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| From: | Ambrus Sumegi |
| Subject: | RE: GNU Make bug report: broken dry-run functionality with sub-make invocations |
| Date: | Mon, 21 Mar 2022 09:34:47 +0000 |
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For the record, I’ve thought of a sort-of-solution to the “would you have Make parse the shell command” question over the weekend. If the sub-make was called through a function rather than a variable, the whole issue could be a lot more
contained. Having $(make, “<arguments passed to sub-make>”) as the canonical form of invoking other Make instances could guarantee that no other program gets called when the -n switch is used. This way any elaborate multi-line command containing $(MAKE) could
more or less be fixed with a sed command to completely eliminate this problem class. Of course, one could still do something like $(make, $(shell (“some_reckless_command”)), but it would be more obvious, and Make could output an explicit warning about a shell being called together with the sub-make invocation, or even refuse
to execute said shell call. Since on Fri 18/03/2022 20:14,
psmith@gnu.org pointed out that this is also a potential security problem, a future release could deprecate the $(MAKE) variable and switch to the function-based invocation, with shell calls disabled within it by default for the sake of that extra bit of
security. From: Martin Dorey <Martin.Dorey@hitachivantara.com> > the statement after the pipe also gets executed Would you have Make parse the shell command, assuming that SHELL isn't eg /usr/bin/perl, splitting off anything after | and maybe ; and && and, why not, ||, so it only dry-runs the part of the
command that invoked $(MAKE)? The current behavior is documented, https://www.gnu.org/software/make/manual/html_node/MAKE-Variable.html#MAKE-Variable saying: >> whenever a recipe line of a rule contains the variable To put it another way: the Makefile needs to cope. Not doing the tee if the directory doesn't exist would perhaps be most straightforward: martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$ diff -u Makefile{.orig,}
--- Makefile.orig 2022-03-17 11:13:46.000328340 -0700 +++ Makefile 2022-03-17 11:15:04.980482898 -0700 @@ -8,4 +8,4 @@ .PHONY: main_target main_target: create_logdirs - $(MAKE) external_target | tee logs/external_task.log + $(MAKE) external_target | { if test -d logs; then tee logs/external_task.log; else cat; fi; } martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$
... though that means writing to the log with -n if the directory does exist, which is perhaps undesirable. You could scrape the --dry-run flag out of MAKEFLAGS, where it seems to get turned into
n: martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$ diff -u Makefile{.orig,}
--- Makefile.orig 2022-03-17 11:13:46.000328340 -0700 +++ Makefile 2022-03-17 11:23:29.579910454 -0700 @@ -8,4 +8,4 @@ .PHONY: main_target main_target: create_logdirs - $(MAKE) external_target | tee logs/external_task.log + $(MAKE) external_target $(if $(findstring n,$(filter-out --%,$(MAKEFLAGS))),,| tee logs/external_task.log) martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$ That coped with -nj --no-print-directory on the one version of Make that I tested it with, but I don't know how portable that would prove. Thank you for a nicely written up report with a minimal test case. From: Bug-make <bug-make-bounces+martin.dorey=hds.com@gnu.org> on behalf of Ambrus Sumegi <Ambrus.Sumegi@arm.com> ***** EXTERNAL EMAIL ***** Dear Devs, I stumbled upon a rather rare case where Make produces a false error with the
--dry-run switch. I’ve attached a sample Makefile for reproduction. The output of make main_target
with this file is the following: $ make main_target mkdir logs make external_target | tee logs/external_task.log make[1]: Entering directory '/tmp/21176961.tmpdir/bugrepro' This could be in a separate file somewhere make[1]: Leaving directory '/tmp/21176961.tmpdir/bugrepro' Nothing interesting there. But with the
-n or --dry-run switch I get: $ make main_target -n mkdir logs make external_target | tee logs/external_task.log tee: logs/external_task.log: No such file or directory make[1]: Entering directory '/tmp/21176961.tmpdir/bugrepro' echo "This could be in a separate file somewhere" make[1]: Leaving directory '/tmp/21176961.tmpdir/bugrepro' make: *** [Makefile:11: main_target] Error 1 I get that the sub-make invocation gets executed with the switch passed to it as well, and that is correct functionality. But then the statement after the pipe also gets executed and throws an error about the missing log directory due
to the prerequisite target not having been run. This causes false failures in release checks that use the
--dry-run option of Make. This behavior is the same in both versions of GNU make that I have access to on the production system I’m using, 3.82 and 4.3 $ uname -r 3.10.0-693.21.1.el7.x86_64 $ make --version GNU Make 3.82 Built for x86_64-redhat-linux-gnu Copyright (C) 2010 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later
http://gnu.org/licenses/gpl.html This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. # (…) Loading other version $ make --version GNU Make 4.3 Built for x86_64-pc-linux-gnu Copyright (C) 1988-2020 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later
http://gnu.org/licenses/gpl.html This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person,
use it for any purpose, or store or copy the information in any medium. Thank you.
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