C++: Add a 'shared' interprocedural control-flow library. I am keeping it in the cpp directory now to avoid qlpack headache.

Author: MathiasVP

cpp/ql/lib/semmle/code/cpp/interproccontrolflow/shared/ControlFlow.qll

@@ -0,0 +1,140 @@
+private import codeql.util.Location
+
+/** Provides language-specific control flow parameters. */
+signature module InputSig<LocationSig Location> {
+  /**
+   * A node in the control flow graph.
+   */
+  class Node {
+    /** Gets a textual representation of this element. */
+    string toString();
+
+    /** Gets the location of this node. */
+    Location getLocation();
+  }
+
+  class CallNode extends Node;
+
+  class Callable;
+
+  predicate edge(Node n1, Node n2);
+
+  predicate callTarget(CallNode call, Callable target);
+
+  predicate flowEntry(Callable c, Node entry);
+
+  predicate flowExit(Callable c, Node exitNode);
+
+  Callable getEnclosingCallable(Node n);
+
+  predicate hiddenNode(Node n);
+
+  class Split {
+    string toString();
+
+    Location getLocation();
+
+    predicate entry(Node n1, Node n2);
+
+    predicate exit(Node n1, Node n2);
+
+    predicate blocked(Node n1, Node n2);
+  }
+}
+
+private module Configs<LocationSig Location, InputSig<Location> Lang> {
+  private import Lang
+
+  /** An input configuration for control flow. */
+  signature module ConfigSig {
+    /** Holds if `source` is a relevant control flow source. */
+    predicate isSource(Node src);
+
+    /** Holds if `sink` is a relevant control flow sink. */
+    predicate isSink(Node sink);
+
+    /** Holds if control flow should not proceed along the edge `n1 -> n2`. */
+    default predicate isBarrierEdge(Node n1, Node n2) { none() }
+
+    /**
+     * Holds if control flow through `node` is prohibited. This completely
+     * removes `node` from the control flow graph.
+     */
+    default predicate isBarrier(Node n) { none() }
+  }
+
+  /** An input configuration for control flow using a label. */
+  signature module LabelConfigSig {
+    class Label;
+
+    /**
+     * Holds if `source` is a relevant control flow source with the given
+     * initial `l`.
+     */
+    predicate isSource(Node src, Label l);
+
+    /**
+     * Holds if `sink` is a relevant control flow sink accepting `l`.
+     */
+    predicate isSink(Node sink, Label l);
+
+    /**
+     * Holds if control flow should not proceed along the edge `n1 -> n2` when
+     * the label is `l`.
+     */
+    default predicate isBarrierEdge(Node n1, Node n2, Label l) { none() }
+
+    /**
+     * Holds if control flow through `node` is prohibited when the label
+     * is `l`.
+     */
+    default predicate isBarrier(Node n, Label l) { none() }
+  }
+}
+
+module ControlFlowMake<LocationSig Location, InputSig<Location> Lang> {
+  private import Lang
+  private import internal.ControlFlowImpl::MakeImpl<Location, Lang>
+  import Configs<Location, Lang>
+
+  /**
+   * The output of a global control flow computation.
+   */
+  signature module GlobalFlowSig {
+    /**
+     * A `Node` that is reachable from a source, and which can reach a sink.
+     */
+    class PathNode;
+
+    /**
+     * Holds if control can flow from `source` to `sink`.
+     *
+     * The corresponding paths are generated from the end-points and the graph
+     * included in the module `PathGraph`.
+     */
+    predicate flowPath(PathNode source, PathNode sink);
+  }
+
+  /**
+   * Constructs a global control flow computation.
+   */
+  module Global<ConfigSig Config> implements GlobalFlowSig {
+    private module C implements FullConfigSig {
+      import DefaultLabel<Config>
+      import Config
+    }
+
+    import Impl<C>
+  }
+
+  /**
+   * Constructs a global control flow computation using a flow label.
+   */
+  module GlobalWithLabel<LabelConfigSig Config> implements GlobalFlowSig {
+    private module C implements FullConfigSig {
+      import Config
+    }
+
+    import Impl<C>
+  }
+}