Make fuzzerTestOneInput void

Java assertion errors are impossible to deduplicate and easily replaced
by an assert or a check and a custom exception.

This commit makes both variants of fuzzerTestOneInput void methods and
    adds a note about this change to the respective error message.

10 files changed, 19 insertions, 35 deletions

diff --git a/examples/src/main/java/com/example/ExampleFuzzer.java b/examples/src/main/java/com/example/ExampleFuzzer.java
index 40dcb697..b41f9c77 100644
--- a/examples/src/main/java/com/example/ExampleFuzzer.java
+++ b/examples/src/main/java/com/example/ExampleFuzzer.java
@@ -22,7 +22,7 @@ public class ExampleFuzzer {
     // Optional initialization to be run before the first call to fuzzerTestOneInput.
   }
 
-  public static boolean fuzzerTestOneInput(FuzzedDataProvider data) {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     String input = data.consumeRemainingAsString();
     // Without the hook in ExampleFuzzerHooks.java, the value of random would change on every
     // invocation, making it almost impossible to guess for the fuzzer.
@@ -31,7 +31,6 @@ public class ExampleFuzzer {
         && input.charAt(25) == 'C') {
       mustNeverBeCalled();
     }
-    return false;
   }
 
   private static void mustNeverBeCalled() {
diff --git a/examples/src/main/java/com/example/ExampleFuzzerWithNative.java b/examples/src/main/java/com/example/ExampleFuzzerWithNative.java
index 801e84ea..853501bf 100644
--- a/examples/src/main/java/com/example/ExampleFuzzerWithNative.java
+++ b/examples/src/main/java/com/example/ExampleFuzzerWithNative.java
@@ -21,14 +21,13 @@ public class ExampleFuzzerWithNative {
     System.loadLibrary("native");
   }
 
-  public static boolean fuzzerTestOneInput(FuzzedDataProvider data) {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     int val = data.consumeInt();
     String stringData = data.consumeRemainingAsString();
     if (val == 17759716 && stringData.length() > 10 && stringData.contains("jazzer")) {
       // call native function which contains a crash
       new ExampleFuzzerWithNative().parse(stringData);
     }
-    return false;
   }
 
   private native boolean parse(String bytes);
diff --git a/examples/src/main/java/com/example/ExampleValueProfileFuzzer.java b/examples/src/main/java/com/example/ExampleValueProfileFuzzer.java
index 1eb55df0..1200c560 100644
--- a/examples/src/main/java/com/example/ExampleValueProfileFuzzer.java
+++ b/examples/src/main/java/com/example/ExampleValueProfileFuzzer.java
@@ -27,14 +27,14 @@ public class ExampleValueProfileFuzzer {
     return input ^ key;
   }
 
-  public static boolean fuzzerTestOneInput(FuzzedDataProvider data) {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     // Without -use_value_profile=1, the fuzzer gets stuck here as there is no direct correspondence
     // between the input bytes and the compared string. With value profile, the fuzzer can guess the
     // expected input byte by byte, which takes linear rather than exponential time.
     if (base64(data.consumeBytes(6)).equals("SmF6emVy")) {
       long[] plaintextBlocks = data.consumeLongs(2);
       if (plaintextBlocks.length != 2)
-        return false;
+        return;
       if (insecureEncrypt(plaintextBlocks[0]) == 0x9fc48ee64d3dc090L) {
         // Without --fake_pcs (enabled by default with -use_value_profile=1), the fuzzer would get
         // stuck here as the value profile information for long comparisons would not be able to
@@ -44,7 +44,6 @@ public class ExampleValueProfileFuzzer {
         }
       }
     }
-    return false;
   }
 
   private static void mustNeverBeCalled() {
diff --git a/examples/src/main/java/com/example/FastJsonFuzzer.java b/examples/src/main/java/com/example/FastJsonFuzzer.java
index 5c203ffb..2e5d4797 100644
--- a/examples/src/main/java/com/example/FastJsonFuzzer.java
+++ b/examples/src/main/java/com/example/FastJsonFuzzer.java
@@ -21,12 +21,10 @@ import com.code_intelligence.jazzer.api.FuzzedDataProvider;
 // Found the issues described in
 // https://github.com/alibaba/fastjson/issues/3631
 public class FastJsonFuzzer {
-  public static boolean fuzzerTestOneInput(FuzzedDataProvider data) {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     try {
       JSON.parse(data.consumeRemainingAsString());
-    } catch (JSONException e) {
-      return false;
+    } catch (JSONException ignored) {
     }
-    return false;
   }
 }
diff --git a/examples/src/main/java/com/example/GifImageParserFuzzer.java b/examples/src/main/java/com/example/GifImageParserFuzzer.java
index 276bdb84..ab7de907 100644
--- a/examples/src/main/java/com/example/GifImageParserFuzzer.java
+++ b/examples/src/main/java/com/example/GifImageParserFuzzer.java
@@ -23,12 +23,10 @@ import org.apache.commons.imaging.formats.gif.GifImageParser;
 // Found https://issues.apache.org/jira/browse/IMAGING-277 and
 // https://issues.apache.org/jira/browse/IMAGING-278.
 public class GifImageParserFuzzer {
-  public static boolean fuzzerTestOneInput(byte[] input) {
+  public static void fuzzerTestOneInput(byte[] input) {
     try {
       new GifImageParser().getBufferedImage(new ByteSourceArray(input), new HashMap<>());
-    } catch (IOException | ImageReadException e) {
-      return false;
+    } catch (IOException | ImageReadException ignored) {
     }
-    return false;
   }
 }
diff --git a/examples/src/main/java/com/example/JacksonCborFuzzer.java b/examples/src/main/java/com/example/JacksonCborFuzzer.java
index 3d847751..902c1d96 100644
--- a/examples/src/main/java/com/example/JacksonCborFuzzer.java
+++ b/examples/src/main/java/com/example/JacksonCborFuzzer.java
@@ -22,15 +22,13 @@ import java.io.IOException;
 // https://github.com/FasterXML/jackson-databind/pull/3032 if executed with
 // `--keep_going=3 -seed=2735196724`.
 public class JacksonCborFuzzer {
-  public static boolean fuzzerTestOneInput(byte[] input) {
+  public static void fuzzerTestOneInput(byte[] input) {
     CBORFactory factory = new CBORFactory();
     ObjectMapper mapper = new ObjectMapper(factory);
     mapper.enableDefaultTyping();
     try {
       mapper.readTree(input);
-    } catch (IOException e) {
-      return false;
+    } catch (IOException ignored) {
     }
-    return false;
   }
 }
diff --git a/examples/src/main/java/com/example/JpegImageParserFuzzer.java b/examples/src/main/java/com/example/JpegImageParserFuzzer.java
index 4040daee..ba3e7c81 100644
--- a/examples/src/main/java/com/example/JpegImageParserFuzzer.java
+++ b/examples/src/main/java/com/example/JpegImageParserFuzzer.java
@@ -22,12 +22,10 @@ import org.apache.commons.imaging.formats.jpeg.JpegImageParser;
 
 // Found https://issues.apache.org/jira/browse/IMAGING-275.
 public class JpegImageParserFuzzer {
-  public static boolean fuzzerTestOneInput(byte[] input) {
+  public static void fuzzerTestOneInput(byte[] input) {
     try {
       new JpegImageParser().getBufferedImage(new ByteSourceArray(input), new HashMap<>());
-    } catch (IOException | ImageReadException e) {
-      return false;
+    } catch (IOException | ImageReadException ignored) {
     }
-    return false;
   }
 }
diff --git a/examples/src/main/java/com/example/JsonSanitizerFuzzer.java b/examples/src/main/java/com/example/JsonSanitizerFuzzer.java
index ef13f369..31831616 100644
--- a/examples/src/main/java/com/example/JsonSanitizerFuzzer.java
+++ b/examples/src/main/java/com/example/JsonSanitizerFuzzer.java
@@ -20,7 +20,7 @@ import com.google.gson.JsonElement;
 import com.google.json.JsonSanitizer;
 
 public class JsonSanitizerFuzzer {
-  public static boolean fuzzerTestOneInput(FuzzedDataProvider data) {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     String input = data.consumeRemainingAsString();
     String validJson;
     try {
@@ -28,15 +28,14 @@ public class JsonSanitizerFuzzer {
     } catch (ArrayIndexOutOfBoundsException e) {
       // ArrayIndexOutOfBoundsException is expected if nesting depth is
       // exceeded.
-      return false;
+      return;
     }
     Gson gson = new Gson();
     gson.fromJson(validJson, JsonElement.class);
     if (validJson.contains("</script>") || validJson.contains("<script")
         || validJson.contains("<!--") || validJson.contains("]]>")) {
       System.out.println(validJson);
-      return true;
+      throw new IllegalStateException("Output contains forbidden substring");
     }
-    return false;
   }
 }
diff --git a/examples/src/main/java/com/example/TiffImageParserFuzzer.java b/examples/src/main/java/com/example/TiffImageParserFuzzer.java
index 6dd127c2..5fa1af2d 100644
--- a/examples/src/main/java/com/example/TiffImageParserFuzzer.java
+++ b/examples/src/main/java/com/example/TiffImageParserFuzzer.java
@@ -22,12 +22,10 @@ import org.apache.commons.imaging.formats.tiff.TiffImageParser;
 
 // Found https://issues.apache.org/jira/browse/IMAGING-276.
 public class TiffImageParserFuzzer {
-  public static boolean fuzzerTestOneInput(byte[] input) {
+  public static void fuzzerTestOneInput(byte[] input) {
     try {
       new TiffImageParser().getBufferedImage(new ByteSourceArray(input), new HashMap<>());
-    } catch (IOException | ImageReadException e) {
-      return false;
+    } catch (IOException | ImageReadException ignored) {
     }
-    return false;
   }
 }
diff --git a/examples/src/main/java/com/example/TurboJpegFuzzer.java b/examples/src/main/java/com/example/TurboJpegFuzzer.java
index 0a0059e4..b9ea715b 100644
--- a/examples/src/main/java/com/example/TurboJpegFuzzer.java
+++ b/examples/src/main/java/com/example/TurboJpegFuzzer.java
@@ -29,7 +29,7 @@ public class TurboJpegFuzzer {
     new TJDecompressor();
   }
 
-  public static boolean fuzzerTestOneInput(FuzzedDataProvider data) {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     try {
       int flagsDecompress = data.consumeInt();
       int flagsTransform = data.consumeInt();
@@ -52,10 +52,8 @@ public class TurboJpegFuzzer {
         tjd = new TJDecompressor(data.consumeRemainingAsBytes());
       }
       tjd.decompress(buffer, 0, 0, desiredWidth, 0, desiredHeight, pixelFormat, flagsDecompress);
-    } catch (Exception e) {
+    } catch (Exception ignored) {
       // We are not looking for Java exceptions, but segfaults and ASan reports.
-      return false;
     }
-    return false;
   }
 }