strncpy_s.c File Reference

#include "safe_str_lib.h"

Include dependency graph for strncpy_s.c:

Functions
EXPORT errno_t	strncpy_s (char *restrict dest, rsize_t dmax, const char *restrict src, rsize_t slen)
	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. More...

Function Documentation

strncpy_s()

EXPORT errno_t strncpy_s	(	char *restrict	dest,
		rsize_t	dmax,
		const char *restrict	src,
		rsize_t	slen
	)

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 unspecified values when strncpy_s returns. With SAFECLIB_STR_NULL_SLACK defined the rest is cleared with NULL bytes.

Remarks

SPECIFIED IN

• C11 standard (ISO/IEC 9899:2011): 7.21.2.4 The strncpy function (p: 326-327) http://en.cppreference.com/w/c/string/byte/strncpy
• ISO/IEC TR 24731-1, Programming languages, environments and system software interfaces, Extensions to the C Library, Part I: Bounds-checking interfaces

Parameters

[out]	dest	pointer to string that will be replaced by src.
[in]	dmax	restricted maximum length of dest
[in]	src	pointer to the string that will be copied to dest
[in]	slen	the maximum number of characters to copy from src

Precondition

dmax shall not be 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) to avoid truncation.

Copying shall not take place between objects that overlap.

Note

C11 uses RSIZE_MAX, not RSIZE_MAX_STR.

Returns

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 values

EOK	successful operation, the characters in src were copied to dest and the result is null terminated.
ESNULLP	when dest/src is NULL pointer
ESZEROL	when dmax = 0. Before C11 also with slen = 0
ESLEMAX	when dmax/slen > RSIZE_MAX_STR
ESOVRLP	when strings overlap
ESNOSPC	when dest < src

See also

strcat_s(), strncat_s(), strcpy_s(), wcsncpy_s()