vsnprintf_s.c File Reference

#include "safe_str_lib.h"

Include dependency graph for vsnprintf_s.c:

Functions
EXPORT int	vsnprintf_s (char *restrict dest, rsize_t dmax, const char *restrict fmt, va_list ap)
	The truncating vsnprintf_s function composes a string with same test that would be printed if format was used on printf. More...

Function Documentation

vsnprintf_s()

EXPORT int vsnprintf_s	(	char *restrict	dest,
		rsize_t	dmax,
		const char *restrict	fmt,
		va_list	ap
	)

The truncating vsnprintf_s function composes a string with same test that would be printed if format was used on printf.

Instead of being printed, the content is stored in dest. Warning: Unlike the safe variant vsprintf_s, vsnprintf_s does not guarantee that the buffer will be null-terminated unless the buffer size is zero. More than dmax - 1 characters might be written!

Note

POSIX specifies that errno is set on error. However, the safeclib extended ES* errors do not set errno, only when the underlying system vsnprintf call fails, errno is set.

Remarks

SPECIFIED IN

• C11 standard (ISO/IEC 9899:2011): K.3.5.3.12 The vsnprintf_s function (p: 600) http://en.cppreference.com/w/c/io/vfprintf
• only included in safeclib with –enable-unsafe

Parameters

[out]	dest	pointer to string that will be written into.
[in]	dmax	restricted maximum length of dest
[in]	fmt	format-control string.
[in]	ap	optional arguments

Precondition

Neither dest nor fmt shall be a null pointer.

dmax shall not be greater than RSIZE_MAX_STR.

dmax shall not equal zero.

dmax shall be greater than strnlen_s(dest, dmax).

fmt shall not contain the conversion specifier n.

None of the arguments corresponding to s is a null pointer. (not yet)

No encoding error shall occur.

Note

C11 uses RSIZE_MAX, not RSIZE_MAX_STR.

Returns

On success the total number of characters written is returned.

On failure a negative number is returned.

If the buffer dest is too small for the formatted text, including the terminating null, then the buffer is set to an empty string by placing a null character at dest[0], and the invalid parameter handler is invoked. Unlike vsnprintf, vsprintf_s guarantees that the buffer will be null-terminated unless the buffer size is zero.

Return values

-ESNULLP	when dest/fmt is NULL pointer
-ESZEROL	when dmax = 0
-ESLEMAX	when dmax > RSIZE_MAX_STR
-EINVAL	when fmt contains n

See also

sprintf_s(), vsprintf_s()