[Buildroot] [PATCH v2] Fix issue with printvars executing giant shell command
Yann E. MORIN
yann.morin.1998 at free.fr
Mon Sep 17 19:42:55 UTC 2018
Trent, All,
On 2018-09-17 11:10 -0700, Trent Piepho spake thusly:
> The underlying problem is that $(foreach V,1 2 3,) does not evaluate to
> an empty string. It evaluates to " ", three empty strings separated by
> whitespace.
>
> A construct of this format, with a giant list in the foreach, is part of
> the printvars command. This means that "@:$(foreach ....)", which is
> intended to expand to a null command, in fact expands to "@: "
> with a great deal of whitespace. Make chooses to execute this command
> with:
> execve("/bin/sh", ["/bin/sh", "-c", ": "]
>
> But with far more whitespace. So much that it can exceed shell command
> line length limits.
>
> This solution is to move the foreach to another step in the recipe. The
> "@:" is retained as the first line so the recipe is not Empty, which
> would cause a change in make behavior when make builds the target. The
> 2nd line, all whitespace, will be skipped by make.
>
> Signed-off-by: Trent Piepho <tpiepho at impinj.com>
Tested-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
Acked-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
Regards,
Yann E. MORIN.
> ---
> Makefile | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 2c6af12989..57e776056c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -988,7 +988,8 @@ $(BUILD_DIR)/.br2-external.in: $(BUILD_DIR)
> # displayed.
> .PHONY: printvars
> printvars:
> - @:$(foreach V, \
> + @:
> + $(foreach V, \
> $(sort $(if $(VARS),$(filter $(VARS),$(.VARIABLES)),$(.VARIABLES))), \
> $(if $(filter-out environment% default automatic, \
> $(origin $V)), \
> --
> 2.14.4
>
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