From 9f0dbda0363ecaeaa5fde2aa49e33f542b9b85e4 Mon Sep 17 00:00:00 2001
From: Jasmine Karthikeyan <25208576+jaskarth@users.noreply.github.com>
Date: Sun, 18 Aug 2024 15:56:02 -0400
Subject: [PATCH] Avoid race condition crashes when handling duplicate classes

---
 .../java/decompiler/main/ClassesProcessor.java   | 16 +++++++++++++++-
 .../decompiler/main/extern/IContextSource.java   |  5 ++++-
 .../java/decompiler/struct/ContextUnit.java      | 12 +++++++-----
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/src/org/jetbrains/java/decompiler/main/ClassesProcessor.java b/src/org/jetbrains/java/decompiler/main/ClassesProcessor.java
index 567a3feca5..3252b57772 100644
--- a/src/org/jetbrains/java/decompiler/main/ClassesProcessor.java
+++ b/src/org/jetbrains/java/decompiler/main/ClassesProcessor.java
@@ -102,8 +102,22 @@ public void loadClasses(IIdentifierRenamer renamer) {
       excludedMatcher = Pattern.compile(excludedRegex).matcher("");
     }
 
+    // Filter any duplicate classes
+
+    List<StructClass> ownClasses = context.getOwnClasses();
+    List<StructClass> classes = new ArrayList<>();
+    Set<String> names = new LinkedHashSet<>();
+
+    for (StructClass cl : ownClasses) {
+      if (names.add(cl.qualifiedName)) {
+        classes.add(cl);
+      } else {
+        DecompilerContext.getLogger().writeMessage("Skipping processing already existing class: " + cl.qualifiedName, IFernflowerLogger.Severity.ERROR);
+      }
+    }
+
     // create class nodes
-    for (StructClass cl : context.getOwnClasses()) {
+    for (StructClass cl : classes) {
       if (excludedMatcher != null && excludedMatcher.reset(cl.qualifiedName).matches()) {
         continue;
       }
diff --git a/src/org/jetbrains/java/decompiler/main/extern/IContextSource.java b/src/org/jetbrains/java/decompiler/main/extern/IContextSource.java
index 3dd82b1b8a..51e52eba9c 100644
--- a/src/org/jetbrains/java/decompiler/main/extern/IContextSource.java
+++ b/src/org/jetbrains/java/decompiler/main/extern/IContextSource.java
@@ -260,6 +260,9 @@ public String path() {
       }
     }
 
-
+    @Override
+    public String toString() {
+      return "E[" + basePath + "]";
+    }
   }
 }
diff --git a/src/org/jetbrains/java/decompiler/struct/ContextUnit.java b/src/org/jetbrains/java/decompiler/struct/ContextUnit.java
index b1fd3b753b..bb39d60163 100644
--- a/src/org/jetbrains/java/decompiler/struct/ContextUnit.java
+++ b/src/org/jetbrains/java/decompiler/struct/ContextUnit.java
@@ -13,10 +13,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.LinkedList;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Function;
@@ -150,13 +147,18 @@ public void save(final Function<String, StructClass> loader) throws IOException
     ForkJoinPool pool = new ForkJoinPool(threads, namingScheme(), null, true);
     final DecompilerContext rootContext = DecompilerContext.getCurrentContext();
     final List<ClassContext> toDump = new ArrayList<>(classEntries.size());
+    Set<String> seen = new LinkedHashSet<>();
 
     // collect classes
     for (int i = 0; i < classEntries.size(); i++) {
       StructClass cl = loader.apply(classEntries.get(i));
       String entryName = decompiledData.getClassEntryName(cl, classEntries.get(i));
       if (entryName != null) {
-        toDump.add(new ClassContext(cl, entryName));
+        if (seen.add(cl.qualifiedName)) {
+          toDump.add(new ClassContext(cl, entryName));
+        } else {
+          DecompilerContext.getLogger().writeMessage("Skipping writing already existing class: " + cl.qualifiedName, IFernflowerLogger.Severity.ERROR);
+        }
       }
     }