libsepol, libsemanage: add a macro to silence static analyzer warning…

…s in tests

Several static analyzers (clang's one, Facebook Infer, etc.) warn about
NULL pointer dereferences after a call to CU_ASSERT_PTR_NOT_NULL_FATAL()
in the test code written using CUnit framework. This is because this
CUnit macro is too complex for them to understand that the pointer
cannot be NULL: it is translated to a call to CU_assertImplementation()
with an argument as TRUE in order to mean that the call is fatal if the
asserted condition failed (cf.
http://cunit.sourceforge.net/doxdocs/group__Framework.html).

A possible solution could consist in replacing the
CU_ASSERT_..._FATAL() calls by assert() ones, as most static analyzers
know about assert(). Nevertheless this seems to go against CUnit's API.

An alternative solution consists in overriding CU_ASSERT_..._FATAL()
macros in order to expand to assert() after a call to the matching
CU_ASSERT_...() non-fatal macro. This appears to work fine and to remove
many false-positive warnings from various static analyzers.

As this substitution should only occur when using static analyzer, put
it under #ifdef __CHECKER__, which is the macro used by sparse when
analyzing the Linux kernel.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>

libsemanage/tests/test_utilities.c

@@ -34,6 +34,8 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "utilities.h"
+
 void test_semanage_is_prefix(void);
 void test_semanage_split_on_space(void);
 void test_semanage_split(void);

libsemanage/tests/utilities.h

@@ -41,6 +41,32 @@
 		CU_ASSERT_STRING_EQUAL(__str, __str2); \
 	} while (0)
 
+
+/* Override CU_*_FATAL() in order to help static analyzers by really asserting that an assertion holds */
+#ifdef __CHECKER__
+
+#undef CU_ASSERT_FATAL
+#define CU_ASSERT_FATAL(value) do { \
+		int _value = (value); \
+		CU_ASSERT(_value); \
+		assert(_value); \
+	} while (0)
+
+#undef CU_FAIL_FATAL
+#define CU_FAIL_FATAL(msg) do { \
+		CU_FAIL(msg); \
+		assert(0); \
+	} while (0)
+
+#undef CU_ASSERT_PTR_NOT_NULL_FATAL
+#define CU_ASSERT_PTR_NOT_NULL_FATAL(value) do { \
+		const void *_value = (value); \
+		CU_ASSERT_PTR_NOT_NULL(_value); \
+		assert(_value != NULL); \
+	} while (0)
+
+#endif /* __CHECKER__ */
+
 #define I_NULL  -1
 #define I_FIRST  0
 #define I_SECOND 1

libsepol/tests/helpers.h

@@ -24,9 +24,38 @@
 
 #include <sepol/policydb/policydb.h>
 #include <sepol/policydb/conditional.h>
+#include <CUnit/Basic.h>
 
 /* helper functions */
 
+/* Override CU_*_FATAL() in order to help static analyzers by really asserting that an assertion holds */
+#ifdef __CHECKER__
+
+#include <assert.h>
+
+#undef CU_ASSERT_FATAL
+#define CU_ASSERT_FATAL(value) do { \
+		int _value = (value); \
+		CU_ASSERT(_value); \
+		assert(_value); \
+	} while (0)
+
+#undef CU_FAIL_FATAL
+#define CU_FAIL_FATAL(msg) do { \
+		CU_FAIL(msg); \
+		assert(0); \
+	} while (0)
+
+#undef CU_ASSERT_PTR_NOT_NULL_FATAL
+#define CU_ASSERT_PTR_NOT_NULL_FATAL(value) do { \
+		const void *_value = (value); \
+		CU_ASSERT_PTR_NOT_NULL(_value); \
+		assert(_value != NULL); \
+	} while (0)
+
+#endif /* __CHECKER__ */
+
+
 /* Load a source policy into p. policydb_init will called within this function.
  * 
  * Example: test_load_policy(p, POLICY_BASE, 1, "foo", "base.conf") will load the

libsepol/tests/test-common.c

@@ -26,6 +26,8 @@
 
 #include <CUnit/Basic.h>
 
+#include "helpers.h"
+
 void test_sym_presence(policydb_t * p, const char *id, int sym_type, unsigned int scope_type, unsigned int *decls, unsigned int len)
 {
 	scope_datum_t *scope;

libsepol/tests/test-deps.c

@@ -66,6 +66,8 @@
 #include <sepol/debug.h>
 #include <sepol/handle.h>
 
+#include "helpers.h"
+
 #define BASE_MODREQ_TYPE_GLOBAL    0
 #define BASE_MODREQ_ATTR_GLOBAL    1
 #define BASE_MODREQ_OBJ_GLOBAL     2

libsepol/tests/test-expander-attr-map.c

@@ -21,6 +21,7 @@
 
 #include "test-expander-attr-map.h"
 #include "test-common.h"
+#include "helpers.h"
 
 #include <sepol/policydb/policydb.h>
 #include <CUnit/Basic.h>

libsepol/tests/test-expander-roles.c

@@ -22,6 +22,7 @@
 
 #include "test-expander-roles.h"
 #include "test-common.h"
+#include "helpers.h"
 
 #include <sepol/policydb/policydb.h>
 #include <CUnit/Basic.h>

libsepol/tests/test-expander-users.c

@@ -21,6 +21,7 @@
  */
 
 #include "test-expander-users.h"
+#include "helpers.h"
 
 #include <sepol/policydb/policydb.h>
 #include <CUnit/Basic.h>

scripts/run-scan-build

@@ -22,7 +22,11 @@ export RUBYLIB="$DESTDIR/$(${RUBY:-ruby} -e 'puts RbConfig::CONFIG["vendorlibdir
 
 # Build and analyze
 make -C .. CC=clang clean distclean -j"$(nproc)"
-scan-build -analyze-headers -o "$OUTPUTDIR" make -C .. CC=clang DESTDIR="$DESTDIR" install install-pywrap install-rubywrap all test
+scan-build -analyze-headers -o "$OUTPUTDIR" make -C .. \
+    CC=clang \
+    DESTDIR="$DESTDIR" \
+    CFLAGS="-O2 -Wall -D__CHECKER__ -I$DESTDIR/usr/include" \
+    install install-pywrap install-rubywrap all test
 
 # Reduce the verbosity in order to keep the message from scan-build saying
 # "scan-build: Run 'scan-view /.../output-scan-build/2018-...' to examine bug reports.