Re: [PATCH] mingw: make stderr unbuffered again

Am 15.02.2017 um 13:32 schrieb Johannes Schindelin:

On Tue, 14 Feb 2017, Johannes Sixt wrote:

quoted

Am 14.02.2017 um 15:47 schrieb Johannes Schindelin:

quoted

On Mon, 13 Feb 2017, Junio C Hamano wrote:

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Johannes Schindelin [off-list ref] writes:

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What we forgot was to mark stderr as unbuffered again.

I do not see how the earlier patch turned stderr from unbuffered to
buffered, as it did not add or remove any setvbuf() call. Can you
explain?

[ motivation and history of js/mingw-isatty snipped ]

So instead of "bending" the target HANDLE of the existing stdout/stderr
(which would *naturally* have kept the buffered/unbuffered nature as-is),
we now redirect with correct API calls.

Your statement implies that at the time when winansi_init() begins, stdio is already initialized and the buffered/unbuffered state has been set for stderr. I would think that this is true.

Then we swap out the file handle underlying stderr in swap_osfhnd() using dup2(). Why would that change the buffered state of stdio?

And the patch I provided at the
bottom of this mail thread reinstates the unbuffered nature of stderr now
that it gets reopened.

Hopefully that makes it clear why the setvbuf() call is required now, but
was previously unnecessary?

Unfortunately, no. I do not see how dup2() causes a change in stdio state. I must be missing something (and that may be a basic misunderstanding of how stdio is initialized).

-- Hannes