2019-08-25 13:30:16

by Masahiro Yamada

[permalink] [raw]
Subject: [PATCH] kbuild: add $(BASH) to run scripts with bash-extension

CONFIG_SHELL falls back to sh when bash is not installed on the system,
but nobody is testing such a case since bash is usually installed.
That is, shell scripts invoked by CONFIG_SHELL are only tested with
bash.

It makes it difficult to test whether the hashbang #!/bin/sh is real.
In fact, I saw some patches trying to add bash-extension to #!/bin/sh
script.

Besides, some shell scripts invoked by CONFIG_SHELL use bash-extension
and #!/bin/bash is specified as the hashbang, while CONFIG_SHELL may
not always be set to bash.

Probably, the right thing to do is to introduce BASH that is bash by
default, and always set CONFIG_SHELL to sh. Replace $(CONFIG_SHELL)
with $(BASH) for #!/bin/bash scripts.

If somebody tries to add bash-extension to a #!/bin/sh script, it will
be caught by somebody because /bin/sh is a symlink to dash on some
major distributions.

Signed-off-by: Masahiro Yamada <[email protected]>
---

Makefile | 11 +++++------
kernel/Makefile | 2 +-
scripts/Makefile.lib | 2 +-
3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/Makefile b/Makefile
index 3f95d1d04b08..23d8fa6b047b 100644
--- a/Makefile
+++ b/Makefile
@@ -404,9 +404,7 @@ KCONFIG_CONFIG ?= .config
export KCONFIG_CONFIG

# SHELL used by kbuild
-CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
- else if [ -x /bin/bash ]; then echo /bin/bash; \
- else echo sh; fi ; fi)
+CONFIG_SHELL := sh

HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null)
HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null)
@@ -443,6 +441,7 @@ PYTHON = python
PYTHON2 = python2
PYTHON3 = python3
CHECK = sparse
+BASH = bash

CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
-Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
@@ -488,7 +487,7 @@ KBUILD_LDFLAGS :=
GCC_PLUGINS_CFLAGS :=
CLANG_FLAGS :=

-export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC
+export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC
export CPP AR NM STRIP OBJCOPY OBJDUMP OBJSIZE PAHOLE LEX YACC AWK INSTALLKERNEL
export PERL PYTHON PYTHON2 PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
@@ -1694,7 +1693,7 @@ clean: $(clean-dirs)
# Generate tags for editors
# ---------------------------------------------------------------------------
quiet_cmd_tags = GEN $@
- cmd_tags = $(CONFIG_SHELL) $(srctree)/scripts/tags.sh $@
+ cmd_tags = $(BASH) $(srctree)/scripts/tags.sh $@

tags TAGS cscope gtags: FORCE
$(call cmd,tags)
@@ -1715,7 +1714,7 @@ versioncheck:
| xargs $(PERL) -w $(srctree)/scripts/checkversion.pl

coccicheck:
- $(Q)$(CONFIG_SHELL) $(srctree)/scripts/$@
+ $(Q)$(BASH) $(srctree)/scripts/$@

namespacecheck:
$(PERL) $(srctree)/scripts/namespace.pl
diff --git a/kernel/Makefile b/kernel/Makefile
index ef0d95a190b4..4deab893ca83 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -126,7 +126,7 @@ $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
$(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz

quiet_cmd_genikh = CHK $(obj)/kheaders_data.tar.xz
-cmd_genikh = $(CONFIG_SHELL) $(srctree)/kernel/gen_kheaders.sh $@
+cmd_genikh = $(BASH) $(srctree)/kernel/gen_kheaders.sh $@
$(obj)/kheaders_data.tar.xz: FORCE
$(call cmd,genikh)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 888e5c830646..7ab17712ab24 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -364,7 +364,7 @@ UIMAGE_ENTRYADDR ?= $(UIMAGE_LOADADDR)
UIMAGE_NAME ?= 'Linux-$(KERNELRELEASE)'

quiet_cmd_uimage = UIMAGE $@
- cmd_uimage = $(CONFIG_SHELL) $(MKIMAGE) -A $(UIMAGE_ARCH) -O linux \
+ cmd_uimage = $(BASH) $(MKIMAGE) -A $(UIMAGE_ARCH) -O linux \
-C $(UIMAGE_COMPRESSION) $(UIMAGE_OPTS-y) \
-T $(UIMAGE_TYPE) \
-a $(UIMAGE_LOADADDR) -e $(UIMAGE_ENTRYADDR) \
--
2.17.1


2019-10-01 09:59:19

by Geert Uytterhoeven

[permalink] [raw]
Subject: Re: [PATCH] kbuild: add $(BASH) to run scripts with bash-extension

Hi Yamada-san,

On Sun, Aug 25, 2019 at 3:29 PM Masahiro Yamada
<[email protected]> wrote:
> CONFIG_SHELL falls back to sh when bash is not installed on the system,
> but nobody is testing such a case since bash is usually installed.
> That is, shell scripts invoked by CONFIG_SHELL are only tested with
> bash.
>
> It makes it difficult to test whether the hashbang #!/bin/sh is real.
> In fact, I saw some patches trying to add bash-extension to #!/bin/sh
> script.
>
> Besides, some shell scripts invoked by CONFIG_SHELL use bash-extension
> and #!/bin/bash is specified as the hashbang, while CONFIG_SHELL may
> not always be set to bash.
>
> Probably, the right thing to do is to introduce BASH that is bash by
> default, and always set CONFIG_SHELL to sh. Replace $(CONFIG_SHELL)
> with $(BASH) for #!/bin/bash scripts.
>
> If somebody tries to add bash-extension to a #!/bin/sh script, it will
> be caught by somebody because /bin/sh is a symlink to dash on some
> major distributions.
>
> Signed-off-by: Masahiro Yamada <[email protected]>

This is now commit 858805b336be1cab ("kbuild: add $(BASH) to run scripts
with bash-extension").

This commit has the strange side-effect of inserting the contents of a
localversion file in the build directory twice.

Steps to reproduce:

src-dir$ echo src > localversion
build-dir$ echo build > localversion
build-dir$ make defconfig; make include/generated/utsrelease.h;
cat include/generated/utsrelease.h
...
#define UTS_RELEASE "5.3.0-rc4buildbuildsrc+"

Building in the source directory is OK.

src-dir$ make defconfig; make include/generated/utsrelease.h; cat
include/generated/utsrelease.h
...
#define UTS_RELEASE "5.3.0-rc4src+"

Changing scripts/setlocalversion to use /bin/bash does not fix the issue.

Do you have a clue?
Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds