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

[Evgeni Dobrev via buildroot <buildroot@buildroot.org>]

Hi Yann,

indeed the support for [^] vs [!] is more complicated than I thought
initially ( see "Rationale" under https://github.com/koalaman/shellcheck/wiki/SC3026 ).

Would the following be a bad idea:

echo "find $$(TARGET_DIR)/run $$(TARGET_DIR)/tmp -mindepth 1 -delete" >> $$(FAKEROOT_SCRIPT)

- it avoids the glob support complication
- it is shorter

Regards,

Evgeni



On Wed, Jan 26, 2022 at 11:17:08PM +0100, Yann E. MORIN wrote:
> 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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