8230743: StringJoiner does not handle too large strings correctly

Reviewed-by: rriggs, psandoz, martin

src/java.base/share/classes/java/util/StringJoiner.java

@@ -125,6 +125,7 @@ public final class StringJoiner {
         this.prefix = prefix.toString();
         this.delimiter = delimiter.toString();
         this.suffix = suffix.toString();
+        checkAddLength(0, 0);
     }
 
     /**
@@ -202,13 +203,22 @@ public final class StringJoiner {
         } else {
             if (size == elts.length)
                 elts = Arrays.copyOf(elts, 2 * size);
-            len += delimiter.length();
+            len = checkAddLength(len, delimiter.length());
         }
-        len += elt.length();
+        len = checkAddLength(len, elt.length());
         elts[size++] = elt;
         return this;
     }
 
+    private int checkAddLength(int oldLen, int inc) {
+        long newLen = (long)oldLen + (long)inc;
+        long tmpLen = newLen + (long)prefix.length() + (long)suffix.length();
+        if (tmpLen != (int)tmpLen) {
+            throw new OutOfMemoryError("Requested array size exceeds VM limit");
+        }
+        return (int)newLen;
+    }
+
     /**
      * Adds the contents of the given {@code StringJoiner} without prefix and
      * suffix as the next element if it is non-empty. If the given {@code

test/jdk/java/util/StringJoiner/MergeTest.java

@@ -25,12 +25,14 @@
  * @test
  * @bug 8017231 8020977 8054221
  * @summary test  StringJoiner::merge
+ * @modules java.base/jdk.internal.util
  * @run testng MergeTest
  */
 
 import java.util.StringJoiner;
 import java.util.stream.Stream;
 import org.testng.annotations.Test;
+import static jdk.internal.util.ArraysSupport.MAX_ARRAY_LENGTH;
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.fail;
 
@@ -167,4 +169,19 @@ public class MergeTest {
             assertEquals(sj.merge(sj).toString(), fixes.pre0 + "a,b,a,b,a,b,a,b" + fixes.suf0);
         });
     }
+
+    public void OOM() {
+        String maxString = "*".repeat(MAX_ARRAY_LENGTH);
+
+        try {
+            StringJoiner sj1 = new StringJoiner("", "", "");
+            sj1.add(maxString);
+            StringJoiner sj2 = new StringJoiner("", "", "");
+            sj2.add(maxString);
+            sj1.merge(sj2);
+            fail("Should have thrown OutOfMemoryError");
+        } catch (OutOfMemoryError ex) {
+            // okay
+        }
+    }
 }

test/jdk/java/util/StringJoiner/StringJoinerTest.java

@@ -24,13 +24,17 @@
  * @test
  * @bug 5015163 7172553
  * @summary tests StringJoinerTest
+ * @modules java.base/jdk.internal.util
  * @run testng StringJoinerTest
  * @author Jim Gish
  */
 import java.util.ArrayList;
 import java.util.StringJoiner;
 import org.testng.annotations.Test;
+import static jdk.internal.util.ArraysSupport.MAX_ARRAY_LENGTH;
 import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.fail;
+
 
 @Test(groups = {"unit","string","util","libs"})
 public class StringJoinerTest {
@@ -320,5 +324,49 @@ public class StringJoinerTest {
         testCombos(",", "", ">");
         testCombos(",", "<", ">");
     }
+
+    public void OOM1() {
+        String maxString = "*".repeat(MAX_ARRAY_LENGTH);
+
+        try {
+            new StringJoiner(maxString, maxString, maxString).toString();
+            fail("Should have thrown OutOfMemoryError");
+        } catch (OutOfMemoryError ex) {
+            // okay
+        }
+    }
+
+    public void OOM2() {
+        String maxString = "*".repeat(MAX_ARRAY_LENGTH);
+
+        try {
+            new StringJoiner(maxString, maxString, "").toString();
+            fail("Should have thrown OutOfMemoryError");
+        } catch (OutOfMemoryError ex) {
+            // okay
+        }
+    }
+
+    public void OOM3() {
+        String maxString = "*".repeat(MAX_ARRAY_LENGTH);
+
+        try {
+            new StringJoiner(maxString, "", maxString).toString();
+            fail("Should have thrown OutOfMemoryError");
+        } catch (OutOfMemoryError ex) {
+            // okay
+        }
+    }
+
+    public void OOM4() {
+        String maxString = "*".repeat(MAX_ARRAY_LENGTH);
+
+        try {
+            new StringJoiner("", maxString, maxString).toString();
+            fail("Should have thrown OutOfMemoryError");
+        } catch (OutOfMemoryError ex) {
+            // okay
+        }
+    }
 }