Re: [PATCH v2 1/2] kbuild: deb-pkg: use Debian compliant shebang for debian/rules

From: Nathan Chancellor
Date: Tue Aug 01 2023 - 12:52:10 EST


On Tue, Aug 01, 2023 at 09:19:25PM +0900, Masahiro Yamada wrote:
> Debian Policy "4.9. Main building script: debian/rules" requires
> "debian/rules must start with the line #!/usr/bin/make -f". [1]
>
> Currently, Kbuild does not follow this policy.
>
> When Kbuild generates debian/rules, "#!$(command -v $MAKE) -f" is
> expanded by shell. The resuling string may not be "#!/usr/bin/make -f".
>
> There was a reason to opt out the Debian policy.
>
> If you run '/path/to/my/custom/make deb-pkg', debian/rules must also be
> invoked by the same Make program. If #!/usr/bin/make were hard-coded in
> debian/rules, the sub-make would be executed by a possibly different
> Make version.
>
> This is problematic due to the MAKEFLAGS incompatibility, especially the
> job server flag. Old Make versions used --jobserver-fds to propagate job
> server file descriptors, but Make >= 4.2 uses --jobserver-auth. The flag
> disagreement between the parent/child Makes would result in a process
> fork explosion.
>
> However, having a non-standard path in the shebang causes another issue;
> the generated source package is not portable as such a path does not
> exist in other build environments.
>
> This commit solves those conflicting demands.
>
> Hard-code '#!/usr/bin/make -f' in debian/rules to create a portable and
> Debian-compliant source package.
>
> Pass '--rules-file=$(MAKE) -f debian/rules' when dpkg-buildpackage is
> invoked from Makefile so that debian/rules is executed by the same Make
> program as used to start Kbuild.
>
> [1] https://www.debian.org/doc/debian-policy/ch-source.html#main-building-script-debian-rules
>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>

Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>

> ---
>
> (no changes since v1)
>
> scripts/Makefile.package | 2 +-
> scripts/package/mkdebian | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/Makefile.package b/scripts/Makefile.package
> index 85beab0363d7..f8a948ec2c6b 100644
> --- a/scripts/Makefile.package
> +++ b/scripts/Makefile.package
> @@ -148,7 +148,7 @@ deb-pkg srcdeb-pkg bindeb-pkg:
> $(if $(findstring source, $(build-type)), \
> --unsigned-source --compression=$(KDEB_SOURCE_COMPRESS)) \
> $(if $(findstring binary, $(build-type)), \
> - -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch), \
> + --rules-file='$(MAKE) -f debian/rules' -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch), \
> --no-check-builddeps) \
> $(DPKG_FLAGS))
>
> diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
> index 9105abab9728..2829f5b8aea6 100755
> --- a/scripts/package/mkdebian
> +++ b/scripts/package/mkdebian
> @@ -264,7 +264,7 @@ EOF
> fi
>
> cat <<EOF > debian/rules
> -#!$(command -v $MAKE) -f
> +#!/usr/bin/make -f
>
> srctree ?= .
> KERNELRELEASE = ${KERNELRELEASE}
> --
> 2.39.2
>