[Yaffs] i'm puzzled about obj->short_name，could anyone help …

as i read the source code of yaffs2 ,i found yaffs2 only store short_name
in a file's yaffs_object structure.
when find file by name,it may use the short name to identify the file ,but
when 2 files have names that the the first few chars are same how to
distinguish them?
what's more if uses short name,it will not equal to the given name.so how
does short name works?
i think it's my fault but i'm not sure where is the error,could any help me.
thanks very much.
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Regards,
Ezio.