sbase/expr.c

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/* $OpenBSD: src/bin/expr/expr.c,v 1.19 2013/11/21 15:54:45 deraadt Exp $ */
/* $NetBSD: expr.c,v 1.3.6.1 1996/06/04 20:41:47 cgd Exp $ */
/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <locale.h>
#include <ctype.h>
#include <regex.h>
#include <err.h>
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static struct val *make_int(int);
static struct val *make_str(char *);
static void free_value(struct val *);
static int is_integer(struct val *, int *);
static int to_integer(struct val *);
static void to_string(struct val *);
static int is_zero_or_null(struct val *);
static void nexttoken(int);
static void error(void);
static struct val *eval6(void);
static struct val *eval5(void);
static struct val *eval4(void);
static struct val *eval3(void);
static struct val *eval2(void);
static struct val *eval1(void);
static struct val *eval0(void);
enum token {
OR, AND, EQ, LT, GT, ADD, SUB, MUL, DIV, MOD, MATCH, RP, LP,
NE, LE, GE, OPERAND, EOI
};
struct val {
enum {
integer,
string
} type;
union {
char *s;
int i;
} u;
};
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static enum token token;
static struct val *tokval;
static char **av;
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static struct val *
make_int(int i)
{
struct val *vp;
vp = (struct val *) malloc(sizeof(*vp));
if (vp == NULL) {
err(3, NULL);
}
vp->type = integer;
vp->u.i = i;
return vp;
}
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static struct val *
make_str(char *s)
{
struct val *vp;
vp = (struct val *) malloc(sizeof(*vp));
if (vp == NULL || ((vp->u.s = strdup(s)) == NULL)) {
err(3, NULL);
}
vp->type = string;
return vp;
}
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static void
free_value(struct val *vp)
{
if (vp->type == string)
free(vp->u.s);
free(vp);
}
/* determine if vp is an integer; if so, return it's value in *r */
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static int
is_integer(struct val *vp, int *r)
{
char *s;
int neg;
int i;
if (vp->type == integer) {
*r = vp->u.i;
return 1;
}
/*
* POSIX.2 defines an "integer" as an optional unary minus
* followed by digits.
*/
s = vp->u.s;
i = 0;
neg = (*s == '-');
if (neg)
s++;
while (*s) {
if (!isdigit((unsigned char)*s))
return 0;
i *= 10;
i += *s - '0';
s++;
}
if (neg)
i *= -1;
*r = i;
return 1;
}
/* coerce to vp to an integer */
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static int
to_integer(struct val *vp)
{
int r;
if (vp->type == integer)
return 1;
if (is_integer(vp, &r)) {
free(vp->u.s);
vp->u.i = r;
vp->type = integer;
return 1;
}
return 0;
}
/* coerce to vp to an string */
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static void
to_string(struct val *vp)
{
char *tmp;
if (vp->type == string)
return;
if (asprintf(&tmp, "%d", vp->u.i) == -1)
err(3, NULL);
vp->type = string;
vp->u.s = tmp;
}
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static int
is_zero_or_null(struct val *vp)
{
if (vp->type == integer) {
return (vp->u.i == 0);
} else {
return (*vp->u.s == 0 || (to_integer(vp) && vp->u.i == 0));
}
/* NOTREACHED */
}
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static void
nexttoken(int pat)
{
char *p;
if ((p = *av) == NULL) {
token = EOI;
return;
}
av++;
if (pat == 0 && p[0] != '\0') {
if (p[1] == '\0') {
const char *x = "|&=<>+-*/%:()";
char *i; /* index */
if ((i = strchr(x, *p)) != NULL) {
token = i - x;
return;
}
} else if (p[1] == '=' && p[2] == '\0') {
switch (*p) {
case '<':
token = LE;
return;
case '>':
token = GE;
return;
case '!':
token = NE;
return;
}
}
}
tokval = make_str(p);
token = OPERAND;
return;
}
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static void
error(void)
{
errx(2, "syntax error");
/* NOTREACHED */
}
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static struct val *
eval6(void)
{
struct val *v;
if (token == OPERAND) {
nexttoken(0);
return tokval;
} else if (token == RP) {
nexttoken(0);
v = eval0();
if (token != LP) {
error();
/* NOTREACHED */
}
nexttoken(0);
return v;
} else {
error();
}
/* NOTREACHED */
return NULL;
}
/* Parse and evaluate match (regex) expressions */
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static struct val *
eval5(void)
{
regex_t rp;
regmatch_t rm[2];
char errbuf[256];
int eval;
struct val *l, *r;
struct val *v;
l = eval6();
while (token == MATCH) {
nexttoken(1);
r = eval6();
/* coerce to both arguments to strings */
to_string(l);
to_string(r);
/* compile regular expression */
if ((eval = regcomp(&rp, r->u.s, 0)) != 0) {
regerror(eval, &rp, errbuf, sizeof(errbuf));
errx(2, "%s", errbuf);
}
/* compare string against pattern -- remember that patterns
are anchored to the beginning of the line */
if (regexec(&rp, l->u.s, 2, rm, 0) == 0 && rm[0].rm_so == 0) {
if (rm[1].rm_so >= 0) {
*(l->u.s + rm[1].rm_eo) = '\0';
v = make_str(l->u.s + rm[1].rm_so);
} else {
v = make_int((int)(rm[0].rm_eo - rm[0].rm_so));
}
} else {
if (rp.re_nsub == 0) {
v = make_int(0);
} else {
v = make_str("");
}
}
/* free arguments and pattern buffer */
free_value(l);
free_value(r);
regfree(&rp);
l = v;
}
return l;
}
/* Parse and evaluate multiplication and division expressions */
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static struct val *
eval4(void)
{
struct val *l, *r;
enum token op;
l = eval5();
while ((op = token) == MUL || op == DIV || op == MOD) {
nexttoken(0);
r = eval5();
if (!to_integer(l) || !to_integer(r)) {
errx(2, "non-numeric argument");
}
if (op == MUL) {
l->u.i *= r->u.i;
} else {
if (r->u.i == 0) {
errx(2, "division by zero");
}
if (op == DIV) {
if (l->u.i != INT_MIN || r->u.i != -1)
l->u.i /= r->u.i;
} else {
if (l->u.i != INT_MIN || r->u.i != -1)
l->u.i %= r->u.i;
else
l->u.i = 0;
}
}
free_value(r);
}
return l;
}
/* Parse and evaluate addition and subtraction expressions */
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static struct val *
eval3(void)
{
struct val *l, *r;
enum token op;
l = eval4();
while ((op = token) == ADD || op == SUB) {
nexttoken(0);
r = eval4();
if (!to_integer(l) || !to_integer(r)) {
errx(2, "non-numeric argument");
}
if (op == ADD) {
l->u.i += r->u.i;
} else {
l->u.i -= r->u.i;
}
free_value(r);
}
return l;
}
/* Parse and evaluate comparison expressions */
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static struct val *
eval2(void)
{
struct val *l, *r;
enum token op;
int v = 0, li, ri;
l = eval3();
while ((op = token) == EQ || op == NE || op == LT || op == GT ||
op == LE || op == GE) {
nexttoken(0);
r = eval3();
if (is_integer(l, &li) && is_integer(r, &ri)) {
switch (op) {
case GT:
v = (li > ri);
break;
case GE:
v = (li >= ri);
break;
case LT:
v = (li < ri);
break;
case LE:
v = (li <= ri);
break;
case EQ:
v = (li == ri);
break;
case NE:
v = (li != ri);
break;
default:
break;
}
} else {
to_string(l);
to_string(r);
switch (op) {
case GT:
v = (strcoll(l->u.s, r->u.s) > 0);
break;
case GE:
v = (strcoll(l->u.s, r->u.s) >= 0);
break;
case LT:
v = (strcoll(l->u.s, r->u.s) < 0);
break;
case LE:
v = (strcoll(l->u.s, r->u.s) <= 0);
break;
case EQ:
v = (strcoll(l->u.s, r->u.s) == 0);
break;
case NE:
v = (strcoll(l->u.s, r->u.s) != 0);
break;
default:
break;
}
}
free_value(l);
free_value(r);
l = make_int(v);
}
return l;
}
/* Parse and evaluate & expressions */
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static struct val *
eval1(void)
{
struct val *l, *r;
l = eval2();
while (token == AND) {
nexttoken(0);
r = eval2();
if (is_zero_or_null(l) || is_zero_or_null(r)) {
free_value(l);
free_value(r);
l = make_int(0);
} else {
free_value(r);
}
}
return l;
}
/* Parse and evaluate | expressions */
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static struct val *
eval0(void)
{
struct val *l, *r;
l = eval1();
while (token == OR) {
nexttoken(0);
r = eval1();
if (is_zero_or_null(l)) {
free_value(l);
l = r;
} else {
free_value(r);
}
}
return l;
}
int
main(int argc, char *argv[])
{
struct val *vp;
(void) setlocale(LC_ALL, "");
if (argc > 1 && !strcmp(argv[1], "--"))
argv++;
av = argv + 1;
nexttoken(0);
vp = eval0();
if (token != EOI) {
error();
/* NOTREACHED */
}
if (vp->type == integer)
printf("%d\n", vp->u.i);
else
printf("%s\n", vp->u.s);
exit(is_zero_or_null(vp));
}