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Re: [Libcdio-devel] Re: private udf information

From: Rocky Bernstein
Subject: Re: [Libcdio-devel] Re: private udf information
Date: Mon, 18 Oct 2010 23:51:05 -0400

On Mon, Oct 18, 2010 at 6:28 PM, Shaya Potter <address@hidden> wrote:

> as a followup to my previous information, this function I added to my own
> private copy lets me do what I need
> uint32_t udf_get_start_block(const udf_dirent_t *p_udf_dirent)
> {
>  udf_t *p_udf = p_udf_dirent->p_udf;
>  uint32_t i_max_size;
>  lba_t i_start = offset_to_lba(p_udf_dirent, p_udf->i_position, &i_start,
>                                &i_max_size);
>  return i_start;
> }
> a better solution might be a stat() type call that returns a lot of
> information in a struct.

Suppose both struct udf_dirent_s and the udf_get_start_block() prototype
were put in udf.h. In other words suppose these were both made public.

Would that suffice?

A comment about udf_get_start_block is that it looks like at some point one
might want to do the same thing for i_max_size (as you indicated in the
original post); The code to get this would look almost identical as above.
So, as you suggest, perhaps a function returns both values in one shot would
be good.

> On 10/17/2010 08:42 PM, Shaya Potter wrote:
>> in libcdio a bunch of information is kept private and not readily
>> available to programs, what I'm concerned about is basically the
>> start/length of a file.
>> this is in the udf_dirent_t structure, but is hidden from programmers.
>> I care about this as I am trying to write a barebones dvd decrypter that
>> works on images files
>> i.e. I have some DVDs in bad shape, so using 1) lsdvd to authenticate
>> the disk, 2) ddrescue to recover a complete image, but it still has CSS
>> embedded, so then need to remove the CSS, but I have to basically check
>> if I need to rekey on each VOB file and need to know the start of it to
>> rekey on the right block. libcdio's udf support should provide it to me,
>> but as it's hidden, it doesn't.
>> any thoughts on providing an interface to this data?
>> thanks

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