IABSD.fr/src/bin/expr/expr.c

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• Author : tobias
  Date : 2018-03-31 14:50:56
  Hash : b50a997f
  Message : Fix overflows while handling 64 bit integers. Based on FreeBSD's expr and NetBSD's old regression test suite. with input by and ok schwarze

• bin/expr/expr.c

• /*	$OpenBSD: expr.c,v 1.27 2018/03/31 14:50:56 tobias 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 <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  #include <limits.h>
  #include <ctype.h>
  #include <unistd.h>
  #include <regex.h>
  #include <err.h>
  
  struct val	*make_int(int64_t);
  struct val	*make_str(char *);
  void		 free_value(struct val *);
  int		 is_integer(struct val *, int64_t *, const char **);
  int		 to_integer(struct val *, const char **);
  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;
  		int64_t		i;
  	} u;
  };
  
  enum token	token;
  struct val     *tokval;
  char	      **av;
  
  struct val *
  make_int(int64_t i)
  {
  	struct val     *vp;
  
  	vp = 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 = 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, int64_t *r, const char **errstr)
  {
  	const char *errstrp;
  
  	if (errstr == NULL)
  		errstr = &errstrp;
  	*errstr = NULL;
  
  	if (vp->type == integer) {
  		*r = vp->u.i;
  		return 1;
  	}
  
  	/*
  	 * POSIX.2 defines an "integer" as an optional unary minus
  	 * followed by digits. Other representations are unspecified,
  	 * which means that strtonum(3) is a viable option here.
  	 */
  	*r = strtonum(vp->u.s, INT64_MIN, INT64_MAX, errstr);
  	return *errstr == NULL;
  }
  
  
  /* coerce to vp to an integer */
  int
  to_integer(struct val *vp, const char **errstr)
  {
  	int64_t		r;
  
  	if (errstr != NULL)
  		*errstr = NULL;
  
  	if (vp->type == integer)
  		return 1;
  
  	if (is_integer(vp, &r, errstr)) {
  		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, "%lld", 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, NULL) && vp->u.i == 0);
  }
  
  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");
  }
  
  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();
  		nexttoken(0);
  		return v;
  	} else
  		error();
  }
  
  /* 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(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)
  {
  	const char	*errstr;
  	struct val	*l, *r;
  	enum token	 op;
  	volatile int64_t res;
  
  	l = eval5();
  	while ((op = token) == MUL || op == DIV || op == MOD) {
  		nexttoken(0);
  		r = eval5();
  
  		if (!to_integer(l, &errstr))
  			errx(2, "number \"%s\" is %s", l->u.s, errstr);
  		if (!to_integer(r, &errstr))
  			errx(2, "number \"%s\" is %s", r->u.s, errstr);
  
  		if (op == MUL) {
  			res = l->u.i * r->u.i;
  			if (r->u.i != 0 && l->u.i != res / r->u.i)
  				errx(3, "overflow");
  			l->u.i = res;
  		} else {
  			if (r->u.i == 0) {
  				errx(2, "division by zero");
  			}
  			if (op == DIV) {
  				if (l->u.i != INT64_MIN || r->u.i != -1)
  					l->u.i /= r->u.i;
  				else
  					errx(3, "overflow");
  			} else {
  				if (l->u.i != INT64_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 */
  struct val *
  eval3(void)
  {
  	const char	*errstr;
  	struct val	*l, *r;
  	enum token	 op;
  	volatile int64_t res;
  
  	l = eval4();
  	while ((op = token) == ADD || op == SUB) {
  		nexttoken(0);
  		r = eval4();
  
  		if (!to_integer(l, &errstr))
  			errx(2, "number \"%s\" is %s", l->u.s, errstr);
  		if (!to_integer(r, &errstr))
  			errx(2, "number \"%s\" is %s", r->u.s, errstr);
  
  		if (op == ADD) {
  			res = l->u.i + r->u.i;
  			if ((l->u.i > 0 && r->u.i > 0 && res <= 0) ||
  			    (l->u.i < 0 && r->u.i < 0 && res >= 0))
  				errx(3, "overflow");
  			l->u.i = res;
  		} else {
  			res = l->u.i - r->u.i;
  			if ((l->u.i >= 0 && r->u.i < 0 && res <= 0) ||
  			    (l->u.i < 0 && r->u.i > 0 && res >= 0))
  				errx(3, "overflow");
  			l->u.i = res;
  		}
  
  		free_value(r);
  	}
  
  	return l;
  }
  
  /* Parse and evaluate comparison expressions */
  struct val *
  eval2(void)
  {
  	struct val     *l, *r;
  	enum token	op;
  	int64_t		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, NULL) && is_integer(r, &ri, NULL)) {
  			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;
  
  	if (pledge("stdio", NULL) == -1)
  		err(2, "pledge");
  
  	if (argc > 1 && !strcmp(argv[1], "--"))
  		argv++;
  
  	av = argv + 1;
  
  	nexttoken(0);
  	vp = eval0();
  
  	if (token != EOI)
  		error();
  
  	if (vp->type == integer)
  		printf("%lld\n", vp->u.i);
  	else
  		printf("%s\n", vp->u.s);
  
  	return is_zero_or_null(vp);
  }