Re: Invalid nar signature

[Ludovic Courtès]

"Thompson, David" <address@hidden> skribis:

> On Mon, Dec 15, 2014 at 12:19 PM, Ludovic Courtès <address@hidden> 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---

Sorry for the confusion!

Ludo’.