[Buildroot] [PATCH 1/2] Add dependency on bash to gzip for runtime

[Baruch Siach <baruch@tkos.co.il>]

Hi Thomas,

On Thu, Sep 17, 2015 at 07:23:15PM +0200, Thomas Petazzoni wrote:
> On Thu, 17 Sep 2015 19:33:24 +0300 (IDT), Jonathan Ben Avraham wrote:
> 
> > > Then we should probably patch the problem and send upstream. gzip bundled
> > > scripts are pretty trivial, and AFAICS, should work under any POSIX-like
> > > shell.
> > 
> > But we would at least need to ln -s /bin/<ash|dash> /bin/bash in 
> > Buildroot, no? so maybe the upstream fix is to change the hashbangs from 
> > /bin/bash to /bin/sh. Do you really think that the gzip upstream would 
> > accept this?
> 
> All the gzip scripts are in fact generated. zgrep is generated from
> zgrep.in. zgrep.in contains:
> 
> #!/bin/sh
> 
> which gets replaced by the gzip Makefile.am by the value of $(SHELL):
> 
> SUFFIXES = .in
> .in:
>         $(AM_V_GEN)sed \
>                 -e 's|/bin/sh|$(SHELL)|g' \
>                 -e 's|[@]bindir@|'\''$(bindir)'\''|g' \
>                 -e 's|[@]GREP@|$(GREP)|g' \
>                 -e 's|[@]VERSION@|$(VERSION)|g' \
>                 $(srcdir)/$@.in >$@-t \
>           && chmod a+x $@-t \
>           && mv $@-t $@
> 
> Which is completely wrong, because it makes the assumption that
> $(SHELL) on your build machine is going to be available on your target.
> 
> So your patch is in fact wrong I believe, because if someone is using
> zsh, or tcsh or some other shell on their build machine, $(SHELL) will
> point to this shell and not to bash, and the scripts generated by gzip
> will use zsh/tcsh, etc. on the target.
> 
> So the proper way is most likely to adjust the gzip build system so
> that we can pass at configure time a different value for the shell path
> on the target (and it would default to $(SHELL) is not passed).

Based on the following snippet from Buildroot top level Makefile I would 
assume that $(SHELL) is /bin/bash on my host machine:

# 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)

However, 'make printvars' shows

   SHELL=/bin/sh (/bin/sh)

$(SHELL) expands to /bin/sh in the gzip Makefile, and generated scripts carry 
the /bin/sh shebang. I have no idea how.

As for the original problem, I managed to override the environment $(SHELL) as 
indicated in the gzip INSTALL file:

   GZIP_CONF_ENV = CONFIG_SHELL=/bin/bash

So the right fix, I guess, is just

   GZIP_CONF_ENV = CONFIG_SHELL=/bin/sh

baruch

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