = expland ();
+
+  while (curtok == LOR)
+    {
+      set_noeval = 0;
+      if (val1 != 0)
+	{
+	  noeval++;
+	  set_noeval = 1;
+	}
+      readtok ();
+      val2 = expland ();
+      if (set_noeval)
+	noeval--;
+      val1 = val1 || val2;
+      lasttok = LOR;
+    }
+
+  return (val1);
+}
+
+/* Logical AND. */
+static intmax_t
+expland ()
+{
+  register intmax_t val1, val2;
+  int set_noeval;
+
+  val1 = expbor ();
+
+  while (curtok == LAND)
+    {
+      set_noeval = 0;
+      if (val1 == 0)
+	{
+	  set_noeval = 1;
+	  noeval++;
+	}
+      readtok ();
+      val2 = expbor ();
+      if (set_noeval)
+	noeval--;
+      val1 = val1 && val2;
+      lasttok = LAND;
+    }
+
+  return (val1);
+}
+
+/* Bitwise OR. */
+static intmax_t
+expbor ()
+{
+  register intmax_t val1, val2;
+
+  val1 = expbxor ();
+
+  while (curtok == BOR)
+    {
+      readtok ();
+      val2 = expbxor ();
+      val1 = val1 | val2;
+      lasttok = NUM;
+    }
+
+  return (val1);
+}
+
+/* Bitwise XOR. */
+static intmax_t
+expbxor ()
+{
+  register intmax_t val1, val2;
+
+  val1 = expband ();
+
+  while (curtok == BXOR)
+    {
+      readtok ();
+      val2 = expband ();
+      val1 = val1 ^ val2;
+      lasttok = NUM;
+    }
+
+  return (val1);
+}
+
+/* Bitwise AND. */
+static intmax_t
+expband ()
+{
+  register intmax_t val1, val2;
+
+  val1 = exp5 ();
+
+  while (curtok == BAND)
+    {
+      readtok ();
+      val2 = exp5 ();
+      val1 = val1 & val2;
+      lasttok = NUM;
+    }
+
+  return (val1);
+}
+
+static intmax_t
+exp5 ()
+{
+  register intmax_t val1, val2;
+
+  val1 = exp4 ();
+
+  while ((curtok == EQEQ) || (curtok == NEQ))
+    {
+      int op = curtok;
+
+      readtok ();
+      val2 = exp4 ();
+      if (op == EQEQ)
+	val1 = (val1 == val2);
+      else if (op == NEQ)
+	val1 = (val1 != val2);
+      lasttok = NUM;
+    }
+  return (val1);
+}
+
+static intmax_t
+exp4 ()
+{
+  register intmax_t val1, val2;
+
+  val1 = expshift ();
+  while ((curtok == LEQ) ||
+	 (curtok == GEQ) ||
+	 (curtok == LT) ||
+	 (curtok == GT))
+    {
+      int op = curtok;
+
+      readtok ();
+      val2 = expshift ();
+
+      if (op == LEQ)
+	val1 = val1 <= val2;
+      else if (op == GEQ)
+	val1 = val1 >= val2;
+      else if (op == LT)
+	val1 = val1 < val2;
+      else			/* (op == GT) */
+	val1 = val1 > val2;
+      lasttok = NUM;
+    }
+  return (val1);
+}
+
+/* Left and right shifts. */
+static intmax_t
+expshift ()
+{
+  register intmax_t val1, val2;
+
+  val1 = exp3 ();
+
+  while ((curtok == LSH) || (curtok == RSH))
+    {
+      int op = curtok;
+
+      readtok ();
+      val2 = exp3 ();
+
+      if (op == LSH)
+	val1 = val1 << val2;
+      else
+	val1 = val1 >> val2;
+      lasttok = NUM;
+    }
+
+  return (val1);
+}
+
+static intmax_t
+exp3 ()
+{
+  register intmax_t val1, val2;
+
+  val1 = expmuldiv ();
+
+  while ((curtok == PLUS) || (curtok == MINUS))
+    {
+      int op = curtok;
+
+      readtok ();
+      val2 = expmuldiv ();
+
+      if (op == PLUS)
+	val1 += val2;
+      else if (op == MINUS)
+	val1 -= val2;
+      lasttok = NUM;
+    }
+  return (val1);
+}
+
+static intmax_t
+expmuldiv ()
+{
+  register intmax_t val1, val2;
+#if defined (HAVE_IMAXDIV)
+  imaxdiv_t idiv;
+#endif
+
+  val1 = exppower ();
+
+  while ((curtok == MUL) ||
+	 (curtok == DIV) ||
+	 (curtok == MOD))
+    {
+      int op = curtok;
+      char *stp, *sltp;
+
+      stp = tp;
+      readtok ();
+
+      val2 = exppower ();
+
+      /* Handle division by 0 and twos-complement arithmetic overflow */
+      if (((op == DIV) || (op == MOD)) && (val2 == 0))
+	{
+	  if (noeval == 0)
+	    {
+	      sltp = lasttp;
+	      lasttp = stp;
+	      while (lasttp && *lasttp && whitespace (*lasttp))
+		lasttp++;
+	      evalerror (_("division by 0"));
+	      lasttp = sltp;
+	    }
+	  else
+	    val2 = 1;
+	}
+      else if (op == MOD && val1 == INTMAX_MIN && val2 == -1)
+	{
+	  val1 = 0;
+	  continue;
+	}
+      else if (op == DIV && val1 == INTMAX_MIN && val2 == -1)
+	val2 = 1;
+
+      if (op == MUL)
+	val1 *= val2;
+      else if (op == DIV || op == MOD)
+#if defined (HAVE_IMAXDIV)
+	{
+	  idiv = imaxdiv (val1, val2);
+	  val1 = (op == DIV) ? idiv.quot : idiv.rem;
+	}
+#else
+	val1 = (op == DIV) ? val1 / val2 : val1 % val2;
+#endif
+      lasttok = NUM;
+    }
+  return (val1);
+}
+
+static intmax_t
+ipow (base, exp)
+     intmax_t base, exp;
+{
+  intmax_t result;
+
+  result = 1;
+  while (exp)
+    {
+      if (exp & 1)
+	result *= base;
+      exp >>= 1;
+      base *= base;
+    }
+  return result;
+}
+
+static intmax_t
+exppower ()
+{
+  register intmax_t val1, val2, c;
+
+  val1 = exp1 ();
+  while (curtok == POWER)
+    {
+      readtok ();
+      val2 = exppower ();	/* exponentiation is right-associative */
+      lasttok = NUM;
+      if (val2 == 0)
+	return (1);
+      if (val2 < 0)
+	evalerror (_("exponent less than 0"));
+      val1 = ipow (val1, val2);
+    }
+  return (val1);
+}
+
+static intmax_t
+exp1 ()
+{
+  register intmax_t val;
+
+  if (curtok == NOT)
+    {
+      readtok ();
+      val = !exp1 ();
+      lasttok = NUM;
+    }
+  else if (curtok == BNOT)
+    {
+      readtok ();
+      val = ~exp1 ();
+      lasttok = NUM;
+    }
+  else if (curtok == MINUS)
+    {
+      readtok ();
+      val = - exp1 ();
+      lasttok = NUM;
+    }
+  else if (curtok == PLUS)
+    {
+      readtok ();
+      val = exp1 ();
+      lasttok = NUM;
+    }
+  else
+    val = exp0 ();
+
+  return (val);
+}
+
+static intmax_t
+exp0 ()
+{
+  register intmax_t val = 0, v2;
+  char *vincdec;
+  int stok;
+  EXPR_CONTEXT ec;
+
+  /* XXX - might need additional logic here to decide whether or not
+	   pre-increment or pre-decrement is legal at this point. */
+  if (curtok == PREINC || curtok == PREDEC)
+    {
+      stok = lasttok = curtok;
+      readtok ();
+      if (curtok != STR)
+	/* readtok() catches this */
+	evalerror (_("identifier expected after pre-increment or pre-decrement"));
+
+      v2 = tokval + ((stok == PREINC) ? 1 : -1);
+      vincdec = itos (v2);
+      if (noeval == 0)
+	{
+#if defined (ARRAY_VARS)
+	  if (curlval.ind != -1)
+	    expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
+	  else
+#endif
+	    if (tokstr)
+	      expr_bind_variable (tokstr, vincdec);
+	}
+      free (vincdec);
+      val = v2;
+
+      curtok = NUM;	/* make sure --x=7 is flagged as an error */
+      readtok ();
+    }
+  else if (curtok == LPAR)
+    {
+      /* XXX - save curlval here?  Or entire expression context? */
+      readtok ();
+      val = EXP_HIGHEST ();
+
+      if (curtok != RPAR) /* ( */
+	evalerror (_("missing `)'"));
+
+      /* Skip over closing paren. */
+      readtok ();
+    }
+  else if ((curtok == NUM) || (curtok == STR))
+    {
+      val = tokval;
+      if (curtok == STR)
+	{
+	  SAVETOK (&ec);
+	  tokstr = (char *)NULL;	/* keep it from being freed */
+          noeval = 1;
+          readtok ();
+          stok = curtok;
+
+	  /* post-increment or post-decrement */
+ 	  if (stok == POSTINC || stok == POSTDEC)
+ 	    {
+ 	      /* restore certain portions of EC */
+ 	      tokstr = ec.tokstr;
+ 	      noeval = ec.noeval;
+ 	      curlval = ec.lval;
+ 	      lasttok = STR;	/* ec.curtok */
+
+	      v2 = val + ((stok == POSTINC) ? 1 : -1);
+	      vincdec = itos (v2);
+	      if (noeval == 0)
+		{
+#if defined (ARRAY_VARS)
+		  if (curlval.ind != -1)
+		    expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
+		  else
+#endif
+		    expr_bind_variable (tokstr, vincdec);
+		}
+	      free (vincdec);
+	      curtok = NUM;	/* make sure x++=7 is flagged as an error */
+ 	    }
+ 	  else
+ 	    {
+	      /* XXX - watch out for pointer aliasing issues here */
+	      if (stok == STR)	/* free new tokstr before old one is restored */
+		FREE (tokstr);
+	      RESTORETOK (&ec);
+ 	    }
+	}
+	  
+      readtok ();
+    }
+  else
+    evalerror (_("syntax error: operand expected"));
+
+  return (val);
+}
+
+static void
+init_lvalue (lv)
+     struct lvalue *lv;
+{
+  lv->tokstr = 0;
+  lv->tokvar = 0;
+  lv->tokval = lv->ind = -1;
+}
+
+static struct lvalue *
+alloc_lvalue ()
+{
+  struct lvalue *lv;
+
+  lv = xmalloc (sizeof (struct lvalue));
+  init_lvalue (lv);
+  return (lv);
+}
+
+static void
+free_lvalue (lv)
+     struct lvalue *lv;
+{
+  free (lv);		/* should be inlined */
+}
+
+static intmax_t
+expr_streval (tok, e, lvalue)
+     char *tok;
+     int e;
+     struct lvalue *lvalue;
+{
+  SHELL_VAR *v;
+  char *value;
+  intmax_t tval;
+  int initial_depth;
+#if defined (ARRAY_VARS)
+  arrayind_t ind;
+  int tflag, aflag;
+#endif
+
+/*itrace("expr_streval: %s: noeval = %d expanded=%d", tok, noeval, already_expanded);*/
+  /* If we are suppressing evaluation, just short-circuit here instead of
+     going through the rest of the evaluator. */
+  if (noeval)
+    return (0);
+
+  initial_depth = expr_depth;
+
+#if defined (ARRAY_VARS)
+  tflag = assoc_expand_once && already_expanded;	/* for a start */
+#endif
+
+  /* [[[[[ */
+#if defined (ARRAY_VARS)
+  aflag = (tflag) ? AV_NOEXPAND : 0;
+  v = (e == ']') ? array_variable_part (tok, tflag, (char **)0, (int *)0) : find_variable (tok);
+#else
+  v = find_variable (tok);
+#endif
+
+  if ((v == 0 || invisible_p (v)) && unbound_vars_is_error)
+    {
+#if defined (ARRAY_VARS)
+      value = (e == ']') ? array_variable_name (tok, tflag, (char **)0, (int *)0) : tok;
+#else
+      value = tok;
+#endif
+
+      last_command_exit_value = EXECUTION_FAILURE;
+      err_unboundvar (value);
+
+#if defined (ARRAY_VARS)
+      if (e == ']')
+	FREE (value);	/* array_variable_name returns new memory */
+#endif
+
+      if (no_longjmp_on_fatal_error && interactive_shell)
+	sh_longjmp (evalbuf, 1);
+
+      if (interactive_shell)
+	{
+	  expr_unwind ();
+	  top_level_cleanup ();
+	  jump_to_top_level (DISCARD);
+	}
+      else
+	jump_to_top_level (FORCE_EOF);
+    }
+
+#if defined (ARRAY_VARS)
+  ind = -1;
+  /* If the second argument to get_array_value doesn't include AV_ALLOWALL,
+     we don't allow references like array[@].  In this case, get_array_value
+     is just like get_variable_value in that it does not return newly-allocated
+     memory or quote the results.  AFLAG is set above and is either AV_NOEXPAND
+     or 0. */
+  value = (e == ']') ? get_array_value (tok, aflag, (int *)NULL, &ind) : get_variable_value (v);
+#else
+  value = get_variable_value (v);
+#endif
+
+  if (expr_depth < initial_depth)
+    {
+      if (no_longjmp_on_fatal_error && interactive_shell)
+	sh_longjmp (evalbuf, 1);
+      return (0);
+    }
+
+  tval = (value && *value) ? subexpr (value) : 0;
+
+  if (lvalue)
+    {
+      lvalue->tokstr = tok;	/* XXX */
+      lvalue->tokval = tval;
+      lvalue->tokvar = v;	/* XXX */
+#if defined (ARRAY_VARS)
+      lvalue->ind = ind;
+#else
+      lvalue->ind = -1;
+#endif
+    }
+	  
+  return (tval);
+}
+
+static int
+_is_multiop (c)
+     int c;
+{
+  switch (c)
+    {
+    case EQEQ:
+    case NEQ:
+    case LEQ:
+    case GEQ:
+    case LAND:
+    case LOR:
+    case LSH:
+    case RSH:
+    case OP_ASSIGN:
+    case COND:
+    case POWER:
+    case PREINC:
+    case PREDEC:
+    case POSTINC:
+    case POSTDEC:
+      return 1;
+    default:
+      return 0;
+    }
+}
+
+static int
+_is_arithop (c)
+     int c;
+{
+  switch (c)
+    {
+    case EQ:
+    case GT:
+    case LT:
+    case PLUS:
+    case MINUS:
+    case MUL:
+    case DIV:
+    case MOD:
+    case NOT:
+    case LPAR:
+    case RPAR:
+    case BAND:
+    case BOR:
+    case BXOR:
+    case BNOT:
+      return 1;		/* operator tokens */
+    case QUES:
+    case COL:
+    case COMMA:
+      return 1;		/* questionable */
+    default:
+      return 0;		/* anything else is invalid */
+    }
+}
+
+/* Lexical analyzer/token reader for the expression evaluator.  Reads the
+   next token and puts its value into curtok, while advancing past it.
+   Updates value of tp.  May also set tokval (for number) or tokstr (for
+   string). */
+static void
+readtok ()
+{
+  register char *cp, *xp;
+  register unsigned char c, c1;
+  register int e;
+  struct lvalue lval;
+
+  /* Skip leading whitespace. */
+  cp = tp;
+  c = e = 0;
+  while (cp && (c = *cp) && (cr_whitespace (c)))
+    cp++;
+
+  if (c)
+    cp++;
+
+  if (c == '\0')
+    {
+      lasttok = curtok;
+      curtok = 0;
+      tp = cp;
+      return;
+    }
+  lasttp = tp = cp - 1;
+
+  if (legal_variable_starter (c))
+    {
+      /* variable names not preceded with a dollar sign are shell variables. */
+      char *savecp;
+      EXPR_CONTEXT ec;
+      int peektok;
+
+      while (legal_variable_char (c))
+	c = *cp++;
+
+      c = *--cp;
+
+#if defined (ARRAY_VARS)
+      if (c == '[')
+	{
+	  e = expr_skipsubscript (tp, cp);		/* XXX - was skipsubscript */
+	  if (cp[e] == ']')
+	    {
+	      cp += e + 1;
+	      c = *cp;
+	      e = ']';
+	    }
+	  else
+	    evalerror (bash_badsub_errmsg);
+	}
+#endif /* ARRAY_VARS */
+
+      *cp = '\0';
+      /* XXX - watch out for pointer aliasing issues here */
+      if (curlval.tokstr && curlval.tokstr == tokstr)
+	init_lvalue (&curlval);
+
+      FREE (tokstr);
+      tokstr = savestring (tp);
+      *cp = c;
+
+      /* XXX - make peektok part of saved token state? */
+      SAVETOK (&ec);
+      tokstr = (char *)NULL;	/* keep it from being freed */
+      tp = savecp = cp;
+      noeval = 1;
+      curtok = STR;
+      readtok ();
+      peektok = curtok;
+      if (peektok == STR)	/* free new tokstr before old one is restored */
+	FREE (tokstr);
+      RESTORETOK (&ec);
+      cp = savecp;
+
+      /* The tests for PREINC and PREDEC aren't strictly correct, but they
+	 preserve old behavior if a construct like --x=9 is given. */
+      if (lasttok == PREINC || lasttok == PREDEC || peektok != EQ)
+        {
+          lastlval = curlval;
+	  tokval = expr_streval (tokstr, e, &curlval);
+        }
+      else
+	tokval = 0;
+
+      lasttok = curtok;
+      curtok = STR;
+    }
+  else if (DIGIT(c))
+    {
+      while (ISALNUM (c) || c == '#' || c == '@' || c == '_')
+	c = *cp++;
+
+      c = *--cp;
+      *cp = '\0';
+
+      tokval = strlong (tp);
+      *cp = c;
+      lasttok = curtok;
+      curtok = NUM;
+    }
+  else
+    {
+      c1 = *cp++;
+      if ((c == EQ) && (c1 == EQ))
+	c = EQEQ;
+      else if ((c == NOT) && (c1 == EQ))
+	c = NEQ;
+      else if ((c == GT) && (c1 == EQ))
+	c = GEQ;
+      else if ((c == LT) && (c1 == EQ))
+	c = LEQ;
+      else if ((c == LT) && (c1 == LT))
+	{
+	  if (*cp == '=')	/* a <<= b */
+	    {
+	      assigntok = LSH;
+	      c = OP_ASSIGN;
+	      cp++;
+	    }
+	  else
+	    c = LSH;
+	}
+      else if ((c == GT) && (c1 == GT))
+	{
+	  if (*cp == '=')
+	    {
+	      assigntok = RSH;	/* a >>= b */
+	      c = OP_ASSIGN;
+	      cp++;
+	    }
+	  else
+	    c = RSH;
+	}
+      else if ((c == BAND) && (c1 == BAND))
+	c = LAND;
+      else if ((c == BOR) && (c1 == BOR))
+	c = LOR;
+      else if ((c == '*') && (c1 == '*'))
+	c = POWER;
+      else if ((c == '-' || c == '+') && c1 == c && curtok == STR)
+	c = (c == '-') ? POSTDEC : POSTINC;
+      else if ((c == '-' || c == '+') && c1 == c && curtok == NUM && (lasttok == PREINC || lasttok == PREDEC))
+	{
+	  /* This catches something like --FOO++ */
+	  if (c == '-')
+	    evalerror ("--: assignment requires lvalue");
+	  else
+	    evalerror ("++: assignment requires lvalue");
+	}
+      else if ((c == '-' || c == '+') && c1 == c)
+	{
+	  /* Quickly scan forward to see if this is followed by optional
+	     whitespace and an identifier. */
+	  xp = cp;
+	  while (xp && *xp && cr_whitespace (*xp))
+	    xp++;
+	  if (legal_variable_starter ((unsigned char)*xp))
+	    c = (c == '-') ? PREDEC : PREINC;
+	  else
+	    /* Could force parsing as preinc or predec and throw an error */
+#if 0
+	    {
+	      /* Posix says unary plus and minus have higher priority than
+		 preinc and predec. */
+	      /* This catches something like --4++ */
+	      if (c == '-')
+		evalerror ("--: assignment requires lvalue");
+	      else
+		evalerror ("++: assignment requires lvalue");
+	    }
+#else
+	    cp--;	/* not preinc or predec, so unget the character */
+#endif
+	}
+      else if (c1 == EQ && member (c, "*/%+-&^|"))
+	{
+	  assigntok = c;	/* a OP= b */
+	  c = OP_ASSIGN;
+	}
+      else if (_is_arithop (c) == 0)
+	{
+	  cp--;
+	  /* use curtok, since it hasn't been copied to lasttok yet */
+	  if (curtok == 0 || _is_arithop (curtok) || _is_multiop (curtok))
+	    evalerror (_("syntax error: operand expected"));
+	  else
+	    evalerror (_("syntax error: invalid arithmetic operator"));
+	}
+      else
+	cp--;			/* `unget' the character */
+
+      /* Should check here to make sure that the current character is one
+	 of the recognized operators and flag an error if not.  Could create
+	 a character map the first time through and check it on subsequent
+	 calls. */
+      lasttok = curtok;
+      curtok = c;
+    }
+  tp = cp;
+}
+
+static void
+evalerror (msg)
+     const char *msg;
+{
+  char *name, *t;
+
+  name = this_command_name;
+  for (t = expression; t && whitespace (*t); t++)
+    ;
+  internal_error (_("%s%s%s: %s (error token is \"%s\")"),
+		   name ? name : "", name ? ": " : "",
+		   t ? t : "", msg, (lasttp && *lasttp) ? lasttp : "");
+  sh_longjmp (evalbuf, 1);
+}
+
+/* Convert a string to an intmax_t integer, with an arbitrary base.
+   0nnn -> base 8
+   0[Xx]nn -> base 16
+   Anything else: [base#]number (this is implemented to match ksh93)
+
+   Base may be >=2 and <=64.  If base is <= 36, the numbers are drawn
+   from [0-9][a-zA-Z], and lowercase and uppercase letters may be used
+   interchangably.  If base is > 36 and <= 64, the numbers are drawn
+   from [0-9][a-z][A-Z]_@ (a = 10, z = 35, A = 36, Z = 61, @ = 62, _ = 63 --
+   you get the picture). */
+
+static intmax_t
+strlong (num)
+     char *num;
+{
+  register char *s;
+  register unsigned char c;
+  int base, foundbase;
+  intmax_t val;
+
+  s = num;
+
+  base = 10;
+  foundbase = 0;
+  if (*s == '0')
+    {
+      s++;
+
+      if (*s == '\0')
+	return 0;
+
+       /* Base 16? */
+      if (*s == 'x' || *s == 'X')
+	{
+	  base = 16;
+	  s++;
+	}
+      else
+	base = 8;
+      foundbase++;
+    }
+
+  val = 0;
+  for (c = *s++; c; c = *s++)
+    {
+      if (c == '#')
+	{
+	  if (foundbase)
+	    evalerror (_("invalid number"));
+
+	  /* Illegal base specifications raise an evaluation error. */
+	  if (val < 2 || val > 64)
+	    evalerror (_("invalid arithmetic base"));
+
+	  base = val;
+	  val = 0;
+	  foundbase++;
+	}
+      else if (ISALNUM(c) || (c == '_') || (c == '@'))
+	{
+	  if (DIGIT(c))
+	    c = TODIGIT(c);
+	  else if (c >= 'a' && c <= 'z')
+	    c -= 'a' - 10;
+	  else if (c >= 'A' && c <= 'Z')
+	    c -= 'A' - ((base <= 36) ? 10 : 36);
+	  else if (c == '@')
+	    c = 62;
+	  else if (c == '_')
+	    c = 63;
+
+	  if (c >= base)
+	    evalerror (_("value too great for base"));
+
+	  val = (val * base) + c;
+	}
+      else
+	break;
+    }
+
+  return (val);
+}
+
+#if defined (EXPR_TEST)
+void *
+xmalloc (n)
+     int n;
+{
+  return (malloc (n));
+}
+
+void *
+xrealloc (s, n)
+     char *s;
+     int n;
+{
+  return (realloc (s, n));
+}
+
+SHELL_VAR *find_variable () { return 0;}
+SHELL_VAR *bind_variable () { return 0; }
+
+char *get_string_value () { return 0; }
+
+procenv_t top_level;
+
+main (argc, argv)
+     int argc;
+     char **argv;
+{
+  register int i;
+  intmax_t v;
+  int expok;
+
+  if (setjmp (top_level))
+    exit (0);
+
+  for (i = 1; i < argc; i++)
+    {
+      v = evalexp (argv[i], 0, &expok);
+      if (expok == 0)
+	fprintf (stderr, _("%s: expression error\n"), argv[i]);
+      else
+	printf ("'%s' -> %ld\n", argv[i], v);
+    }
+  exit (0);
+}
+
+int
+builtin_error (format, arg1, arg2, arg3, arg4, arg5)
+     char *format;
+{
+  fprintf (stderr, "expr: ");
+  fprintf (stderr, format, arg1, arg2, arg3, arg4, arg5);
+  fprintf (stderr, "\n");
+  return 0;
+}
+
+char *
+itos (n)
+     intmax_t n;
+{
+  return ("42");
+}
+
+#endif /* EXPR_TEST */