Use NIO instead of ZipUtil (#513)

* Use nio for zip utils

* Make tests work

* Please work

* Fix some issues with tests

* Fix more issues with tests

* NIOZipUtils -> ZipUtils

* Resolve Juuxel's reviews

* Use our own FS utils

* Improve error handling, add loom Pair

* Add Unit tests + fixes

Co-authored-by: modmuss50 <modmuss50@gmail.com>

build.gradle

@@ -62,7 +62,6 @@ dependencies {
 
 	// libraries
 	implementation ('commons-io:commons-io:2.8.0')
-	implementation ('org.zeroturnaround:zt-zip:1.14')
 	implementation ('com.google.code.gson:gson:2.8.8')
 	implementation ('com.fasterxml.jackson.core:jackson-databind:2.12.5')
 	implementation ('com.google.guava:guava:30.1.1-jre')

src/main/java/net/fabricmc/loom/build/MixinRefmapHelper.java

@@ -27,6 +27,7 @@ package net.fabricmc.loom.build;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.UncheckedIOException;
 import java.nio.file.Path;
 import java.util.Collection;
 import java.util.Collections;
@@ -42,13 +43,12 @@ import com.google.gson.JsonObject;
 import com.google.gson.JsonPrimitive;
 import org.gradle.api.Project;
 import org.jetbrains.annotations.NotNull;
-import org.zeroturnaround.zip.ZipUtil;
-import org.zeroturnaround.zip.transform.StringZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.extension.MixinExtension;
+import net.fabricmc.loom.util.Pair;
+import net.fabricmc.loom.util.ZipUtils;
 
 public final class MixinRefmapHelper {
 	private MixinRefmapHelper() { }
@@ -76,18 +76,17 @@ public final class MixinRefmapHelper {
 
 				String refmapName = container.refmapNameProvider().get();
 
-				return ZipUtil.transformEntries(output, mixinConfigs.map(f -> new ZipEntryTransformerEntry(f, new StringZipEntryTransformer("UTF-8") {
+				try {
-					@Override
+					return ZipUtils.transformJson(JsonObject.class, outputPath, mixinConfigs.map(f -> new Pair<>(f, json -> {
-					protected String transform(ZipEntry zipEntry, String input) {
-						JsonObject json = LoomGradlePlugin.GSON.fromJson(input, JsonObject.class);
-
 						if (!json.has("refmap")) {
 							json.addProperty("refmap", refmapName);
 						}
 
-						return LoomGradlePlugin.GSON.toJson(json);
+						return json;
-					}
+					}))) > 0;
-				})).toArray(ZipEntryTransformerEntry[]::new));
+				} catch (IOException e) {
+					throw new UncheckedIOException("Failed to transform mixin configs in jar", e);
+				}
 			}).reduce(false, Boolean::logicalOr);
 		} catch (Exception e) {
 			project.getLogger().error(e.getMessage());

src/main/java/net/fabricmc/loom/build/nesting/JarNester.java

@@ -25,22 +25,22 @@
 package net.fabricmc.loom.build.nesting;
 
 import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
 import java.util.Collection;
-import java.util.zip.ZipEntry;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import com.google.common.base.Preconditions;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import org.gradle.api.UncheckedIOException;
 import org.gradle.api.logging.Logger;
-import org.zeroturnaround.zip.FileSource;
-import org.zeroturnaround.zip.ZipEntrySource;
-import org.zeroturnaround.zip.ZipUtil;
-import org.zeroturnaround.zip.transform.StringZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
-import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.util.ModUtils;
+import net.fabricmc.loom.util.Pair;
+import net.fabricmc.loom.util.ZipUtils;
 
 public class JarNester {
 	public static void nestJars(Collection<File> jars, File modJar, Logger logger) {
@@ -51,12 +51,16 @@ public class JarNester {
 
 		Preconditions.checkArgument(ModUtils.isMod(modJar), "Cannot nest jars into none mod jar " + modJar.getName());
 
-		ZipUtil.addEntries(modJar, jars.stream().map(file -> new FileSource("META-INF/jars/" + file.getName(), file)).toArray(ZipEntrySource[]::new));
+		try {
+			ZipUtils.add(modJar.toPath(), jars.stream().map(file -> {
+				try {
+					return new Pair<>("META-INF/jars/" + file.getName(), Files.readAllBytes(file.toPath()));
+				} catch (IOException e) {
+					throw new UncheckedIOException(e);
+				}
+			}).collect(Collectors.toList()));
 
-		boolean didNest = ZipUtil.transformEntries(modJar, single(new ZipEntryTransformerEntry("fabric.mod.json", new StringZipEntryTransformer() {
+			int count = ZipUtils.transformJson(JsonObject.class, modJar.toPath(), Stream.of(new Pair<>("fabric.mod.json", json -> {
-			@Override
-			protected String transform(ZipEntry zipEntry, String input) {
-				JsonObject json = LoomGradlePlugin.GSON.fromJson(input, JsonObject.class);
 				JsonArray nestedJars = json.getAsJsonArray("jars");
 
 				if (nestedJars == null || !json.has("jars")) {
@@ -83,13 +87,12 @@ public class JarNester {
 
 				json.add("jars", nestedJars);
 
-				return LoomGradlePlugin.GSON.toJson(json);
+				return json;
-			}
+			})));
-		})));
-		Preconditions.checkArgument(didNest, "Failed to nest jars into " + modJar.getName());
-	}
 
-	private static ZipEntryTransformerEntry[] single(ZipEntryTransformerEntry element) {
+			Preconditions.checkState(count > 0, "Failed to transform fabric.mod.json");
-		return new ZipEntryTransformerEntry[]{element};
+		} catch (IOException e) {
+			throw new java.io.UncheckedIOException("Failed to nest jars into " + modJar.getName(), e);
+		}
 	}
 }

src/main/java/net/fabricmc/loom/build/nesting/NestedDependencyProvider.java

@@ -26,6 +26,7 @@ package net.fabricmc.loom.build.nesting;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
@@ -47,12 +48,12 @@ import org.gradle.api.artifacts.ResolvedArtifact;
 import org.gradle.api.artifacts.ResolvedConfiguration;
 import org.gradle.api.artifacts.ResolvedDependency;
 import org.gradle.api.tasks.bundling.AbstractArchiveTask;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.task.RemapJarTask;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.ZipUtils;
 
 public final class NestedDependencyProvider implements NestedJarProvider {
 	final Project project;
@@ -157,7 +158,7 @@ public final class NestedDependencyProvider implements NestedJarProvider {
 			File file = metaFile.file;
 
 			//A lib that doesnt have a mod.json, we turn it into a fake mod
-			if (!ZipUtil.containsEntry(file, "fabric.mod.json")) {
+			if (!ZipUtils.contains(file.toPath(), "fabric.mod.json")) {
 				LoomGradleExtension extension = LoomGradleExtension.get(project);
 				File tempDir = new File(extension.getFiles().getUserCache(), "temp/modprocessing");
 
@@ -177,7 +178,12 @@ public final class NestedDependencyProvider implements NestedJarProvider {
 					throw new RuntimeException("Failed to copy file", e);
 				}
 
-				ZipUtil.addEntry(tempFile, "fabric.mod.json", generateModForDependency(metaFile).getBytes());
+				try {
+					ZipUtils.add(tempFile.toPath(), "fabric.mod.json", generateModForDependency(metaFile).getBytes());
+				} catch (IOException e) {
+					throw new UncheckedIOException("Failed to add dummy mod while including %s".formatted(file), e);
+				}
+
 				fileList.add(tempFile);
 			} else {
 				// Default copy the jar right in

src/main/java/net/fabricmc/loom/configuration/DependencyProvider.java

@@ -25,6 +25,8 @@
 package net.fabricmc.loom.configuration;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.util.Comparator;
 import java.util.HashMap;
@@ -45,12 +47,12 @@ import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.artifacts.ResolvedDependency;
 import org.gradle.api.artifacts.SelfResolvingDependency;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.providers.MinecraftProvider;
 import net.fabricmc.loom.extension.LoomFiles;
+import net.fabricmc.loom.util.ZipUtils;
 
 public abstract class DependencyProvider {
 	private LoomDependencyManager dependencyManager;
@@ -239,26 +241,31 @@ public abstract class DependencyProvider {
 			} else {
 				group = "net.fabricmc.synthetic";
 				File root = classifierToFile.get(""); //We've built the classifierToFile map, now to try find a name and version for our dependency
+				byte[] modJson;
 
-				if ("jar".equals(FilenameUtils.getExtension(root.getName())) && ZipUtil.containsEntry(root, "fabric.mod.json")) {
+				try {
-					//It's a Fabric mod, see how much we can extract out
+					if ("jar".equals(FilenameUtils.getExtension(root.getName())) && (modJson = ZipUtils.unpackNullable(root.toPath(), "fabric.mod.json")) != null) {
-					JsonObject json = new Gson().fromJson(new String(ZipUtil.unpackEntry(root, "fabric.mod.json"), StandardCharsets.UTF_8), JsonObject.class);
+						//It's a Fabric mod, see how much we can extract out
+						JsonObject json = new Gson().fromJson(new String(modJson, StandardCharsets.UTF_8), JsonObject.class);
 
-					if (json == null || !json.has("id") || !json.has("version")) {
+						if (json == null || !json.has("id") || !json.has("version")) {
-						throw new IllegalArgumentException("Invalid Fabric mod jar: " + root + " (malformed json: " + json + ')');
+							throw new IllegalArgumentException("Invalid Fabric mod jar: " + root + " (malformed json: " + json + ')');
-					}
+						}
 
-					if (json.has("name")) { //Go for the name field if it's got one
+						if (json.has("name")) { //Go for the name field if it's got one
-						name = json.get("name").getAsString();
+							name = json.get("name").getAsString();
+						} else {
+							name = json.get("id").getAsString();
+						}
+
+						version = json.get("version").getAsString();
 					} else {
-						name = json.get("id").getAsString();
+						//Not a Fabric mod, just have to make something up
+						name = FilenameUtils.removeExtension(root.getName());
+						version = "1.0";
 					}
-
+				} catch (IOException e) {
-					version = json.get("version").getAsString();
+					throw new UncheckedIOException("Failed to read input file: " + root, e);
-				} else {
-					//Not a Fabric mod, just have to make something up
-					name = FilenameUtils.removeExtension(root.getName());
-					version = "1.0";
 				}
 			}
 		}

src/main/java/net/fabricmc/loom/configuration/accesswidener/AccessWidenerFile.java

@@ -24,12 +24,15 @@
 
 package net.fabricmc.loom.configuration.accesswidener;
 
+import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 
 import com.google.gson.Gson;
 import com.google.gson.JsonObject;
-import org.zeroturnaround.zip.ZipUtil;
+
+import net.fabricmc.loom.util.ZipUtils;
 
 public record AccessWidenerFile(
 		String name,
@@ -40,7 +43,13 @@ public record AccessWidenerFile(
 	 * Reads the access-widener contained in a mod jar, or returns null if there is none.
 	 */
 	public static AccessWidenerFile fromModJar(Path modJarPath) {
-		byte[] modJsonBytes = ZipUtil.unpackEntry(modJarPath.toFile(), "fabric.mod.json");
+		byte[] modJsonBytes;
+
+		try {
+			modJsonBytes = ZipUtils.unpackNullable(modJarPath, "fabric.mod.json");
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to read access-widener file from: " + modJarPath.toAbsolutePath(), e);
+		}
 
 		if (modJsonBytes == null) {
 			return null;
@@ -55,7 +64,13 @@ public record AccessWidenerFile(
 		String awPath = jsonObject.get("accessWidener").getAsString();
 		String modId = jsonObject.get("id").getAsString();
 
-		byte[] content = ZipUtil.unpackEntry(modJarPath.toFile(), awPath);
+		byte[] content;
+
+		try {
+			content = ZipUtils.unpack(modJarPath, awPath);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Could not find access widener file (%s) defined in the fabric.mod.json file of %s".formatted(awPath, modJarPath.toAbsolutePath()), e);
+		}
 
 		return new AccessWidenerFile(
 				awPath,

src/main/java/net/fabricmc/loom/configuration/accesswidener/AccessWidenerJarProcessor.java

@@ -26,6 +26,7 @@ package net.fabricmc.loom.configuration.accesswidener;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
@@ -34,7 +35,6 @@ import java.util.Arrays;
 import com.google.common.hash.Hashing;
 import org.gradle.api.Project;
 import org.objectweb.asm.commons.Remapper;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.accesswidener.AccessWidener;
 import net.fabricmc.accesswidener.AccessWidenerReader;
@@ -43,6 +43,7 @@ import net.fabricmc.accesswidener.AccessWidenerWriter;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
 import net.fabricmc.loom.configuration.processors.JarProcessor;
+import net.fabricmc.loom.util.ZipUtils;
 
 public class AccessWidenerJarProcessor implements JarProcessor {
 	// Filename used to store hash of input access widener in processed jar file
@@ -87,7 +88,12 @@ public class AccessWidenerJarProcessor implements JarProcessor {
 	public void process(File file) {
 		AccessWidenerTransformer applier = new AccessWidenerTransformer(project.getLogger(), accessWidener);
 		applier.apply(file);
-		ZipUtil.addEntry(file, HASH_FILENAME, inputHash);
+
+		try {
+			ZipUtils.add(file.toPath(), HASH_FILENAME, inputHash);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to write aw jar hash", e);
+		}
 	}
 
 	/**
@@ -111,7 +117,13 @@ public class AccessWidenerJarProcessor implements JarProcessor {
 
 	@Override
 	public boolean isInvalid(File file) {
-		byte[] hash = ZipUtil.unpackEntry(file, HASH_FILENAME);
+		byte[] hash;
+
+		try {
+			hash = ZipUtils.unpackNullable(file.toPath(), HASH_FILENAME);
+		} catch (IOException e) {
+			return true;
+		}
 
 		if (hash == null) {
 			return true;

src/main/java/net/fabricmc/loom/configuration/accesswidener/AccessWidenerTransformer.java

@@ -25,21 +25,22 @@
 package net.fabricmc.loom.configuration.accesswidener;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.List;
 import java.util.Set;
-import java.util.zip.ZipEntry;
+import java.util.stream.Collectors;
 
 import org.gradle.api.logging.Logger;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.ClassWriter;
-import org.zeroturnaround.zip.ZipUtil;
-import org.zeroturnaround.zip.transform.ByteArrayZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
 import net.fabricmc.accesswidener.AccessWidener;
 import net.fabricmc.accesswidener.AccessWidenerClassVisitor;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.Pair;
+import net.fabricmc.loom.util.ZipUtils;
 
 final class AccessWidenerTransformer {
 	private final Logger logger;
@@ -55,28 +56,30 @@ final class AccessWidenerTransformer {
 	 */
 	void apply(File jarFile) {
 		logger.lifecycle("Processing file: " + jarFile.getName());
-		ZipUtil.transformEntries(jarFile, getTransformers(accessWidener.getTargets()));
+
+		try {
+			ZipUtils.transform(jarFile.toPath(), getTransformers(accessWidener.getTargets()));
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to apply access wideners to %s".formatted(jarFile), e);
+		}
 	}
 
-	private ZipEntryTransformerEntry[] getTransformers(Set<String> classes) {
+	private List<Pair<String, ZipUtils.UnsafeUnaryOperator<byte[]>>> getTransformers(Set<String> classes) {
 		return classes.stream()
-				.map(string -> new ZipEntryTransformerEntry(string.replaceAll("\\.", "/") + ".class", getTransformer(string)))
+				.map(string -> new Pair<>(string.replaceAll("\\.", "/") + ".class", getTransformer(string)))
-				.toArray(ZipEntryTransformerEntry[]::new);
+				.collect(Collectors.toList());
 	}
 
-	private ZipEntryTransformer getTransformer(String className) {
+	private ZipUtils.UnsafeUnaryOperator<byte[]> getTransformer(String className) {
-		return new ByteArrayZipEntryTransformer() {
+		return input -> {
-			@Override
+			ClassReader reader = new ClassReader(input);
-			protected byte[] transform(ZipEntry zipEntry, byte[] input) {
+			ClassWriter writer = new ClassWriter(0);
-				ClassReader reader = new ClassReader(input);
+			ClassVisitor classVisitor = AccessWidenerClassVisitor.createClassVisitor(Constants.ASM_VERSION, writer, accessWidener);
-				ClassWriter writer = new ClassWriter(0);
-				ClassVisitor classVisitor = AccessWidenerClassVisitor.createClassVisitor(Constants.ASM_VERSION, writer, accessWidener);
 
-				logger.info("Applying access widener to " + className);
+			logger.info("Applying access widener to " + className);
 
-				reader.accept(classVisitor, 0);
+			reader.accept(classVisitor, 0);
-				return writer.toByteArray();
+			return writer.toByteArray();
-			}
 		};
 	}
 }

src/main/java/net/fabricmc/loom/configuration/mods/ModProcessor.java

@@ -27,6 +27,7 @@ package net.fabricmc.loom.configuration.mods;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -41,9 +42,6 @@ import java.util.zip.ZipEntry;
 import com.google.gson.JsonObject;
 import org.gradle.api.Project;
 import org.objectweb.asm.commons.Remapper;
-import org.zeroturnaround.zip.ZipUtil;
-import org.zeroturnaround.zip.transform.StringZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
 import net.fabricmc.accesswidener.AccessWidenerReader;
 import net.fabricmc.accesswidener.AccessWidenerRemapper;
@@ -57,6 +55,7 @@ import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftMappedProvider;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.TinyRemapperHelper;
+import net.fabricmc.loom.util.ZipUtils;
 import net.fabricmc.tinyremapper.InputTag;
 import net.fabricmc.tinyremapper.NonClassCopyMode;
 import net.fabricmc.tinyremapper.OutputConsumerPath;
@@ -95,14 +94,14 @@ public class ModProcessor {
 
 	private static void stripNestedJars(File file) {
 		// Strip out all contained jar info as we dont want loader to try and load the jars contained in dev.
-		ZipUtil.transformEntries(file, new ZipEntryTransformerEntry[]{(new ZipEntryTransformerEntry("fabric.mod.json", new StringZipEntryTransformer() {
+		try {
-			@Override
+			ZipUtils.transformJson(JsonObject.class, file.toPath(), Map.of("fabric.mod.json", json -> {
-			protected String transform(ZipEntry zipEntry, String input) {
-				JsonObject json = LoomGradlePlugin.GSON.fromJson(input, JsonObject.class);
 				json.remove("jars");
-				return LoomGradlePlugin.GSON.toJson(json);
+				return json;
-			}
+			}));
-		}))});
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to strip nested jars from %s".formatted(file), e);
+		}
 	}
 
 	/**
@@ -180,7 +179,7 @@ public class ModProcessor {
 				String accessWidener = info.getAccessWidener();
 
 				if (accessWidener != null) {
-					accessWidenerMap.put(info, remapAccessWidener(ZipUtil.unpackEntry(info.inputFile, accessWidener), remapper.getRemapper()));
+					accessWidenerMap.put(info, remapAccessWidener(ZipUtils.unpack(info.inputFile.toPath(), accessWidener), remapper.getRemapper()));
 				}
 
 				remapper.apply(outputConsumer, tagMap.get(info));
@@ -199,7 +198,7 @@ public class ModProcessor {
 			byte[] accessWidener = accessWidenerMap.get(info);
 
 			if (accessWidener != null) {
-				ZipUtil.replaceEntry(info.getRemappedOutput(), info.getAccessWidener(), accessWidener);
+				ZipUtils.replace(info.getRemappedOutput().toPath(), info.getAccessWidener(), accessWidener);
 			}
 
 			info.finaliseRemapping();

src/main/java/net/fabricmc/loom/configuration/processors/JarProcessorManager.java

@@ -24,24 +24,24 @@
 
 package net.fabricmc.loom.configuration.processors;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
 import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
+import java.util.Map;
 import java.util.jar.Attributes;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
 import java.util.stream.Collectors;
-import java.util.zip.ZipEntry;
 
+import com.google.common.base.Preconditions;
 import com.google.common.hash.Hashing;
 import com.google.common.io.CharSource;
-import org.zeroturnaround.zip.ZipUtil;
+
-import org.zeroturnaround.zip.transform.StreamZipEntryTransformer;
+import net.fabricmc.loom.util.ZipUtils;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
 public class JarProcessorManager {
 	private static final String MANIFEST_PATH = "META-INF/MANIFEST.MF";
@@ -107,19 +107,18 @@ public class JarProcessorManager {
 			jarProcessor.process(file);
 		}
 
-		boolean manifestTransformed = ZipUtil.transformEntries(file, new ZipEntryTransformerEntry[] {
+		try {
-				new ZipEntryTransformerEntry(MANIFEST_PATH, new StreamZipEntryTransformer() {
+			int count = ZipUtils.transform(file.toPath(), Map.of(MANIFEST_PATH, bytes -> {
-					@Override
+				Manifest manifest = new Manifest(new ByteArrayInputStream(bytes));
-					protected void transform(ZipEntry zipEntry, InputStream in, OutputStream out) throws IOException {
+				manifest.getMainAttributes().putValue(JAR_PROCESSOR_HASH_ATTRIBUTE, getJarProcessorHash());
-						Manifest manifest = new Manifest(in);
+				ByteArrayOutputStream out = new ByteArrayOutputStream();
-						manifest.getMainAttributes().putValue(JAR_PROCESSOR_HASH_ATTRIBUTE, getJarProcessorHash());
+				manifest.write(out);
-						manifest.write(out);
+				return out.toByteArray();
-					}
+			}));
-				})
-		});
 
-		if (!manifestTransformed) {
+			Preconditions.checkState(count > 0, "Did not add data to jar manifest in " + file);
-			throw new RuntimeException("Could not add data to jar manifest in " + file);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Could not add data to jar manifest in " + file, e);
 		}
 	}
 

src/main/java/net/fabricmc/loom/configuration/providers/mappings/LayeredMappingsDependency.java

@@ -43,14 +43,12 @@ import org.gradle.api.artifacts.FileCollectionDependency;
 import org.gradle.api.artifacts.SelfResolvingDependency;
 import org.gradle.api.file.FileCollection;
 import org.gradle.api.tasks.TaskDependency;
-import org.zeroturnaround.zip.ByteSource;
-import org.zeroturnaround.zip.ZipEntrySource;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.api.mappings.layered.MappingContext;
 import net.fabricmc.loom.api.mappings.layered.MappingLayer;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
+import net.fabricmc.loom.util.ZipUtils;
 import net.fabricmc.mappingio.adapter.MappingDstNsReorder;
 import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch;
 import net.fabricmc.mappingio.format.Tiny2Writer;
@@ -104,9 +102,8 @@ public class LayeredMappingsDependency implements SelfResolvingDependency, FileC
 			MappingSourceNsSwitch nsSwitch = new MappingSourceNsSwitch(nsReorder, MappingsNamespace.INTERMEDIARY.toString(), true);
 			mappings.accept(nsSwitch);
 
-			ZipUtil.pack(new ZipEntrySource[] {
+			Files.deleteIfExists(mappingsFile);
-					new ByteSource("mappings/mappings.tiny", writer.toString().getBytes(StandardCharsets.UTF_8))
+			ZipUtils.add(mappingsFile, "mappings/mappings.tiny", writer.toString().getBytes(StandardCharsets.UTF_8));
-			}, mappingsFile.toFile());
 		}
 	}
 
@@ -119,10 +116,7 @@ public class LayeredMappingsDependency implements SelfResolvingDependency, FileC
 
 		byte[] data = LoomGradlePlugin.OBJECT_MAPPER.writeValueAsString(signatureFixes).getBytes(StandardCharsets.UTF_8);
 
-		ZipUtil.addEntry(
+		ZipUtils.add(mappingsFile, "extras/record_signatures.json", data);
-				mappingsFile.toFile(),
-				new ByteSource("extras/record_signatures.json", data)
-		);
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java

@@ -37,8 +37,8 @@ import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.Objects;
 import java.util.Map;
+import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.regex.Pattern;
 
@@ -48,9 +48,6 @@ import com.google.gson.JsonObject;
 import org.apache.tools.ant.util.StringUtils;
 import org.gradle.api.Project;
 import org.jetbrains.annotations.Nullable;
-import org.zeroturnaround.zip.FileSource;
-import org.zeroturnaround.zip.ZipEntrySource;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
@@ -65,6 +62,7 @@ import net.fabricmc.loom.configuration.providers.minecraft.MinecraftMappedProvid
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.DeletingFileVisitor;
 import net.fabricmc.loom.util.DownloadUtil;
+import net.fabricmc.loom.util.ZipUtils;
 import net.fabricmc.mappingio.MappingReader;
 import net.fabricmc.mappingio.adapter.MappingNsCompleter;
 import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch;
@@ -131,7 +129,8 @@ public class MappingsProviderImpl extends DependencyProvider implements Mappings
 		mappingTree = readMappings();
 
 		if (Files.notExists(tinyMappingsJar) || isRefreshDeps()) {
-			ZipUtil.pack(new ZipEntrySource[] {new FileSource("mappings/mappings.tiny", tinyMappings.toFile())}, tinyMappingsJar.toFile());
+			Files.deleteIfExists(tinyMappingsJar);
+			ZipUtils.add(tinyMappingsJar, "mappings/mappings.tiny", Files.readAllBytes(tinyMappings));
 		}
 
 		if (hasUnpickDefinitions()) {

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftNativesProvider.java

@@ -35,12 +35,12 @@ import java.util.stream.Collectors;
 import org.apache.commons.io.FileUtils;
 import org.gradle.api.GradleException;
 import org.gradle.api.Project;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.util.HashedDownloadUtil;
 import net.fabricmc.loom.util.MirrorUtil;
+import net.fabricmc.loom.util.ZipUtils;
 
 public class MinecraftNativesProvider {
 	private final Project project;
@@ -101,7 +101,7 @@ public class MinecraftNativesProvider {
 				throw new GradleException("Native jar not found at " + libJarFile.getAbsolutePath());
 			}
 
-			ZipUtil.unpack(libJarFile, nativesDir);
+			ZipUtils.unpackAll(libJarFile.toPath(), nativesDir.toPath());
 
 			// Store a file containing the hash of the extracted natives, used on subsequent runs to skip extracting all the natives if they haven't changed
 			File libSha1File = new File(nativesDir, libJarFile.getName() + ".sha1");

src/main/java/net/fabricmc/loom/task/GenerateSourcesTask.java

@@ -62,6 +62,7 @@ import net.fabricmc.loom.configuration.accesswidener.TransitiveAccessWidenerMapp
 import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
 import net.fabricmc.loom.decompilers.LineNumberRemapper;
 import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.FileSystemUtil;
 import net.fabricmc.loom.util.IOStringConsumer;
 import net.fabricmc.loom.util.OperatingSystem;
 import net.fabricmc.loom.util.gradle.ThreadedProgressLoggerConsumer;
@@ -69,7 +70,6 @@ import net.fabricmc.loom.util.gradle.ThreadedSimpleProgressLogger;
 import net.fabricmc.loom.util.gradle.WorkerDaemonClientsManagerHelper;
 import net.fabricmc.loom.util.ipc.IPCClient;
 import net.fabricmc.loom.util.ipc.IPCServer;
-import net.fabricmc.stitch.util.StitchUtil;
 
 public abstract class GenerateSourcesTask extends AbstractLoomTask {
 	public final LoomDecompiler decompiler;
@@ -265,8 +265,8 @@ public abstract class GenerateSourcesTask extends AbstractLoomTask {
 			LineNumberRemapper remapper = new LineNumberRemapper();
 			remapper.readMappings(linemap.toFile());
 
-			try (StitchUtil.FileSystemDelegate inFs = StitchUtil.getJarFileSystem(oldCompiledJar.toFile(), true);
+			try (FileSystemUtil.Delegate inFs = FileSystemUtil.getJarFileSystem(oldCompiledJar.toFile(), true);
-					StitchUtil.FileSystemDelegate outFs = StitchUtil.getJarFileSystem(linemappedJarDestination.toFile(), true)) {
+					FileSystemUtil.Delegate outFs = FileSystemUtil.getJarFileSystem(linemappedJarDestination.toFile(), true)) {
 				remapper.process(logger, inFs.get().getPath("/"), outFs.get().getPath("/"));
 			}
 		}

src/main/java/net/fabricmc/loom/task/RemapJarTask.java

@@ -24,20 +24,21 @@
 
 package net.fabricmc.loom.task;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
-import java.io.InputStream;
+import java.io.UncheckedIOException;
-import java.io.OutputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.jar.Manifest;
-import java.util.zip.ZipEntry;
 
 import com.google.common.base.Preconditions;
 import org.gradle.api.Action;
@@ -52,9 +53,6 @@ import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
 import org.gradle.jvm.tasks.Jar;
 import org.jetbrains.annotations.ApiStatus;
-import org.zeroturnaround.zip.ZipUtil;
-import org.zeroturnaround.zip.transform.StreamZipEntryTransformer;
-import org.zeroturnaround.zip.transform.ZipEntryTransformerEntry;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
@@ -72,6 +70,7 @@ import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.TinyRemapperHelper;
 import net.fabricmc.loom.util.ZipReprocessorUtil;
+import net.fabricmc.loom.util.ZipUtils;
 import net.fabricmc.stitch.util.Pair;
 import net.fabricmc.tinyremapper.TinyRemapper;
 import net.fabricmc.tinyremapper.TinyUtils;
@@ -190,26 +189,31 @@ public class RemapJarTask extends Jar {
 					}
 
 					if (accessWidener != null) {
-						boolean replaced = ZipUtil.replaceEntry(data.output.toFile(), accessWidener.getLeft(), accessWidener.getRight());
+						try {
-						Preconditions.checkArgument(replaced, "Failed to remap access widener");
+							ZipUtils.replace(data.output, accessWidener.getLeft(), accessWidener.getRight());
+						} catch (IOException e) {
+							throw new UncheckedIOException("Failed to replace access widener in output jar", e);
+						}
 					}
 
 					// Add data to the manifest
-					boolean transformed = ZipUtil.transformEntries(data.output.toFile(), new ZipEntryTransformerEntry[]{
+					try {
-							new ZipEntryTransformerEntry(MANIFEST_PATH, new StreamZipEntryTransformer() {
+						int count = ZipUtils.transform(data.output, Map.of(MANIFEST_PATH, bytes -> {
-								@Override
+							var manifest = new Manifest(new ByteArrayInputStream(bytes));
-								protected void transform(ZipEntry zipEntry, InputStream in, OutputStream out) throws IOException {
+							var manifestConfiguration = new JarManifestConfiguration(project);
-									var manifest = new Manifest(in);
-									var manifestConfiguration = new JarManifestConfiguration(project);
 
-									manifestConfiguration.configure(manifest);
+							manifestConfiguration.configure(manifest);
-									manifest.getMainAttributes().putValue("Fabric-Mapping-Namespace", toM);
+							manifest.getMainAttributes().putValue("Fabric-Mapping-Namespace", toM);
 
-									manifest.write(out);
+							ByteArrayOutputStream out = new ByteArrayOutputStream();
-								}
+							manifest.write(out);
-							})
+							return out.toByteArray();
-					});
+						}));
-					Preconditions.checkArgument(transformed, "Failed to transform jar manifest");
+
+						Preconditions.checkState(count > 0, "Did not transform any jar manifest");
+					} catch (IOException e) {
+						throw new UncheckedIOException("Failed to transform jar manifest", e);
+					}
 
 					if (isReproducibleFileOrder() || !isPreserveFileTimestamps()) {
 						try {

src/main/java/net/fabricmc/loom/util/FileSystemUtil.java

@@ -0,0 +1,83 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016-2017 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystemAlreadyExistsException;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.util.Collections;
+import java.util.Map;
+import java.util.function.Supplier;
+
+public final class FileSystemUtil {
+	public record Delegate(FileSystem fs, boolean owner) implements AutoCloseable, Supplier<FileSystem> {
+		@Override
+		public void close() throws IOException {
+			if (owner) {
+				fs.close();
+			}
+		}
+
+		@Override
+		public FileSystem get() {
+			return fs;
+		}
+	}
+
+	private FileSystemUtil() {
+	}
+
+	private static final Map<String, String> jfsArgsCreate = Map.of("create", "true");
+	private static final Map<String, String> jfsArgsEmpty = Collections.emptyMap();
+
+	public static Delegate getJarFileSystem(File file, boolean create) throws IOException {
+		return getJarFileSystem(file.toURI(), create);
+	}
+
+	public static Delegate getJarFileSystem(Path path, boolean create) throws IOException {
+		return getJarFileSystem(path.toUri(), create);
+	}
+
+	public static Delegate getJarFileSystem(URI uri, boolean create) throws IOException {
+		URI jarUri;
+
+		try {
+			jarUri = new URI("jar:" + uri.getScheme(), uri.getHost(), uri.getPath(), uri.getFragment());
+		} catch (URISyntaxException e) {
+			throw new IOException(e);
+		}
+
+		try {
+			return new Delegate(FileSystems.newFileSystem(jarUri, create ? jfsArgsCreate : jfsArgsEmpty), true);
+		} catch (FileSystemAlreadyExistsException e) {
+			return new Delegate(FileSystems.getFileSystem(jarUri), false);
+		}
+	}
+}

src/main/java/net/fabricmc/loom/util/Pair.java

@@ -0,0 +1,28 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util;
+
+public record Pair<L, R>(L left, R right) {
+}

src/main/java/net/fabricmc/loom/util/SourceRemapper.java

@@ -37,7 +37,6 @@ import org.cadixdev.lorenz.MappingSet;
 import org.cadixdev.mercury.Mercury;
 import org.cadixdev.mercury.remapper.MercuryRemapper;
 import org.gradle.api.Project;
-import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
@@ -46,7 +45,6 @@ import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
 import net.fabricmc.loom.util.gradle.ProgressLoggerHelper;
 import net.fabricmc.lorenztiny.TinyMappingsReader;
 import net.fabricmc.mappingio.tree.MemoryMappingTree;
-import net.fabricmc.stitch.util.StitchUtil;
 
 public class SourceRemapper {
 	private final Project project;
@@ -126,7 +124,7 @@ public class SourceRemapper {
 			// create tmp directory
 			isSrcTmp = true;
 			srcPath = Files.createTempDirectory("fabric-loom-src");
-			ZipUtil.unpack(source, srcPath.toFile());
+			ZipUtils.unpackAll(source.toPath(), srcPath);
 		}
 
 		if (!destination.isDirectory() && destination.exists()) {
@@ -135,7 +133,7 @@ public class SourceRemapper {
 			}
 		}
 
-		StitchUtil.FileSystemDelegate dstFs = destination.isDirectory() ? null : StitchUtil.getJarFileSystem(destination, true);
+		FileSystemUtil.Delegate dstFs = destination.isDirectory() ? null : FileSystemUtil.getJarFileSystem(destination, true);
 		Path dstPath = dstFs != null ? dstFs.get().getPath("/") : destination.toPath();
 
 		try {

src/main/java/net/fabricmc/loom/util/ZipUtils.java

@@ -0,0 +1,230 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.StandardOpenOption;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+import org.jetbrains.annotations.Nullable;
+
+import net.fabricmc.loom.LoomGradlePlugin;
+
+public class ZipUtils {
+	public static boolean contains(Path zip, String path) {
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, false)) {
+			Path fsPath = fs.get().getPath(path);
+
+			return Files.exists(fsPath);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to check file from zip", e);
+		}
+	}
+
+	public static void unpackAll(Path zip, Path output) throws IOException {
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, false);
+				Stream<Path> walk = Files.walk(fs.get().getPath("/"))) {
+			Iterator<Path> iterator = walk.iterator();
+
+			while (iterator.hasNext()) {
+				Path fsPath = iterator.next();
+				if (!Files.isRegularFile(fsPath)) continue;
+				Path dstPath = output.resolve(fs.get().getPath("/").relativize(fsPath).toString());
+				Path dstPathParent = dstPath.getParent();
+				if (dstPathParent != null) Files.createDirectories(dstPathParent);
+				Files.copy(fsPath, dstPath, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES);
+			}
+		}
+	}
+
+	public static byte @Nullable [] unpackNullable(Path zip, String path) throws IOException {
+		try {
+			return unpack(zip, path);
+		} catch (NoSuchFileException e) {
+			return null;
+		}
+	}
+
+	public static byte[] unpack(Path zip, String path) throws IOException {
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, false)) {
+			Path fsPath = fs.get().getPath(path);
+
+			if (Files.exists(fsPath)) {
+				return Files.readAllBytes(fsPath);
+			} else {
+				throw new NoSuchFileException(fsPath.toString());
+			}
+		}
+	}
+
+	public static void pack(Path from, Path zip) throws IOException {
+		Files.deleteIfExists(zip);
+
+		if (!Files.isDirectory(from)) throw new IllegalArgumentException(from + " is not a directory!");
+
+		int count = 0;
+
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, true);
+				Stream<Path> walk = Files.walk(from)) {
+			Iterator<Path> iterator = walk.iterator();
+
+			while (iterator.hasNext()) {
+				Path fromPath = iterator.next();
+				if (!Files.isRegularFile(fromPath)) continue;
+				Path fsPath = fs.get().getPath(from.relativize(fromPath).toString());
+				Path fsPathParent = fsPath.getParent();
+				if (fsPathParent != null) Files.createDirectories(fsPathParent);
+				Files.copy(fromPath, fsPath, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES);
+				count++;
+			}
+		}
+
+		if (count == 0) {
+			throw new IOException("Noting packed into %s from %s".formatted(zip, from));
+		}
+	}
+
+	public static void add(Path zip, String path, byte[] bytes) throws IOException {
+		add(zip, Collections.singleton(new Pair<>(path, bytes)));
+	}
+
+	public static void add(Path zip, Iterable<Pair<String, byte[]>> files) throws IOException {
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, true)) {
+			for (Pair<String, byte[]> pair : files) {
+				Path fsPath = fs.get().getPath(pair.left());
+				Path fsPathParent = fsPath.getParent();
+				if (fsPathParent != null) Files.createDirectories(fsPathParent);
+				Files.write(fsPath, pair.right(), StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
+			}
+		}
+	}
+
+	public static void replace(Path zip, String path, byte[] bytes) throws IOException {
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, true)) {
+			Path fsPath = fs.get().getPath(path);
+
+			if (Files.exists(fsPath)) {
+				Files.write(fsPath, bytes, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
+			} else {
+				throw new NoSuchFileException(fsPath.toString());
+			}
+		}
+	}
+
+	public static int transformString(Path zip, Collection<Pair<String, UnsafeUnaryOperator<String>>> transforms) throws IOException {
+		return transformString(zip, transforms.stream());
+	}
+
+	public static int transformString(Path zip, Stream<Pair<String, UnsafeUnaryOperator<String>>> transforms) throws IOException {
+		return transformString(zip, collectTransformersStream(transforms));
+	}
+
+	public static int transformString(Path zip, Map<String, UnsafeUnaryOperator<String>> transforms) throws IOException {
+		return transformMapped(zip, transforms, bytes -> new String(bytes, StandardCharsets.UTF_8), s -> s.getBytes(StandardCharsets.UTF_8));
+	}
+
+	public static <T> int transformJson(Class<T> typeOfT, Path zip, Collection<Pair<String, UnsafeUnaryOperator<T>>> transforms) throws IOException {
+		return transformJson(typeOfT, zip, transforms.stream());
+	}
+
+	public static <T> int transformJson(Class<T> typeOfT, Path zip, Stream<Pair<String, UnsafeUnaryOperator<T>>> transforms) throws IOException {
+		return transformJson(typeOfT, zip, collectTransformersStream(transforms));
+	}
+
+	public static <T> int transformJson(Class<T> typeOfT, Path zip, Map<String, UnsafeUnaryOperator<T>> transforms) throws IOException {
+		return transformMapped(zip, transforms, bytes -> LoomGradlePlugin.GSON.fromJson(new InputStreamReader(new ByteArrayInputStream(bytes)), typeOfT),
+				s -> LoomGradlePlugin.GSON.toJson(s, typeOfT).getBytes(StandardCharsets.UTF_8));
+	}
+
+	public static int transform(Path zip, Collection<Pair<String, UnsafeUnaryOperator<byte[]>>> transforms) throws IOException {
+		return transform(zip, transforms.stream());
+	}
+
+	public static int transform(Path zip, Stream<Pair<String, UnsafeUnaryOperator<byte[]>>> transforms) throws IOException {
+		return transform(zip, collectTransformersStream(transforms));
+	}
+
+	public static <T> int transformMapped(Path zip, Map<String, UnsafeUnaryOperator<T>> transforms, Function<byte[], T> deserializer, Function<T, byte[]> serializer) throws IOException {
+		Map<String, UnsafeUnaryOperator<byte[]>> newTransforms = new HashMap<>();
+
+		for (Map.Entry<String, UnsafeUnaryOperator<T>> entry : transforms.entrySet()) {
+			if (entry.getValue() != null) {
+				newTransforms.put(entry.getKey(), bytes -> {
+					return serializer.apply(entry.getValue().apply(deserializer.apply(bytes)));
+				});
+			}
+		}
+
+		return transform(zip, newTransforms);
+	}
+
+	public static int transform(Path zip, Map<String, UnsafeUnaryOperator<byte[]>> transforms) throws IOException {
+		int replacedCount = 0;
+
+		try (FileSystemUtil.Delegate fs = FileSystemUtil.getJarFileSystem(zip, false)) {
+			for (Map.Entry<String, UnsafeUnaryOperator<byte[]>> entry : transforms.entrySet()) {
+				Path fsPath = fs.get().getPath(entry.getKey());
+
+				if (Files.exists(fsPath) && entry.getValue() != null) {
+					Files.write(fsPath, entry.getValue().apply(Files.readAllBytes(fsPath)), StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
+					replacedCount++;
+				}
+			}
+		}
+
+		return replacedCount;
+	}
+
+	@FunctionalInterface
+	public interface UnsafeUnaryOperator<T> {
+		T apply(T arg) throws IOException;
+	}
+
+	private static <T> Map<String, UnsafeUnaryOperator<T>> collectTransformersStream(Stream<Pair<String, UnsafeUnaryOperator<T>>> transforms) {
+		Map<String, UnsafeUnaryOperator<T>> map = new HashMap<>();
+		Iterator<Pair<String, UnsafeUnaryOperator<T>>> iterator = transforms.iterator();
+
+		while (iterator.hasNext()) {
+			Pair<String, UnsafeUnaryOperator<T>> next = iterator.next();
+			map.put(next.left(), next.right());
+		}
+
+		return map;
+	}
+}

src/test/groovy/net/fabricmc/loom/test/integration/AccessWidenerTest.groovy

@@ -25,7 +25,7 @@
 package net.fabricmc.loom.test.integration
 
 import net.fabricmc.loom.test.util.GradleProjectTestTrait
-import org.zeroturnaround.zip.ZipUtil
+import net.fabricmc.loom.util.ZipUtils
 import spock.lang.Specification
 import spock.lang.Unroll
 
@@ -54,7 +54,7 @@ class AccessWidenerTest extends Specification implements GradleProjectTestTrait
 	def "transitive accesswidener (gradle #version)"() {
 		setup:
 			def gradle = gradleProject(project: "transitiveAccesswidener", version: version)
-			ZipUtil.pack(new File(gradle.projectDir, "dummyDependency"), new File(gradle.projectDir, "dummy.jar"))
+			ZipUtils.pack(new File(gradle.projectDir, "dummyDependency").toPath(), new File(gradle.projectDir, "dummy.jar").toPath())
 
 		when:
 			def result = gradle.run(task: "build")

src/test/groovy/net/fabricmc/loom/test/integration/UnpickTest.groovy

@@ -25,8 +25,7 @@
 package net.fabricmc.loom.test.integration
 
 import net.fabricmc.loom.test.util.GradleProjectTestTrait
-
+import net.fabricmc.loom.util.ZipUtils
-import org.zeroturnaround.zip.ZipUtil
 import spock.lang.Specification
 
 import java.nio.charset.StandardCharsets
@@ -66,6 +65,6 @@ class UnpickTest extends Specification implements GradleProjectTestTrait {
 
 	private static String getClassSource(GradleProject gradle, String classname, String mappings = MAPPINGS) {
 		File sourcesJar = gradle.getGeneratedSources(mappings)
-		return new String(ZipUtil.unpackEntry(sourcesJar, classname), StandardCharsets.UTF_8)
+		return new String(ZipUtils.unpack(sourcesJar.toPath(), classname), StandardCharsets.UTF_8)
 	}
 }

src/test/groovy/net/fabricmc/loom/test/unit/ZipUtilsTest.groovy

@@ -0,0 +1,124 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.unit
+
+import net.fabricmc.loom.util.Pair
+import net.fabricmc.loom.util.ZipUtils
+import spock.lang.Specification
+
+import java.nio.charset.StandardCharsets
+import java.nio.file.Files
+
+class ZipUtilsTest extends Specification {
+    def "pack"() {
+        given:
+            def dir = File.createTempDir()
+            def zip = File.createTempFile("loom-zip-test", ".zip").toPath()
+            new File(dir, "test.txt").text = "This is a test of packing"
+
+        when:
+            ZipUtils.pack(dir.toPath(), zip)
+
+        then:
+            Files.exists(zip)
+            ZipUtils.contains(zip, "test.txt")
+            !ZipUtils.contains(zip, "nope.txt")
+            new String( ZipUtils.unpack(zip, "test.txt"), StandardCharsets.UTF_8) == "This is a test of packing"
+    }
+
+    def "transform string"() {
+        given:
+            def dir = File.createTempDir()
+            def zip = File.createTempFile("loom-zip-test", ".zip").toPath()
+            new File(dir, "test.txt").text = "This is a test of transforming"
+
+        when:
+            ZipUtils.pack(dir.toPath(), zip)
+            def transformed = ZipUtils.transformString(zip, [
+                    new Pair<String, ZipUtils.UnsafeUnaryOperator<String>>("test.txt", new ZipUtils.UnsafeUnaryOperator<String>() {
+                        @Override
+                        String apply(String arg) throws IOException {
+                            return arg.toUpperCase()
+                        }
+                    })
+            ])
+
+        then:
+            transformed == 1
+            ZipUtils.contains(zip, "test.txt")
+            new String( ZipUtils.unpack(zip, "test.txt"), StandardCharsets.UTF_8) == "THIS IS A TEST OF TRANSFORMING"
+    }
+
+    def "replace string"() {
+        given:
+            def dir = File.createTempDir()
+            def zip = File.createTempFile("loom-zip-test", ".zip").toPath()
+            new File(dir, "test.txt").text = "This has not been replaced"
+
+        when:
+            ZipUtils.pack(dir.toPath(), zip)
+            ZipUtils.replace(zip, "test.txt", "This has been replaced".bytes)
+
+        then:
+            ZipUtils.contains(zip, "test.txt")
+            new String(ZipUtils.unpack(zip, "test.txt"), StandardCharsets.UTF_8) == "This has been replaced"
+    }
+
+    def "add file"() {
+        given:
+            def dir = File.createTempDir()
+            def zip = File.createTempFile("loom-zip-test", ".zip").toPath()
+            new File(dir, "test.txt").text = "This is original"
+
+        when:
+            ZipUtils.pack(dir.toPath(), zip)
+            ZipUtils.add(zip, "test2.txt", "This has been added".bytes)
+
+        then:
+            ZipUtils.contains(zip, "test.txt")
+            ZipUtils.contains(zip, "test2.txt")
+            new String(ZipUtils.unpack(zip, "test.txt"), StandardCharsets.UTF_8) == "This is original"
+            new String(ZipUtils.unpack(zip, "test2.txt"), StandardCharsets.UTF_8) == "This has been added"
+    }
+
+    def "unpack all"() {
+        given:
+            def input = File.createTempDir()
+            def output = File.createTempDir()
+
+            def zip = File.createTempFile("loom-zip-test", ".zip").toPath()
+            new File(input, "test.txt").text = "This is a test of unpacking all"
+
+            def outputFile = new File(output, "test.txt")
+
+        when:
+            ZipUtils.pack(input.toPath(), zip)
+            ZipUtils.unpackAll(zip, output.toPath())
+
+        then:
+            outputFile.exists()
+            outputFile.text == "This is a test of unpacking all"
+    }
+}

src/test/groovy/net/fabricmc/loom/test/util/GradleProjectTestTrait.groovy

@@ -26,9 +26,9 @@ package net.fabricmc.loom.test.util
 
 import groovy.transform.Immutable
 import net.fabricmc.loom.test.LoomTestConstants
+import net.fabricmc.loom.util.ZipUtils
 import org.gradle.testkit.runner.BuildResult
 import org.gradle.testkit.runner.GradleRunner
-import org.zeroturnaround.zip.ZipUtil
 import spock.lang.Shared
 
 trait GradleProjectTestTrait {
@@ -192,7 +192,7 @@ trait GradleProjectTestTrait {
 
         String getOutputZipEntry(String filename, String entryName) {
             def file = getOutputFile(filename)
-            def bytes = ZipUtil.unpackEntry(file, entryName)
+            def bytes = ZipUtils.unpackNullable(file.toPath(), entryName)
 
             if (bytes == null) {
                 throw new FileNotFoundException("Could not find ${entryName} in ${entryName}")
@@ -203,7 +203,7 @@ trait GradleProjectTestTrait {
 
         boolean hasOutputZipEntry(String filename, String entryName) {
             def file = getOutputFile(filename)
-            return ZipUtil.unpackEntry(file, entryName) != null
+            return ZipUtils.unpackNullable(file.toPath(), entryName) != null
         }
 
         File getGeneratedSources(String mappings) {