[Buildroot] [PATCH] support/dependencies: detect and bailout when PATH contains spaces/TABs

[Buildroot] [PATCH] support/dependencies: detect and bailout when PATH contains spaces/TABs

[Yann E. MORIN]

In Makefiles, variables are split, filtered, and otherwise mangled on a
space as a separator. In a shell, they will also be split on TABs.

We split and filter and iterate of variables in a lot of places, and
most importantluy, spaces in PATH is very seldom tested, if at all, so a
lot of packages will not be working properly in such a situation.

For example, the config.guess contains constructs that are not resilient
to a space in PATH:
    PATH=$PATH:/.attbin ; export PATH

Also, our fakedate will iterate over PATH:

    for P in `echo $PATH | tr ':' ' '`; do

Those are only two cases, but the first means basically all
autotools-based packages are susceptible to subtle breakage.

Furthermore, Buildroot itself does not support that the top-level or
output directories are in a path with spaces anyway.

So, instead of chasing all cases that might be potentially broken,
let's just detect the case and bail out, like we already do when PATH
contains a \n, or when it contains the current working directory.

Reported-by: Dan Raymond <draymond@foxvalley.net>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

---
Notes: Dan had provided a patch [0] that would fix their own specific
issue when runing linux-menuconfig, but I believe this is by far
insufficient to properly solve the issues with spaces in PATH, and I
believe it can't be reliably fixed (at least not in the foreseeable
future with our available manpower), so I prefer that we detect the
situation and bail out.

[0] https://patchwork.ozlabs.org/project/buildroot/patch/16100eb6-bac8-2e4d-65f2-26333179f3b8 at foxvalley.net/
---
 support/dependencies/dependencies.sh | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/support/dependencies/dependencies.sh b/support/dependencies/dependencies.sh
index b44d28682c..8cbfa984c7 100755
--- a/support/dependencies/dependencies.sh
+++ b/support/dependencies/dependencies.sh
@@ -2,6 +2,8 @@
 # vi: set sw=4 ts=4:
 
 export LC_ALL=C
+TAB="$(printf '\t')"
+NL="$(printf '\n')"
 
 # Verify that grep works
 echo "WORKS" | grep "WORKS" >/dev/null 2>&1
@@ -35,9 +37,9 @@ case ":${PATH:-unset}:" in
 	echo "PATH environment variable. This doesn't work."
 	exit 1
 	;;
-(*"
-"*)	printf "\n"
-	printf "Your PATH contains a newline (\\\n) character.\n"
+(*" "*|*"${TAB}"*|*"${NL}"*)
+	printf "\n"
+	printf "Your PATH contains spaces, TABs, and/or newline (\\\n) characters.\n"
 	printf "This doesn't work. Fix you PATH.\n"
 	exit 1
 	;;
-- 
2.25.1

[Buildroot] environment variables with spaces (request for comments)

[Dan Raymond]

I encountered a bug in Buildroot that resulted in a failure to run 'make 
linux-menuconfig'.? I tracked down the problem to a bug in 
package/pkg-kconfig.mk that was attempting to remove a set of variables 
from an environment string.? The problem is that a naive technique was 
being used that did not account for quoted variables that contained 
embedded spaces.? To be clear, 'make menuconfig' from the linux kernel 
tree works fine: this bug is in Buildroot only.? The reason I discovered 
this bug (and others may not) is because my PATH environment variable 
contains embedded spaces (which may be uncommon but valid and sometimes 
necessary).

I implemented/tested/submitted a patch that reliably fixes the bug.

Yann MORIN objected to my patch because he believes some of the packages 
Buildroot supports contain similar bugs.? I responded to his objection 
but he ignored my response and submitted his own patch that undermines 
mine by intentionally causing ALL make targets to fail when the PATH 
environment variable contains embedded spaces.? I don't think that 
starting a "patch war" is productive or contributes to the goals of the 
Buildroot community.? Can we have a discussion instead and come to a 
consensus on this matter?

[Buildroot] environment variables with spaces (request for comments)

[Arnout Vandecappelle]

On 02/03/2021 16:43, Dan Raymond wrote:
> I encountered a bug in Buildroot that resulted in a failure to run 'make
> linux-menuconfig'.? I tracked down the problem to a bug in
> package/pkg-kconfig.mk that was attempting to remove a set of variables from an
> environment string.? The problem is that a naive technique was being used that
> did not account for quoted variables that contained embedded spaces.? To be
> clear, 'make menuconfig' from the linux kernel tree works fine: this bug is in
> Buildroot only.? The reason I discovered this bug (and others may not) is
> because my PATH environment variable contains embedded spaces (which may be
> uncommon but valid and sometimes necessary).
> 
> I implemented/tested/submitted a patch that reliably fixes the bug.
> 
> Yann MORIN objected to my patch because he believes some of the packages
> Buildroot supports contain similar bugs.? I responded to his objection but he
> ignored my response and submitted his own patch that undermines mine by
> intentionally causing ALL make targets to fail when the PATH environment
> variable contains embedded spaces.? I don't think that starting a "patch war" is
> productive or contributes to the goals of the Buildroot community.? Can we have
> a discussion instead and come to a consensus on this matter?

 Yann's point is absolutely valid: any configuration except the most trivial one
will fail to build when PATH contains spaces, and it will do so in a
spectacularly difficult to debug way. So Yann's patch is definitely needed.

 However, that shouldn't stop us from fixing things where we can anyway.

 Thus, I'm inclined to merge both patches. However, I have some reservations
about the fix as well - I'll ventilate those in the patch thread.

 Regards,
 Arnout