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Avoid mods causing double free when BufferBuilder leak fix is enabled

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Moulberry 2023-10-28 09:44:12 -04:00 committed by embeddedt
parent 4054bd8a23
commit e36ba04921
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GPG Key ID: A69433EC199B5613
2 changed files with 49 additions and 3 deletions
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5
common/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/buffer_builder_leak/BufferBuilderMixin.java
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@ -2,7 +2,7 @@ package org.embeddedt.modernfix.common.mixin.bugfix.buffer_builder_leak;
import com.mojang.blaze3d.vertex.BufferBuilder;
import org.embeddedt.modernfix.ModernFix;
import org.lwjgl.system.MemoryUtil;
import org.embeddedt.modernfix.render.UnsafeBufferHelper;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Shadow;
@ -12,7 +12,6 @@ import java.nio.ByteBuffer;
public class BufferBuilderMixin {
@Shadow private ByteBuffer buffer;
private static final MemoryUtil.MemoryAllocator ALLOCATOR = MemoryUtil.getAllocator(false);
private static boolean leakReported = false;
@Override
@ -25,7 +24,7 @@ public class BufferBuilderMixin {
leakReported = true;
ModernFix.LOGGER.warn("One or more BufferBuilders have been leaked, ModernFix will attempt to correct this.");
}
ALLOCATOR.free(MemoryUtil.memAddress0(buf));
UnsafeBufferHelper.free(buf);
buffer = null;
}
} finally {

47
common/src/main/java/org/embeddedt/modernfix/render/UnsafeBufferHelper.java Normal file
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@ -0,0 +1,47 @@
package org.embeddedt.modernfix.render;
import org.embeddedt.modernfix.ModernFix;
import org.lwjgl.system.MemoryUtil;
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
/**
* Helper that frees ByteBuffers allocated by BufferBuilders, and nulls out the address pointer
* to prevent double frees.
*
* @author Moulberry
*/
public class UnsafeBufferHelper {
private static final MemoryUtil.MemoryAllocator ALLOCATOR = MemoryUtil.getAllocator(false);
private static sun.misc.Unsafe UNSAFE = null;
private static long ADDRESS = -1;
static {
try {
final Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
theUnsafe.setAccessible(true);
UNSAFE = (Unsafe)theUnsafe.get(null);
final Field addressField = MemoryUtil.class.getDeclaredField("ADDRESS");
addressField.setAccessible(true);
ADDRESS = addressField.getLong(null);
} catch(Throwable t) {
ModernFix.LOGGER.error("Could load unsafe/buffer address", t);
}
}
public static void free(ByteBuffer buf) {
if(UNSAFE != null && ADDRESS >= 0) {
// set the address to 0 to prevent double free
long address = UNSAFE.getAndSetLong(buf, ADDRESS, 0);
if(address != 0) {
ALLOCATOR.free(address);
}
} else {
ALLOCATOR.free(MemoryUtil.memAddress0(buf));
}
}
}