RtlStringCchCatNA - 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_CCH_FUNCTIONS
/*++
NTSTATUS
RtlStringCchCatN(
_Inout_updates_(cchDest) _Always_(_Post_z_) LPTSTR pszDest,
_In_ size_t cchDest,
_In_ LPCTSTR pszSrc,
_In_ size_t cchToAppend
);
Routine Description:
This routine is a safer version of the C built-in function 'strncat'.
The size of the destination buffer (in characters) is a parameter as well as
the maximum number of characters to append, excluding the null terminator.
This function will not write past the end of the destination buffer and it will
ALWAYS null terminate pszDest (unless it is zero length).
This function returns an NTSTATUS value, and not a pointer. It returns
STATUS_SUCCESS if all of pszSrc or the first cchToAppend characters were appended
to the destination string and it was null terminated, otherwise it will
return a failure code. In failure cases as much of pszSrc will be appended
to pszDest as possible, and pszDest will be null terminated.
Arguments:
pszDest - destination string which must be null terminated
cchDest - size of destination buffer in characters.
length must be (_tcslen(pszDest) + min(cchToAppend, _tcslen(pszSrc)) + 1)
to hold all of the combine string plus the null
terminator.
pszSrc - source string
cchToAppend - maximum number of characters to append
Notes:
Behavior is undefined if source and destination strings overlap.
pszDest and pszSrc should not be NULL. See RtlStringCchCatNEx if you require
the handling of NULL values.
Return Value:
STATUS_SUCCESS - if all of pszSrc or the first cchToAppend characters
were concatenated to pszDest and the resultant dest
string 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 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
RtlStringCchCatNA(
_Inout_updates_(cchDest) _Always_(_Post_z_) NTSTRSAFE_PSTR pszDest,
_In_ size_t cchDest,
_In_reads_or_z_(cchToAppend) STRSAFE_PCNZCH pszSrc,
_In_ size_t cchToAppend)
{
NTSTATUS status;
size_t cchDestLength;
status = RtlStringValidateDestAndLengthA(pszDest,
cchDest,
&cchDestLength,
NTSTRSAFE_MAX_CCH);
if (NT_SUCCESS(status))
{
if (cchToAppend > NTSTRSAFE_MAX_LENGTH)
{
status = STATUS_INVALID_PARAMETER;
}
else
{
status = RtlStringCopyWorkerA(pszDest + cchDestLength,
cchDest - cchDestLength,
NULL,
pszSrc,
cchToAppend);
}
}
return status;
}
View code on GitHub// ntstrsafe.h
NTSTRSAFEDDI RtlStringCchCatNA(
[in, out] NTSTRSAFE_PSTR pszDest,
[in] size_t cchDest,
[in] STRSAFE_PCNZCH pszSrc,
size_t cchToAppend
);
View the official Windows Driver Kit DDI referenceNo description available.
The RtlStringCchCatNW and RtlStringCchCatNA functions concatenate two character-counted strings while limiting the size of the appended string.
pszDest [in, out]A pointer to a buffer which, on input, contains a null-terminated string to which pszSrc will be concatenated. On output, this is the destination buffer that contains the entire resultant string. The string at pszSrc, up to cchMaxAppend characters, is added to the end of the string at pszDest and terminated with a null character.
cchDest [in]The size of the destination buffer, in characters. The maximum number of characters allowed is NTSTRSAFE_MAX_CCH.
pszSrc [in]A pointer to a null-terminated string. This string will be concatenated to the end of the string that is contained in the buffer at pszDest.
cchToAppendThe maximum number of characters to append to the string that is contained in the buffer at pszDest.
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 strings were concatenated without truncation, and the resultant destination buffer is null-terminated. |
| STATUS_BUFFER_OVERFLOW | This warning status means the concatenation operation did not complete due to insufficient buffer space. The destination buffer contains a truncated, null-terminated version of the intended result. |
| 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. |
RtlStringCchCatNW and RtlStringCchCatNA should be used instead of the following functions:
The size, in characters, of the destination buffer is provided to the function to ensure that RtlStringCchCatNW and RtlStringCchCatNA do not write past the end of the buffer.
Use RtlStringCchCatNW to handle Unicode strings and RtlStringCchCatNA 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" | RtlStringCchCatNW |
| char | "string" | RtlStringCchCatNA |
If pszSrc and pszDest point to overlapping strings, the behavior of the function is undefined.
Neither pszSrc nor pszDest can be NULL. If you need to handle NULL string pointer values, use RtlStringCchCatNEx.
For more information about the safe string functions, see Using Safe String Functions.