IABSD.fr/src/lib/libc/stdlib/strtoimax.c

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• Author : millert
  Date : 2017-07-06 16:23:11
  Hash : 6022c2c2
  Message : The 0x (or 0X) prefix in base 16 is optional so only skip over the prefix if the character following it is a valid hex char. The C99 standard is clear that given the string "0xy" zero should be returned and endptr set to point to the "x". OK deraadt@ espie@

• lib/libc/stdlib/strtoimax.c

• /*	$OpenBSD: strtoimax.c,v 1.4 2017/07/06 16:23:11 millert Exp $	*/
  /*
   * Copyright (c) 1992 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 <ctype.h>
  #include <errno.h>
  #include <inttypes.h>
  
  /*
   * Convert a string to an intmax_t
   *
   * Ignores `locale' stuff.  Assumes that the upper and lower case
   * alphabets and digits are each contiguous.
   */
  intmax_t
  strtoimax(const char *nptr, char **endptr, int base)
  {
  	const char *s;
  	intmax_t acc, cutoff;
  	int c;
  	int neg, any, cutlim;
  
  	/*
  	 * Ensure that base is between 2 and 36 inclusive, or the special
  	 * value of 0.
  	 */
  	if (base < 0 || base == 1 || base > 36) {
  		if (endptr != 0)
  			*endptr = (char *)nptr;
  		errno = EINVAL;
  		return 0;
  	}
  
  	/*
  	 * 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.
  	 */
  	s = nptr;
  	do {
  		c = (unsigned char) *s++;
  	} while (isspace(c));
  	if (c == '-') {
  		neg = 1;
  		c = *s++;
  	} else {
  		neg = 0;
  		if (c == '+')
  			c = *s++;
  	}
  	if ((base == 0 || base == 16) && c == '0' &&
  	    (*s == 'x' || *s == 'X') && isxdigit((unsigned char)s[1])) {
  		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 intmax_t is
  	 * [-9223372036854775808..9223372036854775807] and the input base
  	 * is 10, cutoff will be set to 922337203685477580 and cutlim to
  	 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
  	 * accumulated a value > 922337203685477580, 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 ? INTMAX_MIN : INTMAX_MAX;
  	cutlim = cutoff % base;
  	cutoff /= base;
  	if (neg) {
  		if (cutlim > 0) {
  			cutlim -= base;
  			cutoff += 1;
  		}
  		cutlim = -cutlim;
  	}
  	for (acc = 0, any = 0;; c = (unsigned char) *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)
  			continue;
  		if (neg) {
  			if (acc < cutoff || (acc == cutoff && c > cutlim)) {
  				any = -1;
  				acc = INTMAX_MIN;
  				errno = ERANGE;
  			} else {
  				any = 1;
  				acc *= base;
  				acc -= c;
  			}
  		} else {
  			if (acc > cutoff || (acc == cutoff && c > cutlim)) {
  				any = -1;
  				acc = INTMAX_MAX;
  				errno = ERANGE;
  			} else {
  				any = 1;
  				acc *= base;
  				acc += c;
  			}
  		}
  	}
  	if (endptr != 0)
  		*endptr = (char *) (any ? s - 1 : nptr);
  	return (acc);
  }
  DEF_STRONG(strtoimax);