RtlStringCbCatA - 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
RtlStringCbCat(
_Inout_updates_bytes_(cbDest) _Always_(_Post_z_) LPTSTR pszDest,
_In_ size_t cbDest,
_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 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 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
cbDest - size of destination buffer in bytes.
length must be = ((_tcslen(pszDest) + _tcslen(pszSrc) + 1) * sizeof(TCHAR)
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 RtlStringCbCatEx 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
RtlStringCbCatA(
_Inout_updates_bytes_(cbDest) _Always_(_Post_z_) NTSTRSAFE_PSTR pszDest,
_In_ size_t cbDest,
_In_ NTSTRSAFE_PCSTR pszSrc)
{
NTSTATUS status;
size_t cchDestLength;
size_t cchDest = cbDest / sizeof(char);
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 RtlStringCbCatA(
[in, out] NTSTRSAFE_PSTR pszDest,
[in] size_t cbDest,
[in] NTSTRSAFE_PCSTR pszSrc
);
View the official Windows Driver Kit DDI referenceNo description available.
The RtlStringCbCatW and RtlStringCbCatA functions concatenate two byte-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.
cbDest [in]The size of the destination buffer, in bytes. The destination buffer must be large enough to include the concatenated strings and 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).
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 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 STATUS_INVALID_PARAMETER return value means that one of the following occurred: * 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. |
RtlStringCbCatW and RtlStringCbCatA should be used instead of the following functions:
Because RtlStringCbCatW and RtlStringCbCatA receive the size of the destination buffer as input, they will not write past the end of the buffer.
Use RtlStringCbCatW to handle Unicode strings and RtlStringCbCatA to handle ANSI strings. The form to use is determined by your data as shown in the following table.
| String data type | String literal | Function |
|---|---|---|
| WCHAR | L"string" | RtlStringCbCatW |
| char | "string" | RtlStringCbCatA |
If pszSrc and pszDest point to strings that overlap, the behavior of the functions is undefined.
Neither pszSrc nor pszDest can be NULL. If you need to handle NULL string pointer values, use RtlStringCbCatNEx.
For more information about the safe string functions, see Using Safe String Functions.