2004.10.04 15:54 "Re: [Tiff] Re: BigTIFF extension issue", by Joris Van Damme

With Microsoft Windows we are blessed with an operating system which supports long file names, but only looks at the first three characters of the file extension when it decides what to do. In this case a ".bigtif" exension would be treated as the extension ".big" by Windows.

Untrue, I believe. What is your source on this?

I have encountered this problem with FindFirstFile (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/fi ndfirstfile.asp).

The problem was encountered under Windows XP. Note that Windows still supports "short names" (8+3) which only support three character extensions. When testing for short names (support apparently can not be disabled), the existing long extension is truncated to just three characters. The legacy 8+3 support continues to permiate Windows and influence how it works.

This means that an application which requests to find files matching ".tif" will also return files with extension ".tifb" and that ".bigtiff" would be treated the same as ".big".

FindFirstFile and short filenames are *not* contemporary. That is backwards compatibility stuff with 8bit windows. Contemporary applications use PIDL technology, and so does the operating system itself. So your original statement 'In this case a ".bigtif" exension would be treated as the extension ".big" by Windows.' is not true. It may get treated as such by applications using FindFirstFile and short filename mapping.

It's easy enough to check your original statement. Change a file extension from '.tif' to '.tifyadayada'. Check and see if it is still associated with any applications known by the operating system to be able to handle TIFF.

Joris Van Damme
info@awaresystems.be
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