strtol.c
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上传日期:2007-10-30
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- /*
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
- #include <net-snmp/net-snmp-config.h>
- #if defined(LIBC_SCCS) && !defined(lint)
- static char sccsid[] = "@(#)strtol.c 5.4 (Berkeley) 2/23/91";
- #endif /* LIBC_SCCS and not lint */
- #if !HAVE_STRTOL
- #if HAVE_LIMITS_H
- #include <limits.h>
- #endif
- #include <ctype.h>
- #include <errno.h>
- #if HAVE_STDLIB_H
- #include <stdlib.h>
- #endif
- /*
- * Convert a string to a long integer.
- *
- * Ignores `locale' stuff. Assumes that the upper and lower case
- * alphabets and digits are each contiguous.
- */
- long
- strtol(const char *nptr, char **endptr, int base)
- {
- const char *s = nptr;
- unsigned long acc;
- int c;
- unsigned long cutoff;
- int neg = 0, any, cutlim;
- /*
- * Skip white space and pick up leading +/- sign if any. If base is 0,
- * allow 0x for hex and 0 for octal, else assume decimal; if base is
- * already 16, allow 0x.
- */
- do {
- c = *s++;
- } while (isspace(c));
- if (c == '-') {
- neg = 1;
- c = *s++;
- } else if (c == '+')
- c = *s++;
- if ((base == 0 || base == 16) && c == '0' && (*s == 'x' || *s == 'X')) {
- c = s[1];
- s += 2;
- base = 16;
- }
- if (base == 0)
- base = c == '0' ? 8 : 10;
- /*
- * Compute the cutoff value between legal numbers and illegal numbers.
- * That is the largest legal value, divided by the base. An input
- * number that is greater than this value, if followed by a legal
- * input character, is too big. One that is equal to this value may
- * be valid or not; the limit between valid and invalid numbers is
- * then based on the last digit. For instance, if the range for longs
- * is [-2147483648..2147483647] and the input base is 10, cutoff will
- * be set to 214748364 and cutlim to either 7 (neg==0) or 8 (neg==1),
- * meaning that if we have accumulated a value > 214748364, or equal
- * but the next digit is > 7 (or 8), the number is too big, and we
- * will return a range error.
- *
- * Set any if any `digits' consumed; make it negative to indicate
- * overflow.
- */
- cutoff = neg ? -(unsigned long) LONG_MIN : LONG_MAX;
- cutlim = cutoff % (unsigned long) base;
- cutoff /= (unsigned long) base;
- for (acc = 0, any = 0;; c = *s++) {
- if (isdigit(c))
- c -= '0';
- else if (isalpha(c))
- c -= isupper(c) ? 'A' - 10 : 'a' - 10;
- else
- break;
- if (c >= base)
- break;
- if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
- any = -1;
- else {
- any = 1;
- acc *= base;
- acc += c;
- }
- }
- if (any < 0) {
- acc = neg ? LONG_MIN : LONG_MAX;
- errno = ERANGE;
- } else if (neg)
- acc = -acc;
- if (endptr != 0)
- *endptr = any ? s - 1 : (char *) nptr;
- return (acc);
- }
- #endif /* !HAVE_STRTOL */