Java: Extract Bound class to its own file.

Author: aschackmull

java/ql/src/semmle/code/java/dataflow/Bound.qll

@@ -0,0 +1,58 @@
+import java
+private import SSA
+private import RangeUtils
+
+private newtype TBound =
+  TBoundZero() or
+  TBoundSsa(SsaVariable v) { v.getSourceVariable().getType() instanceof IntegralType } or
+  TBoundExpr(Expr e) { e.(FieldRead).getField() instanceof ArrayLengthField and not exists(SsaVariable v | e = v.getAUse()) }
+
+/**
+ * A bound that may be inferred for an expression plus/minus an integer delta.
+ */
+abstract class Bound extends TBound {
+  abstract string toString();
+  /** Gets an expression that equals this bound plus `delta`. */
+  abstract Expr getExpr(int delta);
+  /** Gets an expression that equals this bound. */
+  Expr getExpr() {
+    result = getExpr(0)
+  }
+  predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
+    path = "" and sl = 0 and sc = 0 and el = 0 and ec = 0
+  }
+}
+
+/**
+ * The bound that corresponds to the integer 0. This is used to represent all
+ * integer bounds as bounds are always accompanied by an added integer delta.
+ */
+class ZeroBound extends Bound, TBoundZero {
+  override string toString() { result = "0" }
+  override Expr getExpr(int delta) { result.(ConstantIntegerExpr).getIntValue() = delta }
+}
+
+/**
+ * A bound corresponding to the value of an SSA variable.
+ */
+class SsaBound extends Bound, TBoundSsa {
+  /** Gets the SSA variable that equals this bound. */
+  SsaVariable getSsa() { this = TBoundSsa(result) }
+  override string toString() { result = getSsa().toString() }
+  override Expr getExpr(int delta) { result = getSsa().getAUse() and delta = 0 }
+  override predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
+    getSsa().getLocation().hasLocationInfo(path, sl, sc, el, ec)
+  }
+}
+
+/**
+ * A bound that corresponds to the value of a specific expression that might be
+ * interesting, but isn't otherwise represented by the value of an SSA variable.
+ */
+class ExprBound extends Bound, TBoundExpr {
+  override string toString() { result = getExpr().toString() }
+  override Expr getExpr(int delta) { this = TBoundExpr(result) and delta = 0 }
+  override predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
+    getExpr().hasLocationInfo(path, sl, sc, el, ec)
+  }
+}

java/ql/src/semmle/code/java/dataflow/RangeAnalysis.qll

@@ -72,6 +72,7 @@ private import ParityAnalysis
 private import semmle.code.java.Reflection
 private import semmle.code.java.Collections
 private import semmle.code.java.Maps
+import Bound
 
 cached private module RangeAnalysisCache {
 
@@ -409,61 +410,6 @@ private predicate boundFlowStepDiv(Expr e2, Expr e1, int factor) {
   )
 }
 
-private newtype TBound =
-  TBoundZero() or
-  TBoundSsa(SsaVariable v) { v.getSourceVariable().getType() instanceof IntegralType } or
-  TBoundExpr(Expr e) { e.(FieldRead).getField() instanceof ArrayLengthField and not exists(SsaVariable v | e = v.getAUse()) }
-
-/**
- * A bound that may be inferred for an expression plus/minus an integer delta.
- */
-abstract class Bound extends TBound {
-  abstract string toString();
-  /** Gets an expression that equals this bound plus `delta`. */
-  abstract Expr getExpr(int delta);
-  /** Gets an expression that equals this bound. */
-  Expr getExpr() {
-    result = getExpr(0)
-  }
-  predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
-    path = "" and sl = 0 and sc = 0 and el = 0 and ec = 0
-  }
-}
-
-/**
- * The bound that corresponds to the integer 0. This is used to represent all
- * integer bounds as bounds are always accompanied by an added integer delta.
- */
-class ZeroBound extends Bound, TBoundZero {
-  override string toString() { result = "0" }
-  override Expr getExpr(int delta) { result.(ConstantIntegerExpr).getIntValue() = delta }
-}
-
-/**
- * A bound corresponding to the value of an SSA variable.
- */
-class SsaBound extends Bound, TBoundSsa {
-  /** Gets the SSA variable that equals this bound. */
-  SsaVariable getSsa() { this = TBoundSsa(result) }
-  override string toString() { result = getSsa().toString() }
-  override Expr getExpr(int delta) { result = getSsa().getAUse() and delta = 0 }
-  override predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
-    getSsa().getLocation().hasLocationInfo(path, sl, sc, el, ec)
-  }
-}
-
-/**
- * A bound that corresponds to the value of a specific expression that might be
- * interesting, but isn't otherwise represented by the value of an SSA variable.
- */
-class ExprBound extends Bound, TBoundExpr {
-  override string toString() { result = getExpr().toString() }
-  override Expr getExpr(int delta) { this = TBoundExpr(result) and delta = 0 }
-  override predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
-    getExpr().hasLocationInfo(path, sl, sc, el, ec)
-  }
-}
-
 /**
  * Holds if `b + delta` is a valid bound for `v` at `pos`.
  * - `upper = true`  : `v <= b + delta`
@@ -632,7 +578,7 @@ private predicate baseBound(Expr e, int b, boolean upper) {
  */
 private predicate safeNarrowingCast(NarrowingCastExpr cast, boolean upper) {
   exists(int bound |
-    bounded(cast.getExpr(), TBoundZero(), bound, upper, _, _, _)
+    bounded(cast.getExpr(), any(ZeroBound zb), bound, upper, _, _, _)
     |
     upper = true and bound <= cast.getUpperBound() or
     upper = false and bound >= cast.getLowerBound()