[Nix-dev] [PATCH Nix] Flush substituter output upon ‘\r’

[Ludovic Courtès]

Hi Eelco,

I think the patch below fell through the cracks.  ;-)
Is it OK on your side?

Thanks,
Ludo’.

ludo at gnu.org (Ludovic Courtès) skribis:

> Eelco Dolstra <eelco.dolstra at logicblox.com> skribis:
>
>> On 17/06/14 17:50, Ludovic Courtès wrote:
>>
>>> The patch below changes the store so that it flushes what it reads from
>>> the substituter’s stderr when it encounters either a newline or a
>>> carriage return.
>>> 
>>> The intent is to allow substituters to provide some kind of progress
>>> report, where the status is updated by means of a ‘\r’.
>>
>> What kind of progress report do you mean, and why wouldn't '\n' work for that?
>
> Progress reports:
>
>     0%\r
>     1%\r
>     2%\r
>
>>> As a side effect, this patch removes the “substituter-name: ” prefix on
>>> the lines that are printed.  It can be reinstated if deemed appropriate.
>>
>> Please do, without it there is no indication where the error came from.
>
> Here it is.
>
> Thanks,
> Ludo’.
>
> diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
> index 1293a6e..079972c 100644
> --- a/src/libstore/local-store.cc
> +++ b/src/libstore/local-store.cc
> @@ -1141,8 +1141,10 @@ string LocalStore::getLineFromSubstituter(RunningSubstituter & run)
>              if (n == 0) throw EndOfFile(format("substituter `%1%' died unexpectedly") % run.program);
>              err.append(buf, n);
>              string::size_type p;
> -            while ((p = err.find('\n')) != string::npos) {
> -                printMsg(lvlError, run.program + ": " + string(err, 0, p));
> +            while (((p = err.find('\n')) != string::npos)
> +		   || ((p = err.find('\r')) != string::npos)) {
> +	        string thing(err, 0, p + 1);
> +	        writeToStderr(run.program + ": " + thing);
>                  err = string(err, p + 1);
>              }
>          }