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Annotation of 43BSDReno/lib/libc/stdlib/strtol.c, revision 1.1.1.1

1.1       root        1: /*-
                      2:  * Copyright (c) 1990 The Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that: (1) source distributions retain this entire copyright
                      7:  * notice and comment, and (2) distributions including binaries display
                      8:  * the following acknowledgement:  ``This product includes software
                      9:  * developed by the University of California, Berkeley and its contributors''
                     10:  * in the documentation or other materials provided with the distribution
                     11:  * and in all advertising materials mentioning features or use of this
                     12:  * software. Neither the name of the University nor the names of its
                     13:  * contributors may be used to endorse or promote products derived
                     14:  * from this software without specific prior written permission.
                     15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     18:  */
                     19: 
                     20: #if defined(LIBC_SCCS) && !defined(lint)
                     21: static char sccsid[] = "@(#)strtol.c   5.3 (Berkeley) 5/17/90";
                     22: #endif /* LIBC_SCCS and not lint */
                     23: 
                     24: #include <limits.h>
                     25: #include <ctype.h>
                     26: #include <errno.h>
                     27: #include <stdlib.h>
                     28: 
                     29: 
                     30: /*
                     31:  * Convert a string to a long integer.
                     32:  *
                     33:  * Ignores `locale' stuff.  Assumes that the upper and lower case
                     34:  * alphabets and digits are each contiguous.
                     35:  */
                     36: long
                     37: strtol(nptr, endptr, base)
                     38:        char *nptr, **endptr;
                     39:        register int base;
                     40: {
                     41:        register char *s = nptr;
                     42:        register unsigned long acc;
                     43:        register int c;
                     44:        register unsigned long cutoff;
                     45:        register int neg = 0, any, cutlim;
                     46: 
                     47:        /*
                     48:         * Skip white space and pick up leading +/- sign if any.
                     49:         * If base is 0, allow 0x for hex and 0 for octal, else
                     50:         * assume decimal; if base is already 16, allow 0x.
                     51:         */
                     52:        do {
                     53:                c = *s++;
                     54:        } while (isspace(c));
                     55:        if (c == '-') {
                     56:                neg = 1;
                     57:                c = *s++;
                     58:        } else if (c == '+')
                     59:                c = *s++;
                     60:        if ((base == 0 || base == 16) &&
                     61:            c == '0' && (*s == 'x' || *s == 'X')) {
                     62:                c = s[1];
                     63:                s += 2;
                     64:                base = 16;
                     65:        }
                     66:        if (base == 0)
                     67:                base = c == '0' ? 8 : 10;
                     68: 
                     69:        /*
                     70:         * Compute the cutoff value between legal numbers and illegal
                     71:         * numbers.  That is the largest legal value, divided by the
                     72:         * base.  An input number that is greater than this value, if
                     73:         * followed by a legal input character, is too big.  One that
                     74:         * is equal to this value may be valid or not; the limit
                     75:         * between valid and invalid numbers is then based on the last
                     76:         * digit.  For instance, if the range for longs is
                     77:         * [-2147483648..2147483647] and the input base is 10,
                     78:         * cutoff will be set to 214748364 and cutlim to either
                     79:         * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
                     80:         * a value > 214748364, or equal but the next digit is > 7 (or 8),
                     81:         * the number is too big, and we will return a range error.
                     82:         *
                     83:         * Set any if any `digits' consumed; make it negative to indicate
                     84:         * overflow.
                     85:         */
                     86:        cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
                     87:        cutlim = cutoff % (unsigned long)base;
                     88:        cutoff /= (unsigned long)base;
                     89:        for (acc = 0, any = 0;; c = *s++) {
                     90:                if (isdigit(c))
                     91:                        c -= '0';
                     92:                else if (isalpha(c))
                     93:                        c -= isupper(c) ? 'A' - 10 : 'a' - 10;
                     94:                else
                     95:                        break;
                     96:                if (c >= base)
                     97:                        break;
                     98:                if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
                     99:                        any = -1;
                    100:                else {
                    101:                        any = 1;
                    102:                        acc *= base;
                    103:                        acc += c;
                    104:                }
                    105:        }
                    106:        if (any < 0) {
                    107:                acc = neg ? LONG_MIN : LONG_MAX;
                    108:                errno = ERANGE;
                    109:        } else if (neg)
                    110:                acc = -acc;
                    111:        if (endptr != 0)
                    112:                *endptr = any ? s - 1 : nptr;
                    113:        return (acc);
                    114: }

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