Re: "ar rP" does not work with relative paths

[christian montanari]

Thanks, Nick.

your explanations gave a good step forward understanding this "gnu-ar".
but I am not convinced in the usefulness of the path (P) options after
all.

thin archives shall be the way forward, hopefully the linker uses the
right search paths to lead to the objects...but this is another matter.

Best Regards,
Christian Montanari.

On Fri, 2011-10-14 at 17:20 +0100, Nick Clifton wrote:
> Hi Christian,
> 
> > GNU ar (GNU Binutils) 2.19
> 
> FYI 2.21 is now out and 2.22 is due soon...
> 
> 
> > and the commands:
> >
> >   ar rP a.ar b/c.o
> >   ar rP a.ar b/c.o
> >
> > will add the object "c.o" twice in the archive "a.ar".
> >
> > is this the correct behaviour?
> 
> Yes.  Although it certainly is not intuitive.  What is happening is that 
> the first invocation of ar adds c.o to the newly created archive.  (Note 
> the file is stored as "c.o" not "b/c.o" as GNU format archives do *not* 
> include pathname information).
> 
> The second invocation of ar then adds b/c.o again because you have used 
> the P command modifier.  This tells ar to expect a non-GNU format 
> archive where pathnames *are* retained.  Thus the filename matching part 
> of the "r" command checks "b/c.o" (from the command line) against "c.o" 
> (from the archive), decides that they are different, and so adds "c.o" 
> again.


> > the constraint also is that my "a.ar" archive will have other objects
> > "c.o" on different paths, and I do not want to be replaced by object
> > "b/c.o".
> >
> > how to handle relative paths in the GNU binutils-ar?
> 
> The only way to do this is to create a thin archive in conjunction with 
> the P modifier.  For example:
> 
>    % ar rTP a.ar b/c.o
>    % ar t a.ar
>    b/c.o
>    % ar rTP a.ar b/c.o
>    % ar t a.ar
>    b/c.o
>    % ar rTP a.ar c/c.o
>    % ar t a.ar
>    b/c.o
>    c/c.o
> 
> Please note however that thin archives do not contain the actual objects 
> themselves, just the (relative) paths to the objects.  So you cannot 
> move them or export them.
> 
> Cheers
>    Nick
> 

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