ADDED   utils/ofzip/GZIPArchive.h
Index: utils/ofzip/GZIPArchive.h
==================================================================
--- utils/ofzip/GZIPArchive.h
+++ utils/ofzip/GZIPArchive.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016
+ *   Jonathan Schleifer <js@heap.zone>
+ *
+ * All rights reserved.
+ *
+ * This file is part of ObjFW. It may be distributed under the terms of the
+ * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
+ * the packaging of this file.
+ *
+ * Alternatively, it may be distributed under the terms of the GNU General
+ * Public License, either version 2 or 3, which can be found in the file
+ * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
+ * file.
+ */
+
+#import "OFGZIPStream.h"
+
+#import "Archive.h"
+
+@interface GZIPArchive: OFObject <Archive>
+{
+	OFGZIPStream *_stream;
+}
+@end

ADDED   utils/ofzip/GZIPArchive.m
Index: utils/ofzip/GZIPArchive.m
==================================================================
--- utils/ofzip/GZIPArchive.m
+++ utils/ofzip/GZIPArchive.m
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016
+ *   Jonathan Schleifer <js@heap.zone>
+ *
+ * All rights reserved.
+ *
+ * This file is part of ObjFW. It may be distributed under the terms of the
+ * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
+ * the packaging of this file.
+ *
+ * Alternatively, it may be distributed under the terms of the GNU General
+ * Public License, either version 2 or 3, which can be found in the file
+ * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
+ * file.
+ */
+
+#include "config.h"
+
+#import "OFApplication.h"
+#import "OFStdIOStream.h"
+
+#import "GZIPArchive.h"
+#import "OFZIP.h"
+
+static OFZIP *app;
+
+@implementation GZIPArchive
++ (void)initialize
+{
+	if (self == [GZIPArchive class])
+		app = [[OFApplication sharedApplication] delegate];
+}
+
++ (instancetype)archiveWithFile: (OFFile*)file
+{
+	return [[[self alloc] initWithFile: file] autorelease];
+}
+
+- initWithFile: (OFFile*)file
+{
+	self = [super init];
+
+	@try {
+		_stream = [[OFGZIPStream alloc] initWithStream: file];
+	} @catch (id e) {
+		[self release];
+		@throw e;
+	}
+
+	return self;
+}
+
+- (void)dealloc
+{
+	[_stream release];
+
+	[super dealloc];
+}
+
+- (void)listFiles
+{
+	[of_stderr writeLine: @"Cannot list files of a .gz archive!"];
+	app->_exitStatus = 1;
+}
+
+- (void)extractFiles: (OFArray OF_GENERIC(OFString*)*)files
+{
+	OFString *fileName;
+	OFFile *output;
+
+	if ([files count] != 0) {
+		[of_stderr writeLine:
+		    @"Cannot extract a specific file of a .gz archive!"];
+		app->_exitStatus = 1;
+		return;
+	}
+
+	fileName = [[app->_archivePath lastPathComponent]
+	    stringByDeletingPathExtension];
+
+	if (app->_outputLevel >= 0)
+		[of_stdout writeFormat: @"Extracting %@...", fileName];
+
+	if (![app shouldExtractFile: fileName
+			outFileName: fileName])
+		return;
+
+	output = [OFFile fileWithPath: fileName
+				 mode: @"wb"];
+	/* TODO: Copy permissions */
+
+	while (![_stream isAtEndOfStream]) {
+		ssize_t length = [app copyBlockFromStream: _stream
+						 toStream: output
+						 fileName: fileName];
+
+		if (length < 0) {
+			app->_exitStatus = 1;
+			return;
+		}
+	}
+
+	if (app->_outputLevel >= 0)
+		[of_stdout writeFormat: @"\rExtracting %@... done\n", fileName];
+}
+@end

Index: utils/ofzip/Makefile
==================================================================
--- utils/ofzip/Makefile
+++ utils/ofzip/Makefile
@@ -1,9 +1,10 @@
 include ../../extra.mk
 
 PROG = ofzip${PROG_SUFFIX}
-SRCS = OFZIP.m		\
+SRCS = GZIPArchive.m	\
+       OFZIP.m		\
        ZIPArchive.m
 
 include ../../buildsys.mk
 
 ${PROG}: ${LIBOBJFW_DEP_LVL2}

Index: utils/ofzip/OFZIP.h
==================================================================
--- utils/ofzip/OFZIP.h
+++ utils/ofzip/OFZIP.h
@@ -13,18 +13,20 @@
  * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
  * file.
  */
 
 #import "OFObject.h"
+#import "OFString.h"
 
 #import "Archive.h"
 
 @interface OFZIP: OFObject
 {
 	int8_t _override;
 @public
 	int8_t _outputLevel;
+	OFString *_archivePath;
 	int _exitStatus;
 }
 
 - (id <Archive>)openArchiveWithPath: (OFString*)path;
 - (bool)shouldExtractFile: (OFString*)fileName

Index: utils/ofzip/OFZIP.m
==================================================================
--- utils/ofzip/OFZIP.m
+++ utils/ofzip/OFZIP.m
@@ -25,10 +25,11 @@
 #import "OFOptionsParser.h"
 #import "OFStdIOStream.h"
 
 #import "OFZIP.h"
 #import "ZIPArchive.h"
+#import "GZIPArchive.h"
 
 #import "OFCreateDirectoryFailedException.h"
 #import "OFInvalidFormatException.h"
 #import "OFOpenItemFailedException.h"
 #import "OFReadFailedException.h"
@@ -197,10 +198,13 @@
 - (id <Archive>)openArchiveWithPath: (OFString*)path
 {
 	OFFile *file;
 	id <Archive> archive;
 
+	[_archivePath release];
+	_archivePath = [path copy];
+
 	@try {
 		file = [OFFile fileWithPath: path
 				       mode: @"rb"];
 	} @catch (OFOpenItemFailedException *e) {
 		[of_stderr writeFormat: @"Failed to open file %@: %s\n",
@@ -207,11 +211,14 @@
 					[e path], strerror([e errNo])];
 		[OFApplication terminateWithStatus: 1];
 	}
 
 	@try {
-		archive = [ZIPArchive archiveWithFile: file];
+		if ([path hasSuffix: @".gz"])
+			archive = [GZIPArchive archiveWithFile: file];
+		else
+			archive = [ZIPArchive archiveWithFile: file];
 	} @catch (OFReadFailedException *e) {
 		[of_stderr writeFormat: @"Failed to read file %@: %s\n",
 					path, strerror([e errNo])];
 		[OFApplication terminateWithStatus: 1];
 	} @catch (OFInvalidFormatException *e) {