DownlevelGetStringScripts function

Provides a list of scripts used in the specified Unicode string.

Syntax

int DownlevelGetStringScripts(
  _In_  DWORD   dwFlags,
  _In_  LPCWSTR lpString,
  _In_  int     cchString,
  _Out_ LPWSTR  lpScripts,
  _In_  int     cchScripts
);

Parameters

dwFlags [in]

Flags specifying options for script retrieval.

Value	Meaning
GSS_ALLOW_INHERITED_COMMON	Retrieve "Qaii" (INHERITED) and "Zyyy" (COMMON) script information. This value does not affect the processing of unassigned characters. These characters in the input string always cause a "Zzzz" (UNASSIGNED script) to appear in the script string.

 

Note

By default, this function ignores any inherited or common characters in the input Unicode string. If GSS_ALLOW_INHERITED_COMMON is not set, neither "Qaii" nor "Zyyy" will appear in the script string, even if the input string contains such characters. If GSS_ALLOW_INHERITED_COMMON is set, and if the input string contains inherited and/or common characters, "Qaii" and/or "Zyyy" appear in the script string. See the Remarks section.

 

lpString [in]

Pointer to the Unicode string to analyze.

cchString [in]

Size, in characters, of the Unicode string indicated by lpString. The application sets this parameter to -1 if the string is null-terminated. If the application sets this parameter to 0, the function retrieves a null Unicode string (L"\0") in lpScripts and returns 1.

lpScripts [out]

Pointer to a buffer in which this function retrieves a null-terminated string representing a list of scripts, using the 4-character notation used in ISO 15924. Each script name consists of four Latin characters, and the names are retrieved in alphabetical order. Each name, including the last, is followed by a semicolon.

Alternatively, this parameter can contain NULL if cchScripts set to 0. In this case, the function returns the required size for the script buffer.

cchScripts [in]

Size, in characters, for the script buffer indicated by lpScripts.

Alternatively, the application can set this parameter to 0. In this case, the function retrieves NULL in lpScripts and returns the required size for the script buffer.

Return value

Returns the number of characters retrieved in the output buffer, including a terminating null character, if successful and cchScripts is set to a nonzero value. The function returns 1 to indicate that no script has been found, for example, when the input string only contains COMMON or INHERITED characters and GSS_ALLOW_INHERITED_COMMON is not set. Given that each found script adds five characters (four characters + delimiter), a simple mathematical operation provides the script count as (return_code - 1) / 5.

If the function succeeds and the value of cchScripts is 0, the return value is the required size, in characters including a terminating null character, for the script buffer. The script count is as described above.

The function returns 0 if it does not succeed. To get extended error information, the application can call GetLastError, which can return one of the following error codes:

• ERROR_BADDB. The function could not access the data. This situation should not normally occur, and typically indicates a bad installation, a disk problem, or the like.
• ERROR_INSUFFICIENT_BUFFER. A supplied buffer size was not large enough, or it was incorrectly set to NULL.
• ERROR_INVALID_FLAGS. The values supplied for flags were not valid.
• ERROR_INVALID_PARAMETER. Any of the parameter values was invalid.

Remarks

This function is useful as part of a strategy to mitigate security issues related to internationalized domain names (IDNs).

The script determination is based on the script values published by the Unicode Consortium in https://www.unicode.org/Public/4.1.0/ucd/Scripts.txt, except that the unassigned characters have the value "Zzzz" (UNASSIGNED) instead of "Zyyy" (COMMON).

Here are some examples of the behavior of this function:

Input string

dwFlags

lpScripts

Scripts

Microsoft.com

0

Latn;

Latin

Microsoft.com

GSS_ALLOW_INHERITED_COMMON

Latn;Zyyy;

Latin + Common

${ROWSPAN2}$Niño${REMOVE}$

004E 0069 0241 006F

${ROWSPAN2}$GSS_ALLOW_INHERITED_COMMON${REMOVE}$

${ROWSPAN2}$Latn;${REMOVE}$

${ROWSPAN2}$Latin${REMOVE}$

Uses LATIN SMALL LETTER N WITH TILDE

${ROWSPAN2}$Niño${REMOVE}$

004E 0069 006E 0303 006F

${ROWSPAN2}$GSS_ALLOW_INHERITED_COMMON${REMOVE}$

${ROWSPAN2}$Latn;Qaii;${REMOVE}$

${ROWSPAN2}$Latin + Inherited${REMOVE}$

Uses COMBINING TILDE

${ROWSPAN2}$Spооf${REMOVE}$

0053 0070 043e 043e 0066

${ROWSPAN2}$0${REMOVE}$

${ROWSPAN2}$Latn;Cyrl;${REMOVE}$

${ROWSPAN2}$Latin + Cyrillic${REMOVE}$

Uses CYRILLIC SMALL LETTER O



U+f000

0

Zzzz;

Unassigned



U+f000

GSS_ALLOW_INHERITED_COMMON

Zzzz;

Unassigned

The required header file and DLL are part of the "Microsoft Internationalized Domain Name (IDN) Mitigation APIs" download available from archive.org.

Requirements

See also

National Language Support

National Language Support Functions

Handling Internationalized Domain Names (IDNs)

DownlevelGetLocaleScripts

DownlevelVerifyScripts

GetStringScripts