Fix #818

release-notes/VERSION-2.x

@@ -64,6 +64,8 @@ JSON library.
   `byte[]`/`char[]`/String-with-offsets input
 #812: Add explicit bounds checks for `JsonFactory.createParser()` methods
   that take `byte[]`/`char[]`-with-offsets input
+#818: Calling `JsonPointer.compile(...)` on very deeply nested expression
+  throws `StackOverflowErrror`
 
 2.13.4 (03-Sep-2022)
 

src/main/java/com/fasterxml/jackson/core/JsonPointer.java

@@ -562,37 +562,56 @@ private final static int _parseIndex(String str) {
         }
         return NumberInput.parseInt(str);
     }
-
-    protected static JsonPointer _parseTail(String input) {
-        final int end = input.length();
+
+    protected static JsonPointer _parseTail(String fullPath)
+    {
+        PointerParent parent = null;
 
         // first char is the contextual slash, skip
-        for (int i = 1; i < end; ) {
-            char c = input.charAt(i);
+        int i = 1;
+        int end = fullPath.length();
+
+        while (i < end) {
+            char c = fullPath.charAt(i);
             if (c == '/') { // common case, got a segment
-                return new JsonPointer(input, input.substring(1, i),
-                        _parseTail(input.substring(i)));
+                parent = new PointerParent(parent, fullPath, fullPath.substring(1, i));
+                fullPath = fullPath.substring(i);
+                i = 1;
+                end = fullPath.length();
+                continue;
             }
             ++i;
             // quoting is different; offline this case
             if (c == '~' && i < end) { // possibly, quote
                 // 04-Oct-2022, tatu: Let's decode escaped segment
                 //   instead of recursive call
                 StringBuilder sb = new StringBuilder(32);
-                i = _extractEscapedSegment(input, i, sb);
+                i = _extractEscapedSegment(fullPath, i, sb);
                 final String segment = sb.toString();
                 if (i < 0) { // end!
-                    return new JsonPointer(input, segment, EMPTY);
+                    return _buildPath(fullPath, segment, parent);
                 }
-                return new JsonPointer(input, segment,
-                        _parseTail(input.substring(i)));
+                parent = new PointerParent(parent, fullPath, segment);
+                fullPath = fullPath.substring(i);
+                i = 1;
+                end = fullPath.length();
+                continue;
             }
             // otherwise, loop on
         }
         // end of the road, no escapes
-        return new JsonPointer(input, input.substring(1), EMPTY);
+        return _buildPath(fullPath, fullPath.substring(1), parent);
     }
 
+    private static JsonPointer _buildPath(String fullPath, String segment,
+            PointerParent parent) {
+        JsonPointer curr = new JsonPointer(fullPath, segment, EMPTY);
+        for (; parent != null; parent = parent.parent) {
+            curr = new JsonPointer(parent.fullPath, parent.segment, curr);
+        }
+        return curr;
+    }
+
     /**
      * Method called to extract the next segment of the path, in case
      * where we seem to have encountered a (tilde-)escaped character
@@ -665,6 +684,28 @@ protected JsonPointer _constructHead(int suffixLength, JsonPointer last)
                 _matchingElementIndex, next._constructHead(suffixLength, last));
     }
 
+    /*
+    /**********************************************************
+    /* Helper class used to replace call stack (2.14+)
+    /**********************************************************
+     */
+
+    /**
+     * Helper class used to replace call stack when parsing JsonPointer
+     * expressions.
+     */
+    private static class PointerParent {
+        public final PointerParent parent;
+        public final String fullPath;
+        public final String segment;
+
+        PointerParent(PointerParent pp, String fp, String sgm) {
+            parent = pp;
+            fullPath = fp;
+            segment = sgm;
+        }
+    }
+
     /*
     /**********************************************************
     /* Support for JDK serialization (2.14+)

src/test/java/com/fasterxml/jackson/failing/Fuzz51806JsonPointerParse818Test.java → src/test/java/com/fasterxml/jackson/core/fuzz/Fuzz51806JsonPointerParse818Test.java

@@ -1,4 +1,4 @@
-package com.fasterxml.jackson.failing;
+package com.fasterxml.jackson.core.fuzz;
 
 import com.fasterxml.jackson.core.BaseTest;
 import com.fasterxml.jackson.core.JsonPointer;

src/test/java/com/fasterxml/jackson/core/io/doubleparser/ParseSignificandWithSwarTest.java

@@ -44,7 +44,7 @@ public void doIllegalTest(String s) {
     public void doLegalTest(String s) {
         double actual = significandToDouble(s.getBytes(StandardCharsets.ISO_8859_1));
         double expected = Double.parseDouble(s);
-        System.out.println(expected + " == " + actual);
+//        System.out.println(expected + " == " + actual);
         assertEquals(expected, actual);
     }