linux-kernel - Re: [PATCH] kbuild: escape single backslashes in macro make-cmd

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Message-ID: <20140807170800.GA1542@ravnborg.org>
Date:	Thu, 7 Aug 2014 19:08:00 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	Michal Marek <mmarek@...e.cz>
Cc:	Konstantin Khlebnikov <koct9i@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	"x86@...nel.org" <x86@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] kbuild: escape single backslashes in macro make-cmd

> 
> The problem is that the bash echo does not interpred _any_ \-sequences
> without -e. So the nicely escaped \\ stays a \\ and we get spurious
> rebuilds with bash instead. It previously worked with bash, because the
> backslash escaping was completely broken. You not only moved it up in
> the chain, but also fixed it by removing one superflous level of
> escaping.
> 
> I'm now testing this, i.e. dropping the backslash escaping completely
> and doing a printf '%s\n' instead. Can you try if it works for you?
> 
> 
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index 122f95c..8a9a4e1 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -215,11 +215,13 @@ else
>  arg-check = $(if $(strip $(cmd_$@)),,1)
>  endif
>  
> -# >'< substitution is for echo to work,
> -# >$< substitution to preserve $ when reloading .cmd file
> -# note: when using inline perl scripts [perl -e '...$$t=1;...']
> -# in $(cmd_xxx) double $$ your perl vars
> -make-cmd = $(subst \\,\\\\,$(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1))))))
> +# Replace >$< with >$$< to preserve $ when reloading the .cmd file
> +# (needed for make)
> +# Replace >#< with >\#< to avoid starting a comment in the .cmd file
> +# (needed for make)
> +# Replace >'< with >'\''< to be able to enclose the whole string in '...'
> +# (needed for the shell)
> +make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))
This is simpler and remotely readble - nice!
As a bonus you added more descriptive comments

Looks good.
You may add my:
Reviewed-by: Sam Ravnborg <sam@...nborg.org>

	Sam
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