8235812: Unicode linebreak with quantifier does not match valid input

Reviewed-by: rriggs

src/java.base/share/classes/java/util/regex/Pattern.java

@@ -2064,7 +2064,7 @@ private Node expr(Node end) {
         Node prev = null;
         Node firstTail = null;
         Branch branch = null;
-        Node branchConn = null;
+        BranchConn branchConn = null;
 
         for (;;) {
             Node node = sequence(end);
@@ -2212,7 +2212,24 @@ private Node sequence(Node end) {
                 break;
             }
 
-            node = closure(node);
+            if (node instanceof LineEnding) {
+                LineEnding le = (LineEnding)node;
+                node = closureOfLineEnding(le);
+
+                if (node != le) {
+                    // LineEnding was replaced with an anonymous group
+                    if (head == null)
+                        head = node;
+                    else
+                        tail.next = node;
+                    // Double return: Tail was returned in root
+                    tail = root;
+                    continue;
+                }
+            } else {
+                node = closure(node);
+            }
+
             /* save the top dot-greedy nodes (.*, .+) as well
             if (node instanceof GreedyCharProperty &&
                 ((GreedyCharProperty)node).cp instanceof Dot) {
@@ -3079,18 +3096,31 @@ private Node group0() {
         if (saveTCNCount < topClosureNodes.size())
             topClosureNodes.subList(saveTCNCount, topClosureNodes.size()).clear();
 
+        return groupWithClosure(node, head, tail, capturingGroup);
+    }
+
+    /**
+     * Transforms a Group with quantifiers into some special constructs
+     * (such as Branch or Loop/GroupCurly), if necessary.
+     *
+     * This method is applied either to actual groups or to the Unicode
+     * linebreak (aka \\R) represented as an anonymous group.
+     */
+    private Node groupWithClosure(Node node, Node head, Node tail,
+                                  boolean capturingGroup)
+    {
         if (node instanceof Ques) {
             Ques ques = (Ques) node;
             if (ques.type == Qtype.POSSESSIVE) {
                 root = node;
                 return node;
             }
-            tail.next = new BranchConn();
-            tail = tail.next;
+            BranchConn branchConn = new BranchConn();
+            tail = tail.next = branchConn;
             if (ques.type == Qtype.GREEDY) {
-                head = new Branch(head, null, tail);
+                head = new Branch(head, null, branchConn);
             } else { // Reluctant quantifier
-                head = new Branch(null, head, tail);
+                head = new Branch(null, head, branchConn);
             }
             root = tail;
             return head;
@@ -3267,6 +3297,31 @@ private Node curly(Node prev, int cmin) {
         return new Curly(prev, cmin, MAX_REPS, qtype);
     }
 
+    /**
+     * Processing repetition of a Unicode linebreak \\R.
+     */
+    private Node closureOfLineEnding(LineEnding le) {
+        int ch = peek();
+        if (ch != '?' && ch != '*' && ch != '+' && ch != '{') {
+            return le;
+        }
+
+        // Replace the LineEnding with an anonymous group
+        // (?:\\u000D\\u000A|[\\u000A\\u000B\\u000C\\u000D\\u0085\\u2028\\u2029])
+        Node grHead = createGroup(true);
+        Node grTail = root;
+        BranchConn branchConn = new BranchConn();
+        branchConn.next = grTail;
+        Node slice = new Slice(new int[] {0x0D, 0x0A});
+        slice.next = branchConn;
+        Node chClass = newCharProperty(x -> x == 0x0A || x == 0x0B ||
+                x == 0x0C || x == 0x0D || x == 0x85 || x == 0x2028 ||
+                x == 0x2029);
+        chClass.next = branchConn;
+        grHead.next = new Branch(slice, chClass, branchConn);
+        return groupWithClosure(closure(grHead), grHead, grTail, false);
+    }
+
     /**
      * Processes repetition. If the next character peeked is a quantifier
      * then new nodes must be appended to handle the repetition.
@@ -4723,18 +4778,19 @@ boolean study(TreeInfo info) {
     static final class Branch extends Node {
         Node[] atoms = new Node[2];
         int size = 2;
-        Node conn;
-        Branch(Node first, Node second, Node branchConn) {
+        BranchConn conn;
+        Branch(Node first, Node second, BranchConn branchConn) {
             conn = branchConn;
             atoms[0] = first;
             atoms[1] = second;
         }
 
         void add(Node node) {
             if (size >= atoms.length) {
-                Node[] tmp = new Node[atoms.length*2];
-                System.arraycopy(atoms, 0, tmp, 0, atoms.length);
-                atoms = tmp;
+                int len = ArraysSupport.newLength(size,
+                        1,    /* minimum growth */
+                        size  /* preferred growth */);
+                atoms = Arrays.copyOf(atoms, len);
             }
             atoms[size++] = node;
         }

test/jdk/java/util/regex/RegExTest.java

@@ -35,7 +35,7 @@
  * 8027645 8035076 8039124 8035975 8074678 6854417 8143854 8147531 7071819
  * 8151481 4867170 7080302 6728861 6995635 6736245 4916384 6328855 6192895
  * 6345469 6988218 6693451 7006761 8140212 8143282 8158482 8176029 8184706
- * 8194667 8197462 8184692 8221431 8224789 8228352 8230829 8236034
+ * 8194667 8197462 8184692 8221431 8224789 8228352 8230829 8236034 8235812
  *
  * @library /test/lib
  * @library /lib/testlibrary/java/lang
@@ -57,7 +57,9 @@
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Random;
 import java.util.Scanner;
 import java.util.function.Function;
@@ -186,6 +188,7 @@ public static void main(String[] args) throws Exception {
         invalidGroupName();
         illegalRepetitionRange();
         surrogatePairWithCanonEq();
+        lineBreakWithQuantifier();
 
         if (failure) {
             throw new
@@ -5000,4 +5003,81 @@ private static void surrogatePairWithCanonEq() {
         }
         report("surrogatePairWithCanonEq");
     }
+
+    // This test is for 8235812
+    private static void lineBreakWithQuantifier() {
+        // key:    pattern
+        // value:  lengths of input that must match the pattern
+        Map<String, List<Integer>> cases = Map.ofEntries(
+            Map.entry("\\R?",      List.of(0, 1)),
+            Map.entry("\\R*",      List.of(0, 1, 2, 3)),
+            Map.entry("\\R+",      List.of(1, 2, 3)),
+            Map.entry("\\R{0}",    List.of(0)),
+            Map.entry("\\R{1}",    List.of(1)),
+            Map.entry("\\R{2}",    List.of(2)),
+            Map.entry("\\R{3}",    List.of(3)),
+            Map.entry("\\R{0,}",   List.of(0, 1, 2, 3)),
+            Map.entry("\\R{1,}",   List.of(1, 2, 3)),
+            Map.entry("\\R{2,}",   List.of(2, 3)),
+            Map.entry("\\R{3,}",   List.of(3)),
+            Map.entry("\\R{0,0}",  List.of(0)),
+            Map.entry("\\R{0,1}",  List.of(0, 1)),
+            Map.entry("\\R{0,2}",  List.of(0, 1, 2)),
+            Map.entry("\\R{0,3}",  List.of(0, 1, 2, 3)),
+            Map.entry("\\R{1,1}",  List.of(1)),
+            Map.entry("\\R{1,2}",  List.of(1, 2)),
+            Map.entry("\\R{1,3}",  List.of(1, 2, 3)),
+            Map.entry("\\R{2,2}",  List.of(2)),
+            Map.entry("\\R{2,3}",  List.of(2, 3)),
+            Map.entry("\\R{3,3}",  List.of(3)),
+            Map.entry("\\R",       List.of(1)),
+            Map.entry("\\R\\R",    List.of(2)),
+            Map.entry("\\R\\R\\R", List.of(3))
+        );
+
+        // key:    length of input
+        // value:  all possible inputs of given length
+        Map<Integer, List<String>> inputs = new HashMap<>();
+        String[] Rs = { "\r\n", "\r", "\n",
+                        "\u000B", "\u000C", "\u0085", "\u2028", "\u2029" };
+        StringBuilder sb = new StringBuilder();
+        for (int len = 0; len <= 3; ++len) {
+            int[] idx = new int[len + 1];
+            do {
+                sb.setLength(0);
+                for (int j = 0; j < len; ++j)
+                    sb.append(Rs[idx[j]]);
+                inputs.computeIfAbsent(len, ArrayList::new).add(sb.toString());
+                idx[0]++;
+                for (int j = 0; j < len; ++j) {
+                    if (idx[j] < Rs.length)
+                        break;
+                    idx[j] = 0;
+                    idx[j+1]++;
+                }
+            } while (idx[len] == 0);
+        }
+
+        // exhaustive testing
+        for (String patStr : cases.keySet()) {
+            Pattern[] pats = patStr.endsWith("R")
+                ? new Pattern[] { Pattern.compile(patStr) }  // no quantifiers
+                : new Pattern[] { Pattern.compile(patStr),          // greedy
+                                  Pattern.compile(patStr + "?") };  // reluctant
+            Matcher m = pats[0].matcher("");
+            for (Pattern p : pats) {
+                m.usePattern(p);
+                for (int len : cases.get(patStr)) {
+                    for (String in : inputs.get(len)) {
+                        if (!m.reset(in).matches()) {
+                            failCount++;
+                            System.err.println("Expected to match '" +
+                                    in + "' =~ /" + p + "/");
+                        }
+                    }
+                }
+            }
+        }
+        report("lineBreakWithQuantifier");
+    }
 }