DOSFS and the short and Long file names.

Chris Johns chrisj at
Thu Aug 4 04:34:59 UTC 2011

On 4/08/11 1:59 PM, Nasir, Aliasgar ( SBU-ETS ) wrote:
> Hi,
> With the RTEMS4.10, we noticed that there is concept about long and
> short file names in the DOSFS.
> We use the DOSFS on an SDCARD. When we try to write a file on the card,
> with file name say ‘Error2.txt’, the DOSFS detects this as a long file
> name and then executes the below code in function
> msdos_find_name_in_fat_file(), while creating the file.
> *if**(*name_type*==*MSDOS_NAME_LONG*)*
> *{*
> *int*slot*=**(((*empty_space_offset***bts2rd*)**+*empty_space_entry*)**/*
> MSDOS_DIRECTORY_ENTRY_STRUCT_SIZE*)**+*lfn_entries*+*1*;*
> msdos_short_name_hex*(*MSDOS_DIR_NAME*(*name_dir_entry*),*slot*);*
> *}*
> The above piece of code modifies the file name as ERR~0005.TXT. This is
> the file name seen when we see the contents of the card on a Windows
> based machine using card reader. The file name of the file as seen from
> the RTEMS shell is still ‘Error2.txt’
> Can anyone guide as what should be done to see a the correct file name
> (Error2.txt) on the Windows machine?

You have used mixed case and this cannot be handled with a short file 
name therefore it has used a long file name which does maintain the 
case. Windows should notice this and show the short and long filenames.

> Regards,
> Ali
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