nsIFile:fileSizeOfLink
From MDC
[edit] Summary
This attribute exposes the size of the symbolic link referenced by this nsIFile.
readonly attribute PRInt64 fileSizeOfLink;
[edit] Remarks
Unlike fileSize, this attribute corresponds to the size of the symbolic link referenced by this nsIFile. If this nsIFile does not reference a symbolic link, then the value of this attribute is undefined.
The value of this attribute is the number of bytes corresponding to the data represented by the symbolic link. Any meta data, such as a resource fork on the Mac, is not included in the measurement of the file size.