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Diffstat (limited to 'expr.c')
| -rw-r--r-- | expr.c | 1671 |
1 files changed, 1671 insertions, 0 deletions
@@ -0,0 +1,1671 @@ +/* expr.c -- arithmetic expression evaluation. */ + +/* Copyright (C) 1990-2020 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 PARAMS((int)); +static void readtok PARAMS((void)); /* lexical analyzer */ + +static void init_lvalue PARAMS((struct lvalue *)); +static struct lvalue *alloc_lvalue PARAMS((void)); +static void free_lvalue PARAMS((struct lvalue *)); + +static intmax_t expr_streval PARAMS((char *, int, struct lvalue *)); +static intmax_t strlong PARAMS((char *)); +static void evalerror PARAMS((const char *)); + +static void pushexp PARAMS((void)); +static void popexp PARAMS((void)); +static void expr_unwind PARAMS((void)); +static void expr_bind_variable PARAMS((char *, char *)); +#if defined (ARRAY_VARS) +static void expr_bind_array_element PARAMS((char *, arrayind_t, char *)); +#endif + +static intmax_t subexpr PARAMS((char *)); + +static intmax_t expcomma PARAMS((void)); +static intmax_t expassign PARAMS((void)); +static intmax_t expcond PARAMS((void)); +static intmax_t explor PARAMS((void)); +static intmax_t expland PARAMS((void)); +static intmax_t expbor PARAMS((void)); +static intmax_t expbxor PARAMS((void)); +static intmax_t expband PARAMS((void)); +static intmax_t exp5 PARAMS((void)); +static intmax_t exp4 PARAMS((void)); +static intmax_t expshift PARAMS((void)); +static intmax_t exp3 PARAMS((void)); +static intmax_t expmuldiv PARAMS((void)); +static intmax_t exppower PARAMS((void)); +static intmax_t exp1 PARAMS((void)); +static intmax_t exp0 PARAMS((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: + /* Handle INTMAX_MIN and INTMAX_MAX * -1 specially here? */ + 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 && e != ']') + v = find_variable_last_nameref (tok, 0); + + 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 + + set_exit_status (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 + interchangeably. 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). */ + +#define VALID_NUMCHAR(c) (ISALNUM(c) || ((c) == '_') || ((c) == '@')) + +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++; + + /* Make sure a base# is followed by a character that can compose a + valid integer constant. Jeremy Townshend <jeremy.townshend@gmail.com> */ + if (VALID_NUMCHAR (*s) == 0) + evalerror (_("invalid integer constant")); + } + else if (VALID_NUMCHAR (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 */ |