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References: <20220224055350.1854078-1-keescook@chromium.org>
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From:   Daniel Latypov <dlatypov@google.com>
Date:   Thu, 24 Feb 2022 10:28:12 -0800
Message-ID: <CAGS_qxo1UkRUbXnX7NkfDCLhqa2-_dn3poKBi=NyGJ4C0EhUmw@mail.gmail.com>
Subject: Re: [PATCH] kunit: tool: Do not colorize output when redirected
To:     Kees Cook <keescook@chromium.org>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
        David Gow <davidgow@google.com>, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
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On Wed, Feb 23, 2022 at 9:53 PM Kees Cook <keescook@chromium.org> wrote:
>
> Filling log files with color codes makes diffs and other comparisons
> difficult. Only emit vt100 codes when the stdout is a TTY.
>
> Cc: Brendan Higgins <brendanhiggins@google.com>
> Cc: linux-kselftest@vger.kernel.org
> Cc: kunit-dev@googlegroups.com
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  tools/testing/kunit/kunit_parser.py | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/tools/testing/kunit/kunit_parser.py b/tools/testing/kunit/kunit_parser.py
> index 05ff334761dd..807ed2bd6832 100644
> --- a/tools/testing/kunit/kunit_parser.py
> +++ b/tools/testing/kunit/kunit_parser.py
> @@ -11,6 +11,7 @@
>
>  from __future__ import annotations
>  import re
> +import sys
>
>  import datetime
>  from enum import Enum, auto
> @@ -503,14 +504,20 @@ RESET = '\033[0;0m'
>
>  def red(text: str) -> str:
>         """Returns inputted string with red color code."""
> +       if not sys.stdout.isatty():
> +               return text

I'd been thinking about doing this for a while.
I'd just gotten used to removing them via sed, or ending pipes with less -R.
I totally agree it's for the best that colors be turned off by default
when piping.

My hesitation was whether we'd want to introduce a flag like grep et al have.
I.e. --color=auto/always/etc.

Pros:
* consistency with grep, maybe less surprise
* allows wrappers around kunit.py to redirect output and still show color
   * this is very niche and I know it. But I happen to own such a wrapper :)

Cons:
* an extra flag that's very niche
  * I'm likely the only person to have ever used `kunit.py run | ... | less -R`
* the logic to check for coloring becomes more complicated, need to add a helper

I'm fine if we just stick with this simpler approach or do it later.
My aforementioned wrapper only redirects stdout when necessary anyways.


>         return '\033[1;31m' + text + RESET
>
>  def yellow(text: str) -> str:
>         """Returns inputted string with yellow color code."""
> +       if not sys.stdout.isatty():
> +               return text
>         return '\033[1;33m' + text + RESET
>
>  def green(text: str) -> str:
>         """Returns inputted string with green color code."""
> +       if not sys.stdout.isatty():
> +               return text
>         return '\033[1;32m' + text + RESET
>
>  ANSI_LEN = len(red(''))
> --
> 2.30.2
>
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