Differential D10469 Diff 27662 lib/libc/string/strncpy_s.c

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lib/libc/string/strncpy_s.c

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				/*
				* Copyright (c) 2017 Juniper Networks. 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.
				*
				* 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 <sys/cdefs.h>
				__FBSDID("$FreeBSD$");

				#include <errno.h>
				#include <stdint.h>
				#include <string.h>
				#include "libc_private.h"

				/* ISO/IEC 9899:2011 K.3.7.1.4 */
				errno_t strncpy_s(char * __restrict s1, rsize_t s1max,
				const char * __restrict s2, rsize_t n)
				{
				rsize_t lim;
				uintptr_t s1e, s2e;
				errno_t ret;
				int zero_fill;
				size_t s, t;

				ret = EINVAL;
				zero_fill = 0;
				if (s1 == NULL) {
				__throw_constraint_handler_s("strncpy_s : s1 is NULL", ret);
				} else if (s1max > RSIZE_MAX) {
				__throw_constraint_handler_s("strncpy_s : s1max > RSIZE_MAX",
				ret);
				} else if (s1max == 0) {
				__throw_constraint_handler_s("strncpy_s : s1max == 0", ret);
				} else if (s2 == NULL) {
				zero_fill = 1;
				__throw_constraint_handler_s("strncpy_s : s2 is NULL", ret);
				} else {
				lim = s1max;
				/* assume s2 size will be ok */
				s = n;
				/*
				* reset s2 size if n > s1max
				*
				* the '=' handles this corner case:
				* n == s1max and s2[n-1] != 0
				* then s1 will not be null terminated
				*/
				if (n >= s1max) {
				/*
				* number of char's
				* slmax -1 to account for the +1 added to result for
				* null terminator.
				*/
				s = strnlen_s(s2, s1max - 1);
				/* +1 to include null terminator */
				s++;
				}
				if (s < s1max)
				lim = s;
				if (lim > 0) {
				s1e = (uintptr_t) s1 + lim;
				s2e = (uintptr_t) s2 + lim;
				if (((uintptr_t) s1 >= (uintptr_t) s2 &&
				(uintptr_t) s1 < s2e) \|\|
				((uintptr_t) s2 >= (uintptr_t) s1 &&
				(uintptr_t) s2 < s1e)) {
				/* do not zero fill on overlapping starts */
				if (s1 != s2)
				zero_fill = 1;
				__throw_constraint_handler_s(
				"strncpy_s : memory overlaps", ret);
				} else {
				if (s == s1max && s2[s1max -1] != 0) {
				zero_fill = 1;
				/*
				* Do not have a special throw string
				* for n == s1max corner case
				*/
				__throw_constraint_handler_s(
				"strncpy_s : s2 will be truncated",
				ret);
				} else {
				/* strncpy does not null terminate. */
				for (t = 0; t < lim; t++) {
				if (s2[t] == 0)
				break;
				s1[t] = s2[t];
				}
				s1[t] = 0;
				ret = 0;
				}
				}
				} else {
				/* trivial, still need to null terminate */
				s1[0] = 0;
				ret = 0;
				}
				}
				if (ret && zero_fill)
				s1[0] = 0;
				return (ret);
				}