Python: Add a way to easily specify constant values for in new Value API.

Author: markshannon

python/ql/src/semmle/python/Exprs.qll

@@ -370,6 +370,7 @@ abstract class ImmutableLiteral extends Expr {
     abstract Object getLiteralObject();
 
     abstract boolean booleanValue();
+
     final Value getLiteralValue() {
         result.(ConstantObjectInternal).getLiteral() = this
     }

python/ql/src/semmle/python/objects/Constants.qll

@@ -189,7 +189,7 @@ private class NoneObjectInternal extends ConstantObjectInternal, TNone {
 }
 
 
-private class IntObjectInternal extends ConstantObjectInternal, TInt {
+class IntObjectInternal extends ConstantObjectInternal, TInt {
 
     override string toString() {
         result = "int " + this.intValue().toString()
@@ -235,7 +235,7 @@ private class IntObjectInternal extends ConstantObjectInternal, TInt {
 
 }
 
-private class FloatObjectInternal extends ConstantObjectInternal, TFloat {
+class FloatObjectInternal extends ConstantObjectInternal, TFloat {
 
     override string toString() {
         if this.floatValue() = this.floatValue().floor() then (
@@ -258,7 +258,7 @@ private class FloatObjectInternal extends ConstantObjectInternal, TFloat {
         result.floatValue() = this.floatValue()
     }
 
-    private float floatValue() {
+    float floatValue() {
         this = TFloat(result)
     }
 
@@ -288,7 +288,7 @@ private class FloatObjectInternal extends ConstantObjectInternal, TFloat {
 }
 
 
-private class UnicodeObjectInternal extends ConstantObjectInternal, TUnicode {
+class UnicodeObjectInternal extends ConstantObjectInternal, TUnicode {
 
     override string toString() {
         result =  "'" + this.strValue() + "'"
@@ -337,7 +337,7 @@ private class UnicodeObjectInternal extends ConstantObjectInternal, TUnicode {
 
 }
 
-private class BytesObjectInternal extends ConstantObjectInternal, TBytes {
+class BytesObjectInternal extends ConstantObjectInternal, TBytes {
 
     override string toString() {
         result =  "'" + this.strValue() + "'"

python/ql/src/semmle/python/objects/ObjectAPI.qll

@@ -191,6 +191,45 @@ module Value {
         name = "False" and result = TFalse()
     }
 
+    /** Gets the `Value` for the integer constant `i`, if it exists.
+     * There will be no `Value` for most integers, but the following are 
+     * guaranteed to exist:
+     * * From zero to 511 inclusive.
+     * * All powers of 2 (up to 2**30)
+     * * Any integer explicitly mentioned in the source program.
+     */
+    Value forInt(int i) {
+        result.(IntObjectInternal).intValue() = i
+    }
+
+    /** Gets the `Value` for the bytes constant `bytes`, if it exists.
+     * There will be no `Value` for most byte strings, unless it is explicitly
+     * declared in the source program.
+     */
+    Value forBytes(string bytes) {
+        result.(BytesObjectInternal).strValue() = bytes
+    }
+
+    /** Gets the `Value` for the unicode constant `text`, if it exists.
+     * There will be no `Value` for most text strings, unless it is explicitly
+     * declared in the source program.
+     */
+    Value forUnicode(string text) {
+        result.(UnicodeObjectInternal).strValue() = text
+    }
+
+    /** Gets the `Value` for the bool constant `b`. */
+    Value forBool(boolean b) {
+        b = true and result = TTrue()
+        or
+        b = false and result = TFalse()
+    }
+
+    /** Gets the `Value` for `None`. */
+    Value none_() {
+        result = ObjectInternal::none_()
+    }
+
 }
 
 /** Class representing callables in the Python program

python/ql/test/library-tests/PointsTo/api/Constants.expected

@@ -0,0 +1,16 @@
+| 1 | file://:0:0:0:0 | int 1 |
+| 2 | file://:0:0:0:0 | int 2 |
+| 3 | file://:0:0:0:0 | int 3 |
+| 4 | file://:0:0:0:0 | int 4 |
+| 5 | file://:0:0:0:0 | int 5 |
+| 6 | file://:0:0:0:0 | int 6 |
+| 7 | file://:0:0:0:0 | int 7 |
+| 8 | file://:0:0:0:0 | int 8 |
+| 9 | file://:0:0:0:0 | int 9 |
+| 10 | file://:0:0:0:0 | int 10 |
+| 1000 | file://:0:0:0:0 | int 1000 |
+| 1004 | file://:0:0:0:0 | int 1004 |
+| b'b' | file://:0:0:0:0 | 'b' |
+| b'd' | file://:0:0:0:0 | 'd' |
+| u'a' | file://:0:0:0:0 | 'a' |
+| u'c' | file://:0:0:0:0 | 'c' |

python/ql/test/library-tests/PointsTo/api/Constants.ql

@@ -0,0 +1,20 @@
+
+import python
+
+from string txt, Value val
+where
+exists(string s |
+    txt = "u'" + s + "'" and val = Value::forUnicode(s)
+    or
+    txt = "b'" + s + "'" and val = Value::forBytes(s)
+    |
+    s = "a" or s = "b" or s = "c" or s = "d"
+)
+or
+exists(int i |
+    txt = i.toString() and val = Value::forInt(i)
+    |
+    i in [1..10] or i in [1000..1010]
+)
+
+select txt, val

python/ql/test/library-tests/PointsTo/api/test.py

@@ -0,0 +1,6 @@
+u"a"
+b"b"
+u"c"
+b"d"
+1000
+1004