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References: <20220128220131.10956-1-brenda.streiff@ni.com>
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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Mon, 7 Feb 2022 22:44:15 +0900
Message-ID: <CAK7LNASdD=xHb24sj80CsG90QVDBXFhFV10MvybdwGf2xx27Kw@mail.gmail.com>
Subject: Re: [PATCH] kconfig: let 'shell' return enough output for deep path names
To:     Brenda Streiff <brenda.streiff@ni.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Sat, Jan 29, 2022 at 7:02 AM Brenda Streiff <brenda.streiff@ni.com> wrot=
e:
>
> The 'shell' built-in only returns the first 256 bytes of the command's
> output. In some cases, 'shell' is used to return a path; by bumping up
> the buffer size to 4096 this lets us capture up to PATH_MAX.
>
> The specific case where I ran into this was due to commit 1e860048c53e
> ("gcc-plugins: simplify GCC plugin-dev capability test"). After this
> change, we now use `$(shell,$(CC) -print-file-name=3Dplugin)` to return
> a path; if the gcc path is particularly long, then the path ends up
> truncated at the 256 byte mark, which makes the HAVE_GCC_PLUGINS
> depends test always fail.
>
> Signed-off-by: Brenda Streiff <brenda.streiff@ni.com>

Thanks, applied to linux-kbuild,
(but I dropped the change to tests)


> ---
>  scripts/kconfig/preprocess.c                                  | 2 +-
>  scripts/kconfig/tests/preprocess/builtin_func/Kconfig         | 3 +++
>  scripts/kconfig/tests/preprocess/builtin_func/expected_stdout | 1 +
>  3 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
> index 0590f86df6e4..748da578b418 100644
> --- a/scripts/kconfig/preprocess.c
> +++ b/scripts/kconfig/preprocess.c
> @@ -141,7 +141,7 @@ static char *do_lineno(int argc, char *argv[])
>  static char *do_shell(int argc, char *argv[])
>  {
>         FILE *p;
> -       char buf[256];
> +       char buf[4096];
>         char *cmd;
>         size_t nread;
>         int i;
> diff --git a/scripts/kconfig/tests/preprocess/builtin_func/Kconfig b/scri=
pts/kconfig/tests/preprocess/builtin_func/Kconfig
> index baa328827911..e9791a97f731 100644
> --- a/scripts/kconfig/tests/preprocess/builtin_func/Kconfig
> +++ b/scripts/kconfig/tests/preprocess/builtin_func/Kconfig
> @@ -25,3 +25,6 @@ $(warning,$(shell,printf 'hello\nworld\n\n4\n\n\n'))
>  # 'lineno' to the line number.
>  $(warning,filename=3D$(filename))
>  $(warning,lineno=3D$(lineno))
> +
> +# 'shell' can return more than 256 bytes of output
> +$(info,$(shell,printf 'hello%01024dworld\n' '0'))
> diff --git a/scripts/kconfig/tests/preprocess/builtin_func/expected_stdou=
t b/scripts/kconfig/tests/preprocess/builtin_func/expected_stdout
> index 82de3a7e97de..8e03e4dfe8f6 100644
> --- a/scripts/kconfig/tests/preprocess/builtin_func/expected_stdout
> +++ b/scripts/kconfig/tests/preprocess/builtin_func/expected_stdout
> @@ -1 +1,2 @@
>  hello world 0
> +hello0000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000000000000000000000=
000000000000000000000000000000000000000000000000000000000world
> --
> 2.20.1
>


--=20
Best Regards
Masahiro Yamada