RtlStringCchPrintfA - 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_CCH_FUNCTIONS
/*++
NTSTATUS
RtlStringCchPrintf(
_Out_writes_(cchDest) _Always_(_Post_z_) LPTSTR pszDest,
_In_ size_t cchDest,
_In_ _Printf_format_string_ LPCTSTR pszFormat,
...
);
Routine Description:
This routine is a safer version of the C built-in function 'sprintf'.
The size of the destination buffer (in characters) is a parameter and
this function will not write past the end of this buffer and it will
ALWAYS null terminate the destination buffer (unless it is zero length).
This function returns an NTSTATUS value, and not a pointer. It returns
STATUS_SUCCESS if the string was printed without truncation and null terminated,
otherwise it will return a failure code. In failure cases it will return
a truncated version of the ideal result.
Arguments:
pszDest - destination string
cchDest - size of destination buffer in characters
length must be sufficient to hold the resulting formatted
string, including the null terminator.
pszFormat - format string which must be null terminated
... - additional parameters to be formatted according to
the format string
Notes:
Behavior is undefined if destination, format strings or any arguments
strings overlap.
pszDest and pszFormat should not be NULL. See RtlStringCchPrintfEx if you
require the handling of NULL values.
Return Value:
STATUS_SUCCESS - if there was sufficient space in the dest buffer for
the resultant string and it was null terminated.
failure - you can use the macro NTSTATUS_CODE() to get a win32
error code for all hresult failure cases
STATUS_BUFFER_OVERFLOW /
NTSTATUS_CODE(status) == ERROR_INSUFFICIENT_BUFFER
- this return value is an indication that the print
operation failed due to insufficient space. When this
error occurs, the destination buffer is modified to
contain a truncated version of the ideal result and is
null terminated. This is useful for situations where
truncation is ok.
It is strongly recommended to use the NT_SUCCESS() macro to test the
return value of this function
--*/
NTSTRSAFEDDI
RtlStringCchPrintfA(
_Out_writes_(cchDest) _Always_(_Post_z_) NTSTRSAFE_PSTR pszDest,
_In_ size_t cchDest,
_In_ _Printf_format_string_ NTSTRSAFE_PCSTR pszFormat,
...)
{
NTSTATUS status;
status = RtlStringValidateDestA(pszDest, cchDest, NTSTRSAFE_MAX_CCH);
if (NT_SUCCESS(status))
{
va_list argList;
va_start(argList, pszFormat);
status = RtlStringVPrintfWorkerA(pszDest,
cchDest,
NULL,
pszFormat,
argList);
va_end(argList);
}
else if (cchDest > 0)
{
*pszDest = '\0';
}
return status;
}
View code on GitHub// ntstrsafe.h
NTSTRSAFEDDI RtlStringCchPrintfA(
[out] NTSTRSAFE_PSTR pszDest,
[in] size_t cchDest,
[in] NTSTRSAFE_PCSTR pszFormat,
...
);
View the official Windows Driver Kit DDI referenceNo description available.
The RtlStringCchPrintfW and RtlStringCchPrintfA functions create a character-counted text string, with formatting that is based on supplied formatting information.
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.
cchDest [in]The size of the destination buffer, in characters. The buffer must be large enough to contain the formatted string plus the terminating null character. The maximum number of characters allowed is NTSTRSAFE_MAX_CCH.
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.
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 cchDest 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. |
RtlStringCchPrintfW and RtlStringCchPrintfA should be used instead of the following functions:
All of these functions accept a format string and a list of arguments and return a formatted string. RtlStringCchPrintfW and RtlStringCchPrintfA accept the size, in characters, of the destination buffer to ensure that the functions do not write past the end of the buffer.
Use RtlStringCchPrintfW to handle Unicode strings and RtlStringCchPrintfA to handle ANSI strings. The form you use depends on your data.
| String data type | String literal | Function |
|---|---|---|
| WCHAR | L"string" | RtlStringCchPrintfW |
| char | "string" | RtlStringCchPrintfA |
If pszDest and pszFormat point to overlapping strings, or if any argument strings overlap, behavior of the function is undefined.
Neither pszFormat nor pszDest can be NULL. If you need to handle NULL string pointer values, use RtlStringCchPrintfEx.
The following example shows a simple use of RtlStringCchPrintfW using four arguments.
WCHAR pszDest[30];
size_t cchDest = 30;
LPCWSTR pszFormat = L"%s %d + %d = %d.";
WCHAR* pszTxt = L"The answer is";
NTSTATUS status =
RtlStringCchPrintfW(pszDest, cchDest, pszFormat, pszTxt, 1, 2, 3);
The resultant string is "The answer is 1 + 2 = 3." It is contained in the buffer at pszDest.
For more information about the safe string functions, see Using Safe String Functions.