Microsoft KB Archive/129544

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PRB: CreateFile Does Not Handle OEM Chars as Expected

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Q129544

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The information in this article applies to:


 * Microsoft Win32s versions 1.2, 1.25, 1.25a, 1.3, 1.30a, 1.3c

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SYMPTOMS
When CreateFile is passed a filename string that contains an OEM character, the name of the file created is not as expected. In particular, a file created with CreateFile cannot be opened with OpenFile when OpenFile is passed the same filename string.

For example, suppose that the ANSI filename string contains a lower-case e accent character (0x0e9). The file created by CreateFile contains an upper-case E and the file created by OpenFile contains an upper-case E accent character.

CAUSE
CreateFile is implemented with calls to MS-DOS. MS-DOS converts the given file names to upper-case letters. OpenFile is implemented with a thunk to the 16-bit Windows OpenFile. OpenFile converts the file name to upper-case before calling MS-DOS. The conversion that the 16-bit OpenFile is doing is different from the conversion performed by MS-DOS for the OEM characters. The result is that different filenames are created for the same string passed to CreateFile and OpenFile if the name contains OEM characters.

RESOLUTION
To make the file name created by CreateFile consistent with the file name created by OpenFile, call AnsiUpper on the file name string before calling CreateFile.

STATUS
This behavior is by design and will not be changed in Win32s, because it may break existing Win32-based applications.

MORE INFORMATION
The 16-bit OpenFile will fail to find an existing file if the file contains OEM characters but not an explicit full path. This also occurs with the 32-bit OpenFile, because it is thunked to the 16-bit OpenFile.

SearchFile will also fail to find files if the file name contains OEM characters or if the search path (lpszpath != NULL) contains OEM characters.

NOTE: In 16-bit Windows and Win32s 1.2 and earlier, OpenFile returns the filename in OEM characters. However, the Win32 API documentation states that OpenFile should return an ANSI string. Starting with the next version of Win32s, OpenFile will return an ANSI string, as it does under Windows NT.

Additional query words: 1.20

Keywords : kbOSWin32s

Issue type :

Technology : kbWin32sSearch kbWin32s120 kbWin32s125 kbWin32s125a kbWin32s130 kbWin32s130a kbWin32s130c