519 lines
8.4 KiB
C
519 lines
8.4 KiB
C
/* $OpenBSD: expr.c,v 1.28 2022/01/28 05:15:05 guenther Exp $ */
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/* $NetBSD: expr.c,v 1.3.6.1 1996/06/04 20:41:47 cgd Exp $ */
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/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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#include <ctype.h>
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#include <unistd.h>
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#include <regex.h>
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#include <err.h>
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struct val *make_int(int64_t);
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struct val *make_str(char *);
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void free_value(struct val *);
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int is_integer(struct val *, int64_t *, const char **);
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int to_integer(struct val *, const char **);
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void to_string(struct val *);
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int is_zero_or_null(struct val *);
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void nexttoken(int);
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__dead void error(void);
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struct val *eval6(void);
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struct val *eval5(void);
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struct val *eval4(void);
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struct val *eval3(void);
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struct val *eval2(void);
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struct val *eval1(void);
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struct val *eval0(void);
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enum token {
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OR, AND, EQ, LT, GT, ADD, SUB, MUL, DIV, MOD, MATCH, RP, LP,
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NE, LE, GE, OPERAND, EOI
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};
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struct val {
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enum {
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integer,
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string
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} type;
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union {
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char *s;
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int64_t i;
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} u;
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};
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enum token token;
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struct val *tokval;
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char **av;
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struct val *
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make_int(int64_t i)
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{
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struct val *vp;
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vp = malloc(sizeof(*vp));
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if (vp == NULL) {
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err(3, NULL);
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}
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vp->type = integer;
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vp->u.i = i;
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return vp;
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}
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struct val *
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make_str(char *s)
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{
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struct val *vp;
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vp = malloc(sizeof(*vp));
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if (vp == NULL || ((vp->u.s = strdup(s)) == NULL)) {
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err(3, NULL);
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}
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vp->type = string;
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return vp;
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}
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void
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free_value(struct val *vp)
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{
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if (vp->type == string)
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free(vp->u.s);
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free(vp);
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}
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/* determine if vp is an integer; if so, return its value in *r */
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int
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is_integer(struct val *vp, int64_t *r, const char **errstr)
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{
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const char *errstrp;
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if (errstr == NULL)
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errstr = &errstrp;
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*errstr = NULL;
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if (vp->type == integer) {
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*r = vp->u.i;
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return 1;
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}
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/*
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* POSIX.2 defines an "integer" as an optional unary minus
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* followed by digits. Other representations are unspecified,
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* which means that strtonum(3) is a viable option here.
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*/
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*r = strtonum(vp->u.s, INT64_MIN, INT64_MAX, errstr);
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return *errstr == NULL;
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}
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/* coerce to vp to an integer */
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int
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to_integer(struct val *vp, const char **errstr)
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{
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int64_t r;
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if (errstr != NULL)
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*errstr = NULL;
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if (vp->type == integer)
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return 1;
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if (is_integer(vp, &r, errstr)) {
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free(vp->u.s);
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vp->u.i = r;
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vp->type = integer;
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return 1;
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}
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return 0;
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}
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/* coerce to vp to an string */
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void
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to_string(struct val *vp)
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{
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char *tmp;
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if (vp->type == string)
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return;
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if (asprintf(&tmp, "%lld", vp->u.i) == -1)
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err(3, NULL);
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vp->type = string;
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vp->u.s = tmp;
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}
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int
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is_zero_or_null(struct val *vp)
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{
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if (vp->type == integer)
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return vp->u.i == 0;
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else
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return *vp->u.s == 0 || (to_integer(vp, NULL) && vp->u.i == 0);
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}
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void
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nexttoken(int pat)
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{
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char *p;
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if ((p = *av) == NULL) {
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token = EOI;
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return;
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}
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av++;
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if (pat == 0 && p[0] != '\0') {
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if (p[1] == '\0') {
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const char *x = "|&=<>+-*/%:()";
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char *i; /* index */
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if ((i = strchr(x, *p)) != NULL) {
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token = i - x;
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return;
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}
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} else if (p[1] == '=' && p[2] == '\0') {
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switch (*p) {
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case '<':
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token = LE;
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return;
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case '>':
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token = GE;
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return;
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case '!':
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token = NE;
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return;
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}
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}
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}
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tokval = make_str(p);
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token = OPERAND;
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return;
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}
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__dead void
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error(void)
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{
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errx(2, "syntax error");
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}
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struct val *
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eval6(void)
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{
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struct val *v;
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if (token == OPERAND) {
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nexttoken(0);
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return tokval;
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} else if (token == RP) {
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nexttoken(0);
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v = eval0();
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if (token != LP)
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error();
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nexttoken(0);
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return v;
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} else
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error();
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}
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/* Parse and evaluate match (regex) expressions */
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struct val *
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eval5(void)
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{
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regex_t rp;
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regmatch_t rm[2];
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char errbuf[256];
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int eval;
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struct val *l, *r;
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struct val *v;
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l = eval6();
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while (token == MATCH) {
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nexttoken(1);
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r = eval6();
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/* coerce to both arguments to strings */
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to_string(l);
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to_string(r);
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/* compile regular expression */
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if ((eval = regcomp(&rp, r->u.s, 0)) != 0) {
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regerror(eval, &rp, errbuf, sizeof(errbuf));
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errx(2, "%s", errbuf);
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}
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/* compare string against pattern -- remember that patterns
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are anchored to the beginning of the line */
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if (regexec(&rp, l->u.s, 2, rm, 0) == 0 && rm[0].rm_so == 0) {
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if (rm[1].rm_so >= 0) {
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*(l->u.s + rm[1].rm_eo) = '\0';
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v = make_str(l->u.s + rm[1].rm_so);
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} else {
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v = make_int(rm[0].rm_eo - rm[0].rm_so);
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}
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} else {
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if (rp.re_nsub == 0) {
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v = make_int(0);
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} else {
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v = make_str("");
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}
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}
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/* free arguments and pattern buffer */
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free_value(l);
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free_value(r);
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regfree(&rp);
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l = v;
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}
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return l;
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}
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/* Parse and evaluate multiplication and division expressions */
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struct val *
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eval4(void)
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{
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const char *errstr;
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struct val *l, *r;
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enum token op;
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volatile int64_t res;
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l = eval5();
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while ((op = token) == MUL || op == DIV || op == MOD) {
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nexttoken(0);
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r = eval5();
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if (!to_integer(l, &errstr))
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errx(2, "number \"%s\" is %s", l->u.s, errstr);
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if (!to_integer(r, &errstr))
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errx(2, "number \"%s\" is %s", r->u.s, errstr);
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if (op == MUL) {
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res = l->u.i * r->u.i;
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if (r->u.i != 0 && l->u.i != res / r->u.i)
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errx(3, "overflow");
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l->u.i = res;
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} else {
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if (r->u.i == 0) {
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errx(2, "division by zero");
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}
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if (op == DIV) {
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if (l->u.i != INT64_MIN || r->u.i != -1)
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l->u.i /= r->u.i;
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else
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errx(3, "overflow");
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} else {
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if (l->u.i != INT64_MIN || r->u.i != -1)
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l->u.i %= r->u.i;
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else
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l->u.i = 0;
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}
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}
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free_value(r);
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}
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return l;
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}
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/* Parse and evaluate addition and subtraction expressions */
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struct val *
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eval3(void)
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{
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const char *errstr;
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struct val *l, *r;
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enum token op;
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volatile int64_t res;
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l = eval4();
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while ((op = token) == ADD || op == SUB) {
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nexttoken(0);
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r = eval4();
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if (!to_integer(l, &errstr))
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errx(2, "number \"%s\" is %s", l->u.s, errstr);
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if (!to_integer(r, &errstr))
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errx(2, "number \"%s\" is %s", r->u.s, errstr);
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if (op == ADD) {
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res = l->u.i + r->u.i;
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if ((l->u.i > 0 && r->u.i > 0 && res <= 0) ||
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(l->u.i < 0 && r->u.i < 0 && res >= 0))
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errx(3, "overflow");
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l->u.i = res;
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} else {
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res = l->u.i - r->u.i;
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if ((l->u.i >= 0 && r->u.i < 0 && res <= 0) ||
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(l->u.i < 0 && r->u.i > 0 && res >= 0))
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errx(3, "overflow");
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l->u.i = res;
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}
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free_value(r);
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}
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return l;
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}
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/* Parse and evaluate comparison expressions */
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struct val *
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eval2(void)
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{
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struct val *l, *r;
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enum token op;
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int64_t v = 0, li, ri;
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l = eval3();
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while ((op = token) == EQ || op == NE || op == LT || op == GT ||
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op == LE || op == GE) {
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nexttoken(0);
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r = eval3();
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if (is_integer(l, &li, NULL) && is_integer(r, &ri, NULL)) {
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switch (op) {
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case GT:
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v = (li > ri);
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break;
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case GE:
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v = (li >= ri);
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break;
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case LT:
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v = (li < ri);
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break;
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case LE:
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v = (li <= ri);
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break;
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case EQ:
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v = (li == ri);
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break;
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case NE:
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v = (li != ri);
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break;
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default:
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break;
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}
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} else {
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to_string(l);
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to_string(r);
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switch (op) {
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case GT:
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v = (strcoll(l->u.s, r->u.s) > 0);
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break;
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case GE:
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v = (strcoll(l->u.s, r->u.s) >= 0);
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break;
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case LT:
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v = (strcoll(l->u.s, r->u.s) < 0);
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break;
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case LE:
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v = (strcoll(l->u.s, r->u.s) <= 0);
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break;
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case EQ:
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v = (strcoll(l->u.s, r->u.s) == 0);
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break;
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case NE:
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v = (strcoll(l->u.s, r->u.s) != 0);
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break;
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default:
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break;
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}
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}
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free_value(l);
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free_value(r);
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l = make_int(v);
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}
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return l;
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}
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/* Parse and evaluate & expressions */
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struct val *
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eval1(void)
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{
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struct val *l, *r;
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l = eval2();
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while (token == AND) {
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nexttoken(0);
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r = eval2();
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if (is_zero_or_null(l) || is_zero_or_null(r)) {
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free_value(l);
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free_value(r);
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l = make_int(0);
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} else {
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free_value(r);
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}
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}
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return l;
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}
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/* Parse and evaluate | expressions */
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struct val *
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eval0(void)
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{
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struct val *l, *r;
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l = eval1();
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while (token == OR) {
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nexttoken(0);
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r = eval1();
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if (is_zero_or_null(l)) {
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free_value(l);
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l = r;
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} else {
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free_value(r);
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}
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}
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return l;
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}
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int
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main(int argc, char *argv[])
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{
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struct val *vp;
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if (pledge("stdio", NULL) == -1)
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err(2, "pledge");
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if (argc > 1 && !strcmp(argv[1], "--"))
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argv++;
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av = argv + 1;
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nexttoken(0);
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vp = eval0();
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if (token != EOI)
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error();
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if (vp->type == integer)
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printf("%lld\n", vp->u.i);
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else
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printf("%s\n", vp->u.s);
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return is_zero_or_null(vp);
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}
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