linux-kernel - Re: [PATCH] kbuild: revert $(realpath ...) to $(shell cd ... && /bin/pwd)

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Date:   Mon, 2 Oct 2017 12:27:22 +0100
From:   Julien Grall <julien.grall@....com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kbuild@...r.kernel.org
Cc:     linux-pm@...r.kernel.org, Michal Marek <mmarek@...e.com>,
        David Carrillo-Cisneros <davidcc@...gle.com>,
        linux-kernel@...r.kernel.org, Thomas Renninger <trenn@...e.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH] kbuild: revert $(realpath ...) to $(shell cd ... &&
 /bin/pwd)

Hello,

On 02/10/17 09:07, Masahiro Yamada wrote:
> I thought commit 8e9b46679923 ("kbuild: use $(abspath ...) instead of
> $(shell cd ... && /bin/pwd)") was a safe conversion, but it changed
> the behavior.
> 
> $(abspath ...) / $(realpath ...) does not expand shell special
> characters, such as '~'.
> 
> Here is a simple Makefile example:
> 
>    ---------------->8----------------
>    $(info /bin/pwd: $(shell cd ~/; /bin/pwd))
>    $(info abspath: $(abspath ~/))
>    $(info realpath: $(realpath ~/))
>    all:
>            @:
>    ---------------->8----------------
> 
>    $ make
>    /bin/pwd: /home/masahiro
>    abspath: /home/masahiro/workspace/~
>    realpath:
> 
> This can be a real problem if 'make O=~/foo' is invoked from another
> Makefile or primitive shell like dash.
> 
> This commit partially reverts 8e9b46679923.
> 
> Fixes: 8e9b46679923 ("kbuild: use $(abspath ...) instead of $(shell cd ... && /bin/pwd)")
> Reported-by: Julien Grall <julien.grall@....com>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Tested-by: Julien Grall <julien.grall@....com>

Regards,

> ---
> 
>   Makefile                       | 4 ++--
>   tools/power/cpupower/Makefile  | 2 +-
>   tools/scripts/Makefile.include | 6 +++---
>   3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index cf007a3..1b48717 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -130,8 +130,8 @@ endif
>   ifneq ($(KBUILD_OUTPUT),)
>   # check that the output directory actually exists
>   saved-output := $(KBUILD_OUTPUT)
> -$(shell [ -d $(KBUILD_OUTPUT) ] || mkdir -p $(KBUILD_OUTPUT))
> -KBUILD_OUTPUT := $(realpath $(KBUILD_OUTPUT))
> +KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
> +								&& /bin/pwd)
>   $(if $(KBUILD_OUTPUT),, \
>        $(error failed to create output directory "$(saved-output)"))
>   
> diff --git a/tools/power/cpupower/Makefile b/tools/power/cpupower/Makefile
> index 4c5a481..d6e1c02 100644
> --- a/tools/power/cpupower/Makefile
> +++ b/tools/power/cpupower/Makefile
> @@ -26,7 +26,7 @@ endif
>   
>   ifneq ($(OUTPUT),)
>   # check that the output directory actually exists
> -OUTDIR := $(realpath $(OUTPUT))
> +OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
>   $(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
>   endif
>   
> diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
> index 9dc8f07..1e8b611 100644
> --- a/tools/scripts/Makefile.include
> +++ b/tools/scripts/Makefile.include
> @@ -1,7 +1,7 @@
>   ifneq ($(O),)
>   ifeq ($(origin O), command line)
> -	ABSOLUTE_O := $(realpath $(O))
> -	dummy := $(if $(ABSOLUTE_O),,$(error O=$(O) does not exist))
> +	dummy := $(if $(shell test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
> +	ABSOLUTE_O := $(shell cd $(O) ; pwd)
>   	OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
>   	COMMAND_O := O=$(ABSOLUTE_O)
>   ifeq ($(objtree),)
> @@ -12,7 +12,7 @@ endif
>   
>   # check that the output directory actually exists
>   ifneq ($(OUTPUT),)
> -OUTDIR := $(realpath $(OUTPUT))
> +OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
>   $(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
>   endif
>   
> 

-- 
Julien Grall