Windows Driver Kit: Kernel-Mode Driver Architecture
RtlStringCchCopy
The RtlStringCchCopyW and RtlStringCchCopyA functions copy a null-terminated source string into a destination buffer of specified length.
NTSTATUS
RtlStringCchCopyW(
OUT LPWSTR pszDest,
IN size_t cchDest,
IN LPCWSTR pszSrc
);
NTSTATUS
RtlStringCchCopyA(
OUT LPSTR pszDest,
IN size_t cchDest,
IN LPCSTR pszSrc
);
Parameters
- pszDest
- Supplies a pointer to a caller-supplied buffer that receives the copied string. The string at pszSrc is copied to the buffer at pszDest and terminated with a NULL character.
- cchDest
- Supplies the size, in characters, of the destination buffer. The maximum number of characters allowed is NTSTRSAFE_MAX_CCH.
- pszSrc
- Supplies a pointer to a caller-supplied, null-terminated string.
Return Value
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 value | Meaning |
|---|
| STATUS_SUCCESS | This success status means source data was present, the operation completed 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 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.
- A NULL pointer was present.
- The destination buffer length is zero.
Comments
RtlStringCchCopyW and RtlStringCchCopyA should be used instead of the following functions:
These functions are not replacements for strncpy. Use RtlStringCchCopyN or RtlStringCchCopyNEx to replace strncpy.
The size, in characters, of the destination buffer is provided to RtlStringCchCopyW and RtlStringCchCopyA to ensure that they do not write past the end of the buffer.
Use RtlStringCchCopyW to handle Unicode strings and RtlStringCchCopyA to handle ANSI strings. The form you use depends your data, as shown in the following table.
| String data type | String literal | Function |
|---|
| WCHAR | L"string" | RtlStringCchCopyW |
| char | "string" | RtlStringCchCopyA |
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 RtlStringCchCopyEx.
For more information about the safe string functions, see Using Safe String Functions.
Requirements
IRQL: PASSIVE_LEVEL
Headers: Declared in Ntstrsafe.h. Include Ntstrsafe.h.
Library: Contained in Ntstrsafe.lib.
See Also
RtlStringCbCopy, RtlStringCchCopyEx