acrn-hypervisor/hypervisor/lib/strncpy.c

108 lines
3.2 KiB
C

/*
* Copyright (C) 2018 Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Intel Corporation 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 COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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 <hv_lib.h>
#include <acrn_common.h>
#include <hv_arch.h>
#include <hv_debug.h>
/*
* strncpy_s
*
* description:
* This function copies maximum 'slen'characters from string pointed
* by s to a buffer pointed by d.
*
* input:
* d pointer to dest buffer.
*
* dmax maximum length of dest buffer.
*
* s pointer to the source string.
*
* slen the maximum number of characters to copy from source
* string.
*
* return value:
* dest pointer to dest string if source string is copied
* successfully, or else return null.
*
* notes:
* 1) both dmax and slen should not be 0.
* 2) both d and s should not be null pointers.
* 3) will assert() if overlap happens or dest buffer has no
* enough space.
*/
char *strncpy_s(char *d, size_t dmax, const char *s, size_t slen)
{
char *dest_base;
size_t dest_avail;
uint64_t overlap_guard;
ASSERT((d != NULL) && (s != NULL), "invlaid input d or s");
ASSERT((dmax != 0) && (slen != 0), "invlaid input dmax or slen");
if (d == s)
return d;
overlap_guard = (uint64_t)((d > s) ? (d - s - 1) : (s - d - 1));
dest_base = d;
dest_avail = dmax;
while (dest_avail > 0) {
ASSERT(overlap_guard != 0, "overlap happened.");
if (slen == 0) {
*d = '\0';
return dest_base;
}
*d = *s;
if (*d == '\0')
return dest_base;
d++;
s++;
slen--;
dest_avail--;
overlap_guard--;
}
ASSERT(false, "dest buffer has no enough space.");
/*
* to avoid a string that is not
* null-terminated in dest buffer
*/
dest_base[dmax - 1] = '\0';
return NULL;
}