RtlStringCchCatA - 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
RtlStringCchCat(
_Inout_updates_(cchDest) _Always_(_Post_z_) LPTSTR pszDest,
_In_ size_t cchDest,
_In_ LPCTSTR pszSrc
);
Routine Description:
This routine is a safer version of the C built-in function 'strcat'.
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 concatenated without truncation and 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) + _tcslen(pszSrc) + 1)
to hold all of the combine string plus the null
terminator
pszSrc - source string which must be null terminated
Notes:
Behavior is undefined if source and destination strings overlap.
pszDest and pszSrc should not be NULL. See RtlStringCchCatEx if you require
the handling of NULL values.
Return Value:
STATUS_SUCCESS - if there was source data and it was all concatenated 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
RtlStringCchCatA(
_Inout_updates_(cchDest) _Always_(_Post_z_) NTSTRSAFE_PSTR pszDest,
_In_ size_t cchDest,
_In_ NTSTRSAFE_PCSTR pszSrc)
{
NTSTATUS status;
size_t cchDestLength;
status = RtlStringValidateDestAndLengthA(pszDest,
cchDest,
&cchDestLength,
NTSTRSAFE_MAX_CCH);
if (NT_SUCCESS(status))
{
status = RtlStringCopyWorkerA(pszDest + cchDestLength,
cchDest - cchDestLength,
NULL,
pszSrc,
NTSTRSAFE_MAX_LENGTH);
}
return status;
}
View code on GitHub// ntstrsafe.h
NTSTRSAFEDDI RtlStringCchCatA(
[in, out] NTSTRSAFE_PSTR pszDest,
[in] size_t cchDest,
[in] NTSTRSAFE_PCSTR pszSrc
);
View the official Windows Driver Kit DDI referenceNo description available.
The RtlStringCchCatW and RtlStringCchCatA functions concatenate two character-counted strings.
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 is added to the end of the string at pszDest and terminated with a null character.
cchDest [in]The size, in characters, of the destination buffer. 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.
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, 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 pointer was NULL, but the buffer size was not zero. * The destination buffer length was zero, but a nonzero length source string was present. |
RtlStringCchCatW and RtlStringCchCatA should be used instead of the following functions:
The size, in characters, of the destination buffer is provided to ensure that RtlStringCchCatW and RtlStringCchCatA do not write past the end of the buffer.
Use RtlStringCchCatW to handle Unicode strings and RtlStringCchCatA 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" | RtlStringCchCatW |
| char | "string" | RtlStringCchCatA |
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 RtlStringCchCatEx.
For more information about the safe string functions, see Using Safe String Functions.