RtlUnalignedStringCbLengthW - NtDoc

#ifndef _NTSTRSAFE_H_INCLUDED_
#ifndef NTSTRSAFE_LIB_IMPL
#ifndef NTSTRSAFE_NO_CB_FUNCTIONS
/*++
  NTSTATUS
  RtlUnalignedStringCbLength(
  _In_reads_or_z_(cbMax) LPCUTSTR    psz,
  _In_ _In_range_(1, NTSTRSAFE_MAX_CCH * sizeof(TCHAR)) size_t  cbMax,
  _Out_opt_ _Deref_out_range_(<, cbMax) size_t*   pcbLength   OPTIONAL
  );
  Routine Description:
  This routine is a version of RtlStringCbLength that accepts an unaligned string pointer.
  This function returns an NTSTATUS value, and not a pointer.  It returns
  STATUS_SUCCESS if the string is non-null and the length including the null
  terminator is less than or equal to cbMax bytes.
Arguments:
psz         -   string to check the length of
cbMax       -   maximum number of bytes including the null terminator
that psz is allowed to contain
pcb         -   if the function succeeds and pcb is non-null, the current length
in bytes of psz excluding the null terminator will be returned.
This out parameter is equivalent to the return value of strlen(psz) * sizeof(TCHAR)
Notes:
psz can be null but the function will fail
cbMax should be greater than or equal to sizeof(TCHAR) or the function will fail
Return Value:
STATUS_SUCCESS -   psz is non-null and the length including the null
terminator is less than or equal to cbMax bytes
failure        -   you can use the macro NTSTATUS_CODE() to get a win32
error code for all hresult failure cases
It is strongly recommended to use the NT_SUCCESS() macro to test the
return value of this function.
--*/
#ifdef ALIGNMENT_MACHINE

_Must_inspect_result_
NTSTRSAFEDDI
    RtlUnalignedStringCbLengthW(
            _In_reads_or_z_(cbMax / sizeof(wchar_t)) STRSAFE_PCUNZWCH psz,
            _In_ _In_range_(1, NTSTRSAFE_MAX_CCH * sizeof(wchar_t)) size_t cbMax,
            _Out_opt_ _Deref_out_range_(<, cbMax - 1) size_t* pcbLength)
{
    NTSTATUS status;
    size_t cchMax = cbMax / sizeof(wchar_t);
    size_t cchLength = 0;

    if ((psz == NULL) || (cchMax > NTSTRSAFE_MAX_CCH))
    {
        status = STATUS_INVALID_PARAMETER;
    }
    else
    {
        status = RtlUnalignedStringLengthWorkerW(psz, cchMax, &cchLength);
    }

    if (pcbLength)
    {
        if (NT_SUCCESS(status))
        {
            // safe to multiply cchLength * sizeof(wchar_t) since cchLength < NTSTRSAFE_MAX_CCH and sizeof(wchar_t) is 2
            *pcbLength = cchLength * sizeof(wchar_t);
        }
        else
        {
            *pcbLength = 0;
        }
    }

    return status;
}

#endif
#endif
#endif
#endif
View code on GitHub

#ifndef _NTSTRSAFE_H_INCLUDED_
#ifndef NTSTRSAFE_LIB_IMPL
#ifndef NTSTRSAFE_NO_CB_FUNCTIONS
/*++
  NTSTATUS
  RtlUnalignedStringCbLength(
  _In_reads_or_z_(cbMax) LPCUTSTR    psz,
  _In_ _In_range_(1, NTSTRSAFE_MAX_CCH * sizeof(TCHAR)) size_t  cbMax,
  _Out_opt_ _Deref_out_range_(<, cbMax) size_t*   pcbLength   OPTIONAL
  );
  Routine Description:
  This routine is a version of RtlStringCbLength that accepts an unaligned string pointer.
  This function returns an NTSTATUS value, and not a pointer.  It returns
  STATUS_SUCCESS if the string is non-null and the length including the null
  terminator is less than or equal to cbMax bytes.
Arguments:
psz         -   string to check the length of
cbMax       -   maximum number of bytes including the null terminator
that psz is allowed to contain
pcb         -   if the function succeeds and pcb is non-null, the current length
in bytes of psz excluding the null terminator will be returned.
This out parameter is equivalent to the return value of strlen(psz) * sizeof(TCHAR)
Notes:
psz can be null but the function will fail
cbMax should be greater than or equal to sizeof(TCHAR) or the function will fail
Return Value:
STATUS_SUCCESS -   psz is non-null and the length including the null
terminator is less than or equal to cbMax bytes
failure        -   you can use the macro NTSTATUS_CODE() to get a win32
error code for all hresult failure cases
It is strongly recommended to use the NT_SUCCESS() macro to test the
return value of this function.
--*/
#ifdef ALIGNMENT_MACHINE
// ...
#else

#define RtlUnalignedStringCbLengthW    RtlStringCbLengthW

#endif
#endif
#endif
#endif
View code on GitHub