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Date:   Sat, 12 Dec 2020 18:48:28 +0100
From:   Dominique Martinet <asmadeus@codewreck.org>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     linux-kbuild@vger.kernel.org,
        Michal Marek <michal.lkml@markovi.net>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] kbuild: rewrite ld-version.sh in shell script
Message-ID: <20201212174828.GA17179@nautica>
References: <20201212165431.150750-1-masahiroy@kernel.org>
 <20201212165431.150750-3-masahiroy@kernel.org>
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Masahiro Yamada wrote on Sun, Dec 13, 2020:
> This script was written in awk in spite of the file extension '.sh'.
> Rewrite it as a shell script.

Wow! I wasn't expecting so much, would have sent some rework after the
upcoming merge window.
Thank you.

Some comments below that you can probably ignore, this works for me.


> diff --git a/scripts/ld-version.sh b/scripts/ld-version.sh
> index 0f8a2c0f9502..c214aeb3200d 100755
> --- a/scripts/ld-version.sh
> +++ b/scripts/ld-version.sh
> @@ -1,11 +1,22 @@
> -#!/usr/bin/awk -f
> +#!/bin/sh
>  # SPDX-License-Identifier: GPL-2.0
> -# extract linker version number from stdin and turn into single number
> -	{
> -	gsub(".*\\)", "");
> -	gsub(".*version ", "");
> -	gsub("-.*", "");
> -	split($1,a, ".");
> -	print a[1]*10000 + a[2]*100 + a[3];
> -	exit
> -	}
> +#
> +# Usage: $ ./scripts/ld-version.sh ld
> +#
> +# Print the linker version of `ld' in a 5 or 6-digit form
> +# such as `23501' for GNU ld 2.35.1 etc.
> +
> +first_line="$($* --version | head -n 1)"

Just nitpicking: this ($*) would fail if the argument contains spaces,
it's generally better to use "$@" or "$1" (with quotes)

Probably doesn't matter here as gcc/clang-version scripts have the same
problem, so if someone had a problem with that they probably would have
reported it there.

> +
> +if ! ( echo $first_line | grep -q "GNU ld"); then
> +	echo 0
> +	exit 1
> +fi
> +
> +# Distributions may append an extra string like 2.35-15.fc33
> +# Take the part that consists of numbers and dots.
> +VERSION=$(echo $first_line | sed 's/.* \([^ ]*\)$/\1/' | sed 's/^\(^[0-9.]*\).*/\1/')
> +MAJOR=$(echo $VERSION | cut -d . -f 1)
> +MINOR=$(echo $VERSION | cut -d . -f 2)
> +PATCHLEVEL=$(echo $VERSION | cut -d . -f 3)
> +printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL

There is a bug if there is no dot at all (e.g. if binutils ever releases
a version 3 and call it version 3 and not 3.0, the script would print
30303 because cut when no delimiter is found always returns the whole
string)
This can be fixed by artificially appending a dot to VERSION:
VERSION=$(echo $first_line | sed 's/.* \([^ ]*\)$/\1/' | sed 's/^\(^[0-9.]*\).*/\1./')

I'm not sure it's worth worrying about either.


Thanks again,
-- 
Dominique