RtlStringCbCopyA - 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
RtlStringCbCopy(
_Out_writes_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 'strcpy'.
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 routine is not a replacement for strncpy. That function will pad the
destination string with extra null termination characters if the count is
greater than the length of the source string, and it will fail to null
terminate the destination string if the source string length is greater
than or equal to the count. You can not blindly use this instead of strncpy:
it is common for code to use it to "patch" strings and you would introduce
errors if the code started null terminating in the middle of the string.
This function returns an NTSTATUS value, and not a pointer. It returns
STATUS_SUCCESS if the string was copied without truncation and null terminated,
otherwise it will return a failure code. In failure cases as much of pszSrc
will be copied to pszDest as possible, and pszDest will be null terminated.
Arguments:
pszDest - destination string
cbDest - size of destination buffer in bytes.
length must be = ((_tcslen(src) + 1) * sizeof(TCHAR)) to
hold all of the source including 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 RtlStringCbCopyEx if you require
the handling of NULL values.
Return Value:
STATUS_SUCCESS - if there was source data and it was all copied 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 copy
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
RtlStringCbCopyA(
_Out_writes_bytes_(cbDest) _Always_(_Post_z_) NTSTRSAFE_PSTR pszDest,
_In_ size_t cbDest,
_In_ NTSTRSAFE_PCSTR pszSrc)
{
NTSTATUS status;
size_t cchDest = cbDest / sizeof(char);
status = RtlStringValidateDestA(pszDest, cchDest, NTSTRSAFE_MAX_CCH);
if (NT_SUCCESS(status))
{
status = RtlStringCopyWorkerA(pszDest,
cchDest,
NULL,
pszSrc,
NTSTRSAFE_MAX_LENGTH);
}
else if (cchDest > 0)
{
*pszDest = '\0';
}
return status;
}
View code on GitHub// ntstrsafe.h
NTSTRSAFEDDI RtlStringCbCopyA(
[out] NTSTRSAFE_PSTR pszDest,
[in] size_t cbDest,
[in] NTSTRSAFE_PCSTR pszSrc
);
View the official Windows Driver Kit DDI referenceNo description available.
The RtlStringCbCopyW and RtlStringCbCopyA functions copy a byte-counted string into a buffer.
pszDest [out]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.
cbDest [in]The size, in bytes, of the destination buffer. The buffer must be large enough for the string 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 caller-supplied, null-terminated string.
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 string was copied without truncation, and the resultant destination buffer is null-terminated. |
| STATUS_BUFFER_OVERFLOW | This warning status means the copy 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 cbDest 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. |
RtlStringCbCopyA and RtlStringCbCopyW should be used instead of the following functions:
RtlStringCbCopyA and RtlStringCbCopyW are not replacements for strncpy. To replace strncpy, use RtlStringCbCopyN or RtlStringCbCopyNEx.
The size of the destination buffer is provided to the function to ensure that RtlStringCbCopy does not write past the end of the buffer.
Use RtlStringCbCopyW to handle Unicode strings and RtlStringCbCopyA 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" | RtlStringCbCopyW |
| char | "string" | RtlStringCbCopyA |
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 RtlStringCbCopyEx.
For more information about the safe string functions, see Using Safe String Functions.