bug#27704: [PATCH] daemon: Show actual rather than collateral error when export fails.

[ludo@gnu.org (Ludovic Courtès)]

ludo@gnu.org (Ludovic Courtès) skribis:

> Hello,
>
> Jan Nieuwenhuizen <janneke@gnu.org> skribis:
>
>> Having the wrong permissions on /etc/guix/signing-key.sec gives
>>
>>     guix-daemon: nix/libutil/serialise.cc:15: virtual nix::BufferedSink::~BufferedSink(): Assertion `!bufPos' failed.
>>
>> this patch changes that to
>>
>>     guix-daemon: error: file `/etc/guix/signing-key.sec' should be secret (inaccessible to everybody else)!
>>
>> * nix/nix-daemon/nix-daemon.cc (performOp): Catch any exportPath exception,
>> report and exit on that.  Fixes failing later with uninformative collateral error.
>
> Good catch!
>
>> --- a/nix/nix-daemon/nix-daemon.cc
>> +++ b/nix/nix-daemon/nix-daemon.cc
>> @@ -436,7 +436,13 @@ static void performOp(bool trusted, unsigned int clientVersion,
>>          bool sign = readInt(from) == 1;
>>          startWork();
>>          TunnelSink sink(to);
>> -        store->exportPath(path, sign, sink);
>> +        try {
>> +            store->exportPath(path, sign, sink);
>> +        }
>> +        catch (std::exception &e) {
>> +            fprintf (stderr, "guix-daemon: error: %s\n", e.what ());
>> +            exit (EXIT_FAILURE);
>
> I think we should simply do:
>
>   sink.flush();
>   throw e;
>
> in the ‘catch’ handler.

I’ve confirmed that it works as expected.

Pushed as 2e009ae7cdaee4ce871b3a79d50118762ee29fb6, thanks again!

Ludo’.