GNU bug report logs - #30066
'get-bytevector-some' returns only 1 byte from unbuffered ports

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Message #47 received at 30066 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: Andy Wingo <wingo <at> igalia.com>
Cc: Mark H Weaver <mhw <at> netris.org>, 30066 <at> debbugs.gnu.org
Subject: Re: bug#30066: 'get-bytevector-some' returns only 1 byte from
 unbuffered ports
Date: Fri, 16 Feb 2018 14:19:50 +0100

ludo <at> gnu.org (Ludovic Courtès) skribis:

> Andy Wingo <wingo <at> igalia.com> skribis:
>
>> On Fri 12 Jan 2018 11:15, ludo <at> gnu.org (Ludovic Courtès) writes:
>>
>>> Andy Wingo <wingo <at> igalia.com> skribis:
>>>
>>>> On Thu 11 Jan 2018 22:55, Mark H Weaver <mhw <at> netris.org> writes:
>>>
>>> [...]
>>>
>>>>>>> Out of curiosity, is there a reason why you're using an unbuffered port
>>>>>>> in your use case?
>>>>>>
>>>>>> It’s to implement redirect à la socat:
>>>>>>
>>>>>>   https://git.savannah.gnu.org/cgit/guix.git/commit/?id=17af5d51de7c40756a4a39d336f81681de2ba447
>>>>>
>>>>> Why is an unbuffered port being used here?  Can we change it to a
>>>>> buffered port?
>>>>
>>>> This was also a question I had!  If you make it a buffered port at 4096
>>>> bytes (for example), then get-bytevector-some works exactly like you
>>>> want it to, no?
>>>
>>> It might work, but that’s more by chance no?
>>
>> No, it is reliable.  get-bytevector-some on a buffered port must either
>> return all the buffered bytes or perform exactly one read (up to the
>> buffer size) and either return those bytes or EOF.  As far as I
>> understand, that is exactly what you want.
>
> Indeed, that works well, thanks!  So, after all, problem solved?

I’m closing this as not-a-bug.

Ludo’.

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