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[PATCH v4 3/6] cocci: add a "coccicheck-test" target and test *.cocci rules

From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date
Jul 5, 2022, 13:46 UTC
Message-ID
<patch-v4-3.6-540186e69dc-20220705T134033Z-avarab@gmail.com>
In-Reply-To
<cover-v4-0.6-00000000000-20220705T134033Z-avarab@gmail.com>

Add a "coccicheck-test" target to test our *.cocci rules, and as a demonstration add tests for the rules added in 39ea59a2570 (remove unnecessary NULL check before free(3), 2016-10-08) and 1b83d1251ed (coccinelle: add a rule to make "expression" code use FREE_AND_NULL(), 2017-06-15).

I considered making use of the "spatch --test" option, and the choice of a "tests" over a "t" directory is to make these tests compatible with such a future change.

Unfortunately "spatch --test" doesn't return meaningful exit codes, AFAICT you need to "grep" its output to see if the *.res is what you expect. There's "--test-okfailed", but I didn't find a way to sensibly integrate those (it relies on some in-between status files, but doesn't help with the status codes).

Instead let's use a "--sp-file" pattern similar to the main "coccicheck" rule, with the difference that we use and compare the two *.res files with cmp(1).

The --very-quiet and --no-show-diff options ensure that we don't need to pipe stdout and stderr somewhere. Unlike the "%.cocci.patch" rule we're not using the diff.

The "cmp || git diff" is optimistically giving us better output on failure, but even if we only have POSIX cmp and no system git installed we'll still fail with the "cmp", just with an error message that isn't as friendly. The "2>/dev/null" is in case we don't have a "git" installed.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile                          | 19 +++++++++++++++++++
 contrib/coccinelle/tests/free.c   | 11 +++++++++++
 contrib/coccinelle/tests/free.res |  9 +++++++++
 shared.mak                        |  1 +
 4 files changed, 40 insertions(+)
 create mode 100644 contrib/coccinelle/tests/free.c
 create mode 100644 contrib/coccinelle/tests/free.res
diff --git a/Makefile b/Makefile
index 1ccf13595de..c4064f8394f 100644
--- a/Makefile
+++ b/Makefile
@@ -3123,6 +3123,8 @@ check: $(GENERATED_H)
 		exit 1; \
 	fi
 
+COCCI_TEST_RES = $(wildcard contrib/coccinelle/tests/*.res)
+
 %.cocci.patch: %.cocci $(COCCI_SOURCES)
 	$(QUIET_SPATCH) \
 	if test $(SPATCH_BATCH_SIZE) = 0; then \
@@ -3143,6 +3145,22 @@ check: $(GENERATED_H)
 	then \
 		echo '    ' SPATCH result: $@; \
 	fi
+
+COCCI_TEST_RES_GEN = $(addprefix .build/,$(COCCI_TEST_RES))
+$(COCCI_TEST_RES_GEN): .build/%.res : %.c
+$(COCCI_TEST_RES_GEN): .build/%.res : %.res
+$(COCCI_TEST_RES_GEN): .build/contrib/coccinelle/tests/%.res : contrib/coccinelle/%.cocci
+	$(call mkdir_p_parent_template)
+	$(QUIET_SPATCH_T)$(SPATCH) $(SPATCH_FLAGS) \
+		--very-quiet --no-show-diff \
+		--sp-file $< -o $@ \
+		$(@:.build/%.res=%.c) && \
+	cmp $(@:.build/%=%) $@ || \
+	git -P diff --no-index $(@:.build/%=%) $@ 2>/dev/null; \
+
+.PHONY: coccicheck-test
+coccicheck-test: $(COCCI_TEST_RES_GEN)
+
 coccicheck: $(addsuffix .patch,$(filter-out %.pending.cocci,$(wildcard contrib/coccinelle/*.cocci)))
 
 # See contrib/coccinelle/README
@@ -3404,6 +3422,7 @@ profile-clean:
 	$(RM) $(addsuffix *.gcno,$(addprefix $(PROFILE_DIR)/, $(object_dirs)))
 
 cocciclean:
+	$(RM) -r .build/contrib/coccinelle
 	$(RM) contrib/coccinelle/*.cocci.patch*
 
 clean: profile-clean coverage-clean cocciclean
diff --git a/contrib/coccinelle/tests/free.c b/contrib/coccinelle/tests/free.c
new file mode 100644
index 00000000000..96d4abc0c78
--- /dev/null
+++ b/contrib/coccinelle/tests/free.c
@@ -0,0 +1,11 @@
+int use_FREE_AND_NULL(int *v)
+{
+	free(*v);
+	*v = NULL;
+}
+
+int need_no_if(int *v)
+{
+	if (v)
+		free(v);
+}
diff --git a/contrib/coccinelle/tests/free.res b/contrib/coccinelle/tests/free.res
new file mode 100644
index 00000000000..f90fd9f48e3
--- /dev/null
+++ b/contrib/coccinelle/tests/free.res
@@ -0,0 +1,9 @@
+int use_FREE_AND_NULL(int *v)
+{
+	FREE_AND_NULL(*v);
+}
+
+int need_no_if(int *v)
+{
+	free(v);
+}
diff --git a/shared.mak b/shared.mak
index 4330192e9c3..33f43edbf9a 100644
--- a/shared.mak
+++ b/shared.mak
@@ -70,6 +70,7 @@ ifndef V
 	QUIET_HDR      = @echo '   ' HDR $(<:hcc=h);
 	QUIET_RC       = @echo '   ' RC $@;
 	QUIET_SPATCH   = @echo '   ' SPATCH $<;
+	QUIET_SPATCH_T = @echo '   ' SPATCH TEST $(@:.build/%=%);
 
 ## Used in "Documentation/Makefile"
 	QUIET_ASCIIDOC	= @echo '   ' ASCIIDOC $@;
-- 
2.37.0.913.g50625c3f077
Previous: Ævar Arnfjörð BjarmasonNext: Ævar Arnfjörð Bjarmason
Message 18 of 24 in “cocci: add and apply a rule to find "unused" variables”
  1. cocci: add and apply a rule to find "unused" variablesÆvar Arnfjörð Bjarmason, May 20, 2022
  2. 0/2 add and apply a rule to find "unused" init+freeÆvar Arnfjörð Bjarmason, Jun 21, 2022
  3. 1/2 cocci: add and apply a rule to find "unused" variablesÆvar Arnfjörð Bjarmason, Jun 21, 2022
  4. Junio C HamanoJun 22, 2022
  5. 2/2 cocci: remove "when strict" from unused.cocciÆvar Arnfjörð Bjarmason, Jun 21, 2022
  6. 0/4 add and apply a rule to find "unused" init+freeÆvar Arnfjörð Bjarmason, Jul 1, 2022
  7. 1/4 cocci: add and apply a rule to find "unused" strbufsÆvar Arnfjörð Bjarmason, Jul 1, 2022
  8. Jeff KingJul 1, 2022
  9. Eric SunshineJul 1, 2022
  10. 2/4 cocci: catch unused "strbuf" using an xmalloc() patternÆvar Arnfjörð Bjarmason, Jul 1, 2022
  11. 4/4 cocci: generalize "unused" rule to cover more than "strbuf"Ævar Arnfjörð Bjarmason, Jul 1, 2022
  12. 3/4 cocci: remove "when strict" from unused.cocciÆvar Arnfjörð Bjarmason, Jul 1, 2022
  13. Eric SunshineJul 1, 2022
  14. Jeff KingJul 1, 2022
  15. 0/6 add and apply a rule to find "unused" init+freeÆvar Arnfjörð Bjarmason, Jul 5, 2022
  16. 2/6 Makefile & .gitignore: ignore & clean "git.res", not "*.res"Ævar Arnfjörð Bjarmason, Jul 5, 2022
  17. 1/6 Makefile: remove mandatory "spatch" arguments from SPATCH_FLAGSÆvar Arnfjörð Bjarmason, Jul 5, 2022
  18. 3/6 cocci: add a "coccicheck-test" target and test *.cocci rulesÆvar Arnfjörð Bjarmason, Jul 5, 2022
  19. 4/6 cocci: have "coccicheck{,-pending}" depend on "coccicheck-test"Ævar Arnfjörð Bjarmason, Jul 5, 2022
  20. 5/6 cocci: add and apply a rule to find "unused" strbufsÆvar Arnfjörð Bjarmason, Jul 5, 2022
  21. 6/6 cocci: generalize "unused" rule to cover more than "strbuf"Ævar Arnfjörð Bjarmason, Jul 5, 2022
  22. Junio C HamanoJul 6, 2022
  23. Jeff KingJul 11, 2022
  24. Ævar Arnfjörð BjarmasonJul 11, 2022

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