CPP: Add test cases.

geoffw0 · geoffw0 · commit aa368d8763bc · 2019-07-17T11:38:59.000+01:00
diff --git a/cpp/ql/test/query-tests/Likely Bugs/Arithmetic/BitwiseSignCheck/BitwiseSignCheck.expected b/cpp/ql/test/query-tests/Likely Bugs/Arithmetic/BitwiseSignCheck/BitwiseSignCheck.expected
@@ -1,3 +1,5 @@
 | bsc.cpp:2:10:2:32 | ... > ... | Potential unsafe sign check of a bitwise operation. |
 | bsc.cpp:6:10:6:32 | ... > ... | Potential unsafe sign check of a bitwise operation. |
 | bsc.cpp:10:10:10:33 | ... >= ... | Potential unsafe sign check of a bitwise operation. |
+| bsc.cpp:18:10:18:28 | ... > ... | Potential unsafe sign check of a bitwise operation. |
+| bsc.cpp:30:10:30:20 | ... < ... | Potential unsafe sign check of a bitwise operation. |
diff --git a/cpp/ql/test/query-tests/Likely Bugs/Arithmetic/BitwiseSignCheck/bsc.cpp b/cpp/ql/test/query-tests/Likely Bugs/Arithmetic/BitwiseSignCheck/bsc.cpp
@@ -1,15 +1,31 @@
 bool is_bit_set_v1(int x, int bitnum) {
-  return (x & (1 << bitnum)) > 0;
+  return (x & (1 << bitnum)) > 0; // BAD
 }
 
 bool is_bit_set_v2(int x, int bitnum) {
-  return ((1 << bitnum) & x) > 0;
+  return ((1 << bitnum) & x) > 0; // BAD
 }
 
 bool plain_wrong(int x, int bitnum) {
-  return (x & (1 << bitnum)) >= 0;
+  return (x & (1 << bitnum)) >= 0; // ???
 }
 
 bool is_bit24_set(int x) {
-  return (x & (1 << 24)) > 0;
+  return (x & (1 << 24)) > 0; // GOOD (result will always be positive)
+}
+
+bool is_bit31_set_bad_v1(int x) {
+  return (x & (1 << 31)) > 0; // BAD
+}
+
+bool is_bit31_set_bad_v2(int x) {
+  return 0 < (x & (1 << 31)); // BAD [NOT DETECTED]
+}
+
+bool is_bit31_set_good(int x) {
+  return (x & (1 << 31)) != 0; // GOOD (uses `!=`)
+}
+
+bool deliberately_checking_sign(int x, int y) {
+  return (x & y) < 0; // GOOD (use of `<` implies the sign check is intended) [FALSE POSITIVE]
 }
