Fix issue with printvars executing giant shell command
PATCH v2 1/1 Fix issue with printvars executing giant shell command
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.
--- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
Makefile +2 -1
@@ -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)), \
Signature · 1 line
2.14.4
PATCH v2 1/1 Fix issue with printvars executing giant shell command
Trent, All,
On 2018-09-17 11:10 -0700, Trent Piepho spake thusly:
Quoted 14 lines
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.
Quoted 6 lines
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 <[email protected]>
Regards,
Yann E. MORIN.
Quoted 21 lines
--- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)Makefile +2
-1@@ -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)), \Signature · 1 line
2.14.4
Signature · 6 lines
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Thomas Petazzoni
AppliedPATCH v2 1/1 Fix issue with printvars executing giant shell command
In reply to Trent PiephoHello,
Quoted 19 lines · Trent Piepho
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.
Quoted 4 lines
Signed-off-by Trent Piepho <[email protected]>--- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
Applied to master, thanks.
Thomas
Signature · 3 lines
Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
PATCH v2 1/1 Fix issue with printvars executing giant shell command
In reply to Trent PiephoQuoted 16 lines
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
"Trent" == Trent Piepho <[email protected]> writes:
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.
Quoted 6 lines
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 <[email protected]>
Committed to 2018.02.x, 2018.05.x and 2018.08.x, thanks.
Signature · 1 line
Bye, Peter Korsgaard