/* $OpenBSD: expr.c,v 1.17 2006/06/21 18:28:24 deraadt Exp $ */ /* $NetBSD: expr.c,v 1.3.6.1 1996/06/04 20:41:47 cgd Exp $ */ /* * Written by J.T. Conklin . * Public domain. */ #include #include #include #include #include #include #include struct val *make_int(int); struct val *make_str(char *); void free_value(struct val *); int is_integer(struct val *, int *); int to_integer(struct val *); void to_string(struct val *); int is_zero_or_null(struct val *); void nexttoken(int); __dead void error(void); struct val *eval6(void); struct val *eval5(void); struct val *eval4(void); struct val *eval3(void); struct val *eval2(void); struct val *eval1(void); 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; }; enum token token; struct val *tokval; char **av; 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; } 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; } 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 */ 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(*s)) return 0; i *= 10; i += *s - '0'; s++; } if (neg) i *= -1; *r = i; return 1; } /* coerce to vp to an integer */ 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 */ 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; } 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 */ } 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; } __dead void error(void) { errx(2, "syntax error"); /* NOTREACHED */ } 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 */ } /* Parse and evaluate match (regex) expressions */ 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 */ 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) { l->u.i /= r->u.i; } else { l->u.i %= r->u.i; } } free_value(r); } return l; } /* Parse and evaluate addition and subtraction expressions */ 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 */ 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 */ 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 */ 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)); }