Re: Invalid nar signature

["Thompson, David" <dthompson2@worcester.edu>]

On Mon, Dec 15, 2014 at 4:20 PM, Ludovic Courtès <ludo@gnu.org> wrote:
> "Thompson, David" <dthompson2@worcester.edu> skribis:
>
>> On Mon, Dec 15, 2014 at 12:19 PM, Ludovic Courtès <ludo@gnu.org> wrote:
>>> I think this is due to a subtly misleading file format variation.
>>>
>>> If you look at ‘export-paths’, it does:
>>>
>>>   while there are files to write
>>>     write-long-long 1
>>>     export-path file
>>>   write-long-long 0
>>>
>>> ‘restore-file-set’ does the opposite, which is to read that long-long to
>>> determine whether there’s data coming up, and then to call
>>> ‘restore-file’.
>>
>> Thanks.  I'm still a little confused, though.  I'm not sure what
>> change I need to make in order to satisfy the substituter.  Do I need
>> to write a variant of export-paths that leaves off the initial
>> write-long-long call?
>
> For illustration purposes, here’s a normal sequence:
>
> --8<---------------cut here---------------start------------->8---
> $ wget -O t.nar.bz2 http://hydra.gnu.org/nar/wy70n5zk8qinxjz0wdk9q2hh1zjfb32j-miscfiles-1.5
> $ bunzip2 t.nar.bz2
> $ ./pre-inst-env guile -c '(use-modules (guix serialization)) (call-with-input-file "t.nar" (lambda (port) (restore-file port "restored")))'
> $ ls restored/
> share
> --8<---------------cut here---------------end--------------->8---
>
> ‘restore-file’ is what ‘guix substitute-binary --substitute’ uses.  It
> expects a single store item–i.e., the variant /without/ the leading
> long-long, as you noticed.
>
> To produce that, use ‘write-file’ from (guix serialization):
>
> --8<---------------cut here---------------start------------->8---
> $ ./pre-inst-env guile -c '(use-modules (guix serialization)) (write-file "/gnu/store/wy70n5zk8qinxjz0wdk9q2hh1zjfb32j-miscfiles-1.5" (current-output-port))' > t.nar
> $ ./pre-inst-env guile -c '(use-modules (guix serialization)) (call-with-input-file "t.nar" (lambda (port) (restore-file port "restored")))'
> $ ls restored/
> share
> --8<---------------cut here---------------end--------------->8---

Perfect, thanks!

- Dave