RtlStringCbVPrintfA - NtDoc
Native API online documentation, based on the System Informer
(formerly Process Hacker) phnt
headers
#ifndef _NTSTRSAFE_H_INCLUDED_
#ifndef NTSTRSAFE_LIB_IMPL
#ifndef NTSTRSAFE_NO_CB_FUNCTIONS
/*++
NTSTATUS
RtlStringCbVPrintf(
_Out_writes_bytes_(cbDest) _Always_(_Post_z_) LPTSTR pszDest,
_In_ size_t cbDest,
_In_ _Printf_format_string_ LPCTSTR pszFormat,
_In_ va_list argList
);
Routine Description:
This routine is a safer version of the C built-in function 'vsprintf'.
The size of the destination buffer (in bytes) 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
cbDest - size of destination buffer in bytes
length must be sufficient to hold the resulting formatted
string, including the null terminator.
pszFormat - format string which must be null terminated
argList - va_list from the variable arguments according to the
stdarg.h convention
Notes:
Behavior is undefined if destination, format strings or any arguments
strings overlap.
pszDest and pszFormat should not be NULL. See RtlStringCbVPrintfEx 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
RtlStringCbVPrintfA(
_Out_writes_bytes_(cbDest) _Always_(_Post_z_) NTSTRSAFE_PSTR pszDest,
_In_ size_t cbDest,
_In_ _Printf_format_string_ NTSTRSAFE_PCSTR pszFormat,
_In_ va_list argList)
{
NTSTATUS status;
size_t cchDest = cbDest / sizeof(char);
status = RtlStringValidateDestA(pszDest, cchDest, NTSTRSAFE_MAX_CCH);
if (NT_SUCCESS(status))
{
status = RtlStringVPrintfWorkerA(pszDest,
cchDest,
NULL,
pszFormat,
argList);
}
else if (cchDest > 0)
{
*pszDest = '\0';
}
return status;
}
View code on GitHub// ntstrsafe.h
NTSTRSAFEDDI RtlStringCbVPrintfA(
[out] NTSTRSAFE_PSTR pszDest,
[in] size_t cbDest,
[in] NTSTRSAFE_PCSTR pszFormat,
[in] va_list argList
);
View the official Windows Driver Kit DDI referenceNo description available.
The RtlStringCbVPrintfW and RtlStringCbVPrintfA functions create a byte-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 arguments supplied by argList.
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.
argList [in]A va_list-typed argument list. Arguments contained in the argument list will be interpreted by using the formatting string that is supplied by pszFormat.
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 output 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 created 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 length was zero, but a nonzero length source string was present. |
RtlStringCbVPrintfW and RtlStringCbVPrintfA should be used instead of the following functions:
All of these functions accept a format string, along with a set of arguments in a va_list-typed argument list, and return a formatted string. The size, in bytes, of the destination buffer is provided to RtlStringCbVPrintfW and RtlStringCbVPrintfA to ensure that they do not write past the end of the buffer.
For more information about va_list-typed argument lists, see the Microsoft Windows SDK documentation.
Use RtlStringCbVPrintfW to handle Unicode strings and RtlStringCbVPrintfA 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" | RtlStringCbVPrintfW |
| char | "string" | RtlStringCbVPrintfA |
If pszDest and pszFormat point to overlapping strings or if any argument strings overlap, the behavior of the function is undefined..
Neither pszFormat nor pszDest should be NULL. If you need to handle NULL string pointer values, use RtlStringCbVPrintfEx.
For more information about the safe string functions, see Using Safe String Functions.