Re: [PATCH 1/2] test: notmuch show --format=raw for 4096 byte messages.

Subject: Re: [PATCH 1/2] test: notmuch show --format=raw for 4096 byte messages.

Date: Wed, 01 May 2019 17:12:23 -0300

To: Tomi Ollila, Rob Browning,


From: David Bremner

Tomi Ollila <> writes:

> On Sun, Apr 28 2019, David Bremner wrote:
>> Rob Browning isolated a bug where files of exactly 4096 bytes generate
>> errors because of a zero byte read.
> This happens to be effective test in case where FILE buffering uses 4096
> byte buffers. If it used any other size then this is null test. So this
> test expects implementation detail of stdio (so IMO testing this is waste
> of time).

It's nice to show the next patch actually fixes something.

> What could be useful, is that we just happen to have 4096 byte file in
> our test corpus, and some tests which test other functionality could 
> accidentally fail due to this bug. We could also have 1024, 2048,
> 8192, 16384 bytes (we still cannot say how large buffers any stdio
> buffering uses but... :D)

One problem is that adding new messages to our standard corpus is a
messy operation, and I'm trying to keep the source diff small here.

> And if such messages were generated, instead of add_message those could
> be written "verbatim" from script... so that the file size is not
> dependent how add_message creates it...

Sure, that might make sense, although the script starts to bloat a bit
for the 16k messages. OTOH, I'm fine with replacing the add_message with
a literal 4k message for now.  

I guess we could actually test messages of size BUFSIZ. That isn't
guaranteed to be the actual buffer size, but it seems a better bet than

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