RtlMultiByteToUnicodeN - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
#ifndef _NTRTL_H

/**
 * The RtlMultiByteToUnicodeN routine translates the specified source string into a Unicode string, using the current system ANSI code page (ACP).
 * The source string is not necessarily from a multibyte character set.
 *
 * \param UnicodeString Pointer to a caller-allocated buffer that receives the translated string. UnicodeString buffer must not overlap with MultiByteString buffer.
 * \param MaxBytesInUnicodeString Maximum number of bytes to be written at UnicodeString. If this value causes the translated string to be truncated, RtlMultiByteToUnicodeN does not return an error status.
 * \param BytesInUnicodeString Pointer to a caller-allocated variable that receives the length, in bytes, of the translated string. This parameter can be NULL.
 * \param MultiByteString Pointer to the string to be translated.
 * \param BytesInMultiByteString Size, in bytes, of the string at MultiByteString.
 * \return NTSTATUS Successful or errant status.
 * \sa https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntifs/nf-ntifs-rtlmultibytetounicoden
 */
NTSYSAPI
NTSTATUS
NTAPI
RtlMultiByteToUnicodeN(
    _Out_writes_bytes_to_(MaxBytesInUnicodeString, *BytesInUnicodeString) PWCH UnicodeString,
    _In_ ULONG MaxBytesInUnicodeString,
    _Out_opt_ PULONG BytesInUnicodeString,
    _In_reads_bytes_(BytesInMultiByteString) PCSTR MultiByteString,
    _In_ ULONG BytesInMultiByteString
    );

#endif

View code on GitHub
// ntifs.h

NTSYSAPI NTSTATUS RtlMultiByteToUnicodeN(
  [out]           PWCH       UnicodeString,
  [in]            ULONG      MaxBytesInUnicodeString,
  [out, optional] PULONG     BytesInUnicodeString,
  [in]            const CHAR *MultiByteString,
  [in]            ULONG      BytesInMultiByteString
);

View the official Windows Driver Kit DDI reference

NtDoc

This function is documented in Windows Driver Kit.

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Windows Driver Kit DDI reference (nf-ntifs-rtlmultibytetounicoden)

RtlMultiByteToUnicodeN function

Description

The RtlMultiByteToUnicodeN routine translates the specified source string into a Unicode string, using the current system ANSI code page (ACP). The source string is not necessarily from a multibyte character set.

Parameters

UnicodeString [out]

Pointer to a caller-allocated buffer that receives the translated string. UnicodeString buffer must not overlap with MultiByteString buffer.

MaxBytesInUnicodeString [in]

Maximum number of bytes to be written at UnicodeString. If this value causes the translated string to be truncated, RtlMultiByteToUnicodeN does not return an error status.

BytesInUnicodeString [out, optional]

Pointer to a caller-allocated variable that receives the length, in bytes, of the translated string. This parameter can be NULL.

MultiByteString [in]

Pointer to the string to be translated.

BytesInMultiByteString [in]

Size, in bytes, of the string at MultiByteString.

Return value

RtlMultiByteToUnicodeN returns STATUS_SUCCESS.

Remarks

RtlMultiByteToUnicodeN supports only precomposed Unicode characters that are mapped to the current system ANSI code page installed at system boot.

Although BytesInUnicodeString is optional and can be NULL, callers should provide storage for it, because the received length can be used to determine whether the conversion was successful.

If the current system code page defines a single-byte character set, all ANSI characters in the range 0x00 to 0x7f are simply zero-extended in the corresponding Unicode string to speed the conversion operation. The ANSI value 0x5c in such a code page is translated into the backslash character, even if the current single-byte code page defines this character as the Yen sign.

RtlMultiByteToUnicodeN does not modify the source string unless the UnicodeString and MultiByteString pointers are equivalent. The returned Unicode string is not null-terminated.

Like RtlMultiByteToUnicodeSize, RtlMultiByteToUnicodeN supports only precomposed Unicode characters that are mapped to the current system ANSI code page installed at system boot.

For information about other string-handling routines, see Run-Time Library (RTL) Routines.

See also

RtlMultiByteToUnicodeSize

RtlUnicodeToMultiByteN

View the official Windows Driver Kit DDI reference

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