RtlStringCbPrintfW - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
#ifndef _NTSTRSAFE_H_INCLUDED_
#ifndef NTSTRSAFE_LIB_IMPL
#ifndef _M_CEE_PURE
#ifndef NTSTRSAFE_NO_CB_FUNCTIONS

NTSTRSAFEDDI
    RtlStringCbPrintfW(
            _Out_writes_bytes_(cbDest) _Always_(_Post_z_) NTSTRSAFE_PWSTR pszDest,
            _In_ size_t cbDest,
            _In_ _Printf_format_string_ NTSTRSAFE_PCWSTR pszFormat,
            ...)
{
    NTSTATUS status;
    size_t cchDest = cbDest / sizeof(wchar_t);

    status = RtlStringValidateDestW(pszDest, cchDest, NTSTRSAFE_MAX_CCH);

    if (NT_SUCCESS(status))
    {
        va_list argList;

        va_start(argList, pszFormat);

        status = RtlStringVPrintfWorkerW(pszDest,
                cchDest,
                NULL,
                pszFormat,
                argList);

        va_end(argList);
    }
    else if (cchDest > 0)
    {
        *pszDest = L'\0';
    }

    return status;
}

#endif
#endif
#endif
#endif

View code on GitHub
// ntstrsafe.h

NTSTRSAFEDDI RtlStringCbPrintfW(
  [out] NTSTRSAFE_PWSTR  pszDest,
  [in]  size_t           cbDest,
  [in]  NTSTRSAFE_PCWSTR pszFormat,
        ...              
);
View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (nf-ntstrsafe-rtlstringcbprintfw)

RtlStringCbPrintfW function

Description

The RtlStringCbPrintfW and RtlStringCbPrintfA functions create a byte-counted text string, with formatting that is based on supplied formatting information.

Parameters

pszDest [out]

A pointer to a caller-supplied buffer that receives a formatted, null-terminated string. The function creates this string from both the formatting string that is supplied by pszFormat and the function's argument list.

cbDest [in]

The size of the destination buffer, in bytes. The buffer must be large enough to contain the formatted string plus the terminating null character.

For Unicode strings, the maximum number of bytes is NTSTRSAFE_MAX_CCH * sizeof(WCHAR).

For ANSI strings, the maximum number of bytes is NTSTRSAFE_MAX_CCH * sizeof(char).

pszFormat [in]

A pointer to a null-terminated text string that contains printf-styled formatting directives.

...

A list of arguments that are interpreted by the function based on formatting directives contained in the pszFormat string.

Return value

The function returns one of the NTSTATUS values that are listed in the following table. For information about how to test NTSTATUS values, see Using NTSTATUS Values.

Return code Description
STATUS_SUCCESS This success status means source data was present, the string was created without truncation, and the resultant destination buffer is null-terminated.
STATUS_BUFFER_OVERFLOW This warning status means the operation did not complete due to insufficient space in the destination buffer. The destination buffer contains a truncated version of the output string.
STATUS_INVALID_PARAMETER This error status means the function received an invalid input parameter. For more information, see the following paragraph.

The function returns the STATUS_INVALID_PARAMETER value when:

* The value in cbDest is larger than the maximum buffer size.
* The destination buffer was already full.
* A NULL pointer was present.
* The destination buffer's length was zero, but a nonzero length source string was present.

Remarks

RtlStringCbPrintfW and RtlStringCbPrintfA should be used instead of the following functions:

All of these functions accept a format string and a list of arguments, interpret them, and create a formatted string. The size, in bytes, of the destination buffer is provided to RtlStringCbPrintfW and RtlStringCbPrintfA to ensure that they do not write past the end of the buffer.

Use RtlStringCbPrintfW to handle Unicode strings and RtlStringCbPrintfA to handle ANSI strings. The form you use depends on your data, as shown in the following table.

String data type String literal Function
WCHAR L"string" RtlStringCbPrintfW
char "string" RtlStringCbPrintfA

If pszDest and pszFormat point to overlapping string or if any argument strings overlap, the behavior of the function is undefined.

Neither pszFormat nor pszDest can be NULL. If you need to handle NULL string pointer values, use RtlStringCbPrintfEx.

For more information about the safe string functions, see Using Safe String Functions.

Examples

The following example shows a basic use of RtlStringCbPrintfW using four arguments.

int const arraysize = 30;
WCHAR pszDest[arraysize];
size_t cbDest = arraysize * sizeof(WCHAR);

LPCWSTR pszFormat = L"%s %d + %d = %d.";
WCHAR* pszTxt = L"The answer is";

NTSTATUS status = RtlStringCbPrintfW(pszDest, cbDest, pszFormat, pszTxt, 1, 2, 3);

The resultant string is "The answer is 1 + 2 = 3." It is contained in the buffer at pszDest.

See also

RtlStringCbPrintfEx

RtlStringCbVPrintf

RtlStringCchPrintf

View the official Windows Driver Kit DDI reference

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