[Libcdio-devel] Re: can files in UDF be fragmented?

[Thomas Schmitt]

Hi,

i have to correct myself. In previous mail i wrote:

> Quite helpful is  udf_file_entry_[ts].i_alloc_descs  which i
> recognize from ECMA-167 as the extent counter.
> So all is well if this is 1.

The size is counted in bytes and not in descriptor records.
So it is safe if udf_file_entry_t.i_alloc_descs is 8 or 20.
It might be safe with 16, but then one needs to make sure it is
a single "long_ad" and not two "short_ad".

For the interpretation one would have to check:

  udf_file_entry_t.icb_tag.flags & ICBTAG_FLAG_AD_MASK

for ICBTAG_FLAG_AD_SHORT, ICBTAG_FLAG_AD_LONG, ...

(I did not check whether all these symbols are public. That approach is
 educating for me, but unappealing for any user of the library.)

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For the original topic of this thread:

The extent size of "short_ad" is restricted to 1 GB - 1.
So a reason for fragmentation might already be given if a file is 1 GB
or larger.


Have a nice day :)

Thomas