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/* $OpenBSD: strtoimax.c,v 1.4 2017/07/06 16:23:11 millert Exp $ */ |
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/* |
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* Copyright (c) 1992 The Regents of the University of California. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <ctype.h> |
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#include <errno.h> |
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#include <inttypes.h> |
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/* |
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* Convert a string to an intmax_t |
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* |
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* Ignores `locale' stuff. Assumes that the upper and lower case |
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* alphabets and digits are each contiguous. |
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*/ |
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intmax_t |
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strtoimax(const char *nptr, char **endptr, int base) |
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{ |
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const char *s; |
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intmax_t acc, cutoff; |
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int c; |
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int neg, any, cutlim; |
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/* |
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* Ensure that base is between 2 and 36 inclusive, or the special |
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* value of 0. |
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*/ |
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if (base < 0 || base == 1 || base > 36) { |
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if (endptr != 0) |
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*endptr = (char *)nptr; |
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errno = EINVAL; |
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return 0; |
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} |
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/* |
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* Skip white space and pick up leading +/- sign if any. |
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* If base is 0, allow 0x for hex and 0 for octal, else |
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* assume decimal; if base is already 16, allow 0x. |
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*/ |
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s = nptr; |
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do { |
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c = (unsigned char) *s++; |
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} while (isspace(c)); |
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if (c == '-') { |
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neg = 1; |
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c = *s++; |
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} else { |
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neg = 0; |
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if (c == '+') |
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c = *s++; |
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} |
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if ((base == 0 || base == 16) && c == '0' && |
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(*s == 'x' || *s == 'X') && isxdigit((unsigned char)s[1])) { |
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c = s[1]; |
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s += 2; |
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base = 16; |
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} |
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if (base == 0) |
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base = c == '0' ? 8 : 10; |
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/* |
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* Compute the cutoff value between legal numbers and illegal |
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* numbers. That is the largest legal value, divided by the |
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* base. An input number that is greater than this value, if |
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* followed by a legal input character, is too big. One that |
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* is equal to this value may be valid or not; the limit |
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* between valid and invalid numbers is then based on the last |
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* digit. For instance, if the range for intmax_t is |
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* [-9223372036854775808..9223372036854775807] and the input base |
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* is 10, cutoff will be set to 922337203685477580 and cutlim to |
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* either 7 (neg==0) or 8 (neg==1), meaning that if we have |
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* accumulated a value > 922337203685477580, or equal but the |
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* next digit is > 7 (or 8), the number is too big, and we will |
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* return a range error. |
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* |
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* Set any if any `digits' consumed; make it negative to indicate |
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* overflow. |
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*/ |
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cutoff = neg ? INTMAX_MIN : INTMAX_MAX; |
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cutlim = cutoff % base; |
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cutoff /= base; |
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if (neg) { |
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if (cutlim > 0) { |
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cutlim -= base; |
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cutoff += 1; |
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} |
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cutlim = -cutlim; |
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} |
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for (acc = 0, any = 0;; c = (unsigned char) *s++) { |
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if (isdigit(c)) |
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c -= '0'; |
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else if (isalpha(c)) |
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c -= isupper(c) ? 'A' - 10 : 'a' - 10; |
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else |
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break; |
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if (c >= base) |
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break; |
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if (any < 0) |
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continue; |
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if (neg) { |
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if (acc < cutoff || (acc == cutoff && c > cutlim)) { |
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any = -1; |
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acc = INTMAX_MIN; |
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errno = ERANGE; |
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} else { |
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any = 1; |
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acc *= base; |
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acc -= c; |
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} |
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} else { |
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if (acc > cutoff || (acc == cutoff && c > cutlim)) { |
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any = -1; |
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acc = INTMAX_MAX; |
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errno = ERANGE; |
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} else { |
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any = 1; |
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acc *= base; |
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acc += c; |
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} |
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} |
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} |
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if (endptr != 0) |
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*endptr = (char *) (any ? s - 1 : nptr); |
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return (acc); |
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} |
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DEF_STRONG(strtoimax); |