DiffEditor: Fix git diff parsing for rename + mode change

Sample output:
diff --git a/projects/cosign/build.sh b/projects/argo/build.sh
old mode 100755
new mode 100644
similarity index 88%
rename from projects/cosign/build.sh
rename to projects/argo/build.sh
index 87d865d2..14b8885c
--- a/projects/cosign/build.sh
+++ b/projects/argo/build.sh
@@ -13,7 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
 ################################################################################

+$SRC/cncf-fuzzing/projects/argo/build.sh
+

-compile_go_fuzzer github.com/sigstore/cosign/test FuzzGetPassword fuzz_getPassword gofuzz

Change-Id: Ifa66dfdb80b309d72f524f15c681823ab7e133ba
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/diffeditor/diffeditorplugin.cpp

@@ -1341,6 +1341,26 @@ void DiffEditor::Internal::DiffEditorPlugin::testReadPatch_data()
 
     QTest::newRow("Mode change") << patch << fileDataList9;
 
+    //////////////
+    patch = R"(diff --git a/old.sh b/new.sh
+old mode 100644
+new mode 100755
+similarity index 100%
+rename from old.sh
+rename to new.sh
+)"
+            ;
+
+    fileData1 = FileData();
+    fileData1.leftFileInfo = DiffFileInfo("old.sh");
+    fileData1.rightFileInfo = DiffFileInfo("new.sh");
+    fileData1.fileOperation = FileData::RenameFile;
+
+    QList<FileData> fileDataList10;
+    fileDataList10 << fileData1;
+
+    QTest::newRow("Mode change + rename") << patch << fileDataList10;
+
     //////////////
 
     // Subversion New

src/plugins/diffeditor/diffutils.cpp

@@ -997,12 +997,15 @@ static QList<FileData> readDiffPatch(StringView patch, bool *ok, QFutureInterfac
 // The git diff patch format (CopyFile, RenameFile)
 // 0.  [some text lines to skip, e.g. show description]\n
 // 1.  diff --git a/[leftFileName] b/[rightFileName]\n
-// 2.  [dis]similarity index [0-100]%\n
+// 2a. old mode [oldFileModeNumber]\n
+//     new mode [newFileModeNumber]\n
+// 2b. <Nothing, only in case when no ChangeMode>
+// 3.  [dis]similarity index [0-100]%\n
 //     [copy / rename] from [leftFileName]\n
 //     [copy / rename] to [rightFileName]
-// 3a. <Nothing more, only when similarity index was 100%>
-// 3b. index [leftIndexSha]..[rightIndexSha] <optionally: octalNumber>
-// 4.  --- [leftFileNameOrDevNull]\n
+// 4a. <Nothing more, only when similarity index was 100%>
+// 4b. index [leftIndexSha]..[rightIndexSha] <optionally: octalNumber>
+// 5.  --- [leftFileNameOrDevNull]\n
 //     +++ [rightFileNameOrDevNull]\n
 //     <Chunks>
 
@@ -1164,10 +1167,21 @@ static bool detectFileData(StringView patch, FileData *fileData, StringView *rem
 
     } else {
         // copy / rename
-
+        StringView afterModeOrSimilarity;
         StringView afterSimilarity;
-        // (dis)similarity index [0-100]%
-        readLine(afterDiffGit, &afterSimilarity, &hasNewLine);
+        const StringView secondLine = readLine(afterDiffGit, &afterModeOrSimilarity, &hasNewLine);
+        if (secondLine.startsWith(QLatin1String("old mode "))) {
+            if (!hasNewLine)
+                return false;
+            readLine(afterModeOrSimilarity, &afterModeOrSimilarity, &hasNewLine); // new mode
+            if (!hasNewLine)
+                return false;
+            // (dis)similarity index [0-100]%
+            readLine(afterModeOrSimilarity, &afterSimilarity, &hasNewLine);
+        } else {
+            afterSimilarity = afterModeOrSimilarity;
+        }
+
         if (!hasNewLine)
             return false; // we need to have at least one more line