Re: [PATCH 5/5] format-patch: avoid freopen()

> On Sun, 19 Jun 2016, Eric Sunshine wrote:
>> On Sat, Jun 18, 2016 at 6:04 AM, Johannes Schindelin
>> <johannes.schindelin@gmx.de> wrote:
>> >         if (output_directory) {
>> > +               rev.diffopt.use_color = 0;
>>
>> What is this change about? It doesn't seem to be related to anything
>> else in the patch.
>
> Good point, I completely forgot to mention this is the commit message.
>
> When format-patch calls the diff machinery, want_color() is used to
> determine whether to use ANSI color sequences or not. If use_color is not
> set explicitly, isatty(1) is used to determine whether or not the user
> wants color. When stdout was freopen()ed, this isatty(1) call naturally
> looked at the file descriptor that was reopened, and determined correctly
> that no color was desired.
>
> With the freopen() call gone, stdout may very well be the terminal. But we
> still do not want color because the output is intended to go to a file (at
> least if output_directory is set).

> So how about this commit message (I inserted the "Note: ..." paragraph)?
>
> -- snipsnap --
> format-patch: avoid freopen()
> [...]
> Note: we now have to set use_color = 0 explicitly when writing to files,
> as the auto-detection whether to colorify the output *still* looks at
> stdout (which is no longer freopen()ed, and therefore might still be
> printing to the terminal).