Prevent buffer being resized in `writeFramedPacket`, it is now possible to know if a buffer couldn't be written to

Signed-off-by: TheMode <themode@outlook.fr>

src/main/java/net/minestom/server/utils/PacketUtils.java

@@ -193,7 +193,7 @@ public final class PacketUtils {
         final int contentStart = buffer.position();
 
         Utils.writeVarInt(buffer, packet.getId());
-        packet.write(new BinaryWriter(buffer));
+        packet.write(BinaryWriter.view(buffer)); // ensure that the buffer is not resized/changed
         final int packetSize = buffer.position() - contentStart;
         if (packetSize >= MinecraftServer.getCompressionThreshold()) {
             // Packet large enough, compress
@@ -207,11 +207,11 @@ public final class PacketUtils {
             deflater.deflate(buffer);
             deflater.reset();
 
-            Utils.writeVarIntHeader(buffer, compressedIndex, (buffer.position() - contentStart) + 3);
-            Utils.writeVarIntHeader(buffer, uncompressedIndex, packetSize);
+            Utils.writeVarIntHeader(buffer, compressedIndex, buffer.position() - uncompressedIndex);
+            Utils.writeVarIntHeader(buffer, uncompressedIndex, packetSize); // Data Length
         } else {
             Utils.writeVarIntHeader(buffer, compressedIndex, packetSize + 3);
-            Utils.writeVarIntHeader(buffer, uncompressedIndex, 0);
+            Utils.writeVarIntHeader(buffer, uncompressedIndex, 0); // Data Length (0 since uncompressed)
         }
     }
 
@@ -246,7 +246,7 @@ public final class PacketUtils {
         }
 
         public static LocalCache get(String name, int size) {
-            return CACHES.computeIfAbsent(name, s -> new LocalCache(name, size));
+            return CACHES.computeIfAbsent(name, s -> new LocalCache(s, size));
         }
 
         public String name() {

src/main/java/net/minestom/server/utils/binary/BinaryWriter.java

@@ -7,6 +7,7 @@ import net.minestom.server.coordinate.Point;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.utils.SerializerUtils;
 import net.minestom.server.utils.Utils;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jglrxavpok.hephaistos.nbt.NBT;
 import org.jglrxavpok.hephaistos.nbt.NBTWriter;
@@ -29,32 +30,33 @@ public class BinaryWriter extends OutputStream {
     private ByteBuffer buffer;
     private NBTWriter nbtWriter; // Lazily initialized
 
-    /**
-     * Creates a {@link BinaryWriter} using a heap buffer with a custom initial capacity.
-     *
-     * @param initialCapacity the initial capacity of the binary writer
-     */
-    public BinaryWriter(int initialCapacity) {
-        this.buffer = ByteBuffer.allocate(initialCapacity);
+    private final boolean resizable;
+
+    private BinaryWriter(ByteBuffer buffer, boolean resizable) {
+        this.buffer = buffer;
+        this.resizable = resizable;
     }
 
-    /**
-     * Creates a {@link BinaryWriter} from multiple a single buffer.
-     *
-     * @param buffer the writer buffer
-     */
     public BinaryWriter(@NotNull ByteBuffer buffer) {
         this.buffer = buffer;
+        this.resizable = true;
+    }
+
+    public BinaryWriter(int initialCapacity) {
+        this(ByteBuffer.allocate(initialCapacity));
     }
 
-    /**
-     * Creates a {@link BinaryWriter} with a "reasonably small initial capacity".
-     */
     public BinaryWriter() {
         this(255);
     }
 
+    @ApiStatus.Experimental
+    public static BinaryWriter view(ByteBuffer buffer) {
+        return new BinaryWriter(buffer, false);
+    }
+
     protected void ensureSize(int length) {
+        if (!resizable) return;
         final int position = buffer.position();
         if (position + length >= buffer.limit()) {
             final int newLength = (position + length) * 4;