Re: [Buildroot] [PATCH 1/1] fs: fix /tmp and /run clean-up in POSIX shells

From: "Yann E. MORIN" <yann.morin.1998@free.fr>
To: Evgeni Dobrev <evgeni@studio-punkt.com>
Cc: buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH 1/1] fs: fix /tmp and /run clean-up in POSIX shells
Date: Wed, 26 Jan 2022 23:17:08 +0100	[thread overview]
Message-ID: <20220126221708.GK457876@scaer> (raw)
In-Reply-To: <20220124104116.12902-2-evgeni@studio-punkt.com>

Evgeni, All,

On 2022-01-24 11:41 +0100, Evgeni Dobrev via buildroot spake thusly:
> In POSIX sh, ^ in place of ! in glob bracket expressions
> is undefined.
> 
> Signed-off-by: Evgeni Dobrev <evgeni@studio-punkt.com>
> ---
>  fs/common.mk | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/common.mk b/fs/common.mk
> index 45beb5ae7b..64a94d9ad8 100644
> --- a/fs/common.mk
> +++ b/fs/common.mk
> @@ -186,7 +186,7 @@ $$(BINARIES_DIR)/$$(ROOTFS_$(2)_FINAL_IMAGE_NAME): $$(ROOTFS_$(2)_DEPENDENCIES)
>  
>  	$$(foreach hook,$$(ROOTFS_$(2)_PRE_GEN_HOOKS),\
>  		$$(call PRINTF,$$($$(hook))) >> $$(FAKEROOT_SCRIPT)$$(sep))
> -	echo "rm -rf $$(TARGET_DIR)/run/* $$(TARGET_DIR)/run/.[^.]* $$(TARGET_DIR)/tmp/* $$(TARGET_DIR)/tmp/.[^.]*" >> $$(FAKEROOT_SCRIPT)
> +	echo "rm -rf $$(TARGET_DIR)/run/* $$(TARGET_DIR)/run/.[!.]* $$(TARGET_DIR)/tmp/* $$(TARGET_DIR)/tmp/.[!.]*" >> $$(FAKEROOT_SCRIPT)

TIL that bracket expressions are actually valid and specified by POSIX.

But we do guarantee that we do have bash as a shell when running
Buildroot, so I think it is fair to also run the fs script with bash:

    diff --git a/fs/common.mk b/fs/common.mk
    index 45beb5ae7b..f8a6da6bc4 100644
    --- a/fs/common.mk
    +++ b/fs/common.mk
    @@ -172,7 +172,7 @@ $$(BINARIES_DIR)/$$(ROOTFS_$(2)_FINAL_IMAGE_NAME): $$(ROOTFS_$(2)_DEPENDENCIES)
     		$$(BASE_TARGET_DIR)/ \
     		$$(TARGET_DIR)

    -	echo '#!/bin/sh' > $$(FAKEROOT_SCRIPT)
    +	echo '#!$(SHELL)' > $$(FAKEROOT_SCRIPT)
     	echo "set -e" >> $$(FAKEROOT_SCRIPT)

     	echo "chown -h -R 0:0 $$(TARGET_DIR)" >> $$(FAKEROOT_SCRIPT)

However, $(SHELL) is not always correct, so we'd probably need:

    diff --git a/Makefile b/Makefile
    index 5fc7137e5a..bb9955f5b6 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -30,7 +30,7 @@
     # we want bash as shell
     SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
     	 else if [ -x /bin/bash ]; then echo /bin/bash; \
    -	 else echo sh; fi; fi)
    +	 else which sh; fi; fi)

     # Set O variable if not already done on the command line;
     # or avoid confusing packages that can use the O=<dir> syntax for out-of-tree

But in the end this is quite more changes than what you propose.

Can we also shorten the command?

    echo "rm -rf $$(TARGET_DIR)/{run,tmp}/* $$(TARGET_DIR)/{run,tmp}/.[!.]*" >> $$(FAKEROOT_SCRIPT)

Regards,
Yann E. MORIN.

>  	$$(call PRINTF,$$(ROOTFS_REPRODUCIBLE)) >> $$(FAKEROOT_SCRIPT)
>  	$$(call PRINTF,$$(ROOTFS_SELINUX)) >> $$(FAKEROOT_SCRIPT)
>  	$$(call PRINTF,$$(ROOTFS_$(2)_CMD)) >> $$(FAKEROOT_SCRIPT)
> -- 
> 2.34.1
> 
> _______________________________________________
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> buildroot@buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot

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