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/*------------------------------------------------------------------
* strncpy_s.c
*
* October 2008, Bo Berry
*
* Copyright (c) 2008-2011 by Cisco Systems, Inc
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*------------------------------------------------------------------
*/
#include "safeclib_private.h"
#include "safe_str_constraint.h"
#include "safe_str_lib.h"
/*
* NAME
* strncpy_s
*
* SYNOPSIS
* #include "safe_str_lib.h"
* errno_t
* strncpy_s(char *dest, rsize_t dmax, const char *src, rsize_t slen)
*
* DESCRIPTION
* The strncpy_s function copies not more than slen successive characters
* (characters that follow a null character are not copied) from the
* array pointed to by src to the array pointed to by dest. If no null
* character was copied from src, then dest[n] is set to a null character.
*
* All elements following the terminating null character (if any)
* written by strncpy_s in the array of dmax characters pointed to
* by dest take on the null value when strncpy_s returns.
*
* Specicified in:
* ISO/IEC TR 24731-1, Programming languages, environments
* and system software interfaces, Extensions to the C Library,
* Part I: Bounds-checking interfaces
*
* INPUT PARAMETERS
* dest pointer to string that will be replaced by src.
* The resulting string is null terminated.
*
* dmax restricted maximum length of the resulting dest,
* including the null
*
* src pointer to the string that will be copied
* to string dest
*
* slen the maximum number of characters to copy from src
*
* OUTPUT PARAMETERS
* dest updated with src string
*
* RUNTIME CONSTRAINTS
* Neither dmax nor slen shall be equal to zero.
* Neither dmax nor slen shall be equal zero.
* Neither dmax nor slen shall be greater than RSIZE_MAX_STR.
* If slen is either greater than or equal to dmax, then dmax
* should be more than strnlen_s(src,dmax)
* Copying shall not take place between objects that overlap.
* If there is a runtime-constraint violation, then if dest
* is not a null pointer and dmax greater than RSIZE_MAX_STR,
* then strncpy_s nulls dest.
*
* RETURN VALUE
* EOK successful operation, the characters in src were copied
* to dest and the result is null terminated.
* ESNULLP NULL pointer
* ESZEROL zero length
* ESLEMAX length exceeds max limit
* ESOVRLP strings overlap
* ESNOSPC not enough space to copy src
*
* ALSO SEE
* strcat_s(), strncat_s(), strcpy_s()
*-
*/
errno_t
strncpy_s (char *dest, rsize_t dmax, const char *src, rsize_t slen)
{
rsize_t orig_dmax;
char *orig_dest;
const char *overlap_bumper;
if (dest == NULL) {
invoke_safe_str_constraint_handler("strncpy_s: dest is null",
NULL, ESNULLP);
return RCNEGATE(ESNULLP);
}
if (dmax == 0) {
invoke_safe_str_constraint_handler("strncpy_s: dmax is 0",
NULL, ESZEROL);
return RCNEGATE(ESZEROL);
}
if (dmax > RSIZE_MAX_STR) {
invoke_safe_str_constraint_handler("strncpy_s: dmax exceeds max",
NULL, ESLEMAX);
return RCNEGATE(ESLEMAX);
}
/* hold base in case src was not copied */
orig_dmax = dmax;
orig_dest = dest;
if (src == NULL) {
handle_error(orig_dest, orig_dmax, "strncpy_s: "
"src is null",
ESNULLP);
return RCNEGATE(ESNULLP);
}
if (slen == 0) {
handle_error(orig_dest, orig_dmax, "strncpy_s: "
"slen is zero",
ESZEROL);
return RCNEGATE(ESZEROL);
}
if (slen > RSIZE_MAX_STR) {
handle_error(orig_dest, orig_dmax, "strncpy_s: "
"slen exceeds max",
ESLEMAX);
return RCNEGATE(ESLEMAX);
}
if (dest < src) {
overlap_bumper = src;
while (dmax > 0) {
if (dest == overlap_bumper) {
handle_error(orig_dest, orig_dmax, "strncpy_s: "
"overlapping objects",
ESOVRLP);
return RCNEGATE(ESOVRLP);
}
if (slen == 0) {
/*
* Copying truncated to slen chars. Note that the TR says to
* copy slen chars plus the null char. We null the slack.
*/
#ifdef SAFECLIB_STR_NULL_SLACK
while (dmax) { *dest = '\0'; dmax--; dest++; }
#else
*dest = '\0';
#endif
return RCNEGATE(EOK);
}
*dest = *src;
if (*dest == '\0') {
#ifdef SAFECLIB_STR_NULL_SLACK
/* null slack */
while (dmax) { *dest = '\0'; dmax--; dest++; }
#endif
return RCNEGATE(EOK);
}
dmax--;
slen--;
dest++;
src++;
}
} else {
overlap_bumper = dest;
while (dmax > 0) {
if (src == overlap_bumper) {
handle_error(orig_dest, orig_dmax, "strncpy_s: "
"overlapping objects",
ESOVRLP);
return RCNEGATE(ESOVRLP);
}
if (slen == 0) {
/*
* Copying truncated to slen chars. Note that the TR says to
* copy slen chars plus the null char. We null the slack.
*/
#ifdef SAFECLIB_STR_NULL_SLACK
while (dmax) { *dest = '\0'; dmax--; dest++; }
#else
*dest = '\0';
#endif
return RCNEGATE(EOK);
}
*dest = *src;
if (*dest == '\0') {
#ifdef SAFECLIB_STR_NULL_SLACK
/* null slack */
while (dmax) { *dest = '\0'; dmax--; dest++; }
#endif
return RCNEGATE(EOK);
}
dmax--;
slen--;
dest++;
src++;
}
}
/*
* the entire src was not copied, so zero the string
*/
handle_error(orig_dest, orig_dmax, "strncpy_s: not enough "
"space for src",
ESNOSPC);
return RCNEGATE(ESNOSPC);
}
EXPORT_SYMBOL(strncpy_s);
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