[libvirt] [PATCH 11/35] util: Add macro to overflow check integer assignments
Add a macro that will allow to simplify overflow checks and make them
more universal in case data types change.
---
src/util/virutil.h | 11 +++++++++++
tests/utiltest.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 41 insertions(+)
diff --git a/src/util/virutil.h b/src/util/virutil.h
index c78b357..53025f7 100644
--- a/src/util/virutil.h
+++ b/src/util/virutil.h
@@ -247,4 +247,15 @@ unsigned long long virMemoryLimitTruncate(unsigned long long value);
bool virMemoryLimitIsSet(unsigned long long value);
unsigned long long virMemoryMaxValue(bool ulong);
+/**
+ * VIR_ASSIGN_IS_OVERFLOW:
+ * @rvalue: value that is checked (evaluated twice)
+ * @lvalue: value that the check is against (used in typeof())
+ *
+ * This macro assigns @lvalue to @rvalue and evaluates as true if the value of
+ * @rvalue did not fit into the @lvalue.
+ */
+# define VIR_ASSIGN_IS_OVERFLOW(lvalue, rvalue) \
+ (((lvalue) = (rvalue)) != (rvalue))
+
#endif /* __VIR_UTIL_H__ */
diff --git a/tests/utiltest.c b/tests/utiltest.c
index dfa4290..3a1f8eb 100644
--- a/tests/utiltest.c
+++ b/tests/utiltest.c
@@ -172,6 +172,35 @@ testRoundValueToPowerOfTwo(const void *data ATTRIBUTE_UNUSED)
}
+#define TEST_OVERFLOW(var, val, expect) \
+ tmp = val; \
+ if (VIR_ASSIGN_IS_OVERFLOW(var, tmp) != expect) { \
+ fprintf(stderr, "\noverflow check failed: "
\
+ "var: " #var " val: " #val "\n");
\
+ return -1; \
+ }
+
+static int
+testOverflowCheckMacro(const void *data ATTRIBUTE_UNUSED)
+{
+ long long tmp;
+ unsigned char luchar;
+ char lchar;
+
+ TEST_OVERFLOW(luchar, 254, false);
+ TEST_OVERFLOW(luchar, 255, false);
+ TEST_OVERFLOW(luchar, 256, true);
+ TEST_OVERFLOW(luchar, 767, true);
+
+ TEST_OVERFLOW(lchar, 127, false);
+ TEST_OVERFLOW(lchar, -128, false);
+ TEST_OVERFLOW(lchar, -129, true);
+ TEST_OVERFLOW(lchar, 128, true);
+
+ return 0;
+}
+
+
static int
@@ -193,6 +222,7 @@ mymain(void)
DO_TEST(DiskNameToIndex);
DO_TEST(ParseVersionString);
DO_TEST(RoundValueToPowerOfTwo);
+ DO_TEST(OverflowCheckMacro);
return result == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
}
--
2.4.1