codeql/java/ql/test/query-tests/Nullness/B.java

public class B {
  private boolean maybe;
  public final boolean flag;
  public B(boolean b, boolean f) {
    this.maybe = b;
    this.flag = f;
  }

  public void caller() {
    callee1(new Object());
    callee1(null);
    callee2(new Object());
  }

  public void callee1(Object param) {
    param.toString(); // NPE
  }

  public void callee2(Object param) {
    if (param != null) {
      param.toString(); // OK
    }
    param.toString(); // NPE
  }

  private static boolean customIsNull(Object x) {
    if (x instanceof String) return false;
    if (x == null) return true;
    return x == null;
  }

  public void nullGuards() {
    Object o1 = maybe ? null : new Object();
    if (o1 != null) o1.hashCode(); // OK

    Object o2 = maybe ? null : "";
    if (o2 instanceof String) o2.hashCode(); // OK

    Object o3 = null;
    if ((o3 = maybe ? null : "") != null) o3.hashCode(); // OK

    Object o4 = maybe ? null : "";
    if ((2 > 1 && o4 != null) != false) o4.hashCode(); // OK

    Object o5 = (o4 != null) ? "" : null;
    if (o5 != null) o4.hashCode(); // OK
    if (o4 != null) o5.hashCode(); // OK

    Object o6 = maybe ? null : "";
    if (!customIsNull(o6)) o6.hashCode(); // OK

    Object o7 = maybe ? null : "";
    boolean ok = o7 != null && 2 > 1;
    if (ok)
      o7.hashCode(); // OK
    else
      o7.hashCode(); // NPE

    Object o8 = maybe ? null : "";
    int track = o8 == null ? 42 : 1+1;
    if (track == 2) o8.hashCode(); // OK
    if (track != 42) o8.hashCode(); // OK
    if (track < 42) o8.hashCode(); // OK
    if (track <= 41) o8.hashCode(); // OK
  }

  public void deref() {
    int[] xs = maybe ? null : new int[2];
    if (2 > 1) xs[0] = 5; // NPE
    if (2 > 1) maybe = xs[1] > 5; // NPE
    if (2 > 1) {
      int l = xs.length; // NPE
    }
    if (2 > 1) {
      for (int i : xs) { } // NPE
    }
    if (2 > 1) {
      synchronized(xs) { // NPE
        xs.hashCode(); // Not reported - same basic block
      }
    }
    if (4 > 3) {
      assert xs != null;
      xs[0] = xs[1]; // OK
    }
  }

  public void f(boolean b) {
    String x = b ? null : "abc";
    x = x == null ? "" : x;
    if (x == null)
      x.hashCode(); // OK - dead
    else
      x.hashCode(); // OK
  }

  public void lengthGuard(int[] a, int[] b) {
    int alen = a == null ? 0 : a.length; // OK
    int blen = b == null ? 0 : b.length; // OK
    int sum = 0;
    if (alen == blen) {
      for(int i = 0; i < alen; i++) {
        sum += a[i]; // OK
        sum += b[i]; // OK
      }
    }
    int alen2;
    if (a != null)
      alen2 = a.length; // OK
    else
      alen2 = 0;
    for(int i = 1; i <= alen2; ++i) {
      sum += a[i-1]; // OK
    }
  }

  public void missedGuard(Object obj) {
    obj.hashCode(); // NPE
    int x = obj != null ? 1 : 0;
  }

  private Object mkMaybe() {
    if (maybe) throw new RuntimeException();
    return new Object();
  }

  public void exceptions() {
    Object obj = null;
    try {
      obj = mkMaybe();
    } catch(Exception e) {
    }
    obj.hashCode(); // NPE

    Object obj2 = null;
    try {
      obj2 = mkMaybe();
    } catch(Exception e) {
      assert false;
    }
    obj2.hashCode(); // OK

    Object obj3 = null;
    try {
      obj3 = mkMaybe();
    } finally {
      //cleanup
    }
    obj3.hashCode(); // OK
  }

  public void clearNotNull() {
    Object o = new Object();
    if (o == null) o.hashCode(); // OK
    o.hashCode(); // OK

    try {
      mkMaybe();
    } catch(Exception e) {
      if (e == null) e.hashCode(); // OK
      e.hashCode(); // OK
    }

    Object n = null;
    Object o2 = n == null ? new Object() : n;
    o2.hashCode(); // OK

    Object o3 = "abc";
    if (o3 == null) o3.hashCode(); // OK
    o3.hashCode(); // OK

    Object o4 = "" + null;
    if (o4 == null) o4.hashCode(); // OK
    o4.hashCode(); // OK
  }

  public void correlatedConditions(boolean cond, int num) {
    Object o = null;
    if (cond) o = new Object();
    if (cond) o.hashCode(); // OK

    o = null;
    if (flag) o = "";
    if (flag) o.hashCode(); // OK

    o = null;
    Object other = maybe ? null : "";
    if (other == null) o = "";
    if (other != null)
      o.hashCode(); // NPE
    else
      o.hashCode(); // OK

    Object o2 = (num < 0) ? null : "";
    if (num < 0)
      o2 = "";
    else
      o2.hashCode(); // OK
  }

  public void trackingVariable(int[] a) {
    Object o = null;
    Object other = null;
    if (maybe) {
      o = "abc";
      other = "def";
    }
    if (other instanceof String) o.hashCode(); // OK

    o = null;
    int count = 0;
    boolean found = false;
    for (int i = 0; i < a.length; i++) {
      if (a[i] == 42) {
        o = ((Integer)a[i]).toString();
        count++;
        if (2 > 1) { }
        found = true;
      }
      if (a[i] > 10000) {
        o = null;
        count = 0;
        if (2 > 1) { }
        found = false;
      }
    }
    if (count > 3) o.hashCode(); // OK
    if (found) o.hashCode(); // OK

    Object prev = null;
    for (int i = 0; i < a.length; ++i) {
      if (i != 0) prev.hashCode(); // OK
      prev = a[i];
    }

    String s = null;
    if (2 > 1) {
      boolean s_null = true;
      for (int i : a) {
        s_null = false;
        s = "" + a;
      }
      if (!s_null) s.hashCode(); // OK
    }

    Object r = null;
    MyStatus stat = MyStatus.INIT;
    while (stat == MyStatus.INIT && stat != MyStatus.READY) {
      r = mkMaybe();
      if (2 > 1)
        stat = MyStatus.READY;
    }
    r.hashCode(); // OK
  }

  public enum MyStatus {
    READY,
    INIT
  }

  public void g(Object obj) {
    String msg = null;
    if(obj == null)
      msg = "foo";
    else if(obj.hashCode() > 7) { // OK
      msg = "bar";
    }
    if(msg != null) {
      msg += "foobar";
      throw new RuntimeException(msg);
    }
    obj.hashCode(); // OK
  }

  public void loopCorr(int iters) {
    int[] a = null;
    if (iters > 0) a = new int[iters];
    for (int i = 0; i < iters; ++i)
      a[i] = 0; // OK

    if (iters > 0) {
      String last = null;
      for (int i = 0; i < iters; i++) last = "abc";
      last.hashCode(); // OK
    }

    int[] b = maybe ? null : new int[iters];
    if (iters > 0 && (b == null || b.length < iters)) {
      throw new RuntimeException();
    }
    for (int i = 0; i < iters; ++i) {
      b[i] = 0; // OK
    }
  }

  void test(Exception e, boolean b) {
    Exception ioe = null;
    if (b) {
      ioe = new Exception("");
    }
    if (ioe != null) {
      ioe = e;
    } else {
      ioe.getMessage(); // NPE; always
    }
  }

  public void lengthGuard2(int[] a, int[] b) {
    int alen = a == null ? 0 : a.length; // OK
    int sum = 0;
    int i;
    for(i = 0; i < alen; i++) {
      sum += a[i]; // OK
    }
    int blen = b == null ? 0 : b.length; // OK
    for(i = 0; i < blen; i++) {
      sum += b[i]; // OK
    }
    i = -3;
  }

  public void corrConds2(Object x, Object y) {
    if ((x != null && y == null) || (x == null && y != null)) return;
    if (x != null) y.hashCode(); // OK
    if (y != null) x.hashCode(); // OK
  }

  public void corrConds3(Object y) {
    Object x = null;
    if(y instanceof String) {
      x = new Object();
    }
    if(y instanceof String) {
      x.hashCode(); // Spurious NPE - false positive
    }
  }

  public void corrConds4(Object y) {
    Object x = null;
    if(!(y instanceof String)) {
      x = new Object();
    }
    if(!(y instanceof String)) {
      x.hashCode(); // Spurious NPE - false positive
    }
  }

  public void corrConds5(Object y, Object z) {
    Object x = null;
    if(y == z) {
      x = new Object();
    }
    if(y == z) {
      x.hashCode(); // Spurious NPE - false positive
    }

    Object x2 = null;
    if(y != z) {
      x2 = new Object();
    }
    if(y != z) {
      x2.hashCode(); // Spurious NPE - false positive
    }

    Object x3 = null;
    if(y != z) {
      x3 = new Object();
    }
    if(!(y == z)) {
      x3.hashCode(); // Spurious NPE - false positive
    }
  }

  public void bitwise(Object x, boolean b) {
    boolean notnull = x != null;

    boolean g1 = notnull;
    g1 &= b;
    if (g1) {
      x.hashCode(); // OK
    }

    boolean g2 = b;
    g2 &= notnull;
    if (g2) {
      x.hashCode(); // OK
    }

    boolean g3 = !notnull;
    g3 |= b;
    if (!g3) {
      x.hashCode(); // OK
    }

    boolean g4 = b;
    g4 |= !notnull;
    if (!g4) {
      x.hashCode(); // OK
    }

    boolean g5 = g1 = b & notnull;
    if (g5) {
      x.hashCode(); // OK
    }

    g5 |= b;
    if (g5) {
      x.hashCode(); // NPE
    }
  }

  public void corrCondLoop1(boolean a[]) {
    Object x = new Object();
    for (int i = 0; i < a.length; i++) {
      boolean b = a[i];
      if (b) {
        x = null;
      }
      if (!b) {
        x.hashCode(); // NPE
      }
      // flow can loop around from one iteration to the next
    }
  }

  public void corrCondLoop2(boolean a[]) {
    for (int i = 0; i < a.length; i++) {
      // x is local to the loop iteration and thus cannot loop around and reach the sink
      Object x = new Object();
      boolean b = a[i];
      if (b) {
        x = null;
      }
      if (!b) {
        x.hashCode(); // OK
      }
    }
  }

  public void loopCorrTest1(int[] a) {
    boolean ready = a.length > 7;
    Object x = new Object();
    for (int i = 0; i < a.length; i++) {
      // condition correlates with itself through iterations when ready isn't updated
      if (!ready) {
        x = null;
      } else {
        x.hashCode(); // OK
      }
      if ((a[i] & 1) != 0) {
        ready = (a[i] & 2) != 0;
        x = new Object();
      }
    }
  }

  public void loopCorrTest2(boolean[] a) {
    Object x = new Object();
    boolean cur = a[0];
    for (int i = 1; i < a.length; i++) {
      boolean prev = cur;
      cur = a[i];
      if (!prev) {
        // correctly guarded by !cur from the _previous_ iteration
        x.hashCode(); // Spurious NPE - false positive
      } else {
        x = new Object();
      }
      if (cur) {
        x = null;
      }
    }
  }

  public void loopCorrTest3(String[] ss) {
    Object x = null;
    Object t = null;
    for (String s : ss) {
      if (t == null) {
        t = s;
      } else {
        if (t instanceof String) {
          x = new Object();
          t = new Object();
        }
        // correctly guarded by t: null -> String -> Object
        x.hashCode(); // Spurious NPE - false positive
      }
    }
  }

  public void initCorr(boolean b) {
    Object o2 = b ? null : "";
    if (b)
      o2 = "";
    else
      o2.hashCode(); // OK
  }

  public void complexLoopTest(int[] xs, int[] ys) {
    int len = ys != null ? ys.length : 0;
    for (int i = 0, j = 0; i < xs.length; i++) {
      if (j < len && ys[j] == 42) { // OK
        j++;
      } else if (j > 0) {
        ys[0]++; // OK
      }
    }
  }

  public void trackTest(Object o, int n) {
    boolean isnull = o == null;
    int c = -1;
    if (maybe) { }
    if (c == 100) { return; }
    o.hashCode(); // NPE
  }

  public void testFinally(int[] xs, int[] ys) {
    if (xs.length == 0) return;
    if (ys.length == 0) return;
    String s1 = null;
    String s2 = null;
    for (int x : xs) {
      try {
        if (x == 0) { break; }
        s1 = "1";
        for (int y : ys) {
          if (y == 0) { break; }
          s2 = "2";
        }
      } finally {
      }
      s1.hashCode(); // OK
      s2.hashCode(); // NPE
    }
    s1.hashCode(); // NPE - false negative, Java CFG lacks proper edge label
  }

  public void lenCheck(int[] xs, int n, int t) {
    if (n > 42) return;
    if (maybe) {}
    if (n > 0 && (xs == null || xs.length < n)) {
      return;
    }
    if (maybe) {}
    if (n > 21) return;
    if (maybe) {}
    for (int i = 0; i < n; ++i) {
      xs[i]++; // OK
    }
  }

  public void rangetest(int n) {
    String s = null;
    if (n < 0 || n > 10) s = "A";
    if (n > 100) s.hashCode(); // OK
    if (n == 42) s.hashCode(); // OK
  }
}