Prettify JNI stuff.

native/compile-osx.sh

@@ -6,7 +6,7 @@ export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Hom
 CFLAGS="-O3 -I$JAVA_HOME/include/ -I$JAVA_HOME/include/darwin/ -fPIC -shared"
 
 clang $CFLAGS -lz src/main/c/jni_util.c src/main/c/jni_zlib_deflate.c src/main/c/jni_zlib_inflate.c \
-    -o src/main/resources/macosx/velocity-compress.dylib
+    src/main/c/jni_zlib_common.c -o src/main/resources/macosx/velocity-compress.dylib
 clang $CFLAGS -I $MBEDTLS_ROOT/include -shared $MBEDTLS_ROOT/library/aes.c $MBEDTLS_ROOT/library/aesni.c \
     $MBEDTLS_ROOT/library/platform.c $MBEDTLS_ROOT/library/platform_util.c src/main/c/jni_util.c src/main/c/jni_cipher.c \
     -o src/main/resources/macosx/velocity-cipher.dylib

native/src/main/c/jni_util.c

@@ -1,7 +1,7 @@
 #include <jni.h>
 #include "jni_util.h"
 
-JNIEXPORT void JNICALL
+void JNICALL
 throwException(JNIEnv *env, const char *type, const char *msg)
 {
     jclass klazz = (*env)->FindClass(env, type);

native/src/main/c/jni_zlib_common.c

@@ -0,0 +1,29 @@
+#include <jni.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <zlib.h>
+#include "jni_util.h"
+
+void JNICALL
+check_zlib_free(JNIEnv *env, z_stream *stream, bool deflate)
+{
+    int ret = deflate ? deflateEnd(stream) : inflateEnd(stream);
+    char *msg = stream->msg;
+    free((void*) stream);
+
+    switch (ret) {
+        case Z_OK:
+            break;
+        case Z_STREAM_ERROR:
+            if (msg == NULL) {
+                msg = "stream state inconsistent";
+            }
+            // fall-through
+        case Z_DATA_ERROR:
+            if (msg == NULL) {
+                msg = "data was discarded";
+            }
+            throwException(env, "java/lang/IllegalArgumentException", msg);
+            break;
+    }
+}

native/src/main/c/jni_zlib_common.h

@@ -0,0 +1,6 @@
+#include <jni.h>
+#include <stdbool.h>
+#include <zlib.h>
+
+void JNICALL
+check_zlib_free(JNIEnv *env, z_stream *stream, bool deflate);

native/src/main/c/jni_zlib_deflate.c

@@ -1,8 +1,10 @@
 #include <assert.h>
 #include <jni.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <zlib.h>
 #include "jni_util.h"
+#include "jni_zlib_common.h"
 
 static jfieldID finishedID;
 static jfieldID consumedID;
@@ -27,27 +29,28 @@ Java_com_velocitypowered_natives_compression_NativeZlibDeflate_init(JNIEnv *env,
         return 0;
     }
 
-    char *msg;
     int ret = deflateInit(stream, level);
-
-    switch (ret) {
-        case Z_OK:
-            return (jlong) stream;
-        case Z_MEM_ERROR:
-            free(stream);
-            throwException(env, "java/lang/OutOfMemoryError", "zlib init");
-            return 0;
-        case Z_STREAM_ERROR:
-            free(stream);
-            char message[32];
-            snprintf(message, 32, "invalid level %d", level);
-            throwException(env, "java/lang/IllegalArgumentException", message);
-            return 0;
-        default:
-            msg = stream->msg;
-            free(stream);
-            throwException(env, "java/util/zip/DataFormatException", msg);
-            return 0;
+    if (ret == Z_OK) {
+        return (jlong) stream;
+    } else {
+        char *zlib_msg = stream->msg;
+        free(stream);
+        switch (ret) {
+            case Z_MEM_ERROR:
+                throwException(env, "java/lang/OutOfMemoryError", "zlib init");
+                break;
+            case Z_STREAM_ERROR: {
+                // Thanks Ken and Ritchie!
+                char message[32];
+                snprintf(message, 32, "invalid level %d", level);
+                throwException(env, "java/lang/IllegalArgumentException", message);
+                break;
+            }
+            default:
+                throwException(env, "java/util/zip/DataFormatException", zlib_msg);
+                break;
+        }
+        return 0;
     }
 }
 
@@ -57,24 +60,7 @@ Java_com_velocitypowered_natives_compression_NativeZlibDeflate_free(JNIEnv *env,
     jlong ctx)
 {
     z_stream* stream = (z_stream*) ctx;
-    int ret = deflateEnd(stream);
-    char *msg = stream->msg;
-    free((void*) ctx);
-
-    switch (ret) {
-        case Z_OK:
-            break;
-        case Z_STREAM_ERROR:
-            if (msg == NULL) {
-                msg = "stream state inconsistent";
-            }
-        case Z_DATA_ERROR:
-            if (msg == NULL) {
-                msg = "data was discarded";
-            }
-            throwException(env, "java/lang/IllegalArgumentException", msg);
-            break;
-    }
+    check_zlib_free(env, stream, true);
 }
 
 JNIEXPORT int JNICALL

native/src/main/c/jni_zlib_inflate.c

@@ -1,8 +1,10 @@
 #include <assert.h>
 #include <jni.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <zlib.h>
 #include "jni_util.h"
+#include "jni_zlib_common.h"
 
 static jfieldID finishedID;
 static jfieldID consumedID;
@@ -26,25 +28,23 @@ Java_com_velocitypowered_natives_compression_NativeZlibInflate_init(JNIEnv *env,
         return 0;
     }
 
-    char *msg;
     int ret = inflateInit(stream);
-
-    switch (ret) {
-        case Z_OK:
-            return (jlong) stream;
-        case Z_MEM_ERROR:
-            free(stream);
-            throwException(env, "java/lang/OutOfMemoryError", "zlib init");
-            return 0;
-        case Z_STREAM_ERROR:
-            free(stream);
-            throwException(env, "java/lang/IllegalArgumentException", "stream clobbered?");
-            return 0;
-        default:
-            msg = stream->msg;
-            free(stream);
-            throwException(env, "java/util/zip/DataFormatException", msg);
-            return 0;
+    if (ret == Z_OK) {
+        return (jlong) stream;
+    } else {
+        char *zlib_msg = stream->msg;
+        free(stream);
+        switch (ret) {
+            case Z_MEM_ERROR:
+                throwException(env, "java/lang/OutOfMemoryError", "zlib init");
+                return 0;
+            case Z_STREAM_ERROR:
+                throwException(env, "java/lang/IllegalArgumentException", "stream clobbered?");
+                return 0;
+            default:
+                throwException(env, "java/util/zip/DataFormatException", zlib_msg);
+                return 0;
+        }
     }
 }
 
@@ -54,24 +54,7 @@ Java_com_velocitypowered_natives_compression_NativeZlibInflate_free(JNIEnv *env,
     jlong ctx)
 {
     z_stream* stream = (z_stream*) ctx;
-    int ret = inflateEnd(stream);
-    char *msg = stream->msg;
-    free((void*) ctx);
-
-    switch (ret) {
-        case Z_OK:
-            break;
-        case Z_STREAM_ERROR:
-            if (msg == NULL) {
-                msg = "stream state inconsistent";
-            }
-        case Z_DATA_ERROR:
-            if (msg == NULL) {
-                msg = "data was discarded";
-            }
-            throwException(env, "java/lang/IllegalArgumentException", msg);
-            break;
-    }
+    check_zlib_free(env, stream, false);
 }
 
 JNIEXPORT int JNICALL

native/src/test/java/com/velocitypowered/natives/compression/VelocityCompressorTest.java

@@ -1,5 +1,6 @@
 package com.velocitypowered.natives.compression;
 
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 import static org.junit.jupiter.api.condition.OS.LINUX;
@@ -28,6 +29,12 @@ class VelocityCompressorTest {
     new Random(1).nextBytes(TEST_DATA);
   }
 
+  @Test
+  @EnabledOnOs({MAC, LINUX})
+  void sanityCheckNative() {
+    assertThrows(IllegalArgumentException.class, () -> Natives.compress.get().create(-42));
+  }
+
   @Test
   @EnabledOnOs({MAC, LINUX})
   void nativeIntegrityCheck() throws DataFormatException {