addons/cert.py: Add MSC30-C: Do not use rand() (#1348)

Add function isStandardFunction() that checks if the given function is a standard function.
Only when this function returns true for the currently checked rand() tokens it is reported as a violation.
Tests added for C and C++.

.travis.yml

@@ -131,6 +131,8 @@ script:
   - python3 ../misc.py -verify misc-test.cpp.dump
   - ${CPPCHECK} --dump cert-test.c
   - python3 ../cert.py -verify cert-test.c.dump
+  - ${CPPCHECK} --dump cert-test.cpp
+  - python3 ../cert.py -verify cert-test.cpp.dump
   - ${CPPCHECK} --dump misra-test.c
   - python3 ../misra.py -verify misra-test.c.dump
   - ${CPPCHECK} --dump misra-test.cpp

addons/cert.py

@@ -70,6 +70,19 @@ def isCast(expr):
         return False
     return True
 
+def isStandardFunction(token):
+    if token.function:
+        return False
+    prev = token.previous
+    if prev:
+        if prev.str == '.':
+            return False
+        if prev.str == '::':
+            prevprev = prev.previous
+            if prevprev and not prevprev.str == 'std':
+                return False
+    return True
+
 # Get function arguments
 def getArgumentsRecursive(tok, arguments):
     if tok is None:
@@ -215,6 +228,13 @@ def int31(data, platform):
                     'cert-INT31-c')
                 break
 
+# MSC30-C
+# Do not use the rand() function for generating pseudorandom numbers
+def msc30(data):
+    for token in data.tokenlist:
+        if simpleMatch(token, "rand ( )") and isStandardFunction(token):
+            reportError(token, 'style', 'Do not use the rand() function for generating pseudorandom numbers', 'cert-MSC30-c')
+
 for arg in sys.argv[1:]:
     if arg == '-verify':
         VERIFY = True
@@ -238,6 +258,7 @@ for arg in sys.argv[1:]:
         exp42(cfg)
         exp46(cfg)
         int31(cfg, data.platform)
+        msc30(cfg)
 
     if VERIFY:
         for expected in VERIFY_EXPECTED:

addons/test/cert-test.c

@@ -54,3 +54,10 @@ unsigned char int31(int x)
     x = (unsigned char)-1; // cert-INT31-c
     x = (unsigned long long)-1; // cert-INT31-c
 }
+
+void msc30()
+{
+    unsigned int num = rand(); // cert-MSC30-c
+    int rand = 5;
+    int a = rand;
+}

addons/test/cert-test.cpp

@@ -0,0 +1,21 @@
+// To test:
+// ~/cppcheck/cppcheck --dump cert-test.cpp && python ../cert.py -verify cert-test.cpp.dump
+
+#include <cstdlib>
+
+class msc30TestClass {
+public:
+    static int rand();
+};
+
+void msc30(msc30TestClass & testClass)
+{
+    unsigned int num = rand(); // cert-MSC30-c
+    num = std::rand(); // cert-MSC30-c
+    num = msc30TestClass::rand();
+    num = unknownClass::rand();
+    num = testClass.rand();
+    num = unknownClass.rand();
+    int rand = 5;
+    int a = rand;
+}