mksh/expr.c

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/* $OpenBSD: expr.c,v 1.21 2009/06/01 19:00:57 deraadt Exp $ */
/*-
* Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009
* Thorsten Glaser <tg@mirbsd.org>
*
* Provided that these terms and disclaimer and all copyright notices
* are retained or reproduced in an accompanying document, permission
* is granted to deal in this work without restriction, including un-
* limited rights to use, publicly perform, distribute, sell, modify,
* merge, give away, or sublicence.
*
* This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
* the utmost extent permitted by applicable law, neither express nor
* implied; without malicious intent or gross negligence. In no event
* may a licensor, author or contributor be held liable for indirect,
* direct, other damage, loss, or other issues arising in any way out
* of dealing in the work, even if advised of the possibility of such
* damage or existence of a defect, except proven that it results out
* of said person's immediate fault when using the work as intended.
*/
#include "sh.h"
__RCSID("$MirOS: src/bin/mksh/expr.c,v 1.30 2009/08/08 13:08:50 tg Exp $");
/* The order of these enums is constrained by the order of opinfo[] */
enum token {
/* some (long) unary operators */
O_PLUSPLUS = 0, O_MINUSMINUS,
/* binary operators */
O_EQ, O_NE,
/* assignments are assumed to be in range O_ASN .. O_BORASN */
O_ASN, O_TIMESASN, O_DIVASN, O_MODASN, O_PLUSASN, O_MINUSASN,
O_LSHIFTASN, O_RSHIFTASN, O_BANDASN, O_BXORASN, O_BORASN,
O_LSHIFT, O_RSHIFT,
O_LE, O_GE, O_LT, O_GT,
O_LAND,
O_LOR,
O_TIMES, O_DIV, O_MOD,
O_PLUS, O_MINUS,
O_BAND,
O_BXOR,
O_BOR,
O_TERN,
O_COMMA,
/* things after this aren't used as binary operators */
/* unary that are not also binaries */
O_BNOT, O_LNOT,
/* misc */
OPEN_PAREN, CLOSE_PAREN, CTERN,
/* things that don't appear in the opinfo[] table */
VAR, LIT, END, BAD
};
#define IS_BINOP(op) (((int)op) >= (int)O_EQ && ((int)op) <= (int)O_COMMA)
#define IS_ASSIGNOP(op) ((int)(op) >= (int)O_ASN && (int)(op) <= (int)O_BORASN)
/* precisions; used to be enum prec but we do arithmetics on it */
#define P_PRIMARY 0 /* VAR, LIT, (), ~ ! - + */
#define P_MULT 1 /* * / % */
#define P_ADD 2 /* + - */
#define P_SHIFT 3 /* << >> */
#define P_RELATION 4 /* < <= > >= */
#define P_EQUALITY 5 /* == != */
#define P_BAND 6 /* & */
#define P_BXOR 7 /* ^ */
#define P_BOR 8 /* | */
#define P_LAND 9 /* && */
#define P_LOR 10 /* || */
#define P_TERN 11 /* ?: */
#define P_ASSIGN 12 /* = *= /= %= += -= <<= >>= &= ^= |= */
#define P_COMMA 13 /* , */
#define MAX_PREC P_COMMA
struct opinfo {
char name[4];
int len; /* name length */
int prec; /* precedence: lower is higher */
};
/* Tokens in this table must be ordered so the longest are first
* (eg, += before +). If you change something, change the order
* of enum token too.
*/
static const struct opinfo opinfo[] = {
{ "++", 2, P_PRIMARY }, /* before + */
{ "--", 2, P_PRIMARY }, /* before - */
{ "==", 2, P_EQUALITY }, /* before = */
{ "!=", 2, P_EQUALITY }, /* before ! */
{ "=", 1, P_ASSIGN }, /* keep assigns in a block */
{ "*=", 2, P_ASSIGN },
{ "/=", 2, P_ASSIGN },
{ "%=", 2, P_ASSIGN },
{ "+=", 2, P_ASSIGN },
{ "-=", 2, P_ASSIGN },
{ "<<=", 3, P_ASSIGN },
{ ">>=", 3, P_ASSIGN },
{ "&=", 2, P_ASSIGN },
{ "^=", 2, P_ASSIGN },
{ "|=", 2, P_ASSIGN },
{ "<<", 2, P_SHIFT },
{ ">>", 2, P_SHIFT },
{ "<=", 2, P_RELATION },
{ ">=", 2, P_RELATION },
{ "<", 1, P_RELATION },
{ ">", 1, P_RELATION },
{ "&&", 2, P_LAND },
{ "||", 2, P_LOR },
{ "*", 1, P_MULT },
{ "/", 1, P_MULT },
{ "%", 1, P_MULT },
{ "+", 1, P_ADD },
{ "-", 1, P_ADD },
{ "&", 1, P_BAND },
{ "^", 1, P_BXOR },
{ "|", 1, P_BOR },
{ "?", 1, P_TERN },
{ ",", 1, P_COMMA },
{ "~", 1, P_PRIMARY },
{ "!", 1, P_PRIMARY },
{ "(", 1, P_PRIMARY },
{ ")", 1, P_PRIMARY },
{ ":", 1, P_PRIMARY },
{ "", 0, P_PRIMARY }
};
typedef struct expr_state Expr_state;
struct expr_state {
const char *expression; /* expression being evaluated */
const char *tokp; /* lexical position */
struct tbl *val; /* value from token() */
struct tbl *evaling; /* variable that is being recursively
* expanded (EXPRINEVAL flag set) */
int noassign; /* don't do assigns (for ?:,&&,||) */
enum token tok; /* token from token() */
bool arith; /* evaluating an $(()) expression? */
bool natural; /* unsigned arithmetic calculation */
};
#define bivui(x, op, y) (es->natural ? \
(mksh_ari_t)((x)->val.u op (y)->val.u) : \
(mksh_ari_t)((x)->val.i op (y)->val.i) \
)
#define chvui(x, op) do { \
if (es->natural) \
(x)->val.u = op (x)->val.u; \
else \
(x)->val.i = op (x)->val.i; \
} while (/* CONSTCOND */ 0)
#define stvui(x, n) do { \
if (es->natural) \
(x)->val.u = (n); \
else \
(x)->val.i = (n); \
} while (/* CONSTCOND */ 0)
enum error_type {
ET_UNEXPECTED, ET_BADLIT, ET_RECURSIVE,
ET_LVALUE, ET_RDONLY, ET_STR
};
static void evalerr(Expr_state *, enum error_type, const char *)
__attribute__((noreturn));
static struct tbl *evalexpr(Expr_state *, int);
static void exprtoken(Expr_state *);
static struct tbl *do_ppmm(Expr_state *, enum token, struct tbl *, bool);
static void assign_check(Expr_state *, enum token, struct tbl *);
static struct tbl *tempvar(void);
static struct tbl *intvar(Expr_state *, struct tbl *);
/*
* parse and evaluate expression
*/
int
evaluate(const char *expr, mksh_ari_t *rval, int error_ok, bool arith)
{
struct tbl v;
int ret;
v.flag = DEFINED|INTEGER;
v.type = 0;
ret = v_evaluate(&v, expr, error_ok, arith);
*rval = v.val.i;
return (ret);
}
/*
* parse and evaluate expression, storing result in vp.
*/
int
v_evaluate(struct tbl *vp, const char *expr, volatile int error_ok,
bool arith)
{
struct tbl *v;
Expr_state curstate;
Expr_state * const es = &curstate;
int i;
/* save state to allow recursive calls */
curstate.expression = curstate.tokp = expr;
curstate.noassign = 0;
curstate.arith = arith;
curstate.evaling = NULL;
curstate.natural = false;
newenv(E_ERRH);
i = sigsetjmp(e->jbuf, 0);
if (i) {
/* Clear EXPRINEVAL in of any variables we were playing with */
if (curstate.evaling)
curstate.evaling->flag &= ~EXPRINEVAL;
quitenv(NULL);
if (i == LAEXPR) {
if (error_ok == KSH_RETURN_ERROR)
return (0);
errorfz();
}
unwind(i);
/* NOTREACHED */
}
exprtoken(es);
if (es->tok == END) {
es->tok = LIT;
es->val = tempvar();
}
v = intvar(es, evalexpr(es, MAX_PREC));
if (es->tok != END)
evalerr(es, ET_UNEXPECTED, NULL);
if (es->arith && es->natural)
vp->flag |= INT_U;
if (vp->flag & INTEGER)
setint_v(vp, v, es->arith);
else
/* can fail if readonly */
setstr(vp, str_val(v), error_ok);
quitenv(NULL);
return (1);
}
static void
evalerr(Expr_state *es, enum error_type type, const char *str)
{
char tbuf[2];
const char *s;
es->arith = false;
switch (type) {
case ET_UNEXPECTED:
switch (es->tok) {
case VAR:
s = es->val->name;
break;
case LIT:
s = str_val(es->val);
break;
case END:
s = "end of expression";
break;
case BAD:
tbuf[0] = *es->tokp;
tbuf[1] = '\0';
s = tbuf;
break;
default:
s = opinfo[(int)es->tok].name;
}
warningf(true, "%s: unexpected '%s'", es->expression, s);
break;
case ET_BADLIT:
warningf(true, "%s: bad number '%s'", es->expression, str);
break;
case ET_RECURSIVE:
warningf(true, "%s: expression recurses on parameter '%s'",
es->expression, str);
break;
case ET_LVALUE:
warningf(true, "%s: %s requires lvalue",
es->expression, str);
break;
case ET_RDONLY:
warningf(true, "%s: %s applied to read only variable",
es->expression, str);
break;
default: /* keep gcc happy */
case ET_STR:
warningf(true, "%s: %s", es->expression, str);
break;
}
unwind(LAEXPR);
}
static struct tbl *
evalexpr(Expr_state *es, int prec)
{
struct tbl *vl, *vr = NULL, *vasn;
enum token op;
mksh_ari_t res = 0;
if (prec == P_PRIMARY) {
op = es->tok;
if (op == O_BNOT || op == O_LNOT || op == O_MINUS ||
op == O_PLUS) {
exprtoken(es);
vl = intvar(es, evalexpr(es, P_PRIMARY));
if (op == O_BNOT)
chvui(vl, ~);
else if (op == O_LNOT)
chvui(vl, !);
else if (op == O_MINUS)
chvui(vl, -);
/* op == O_PLUS is a no-op */
} else if (op == OPEN_PAREN) {
exprtoken(es);
vl = evalexpr(es, MAX_PREC);
if (es->tok != CLOSE_PAREN)
evalerr(es, ET_STR, "missing )");
exprtoken(es);
} else if (op == O_PLUSPLUS || op == O_MINUSMINUS) {
exprtoken(es);
vl = do_ppmm(es, op, es->val, true);
exprtoken(es);
} else if (op == VAR || op == LIT) {
vl = es->val;
exprtoken(es);
} else {
evalerr(es, ET_UNEXPECTED, NULL);
/* NOTREACHED */
}
if (es->tok == O_PLUSPLUS || es->tok == O_MINUSMINUS) {
vl = do_ppmm(es, es->tok, vl, false);
exprtoken(es);
}
return (vl);
}
vl = evalexpr(es, prec - 1);
for (op = es->tok; IS_BINOP(op) && opinfo[(int)op].prec == prec;
op = es->tok) {
exprtoken(es);
vasn = vl;
if (op != O_ASN) /* vl may not have a value yet */
vl = intvar(es, vl);
if (IS_ASSIGNOP(op)) {
assign_check(es, op, vasn);
vr = intvar(es, evalexpr(es, P_ASSIGN));
} else if (op != O_TERN && op != O_LAND && op != O_LOR)
vr = intvar(es, evalexpr(es, prec - 1));
if ((op == O_DIV || op == O_MOD || op == O_DIVASN ||
op == O_MODASN) && vr->val.i == 0) {
if (es->noassign)
vr->val.i = 1;
else
evalerr(es, ET_STR, "zero divisor");
}
switch ((int)op) {
case O_TIMES:
case O_TIMESASN:
res = bivui(vl, *, vr);
break;
case O_DIV:
case O_DIVASN:
res = bivui(vl, /, vr);
break;
case O_MOD:
case O_MODASN:
res = bivui(vl, %, vr);
break;
case O_PLUS:
case O_PLUSASN:
res = bivui(vl, +, vr);
break;
case O_MINUS:
case O_MINUSASN:
res = bivui(vl, -, vr);
break;
case O_LSHIFT:
case O_LSHIFTASN:
res = bivui(vl, <<, vr);
break;
case O_RSHIFT:
case O_RSHIFTASN:
res = bivui(vl, >>, vr);
break;
case O_LT:
res = bivui(vl, <, vr);
break;
case O_LE:
res = bivui(vl, <=, vr);
break;
case O_GT:
res = bivui(vl, >, vr);
break;
case O_GE:
res = bivui(vl, >=, vr);
break;
case O_EQ:
res = bivui(vl, ==, vr);
break;
case O_NE:
res = bivui(vl, !=, vr);
break;
case O_BAND:
case O_BANDASN:
res = bivui(vl, &, vr);
break;
case O_BXOR:
case O_BXORASN:
res = bivui(vl, ^, vr);
break;
case O_BOR:
case O_BORASN:
res = bivui(vl, |, vr);
break;
case O_LAND:
if (!vl->val.i)
es->noassign++;
vr = intvar(es, evalexpr(es, prec - 1));
res = bivui(vl, &&, vr);
if (!vl->val.i)
es->noassign--;
break;
case O_LOR:
if (vl->val.i)
es->noassign++;
vr = intvar(es, evalexpr(es, prec - 1));
res = bivui(vl, ||, vr);
if (vl->val.i)
es->noassign--;
break;
case O_TERN:
{
bool ev = vl->val.i != 0;
if (!ev)
es->noassign++;
vl = evalexpr(es, MAX_PREC);
if (!ev)
es->noassign--;
if (es->tok != CTERN)
evalerr(es, ET_STR, "missing :");
exprtoken(es);
if (ev)
es->noassign++;
vr = evalexpr(es, P_TERN);
if (ev)
es->noassign--;
vl = ev ? vl : vr;
}
break;
case O_ASN:
res = vr->val.i;
break;
case O_COMMA:
res = vr->val.i;
break;
}
if (IS_ASSIGNOP(op)) {
stvui(vr, res);
if (vasn->flag & INTEGER)
setint_v(vasn, vr, es->arith);
else
setint(vasn, res);
vl = vr;
} else if (op != O_TERN)
stvui(vl, res);
}
return (vl);
}
static void
exprtoken(Expr_state *es)
{
const char *cp = es->tokp;
int c;
char *tvar;
/* skip white space */
skip_spaces:
while ((c = *cp), ksh_isspace(c))
++cp;
if (es->tokp == es->expression && c == '#') {
/* expression begins with # */
es->natural = true; /* switch to unsigned */
++cp;
goto skip_spaces;
}
es->tokp = cp;
if (c == '\0')
es->tok = END;
else if (ksh_isalphx(c)) {
for (; ksh_isalnux(c); c = *cp)
cp++;
if (c == '[') {
int len;
len = array_ref_len(cp);
if (len == 0)
evalerr(es, ET_STR, "missing ]");
cp += len;
} else if (c == '(' /*)*/ ) {
/* todo: add math functions (all take single argument):
* abs acos asin atan cos cosh exp int log sin sinh sqrt
* tan tanh
*/
;
}
if (es->noassign) {
es->val = tempvar();
es->val->flag |= EXPRLVALUE;
} else {
strndupx(tvar, es->tokp, cp - es->tokp, ATEMP);
es->val = global(tvar);
afree(tvar, ATEMP);
}
es->tok = VAR;
} else if (c == '1' && cp[1] == '#') {
cp += 2;
cp += utf_ptradj(cp);
strndupx(tvar, es->tokp, cp - es->tokp, ATEMP);
goto process_tvar;
} else if (ksh_isdigit(c)) {
while (c != '_' && (ksh_isalnux(c) || c == '#'))
c = *cp++;
strndupx(tvar, es->tokp, --cp - es->tokp, ATEMP);
process_tvar:
es->val = tempvar();
es->val->flag &= ~INTEGER;
es->val->type = 0;
es->val->val.s = tvar;
if (setint_v(es->val, es->val, es->arith) == NULL)
evalerr(es, ET_BADLIT, tvar);
afree(tvar, ATEMP);
es->tok = LIT;
} else {
int i, n0;
for (i = 0; (n0 = opinfo[i].name[0]); i++)
if (c == n0 && strncmp(cp, opinfo[i].name,
(size_t)opinfo[i].len) == 0) {
es->tok = (enum token)i;
cp += opinfo[i].len;
break;
}
if (!n0)
es->tok = BAD;
}
es->tokp = cp;
}
/* Do a ++ or -- operation */
static struct tbl *
do_ppmm(Expr_state *es, enum token op, struct tbl *vasn, bool is_prefix)
{
struct tbl *vl;
mksh_ari_t oval;
assign_check(es, op, vasn);
vl = intvar(es, vasn);
oval = vl->val.i;
if (op == O_PLUSPLUS) {
if (es->natural)
++vl->val.u;
else
++vl->val.i;
} else {
if (es->natural)
--vl->val.u;
else
--vl->val.i;
}
if (vasn->flag & INTEGER)
setint_v(vasn, vl, es->arith);
else
setint(vasn, vl->val.i);
if (!is_prefix) /* undo the inc/dec */
vl->val.i = oval;
return (vl);
}
static void
assign_check(Expr_state *es, enum token op, struct tbl *vasn)
{
if (es->tok == END ||
(vasn->name[0] == '\0' && !(vasn->flag & EXPRLVALUE)))
evalerr(es, ET_LVALUE, opinfo[(int)op].name);
else if (vasn->flag & RDONLY)
evalerr(es, ET_RDONLY, opinfo[(int)op].name);
}
static struct tbl *
tempvar(void)
{
struct tbl *vp;
vp = alloc(sizeof(struct tbl), ATEMP);
vp->flag = ISSET|INTEGER;
vp->type = 0;
vp->areap = ATEMP;
vp->val.i = 0;
vp->name[0] = '\0';
return (vp);
}
/* cast (string) variable to temporary integer variable */
static struct tbl *
intvar(Expr_state *es, struct tbl *vp)
{
struct tbl *vq;
/* try to avoid replacing a temp var with another temp var */
if (vp->name[0] == '\0' &&
(vp->flag & (ISSET|INTEGER|EXPRLVALUE)) == (ISSET|INTEGER))
return (vp);
vq = tempvar();
if (setint_v(vq, vp, es->arith) == NULL) {
if (vp->flag & EXPRINEVAL)
evalerr(es, ET_RECURSIVE, vp->name);
es->evaling = vp;
vp->flag |= EXPRINEVAL;
v_evaluate(vq, str_val(vp), KSH_UNWIND_ERROR, es->arith);
vp->flag &= ~EXPRINEVAL;
es->evaling = NULL;
}
return (vq);
}