[File] offset directicve for file size detection not working! BUG?

[Michał Górny]

On Sun, 2022-09-11 at 03:35 +0200, Jörg Jenderek wrote:
> According to man page magic(4) i can use offset directive to
> show/test for a file size. So i insert after last test a line like:
>  >>>-0		offset	x	FILE_SIZE=%lld
> That show the expected sizes. Then i tried to insert additional
> test lines before calling sub routine. For standard case these
> additional lines fragment look like:
> 
> #>>>0		beshort	x	1ST_VALUE=%x
> > > > -0		offset	=32034	VARIANT_STANDARD
> #>>>>0		beshort	x	1st_VALUE=%x
> > > > > 0		use		degas-bitmap
> 
> Now the sub routine prints other and wrong values. When i try to
> display the first value instead of sub routine, the line with
> "1st_VALUE=" is never executed whereas the line with "1ST_VALUE" is
> executed and show correct value. So i think this is a BUG in file
> command.
> 
> After applying the above mentioned modifications by patch
> file-5.42-images-pi1.diff then for my Atari DEGAS bitmap values
> are wrong.
> 
> Unfortunately i am no c programmer. So maybe somebody can look at
> mentioned item and fix this.

I am not sure whether this is a bug or not but if you call "0 use foo"
after offset, the subroutine starts at the offset you've set for
the offset call, i.e. at the end of file.

-- 
Best regards,
Michał Górny