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

[Nick Clifton]

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