The response to my POSIX interpretation request says that `expr'
is required to be oblivious to overflow and to use the data type `long'. (Division by zero is undefined in ISO C so it's still OK to check for it here.) Add a new `-e' flag to get the old, more useful behavior.
This commit is contained in:
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=96367
@ -30,7 +30,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 22, 2002
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.Dd May 10, 2002
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.Dt EXPR 1
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.Os
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.Sh NAME
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@ -38,7 +38,7 @@
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.Nd evaluate expression
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.Sh SYNOPSIS
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.Nm
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.Op Fl \&-
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.Op Fl e
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.Ar expression
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.Sh DESCRIPTION
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The
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@ -50,15 +50,25 @@ and writes the result on standard output.
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All operators and operands must be passed as separate arguments.
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Several of the operators have special meaning to command interpreters
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and must therefore be quoted appropriately.
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All integer operands are interpreted in base 10.
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.Pp
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Arithmetic operations are performed using signed integer math,
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in the largest integral type available in the C language. The
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Arithmetic operations are performed using signed integer math.
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If the
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.Fl e
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flag is specified, arithmetic uses the C
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.Ql intmax_t
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data type (the largest integral type available), and
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.Nm
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utility will detect arithmetic overflow and division by zero, and
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returns with an exit status of 2 in those cases. If a numeric operand
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is specified which is so large as to overflow conversion to an integer,
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it is parsed as a string instead. All numeric operands are interpreted
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in base 10.
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will detect arithmetic overflow and return an error indication.
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If a numeric operand is specified which is so large as to overflow
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conversion to an integer, it is parsed as a string instead.
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If
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.Fl e
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is not specified, arithmetic operations and parsing of integer
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arguments will overflow silently according to the rules of the C
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standard, and integer computations will be performed using the
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.Ql long
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data type.
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.Pp
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Operators are listed below in order of increasing precedence; all
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are left-associative.
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@ -174,7 +184,7 @@ command, one might rearrange the expression:
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More generally, parenthesize possibly-negative values:
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.Dl a=$(expr \e( $a \e) + 1)
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.It
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The following example prints the filename portion of a pathname stored
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This example prints the filename portion of a pathname stored
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in variable
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.Va a .
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Since
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@ -231,9 +241,6 @@ utility conforms to
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provided that the
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.Ev EXPR_COMPAT
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environment variable is not defined.
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.Tn POSIX
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does not specify whether arithmetic overflow is detected, nor does it specify
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the possible range of integer arguments to
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.Nm ,
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so a portable application must assume that the range is small and that
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overflow may not be detected.
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The
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.Fl e
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flag is an extension.
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@ -70,6 +70,7 @@ int yyerror(const char *);
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int yylex(void);
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int yyparse(void);
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static int eflag;
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char **av;
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%}
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@ -154,7 +155,10 @@ make_str(const char *s)
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* non-digits MUST NOT be considered integers. strtoimax() will
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* figure this out for us.
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*/
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(void)strtoimax(s, &ep, 10);
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if (eflag)
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(void)strtoimax(s, &ep, 10);
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else
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(void)strtol(s, &ep, 10);
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if (*ep != '\0')
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vp->type = string;
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@ -186,9 +190,13 @@ to_integer(struct val *vp)
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/* vp->type == numeric_string, make it numeric */
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errno = 0;
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i = strtoimax(vp->u.s, (char **)NULL, 10);
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if (errno == ERANGE)
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err(ERR_EXIT, NULL);
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if (eflag) {
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i = strtoimax(vp->u.s, (char **)NULL, 10);
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if (errno == ERANGE)
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err(ERR_EXIT, NULL);
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} else {
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i = strtol(vp->u.s, (char **)NULL, 10);
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}
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free (vp->u.s);
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vp->u.i = i;
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@ -273,10 +281,15 @@ main(int argc, char *argv[])
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if (getenv("EXPR_COMPAT") != NULL) {
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av = argv + 1;
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} else {
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while ((c = getopt(argc, argv, "")) != -1)
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while ((c = getopt(argc, argv, "e")) != -1)
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switch (c) {
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case 'e':
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eflag = 1;
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break;
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default:
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fprintf(stderr,"usage: expr [--] expression\n");
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fprintf(stderr,
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"usage: expr [-e] expression\n");
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exit(ERR_EXIT);
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}
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av = argv + optind;
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@ -327,7 +340,7 @@ op_and(struct val *a, struct val *b)
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struct val *
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op_eq(struct val *a, struct val *b)
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{
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struct val *r;
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struct val *r;
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if (isstring (a) || isstring (b)) {
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to_string (a);
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@ -447,6 +460,7 @@ op_ne(struct val *a, struct val *b)
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int
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chk_plus(intmax_t a, intmax_t b, intmax_t r)
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{
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/* sum of two positive numbers must be positive */
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if (a > 0 && b > 0 && r <= 0)
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return 1;
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@ -462,14 +476,18 @@ op_plus(struct val *a, struct val *b)
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{
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struct val *r;
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if (!to_integer (a) || !to_integer (b)) {
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if (!to_integer(a) || !to_integer(b)) {
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errx(ERR_EXIT, "non-numeric argument");
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}
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r = make_integer (/*(intmax_t)*/(a->u.i + b->u.i));
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if (chk_plus (a->u.i, b->u.i, r->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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if (eflag) {
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r = make_integer(a->u.i + b->u.i);
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if (chk_plus(a->u.i, b->u.i, r->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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} else
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r = make_integer((long)a->u.i + (long)b->u.i);
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free_value (a);
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free_value (b);
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return r;
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@ -478,6 +496,7 @@ op_plus(struct val *a, struct val *b)
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int
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chk_minus(intmax_t a, intmax_t b, intmax_t r)
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{
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/* special case subtraction of INTMAX_MIN */
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if (b == INTMAX_MIN) {
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if (a >= 0)
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@ -494,14 +513,18 @@ op_minus(struct val *a, struct val *b)
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{
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struct val *r;
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if (!to_integer (a) || !to_integer (b)) {
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if (!to_integer(a) || !to_integer(b)) {
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errx(ERR_EXIT, "non-numeric argument");
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}
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r = make_integer (/*(intmax_t)*/(a->u.i - b->u.i));
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if (chk_minus (a->u.i, b->u.i, r->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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if (eflag) {
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r = make_integer(a->u.i - b->u.i);
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if (chk_minus(a->u.i, b->u.i, r->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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} else
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r = make_integer((long)a->u.i - (long)b->u.i);
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free_value (a);
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free_value (b);
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return r;
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@ -524,14 +547,18 @@ op_times(struct val *a, struct val *b)
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{
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struct val *r;
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if (!to_integer (a) || !to_integer (b)) {
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if (!to_integer(a) || !to_integer(b)) {
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errx(ERR_EXIT, "non-numeric argument");
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}
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r = make_integer (/*(intmax_t)*/(a->u.i * b->u.i));
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if (chk_times (a->u.i, b->u.i, r->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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if (eflag) {
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r = make_integer(a->u.i * b->u.i);
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if (chk_times(a->u.i, b->u.i, r->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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} else
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r = make_integer((long)a->u.i * (long)b->u.i);
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free_value (a);
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free_value (b);
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return (r);
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@ -553,7 +580,7 @@ op_div(struct val *a, struct val *b)
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{
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struct val *r;
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if (!to_integer (a) || !to_integer (b)) {
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if (!to_integer(a) || !to_integer(b)) {
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errx(ERR_EXIT, "non-numeric argument");
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}
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@ -561,10 +588,14 @@ op_div(struct val *a, struct val *b)
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errx(ERR_EXIT, "division by zero");
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}
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r = make_integer (/*(intmax_t)*/(a->u.i / b->u.i));
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if (chk_div (a->u.i, b->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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if (eflag) {
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r = make_integer(a->u.i / b->u.i);
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if (chk_div(a->u.i, b->u.i)) {
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errx(ERR_EXIT, "overflow");
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}
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} else
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r = make_integer((long)a->u.i / (long)b->u.i);
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free_value (a);
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free_value (b);
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return r;
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@ -575,7 +606,7 @@ op_rem(struct val *a, struct val *b)
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{
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struct val *r;
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if (!to_integer (a) || !to_integer (b)) {
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if (!to_integer(a) || !to_integer(b)) {
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errx(ERR_EXIT, "non-numeric argument");
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}
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@ -583,8 +614,12 @@ op_rem(struct val *a, struct val *b)
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errx(ERR_EXIT, "division by zero");
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}
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r = make_integer (/*(intmax_t)*/(a->u.i % b->u.i));
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/* chk_rem necessary ??? */
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if (eflag)
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r = make_integer(a->u.i % b->u.i);
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/* chk_rem necessary ??? */
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else
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r = make_integer((long)a->u.i % (long)b->u.i);
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free_value (a);
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free_value (b);
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return r;
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