From 9f1854acf8a13de98b5706d1246baa15f15f377e Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Tue, 18 Jan 2022 10:36:33 +0100
Subject: [PATCH] JSON: Further improve the duplicate handling in the parser

Avoid some unnecessary comparisons and add more tests.

Task-number: QTBUG-99799
Change-Id: I3aee9f0b62461d38dadbe8e969444e1cd1f94e68
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
---
 src/corelib/serialization/qjsonparser.cpp     | 18 ++++-
 .../corelib/serialization/json/CMakeLists.txt |  3 +
 .../serialization/json/simple.duplicates.json |  1 +
 .../serialization/json/test.duplicates.json   | 66 +++++++++++++++++++
 .../serialization/json/test3.duplicates.json  | 15 +++++
 .../corelib/serialization/json/tst_qtjson.cpp | 48 +++++++++++---
 6 files changed, 138 insertions(+), 13 deletions(-)
 create mode 100644 tests/auto/corelib/serialization/json/simple.duplicates.json
 create mode 100644 tests/auto/corelib/serialization/json/test.duplicates.json
 create mode 100644 tests/auto/corelib/serialization/json/test3.duplicates.json

diff --git a/src/corelib/serialization/qjsonparser.cpp b/src/corelib/serialization/qjsonparser.cpp
index df66fc2772e..d8d0ad9c2e2 100644
--- a/src/corelib/serialization/qjsonparser.cpp
+++ b/src/corelib/serialization/qjsonparser.cpp
@@ -389,12 +389,24 @@ static Iterator customAssigningUniqueLast(Iterator first, Iterator last,
     if (first == last)
         return last;
 
-    Iterator result = first;
+    // After adjacent_find, we know that *first and *(first+1) compare equal,
+    // and that first+1 != last.
+    Iterator result = first++;
+    Q_ASSERT(compare(*result, *first));
+    assign(*result, *first);
+    Q_ASSERT(first != last);
+
     while (++first != last) {
         if (!compare(*result, *first))
             ++result;
-        if (result != first)
-            assign(*result, *first);
+
+        // Due to adjacent_find above, we know that we've at least eliminated one element.
+        // Therefore we have to move each further element across the gap.
+        Q_ASSERT(result != first);
+
+        // We have to overwrite each element we want to eliminate, to deref() the container.
+        // Therefore we don't try to optimize the number of assignments here.
+        assign(*result, *first);
     }
 
     return ++result;
diff --git a/tests/auto/corelib/serialization/json/CMakeLists.txt b/tests/auto/corelib/serialization/json/CMakeLists.txt
index 77d15bedc31..9022ed9f3d1 100644
--- a/tests/auto/corelib/serialization/json/CMakeLists.txt
+++ b/tests/auto/corelib/serialization/json/CMakeLists.txt
@@ -24,6 +24,9 @@ if(ANDROID OR INTEGRITY)
         "test.json"
         "test2.json"
         "test3.json"
+        "simple.duplicates.json"
+        "test.duplicates.json"
+        "test3.duplicates.json"
     )
 
     qt_internal_add_resource(tst_json "json"
diff --git a/tests/auto/corelib/serialization/json/simple.duplicates.json b/tests/auto/corelib/serialization/json/simple.duplicates.json
new file mode 100644
index 00000000000..6f989e8aa9b
--- /dev/null
+++ b/tests/auto/corelib/serialization/json/simple.duplicates.json
@@ -0,0 +1 @@
+{"":{"":0},"":0}
diff --git a/tests/auto/corelib/serialization/json/test.duplicates.json b/tests/auto/corelib/serialization/json/test.duplicates.json
new file mode 100644
index 00000000000..0d5af8ef749
--- /dev/null
+++ b/tests/auto/corelib/serialization/json/test.duplicates.json
@@ -0,0 +1,66 @@
+[
+    "JSON Test Pattern pass1",
+    {"a":["array with 1 element"]},
+    {},
+    [],
+    -42,
+    true,
+    false,
+    null,
+    {
+        "a": 1234567890,
+        "a": -9876.543210,
+        "a": 0.123456789e-12,
+        "a": 1.234567890E+34,
+        "a":  23456789012E66,
+        "a": 0,
+        "a": 1,
+        "a": " ",
+        "a": "\"",
+        "a": "\\",
+        "a": "\b\f\n\r\t",
+        "a": "/ & \/",
+        "a": "abcdefghijklmnopqrstuvwxyz",
+        "a": "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
+        "a": "0123456789",
+        "a": "digit",
+        "a": "`1~!@#$%^&*()_+-={':[,]}|;.</>?",
+        "a": "\u0123\u4567\u89AB\uCDEF\uabcd\uef4A",
+        "a": true,
+        "a": false,
+        "a": null,
+        "a":[  ],
+        "a":{  },
+        "a": "50 St. James Street",
+        "a": "nix",
+        "a": "// /* <!-- --",
+        "a": " ",
+        "a":[1,2 , 3
+
+,
+
+4 , 5        ,          6           ,7        ],"a":[1,2,3,4,5,6,7],
+        "a": "\"a:[\"array with 1 element\"]}",
+        "a": "&#34; \u0022 %22 0x22 034 &#x22;",
+        "a": "A key can be any string"
+    },
+    0.5 ,98.6
+,
+99.44
+,
+
+1066,
+1e1,
+0.1e1,
+1e-1,
+1e00,
+2e+00,
+2e-00,
+"rosebud",
+{"a": "bar"},
+{"a":{"a":1000,"a":{"a":"nix"}},"a":{"a":{"a":{"a":"$0.01","a":1},"a":{"a":"$4,833.99","a":483399}},"a":[{"a":"PRODUCT","a":"Silicone c","a":"Elite Hori","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":310711221747712.000000,"a":{"a":{"a":"$1.56","a":156},"a":{"a":"$29.99","a":2999},"a":14},"a":1968262863,"a":8515},{"a":"PRODUCT","a":"Nonslip Ch","a":"Specificat","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":175580930637824.000000,"a":{"a":{"a":"$0.45","a":45},"a":{"a":"$194.95","a":19495},"a":34},"a":2534935499,"a":8515},{"a":"PRODUCT","a":"Plastic Ca","a":"Descriptio","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":132488642953216.000000,"a":{"a":{"a":"$0.99","a":99},"a":{"a":"$303.68","a":30368},"a":33},"a":2305624670,"a":8515},{"a":"PRODUCT","a":"Protective","a":"Made of hi","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":108614681362432.000000,"a":{"a":{"a":"$1.70","a":170},"a":{"a":"$99.99","a":9999},"a":11},"a":2120981405,"a":8515},{"a":"PRODUCT","a":"P® 4","a":"Do more th","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":96203484168192.000000,"a":{"a":{"a":"$2.49","a":249},"a":{"a":"$79.95","a":7995},"a":16},"a":2203798762,"a":8515},{"a":"PRODUCT","a":"Case Refle","a":"NCAA iPhon","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":84727583211520.000000,"a":{"a":{"a":"$0.69","a":69},"a":{"a":"$75.52","a":7552},"a":59},"a":1114627445,"a":8515},{"a":"PRODUCT","a":"Infuse Pro","a":"Protect an","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":80831066406912.000000,"a":{"a":{"a":"$0.59","a":59},"a":{"a":"$79.00","a":7900},"a":24},"a":2557462717,"a":8515},{"a":"PRODUCT","a":"Dragonfly ","a":"d","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":70900229603328.000000,"a":{"a":{"a":"$1.05","a":105},"a":{"a":"$94.49","a":9449},"a":30},"a":2442061740,"a":8515},{"a":"PRODUCT","a":"Pho","a":"Snap on Ap","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":65194915004416.000000,"a":{"a":{"a":"$0.01","a":1},"a":{"a":"$414.99","a":41499},"a":39},"a":2004746863,"a":8515},{"a":"PRODUCT","a":"Otterbox i","a":"Your iPhon","a":"someone","a":{"a":"nix"},"a":{"a":[{"a":"nix","a":60,"a":60},{"a":"nix","a":100,"a":100},{"a":"nix","a":160,"a":160},{"a":"nix","a":400,"a":400}]},"a":61515478597632.000000,"a":{"a":{"a":"$3.28","a":328},"a":{"a":"$110.65","a":11065},"a":25},"a":2584611575,"a":8515}],"a":10,"a":2000}},
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diff --git a/tests/auto/corelib/serialization/json/test3.duplicates.json b/tests/auto/corelib/serialization/json/test3.duplicates.json
new file mode 100644
index 00000000000..c635a2523f7
--- /dev/null
+++ b/tests/auto/corelib/serialization/json/test3.duplicates.json
@@ -0,0 +1,15 @@
+{
+    "a": "John",
+    "a": "Smith",
+    "a": 25,
+    "a": {
+        "a": "21 2nd Street",
+        "a": "New York",
+        "a": "NY",
+        "a": "10021"
+    },
+    "a": [
+        { "a": "home", "a": "212 555-1234" },
+        { "a": "fax", "a": "646 555-4567" }
+    ]
+}
diff --git a/tests/auto/corelib/serialization/json/tst_qtjson.cpp b/tests/auto/corelib/serialization/json/tst_qtjson.cpp
index d23f8666901..72dfc4a47d9 100644
--- a/tests/auto/corelib/serialization/json/tst_qtjson.cpp
+++ b/tests/auto/corelib/serialization/json/tst_qtjson.cpp
@@ -175,6 +175,8 @@ private Q_SLOTS:
     void fromToVariantConversions();
 
     void testIteratorComparison();
+
+    void noLeakOnNameClash_data();
     void noLeakOnNameClash();
 
 private:
@@ -3647,22 +3649,48 @@ void tst_QtJson::testIteratorComparison()
     QVERIFY(t.end() > t.begin());
 }
 
+void tst_QtJson::noLeakOnNameClash_data()
+{
+    QTest::addColumn<QString>("fileName");
+    QTest::addColumn<QByteArray>("result");
+    QTest::addRow("simple")
+            << QStringLiteral("simple.duplicates.json")
+            << QByteArray(R"({"": 0})");
+    QTest::addRow("test")
+            << QStringLiteral("test.duplicates.json")
+            << QByteArray(R"([
+                    "JSON Test Pattern pass1", {"a": ["array with 1 element"]}, {}, [], -42, true,
+                    false, null, {"a": "A key can be any string"}, 0.5, 98.6, 99.44, 1066, 10, 1,
+                    0.1, 1, 2, 2, "rosebud", {"a": "bar"}, {"a": {"a": 2000}}, {"a": {"a": 2000}},
+                    {"a": {"a": 2000}}, {"a": {"a": 2000}}
+                ])");
+    QTest::addRow("test3")
+            << QStringLiteral("test3.duplicates.json")
+            << QByteArray(R"({"a": [{"a": "212 555-1234"}, {"a": "646 555-4567"}]})");
+}
+
 void tst_QtJson::noLeakOnNameClash()
 {
-    QJsonDocument doc = QJsonDocument::fromJson("{\"\":{\"\":0},\"\":0}");
-    QVERIFY(!doc.isNull());
-    const QJsonObject obj = doc.object();
+    QFETCH(QString, fileName);
+    QFETCH(QByteArray, result);
 
-    // Removed the duplicate key.
-    QCOMPARE(obj.length(), 1);
+    QFile file(testDataDir + u'/' + fileName);
+    QVERIFY(file.open(QFile::ReadOnly));
+    QByteArray testJson = file.readAll();
+    QVERIFY(!testJson.isEmpty());
 
-    // Retained the last of the duplicates.
-    const QJsonValue val = obj.begin().value();
-    QVERIFY(val.isDouble());
-    QCOMPARE(val.toDouble(), 0.0);
+    QJsonParseError error;
+
+    // Retains the last one of each set of duplicate keys.
+    QJsonDocument doc = QJsonDocument::fromJson(testJson, &error);
+    QVERIFY2(!doc.isNull(), qPrintable(error.errorString()));
+    QJsonDocument expected = QJsonDocument::fromJson(result, &error);
+    QVERIFY2(!expected.isNull(), qPrintable(error.errorString()));
+
+    QCOMPARE(doc, expected);
 
     // It should not leak.
-    // In particular it should not forget to deref the container for the inner object.
+    // In particular it should not forget to deref the container for the inner objects.
 }
 
 QTEST_MAIN(tst_QtJson)