HTTPRepository: improving handling of archives

Avoid hard-coding the archive extension, and ensure the extracted
archive directory is not orphaned on update. Finally, use the
literal filename in the .dirindex when computing the hash, rather
than adding a .tgz extension.

CMakeLists.txt

@@ -286,6 +286,7 @@ else()
     find_package(ZLIB 1.2.4 REQUIRED)
 endif()
 
+find_package(LibLZMA REQUIRED)
 find_package(CURL REQUIRED)
 
 if (SYSTEM_EXPAT)

CMakeModules/FindLibLZMA.cmake

@@ -0,0 +1,124 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+#[=======================================================================[.rst:
+FindLibLZMA
+-----------
+
+Find LZMA compression algorithm headers and library.
+
+
+Imported Targets
+^^^^^^^^^^^^^^^^
+
+This module defines :prop_tgt:`IMPORTED` target ``LibLZMA::LibLZMA``, if
+liblzma has been found.
+
+Result variables
+^^^^^^^^^^^^^^^^
+
+This module will set the following variables in your project:
+
+``LIBLZMA_FOUND``
+  True if liblzma headers and library were found.
+``LIBLZMA_INCLUDE_DIRS``
+  Directory where liblzma headers are located.
+``LIBLZMA_LIBRARIES``
+  Lzma libraries to link against.
+``LIBLZMA_HAS_AUTO_DECODER``
+  True if lzma_auto_decoder() is found (required).
+``LIBLZMA_HAS_EASY_ENCODER``
+  True if lzma_easy_encoder() is found (required).
+``LIBLZMA_HAS_LZMA_PRESET``
+  True if lzma_lzma_preset() is found (required).
+``LIBLZMA_VERSION_MAJOR``
+  The major version of lzma
+``LIBLZMA_VERSION_MINOR``
+  The minor version of lzma
+``LIBLZMA_VERSION_PATCH``
+  The patch version of lzma
+``LIBLZMA_VERSION_STRING``
+  version number as a string (ex: "5.0.3")
+#]=======================================================================]
+
+find_path(LIBLZMA_INCLUDE_DIR lzma.h )
+if(NOT LIBLZMA_LIBRARY)
+  find_library(LIBLZMA_LIBRARY_RELEASE NAMES lzma liblzma NAMES_PER_DIR PATH_SUFFIXES lib)
+  find_library(LIBLZMA_LIBRARY_DEBUG NAMES lzmad liblzmad NAMES_PER_DIR PATH_SUFFIXES lib)
+  include(SelectLibraryConfigurations)
+  select_library_configurations(LIBLZMA)
+else()
+  file(TO_CMAKE_PATH "${LIBLZMA_LIBRARY}" LIBLZMA_LIBRARY)
+endif()
+
+if(LIBLZMA_INCLUDE_DIR AND EXISTS "${LIBLZMA_INCLUDE_DIR}/lzma/version.h")
+    file(STRINGS "${LIBLZMA_INCLUDE_DIR}/lzma/version.h" LIBLZMA_HEADER_CONTENTS REGEX "#define LZMA_VERSION_[A-Z]+ [0-9]+")
+
+    string(REGEX REPLACE ".*#define LZMA_VERSION_MAJOR ([0-9]+).*" "\\1" LIBLZMA_VERSION_MAJOR "${LIBLZMA_HEADER_CONTENTS}")
+    string(REGEX REPLACE ".*#define LZMA_VERSION_MINOR ([0-9]+).*" "\\1" LIBLZMA_VERSION_MINOR "${LIBLZMA_HEADER_CONTENTS}")
+    string(REGEX REPLACE ".*#define LZMA_VERSION_PATCH ([0-9]+).*" "\\1" LIBLZMA_VERSION_PATCH "${LIBLZMA_HEADER_CONTENTS}")
+
+    set(LIBLZMA_VERSION_STRING "${LIBLZMA_VERSION_MAJOR}.${LIBLZMA_VERSION_MINOR}.${LIBLZMA_VERSION_PATCH}")
+    unset(LIBLZMA_HEADER_CONTENTS)
+endif()
+
+# We're using new code known now as XZ, even library still been called LZMA
+# it can be found in http://tukaani.org/xz/
+# Avoid using old codebase
+if (LIBLZMA_LIBRARY)
+  include(CheckLibraryExists)
+  set(CMAKE_REQUIRED_QUIET_SAVE ${CMAKE_REQUIRED_QUIET})
+  set(CMAKE_REQUIRED_QUIET ${LibLZMA_FIND_QUIETLY})
+  if(NOT LIBLZMA_LIBRARY_RELEASE AND NOT LIBLZMA_LIBRARY_DEBUG)
+    set(LIBLZMA_LIBRARY_check ${LIBLZMA_LIBRARY})
+  elseif(LIBLZMA_LIBRARY_RELEASE)
+    set(LIBLZMA_LIBRARY_check ${LIBLZMA_LIBRARY_RELEASE})
+  elseif(LIBLZMA_LIBRARY_DEBUG)
+    set(LIBLZMA_LIBRARY_check ${LIBLZMA_LIBRARY_DEBUG})
+  endif()
+  CHECK_LIBRARY_EXISTS(${LIBLZMA_LIBRARY_check} lzma_auto_decoder "" LIBLZMA_HAS_AUTO_DECODER)
+  CHECK_LIBRARY_EXISTS(${LIBLZMA_LIBRARY_check} lzma_easy_encoder "" LIBLZMA_HAS_EASY_ENCODER)
+  CHECK_LIBRARY_EXISTS(${LIBLZMA_LIBRARY_check} lzma_lzma_preset "" LIBLZMA_HAS_LZMA_PRESET)
+  unset(LIBLZMA_LIBRARY_check)
+  set(CMAKE_REQUIRED_QUIET ${CMAKE_REQUIRED_QUIET_SAVE})
+endif ()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LibLZMA  REQUIRED_VARS  LIBLZMA_LIBRARY
+                                                          LIBLZMA_INCLUDE_DIR
+                                                          LIBLZMA_HAS_AUTO_DECODER
+                                                          LIBLZMA_HAS_EASY_ENCODER
+                                                          LIBLZMA_HAS_LZMA_PRESET
+                                           VERSION_VAR    LIBLZMA_VERSION_STRING
+                                 )
+mark_as_advanced( LIBLZMA_INCLUDE_DIR LIBLZMA_LIBRARY )
+
+if (LIBLZMA_FOUND)
+    set(LIBLZMA_LIBRARIES ${LIBLZMA_LIBRARY})
+    set(LIBLZMA_INCLUDE_DIRS ${LIBLZMA_INCLUDE_DIR})
+    if(NOT TARGET LibLZMA::LibLZMA)
+        add_library(LibLZMA::LibLZMA UNKNOWN IMPORTED)
+        set_target_properties(LibLZMA::LibLZMA PROPERTIES
+                              INTERFACE_INCLUDE_DIRECTORIES ${LIBLZMA_INCLUDE_DIR}
+                              IMPORTED_LINK_INTERFACE_LANGUAGES C)
+
+        if(LIBLZMA_LIBRARY_RELEASE)
+            set_property(TARGET LibLZMA::LibLZMA APPEND PROPERTY
+                IMPORTED_CONFIGURATIONS RELEASE)
+            set_target_properties(LibLZMA::LibLZMA PROPERTIES
+                IMPORTED_LOCATION_RELEASE "${LIBLZMA_LIBRARY_RELEASE}")
+        endif()
+
+        if(LIBLZMA_LIBRARY_DEBUG)
+            set_property(TARGET LibLZMA::LibLZMA APPEND PROPERTY
+                IMPORTED_CONFIGURATIONS DEBUG)
+            set_target_properties(LibLZMA::LibLZMA PROPERTIES
+                IMPORTED_LOCATION_DEBUG "${LIBLZMA_LIBRARY_DEBUG}")
+        endif()
+
+        if(NOT LIBLZMA_LIBRARY_RELEASE AND NOT LIBLZMA_LIBRARY_DEBUG)
+            set_target_properties(LibLZMA::LibLZMA PROPERTIES
+                IMPORTED_LOCATION "${LIBLZMA_LIBRARY}")
+        endif()
+    endif()
+endif ()

SimGearConfig.cmake.in

@@ -1,6 +1,7 @@
 include(CMakeFindDependencyMacro)
 
 find_dependency(ZLIB)
+find_dependency(LibLZMA)
 find_dependency(Threads)
 
 # OSG

simgear/CMakeLists.txt

@@ -168,7 +168,9 @@ target_link_libraries(SimGearCore PRIVATE
     ${COCOA_LIBRARY}
     ${CURL_LIBRARIES}
     ${WINSOCK_LIBRARY}
-    ${SHLWAPI_LIBRARY})
+    ${SHLWAPI_LIBRARY}
+    LibLZMA::LibLZMA
+)
 
 if(SYSTEM_EXPAT)
     target_link_libraries(SimGearCore PRIVATE ${EXPAT_LIBRARIES})

simgear/io/ArchiveExtractor_private.hxx

@@ -0,0 +1,90 @@
+// Copyright (C) 2021  James Turner - <james@flightgear.org>
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+
+
+#pragma once
+
+#include "untar.hxx"
+
+namespace simgear {
+
+class ArchiveExtractorPrivate
+{
+public:
+    ArchiveExtractorPrivate(ArchiveExtractor* o) : outer(o)
+    {
+        assert(outer);
+    }
+
+    virtual ~ArchiveExtractorPrivate() = default;
+
+    typedef enum {
+        INVALID = 0,
+        READING_HEADER,
+        READING_FILE,
+        READING_PADDING,
+        READING_PAX_GLOBAL_ATTRIBUTES,
+        READING_PAX_FILE_ATTRIBUTES,
+        PRE_END_OF_ARCHVE,
+        END_OF_ARCHIVE,
+        ERROR_STATE, ///< states above this are error conditions
+        BAD_ARCHIVE,
+        BAD_DATA,
+        FILTER_STOPPED
+    } State;
+
+    State state = INVALID;
+    ArchiveExtractor* outer = nullptr;
+
+    virtual void extractBytes(const uint8_t* bytes, size_t count) = 0;
+
+    virtual void flush() = 0;
+
+    SGPath extractRootPath()
+    {
+        return outer->_rootPath;
+    }
+
+    ArchiveExtractor::PathResult filterPath(std::string& pathToExtract)
+    {
+        return outer->filterPath(pathToExtract);
+    }
+
+
+    bool isSafePath(const std::string& p) const
+    {
+        if (p.empty()) {
+            return false;
+        }
+
+        // reject absolute paths
+        if (p.at(0) == '/') {
+            return false;
+        }
+
+        // reject paths containing '..'
+        size_t doubleDot = p.find("..");
+        if (doubleDot != std::string::npos) {
+            return false;
+        }
+
+        // on POSIX could use realpath to sanity check
+        return true;
+    }
+};
+
+} // namespace simgear

simgear/io/HTTPRepository.cxx

@@ -265,6 +265,19 @@ public:
                 free(buf);
     }
 
+    /// helper to check and erase 'fooBar' from paths, if passed fooBar.zip, fooBar.tgz, etc.
+    void removeExtractedDirectoryFromList(PathList& paths, const std::string& tarballName)
+    {
+        const auto directoryName = SGPath::fromUtf8(tarballName).file_base();
+        auto it = std::find_if(paths.begin(), paths.end(), [directoryName](const SGPath& p) {
+            return p.isDir() && (p.file() == directoryName);
+        });
+
+        if (it != paths.end()) {
+            paths.erase(it);
+        }
+    }
+
     void updateChildrenBasedOnHash()
     {
       using SAct = HTTPRepository::SyncAction;
@@ -298,6 +311,11 @@ public:
                         orphans.end());
         }
 
+        // ensure the extracted directory corresponding to a tarball, is *not* considered an orphan
+        if (c.type == HTTPRepository::TarballType) {
+            removeExtractedDirectoryFromList(orphans, c.name);
+        }
+
         if (_repository->syncPredicate) {
           const auto pathOnDisk = isNew ? absolutePath() / c.name : *p;
           // never handle deletes here, do them at the end
@@ -320,7 +338,6 @@ public:
           toBeUpdated.push_back(c);
         } else {
           // File/Directory exists and hash is valid.
-
           if (c.type == HTTPRepository::DirectoryType) {
             // If it's a directory,perform a recursive check.
             HTTPDirectory *childDir = childDirectory(c.name);
@@ -509,42 +526,42 @@ public:
                 _repository->totalDownloaded += sz;
                 SGPath p = SGPath(absolutePath(), file);
 
-                if ((p.extension() == "tgz") || (p.extension() == "zip")) {
+                if (it->type == HTTPRepository::TarballType) {
-                  // We require that any compressed files have the same filename as the file or directory
+                    // We require that any compressed files have the same filename as the file or directory
-                  // they expand to, so we can remove the old file/directory before extracting the new
+                    // they expand to, so we can remove the old file/directory before extracting the new
-                  // data.
+                    // data.
-                  SGPath removePath = SGPath(p.base());
+                    SGPath removePath = SGPath(p.base());
-                  bool pathAvailable = true;
+                    bool pathAvailable = true;
-                  if (removePath.exists()) {
+                    if (removePath.exists()) {
-                    if (removePath.isDir()) {
+                        if (removePath.isDir()) {
-                      simgear::Dir pd(removePath);
+                            simgear::Dir pd(removePath);
-                    	pathAvailable = pd.removeChildren();
+                            pathAvailable = pd.removeChildren();
-                    } else {
+                        } else {
-                      pathAvailable = removePath.remove();
+                            pathAvailable = removePath.remove();
+                        }
                     }
-                  }
 
-                  if (pathAvailable) {
+                    if (pathAvailable) {
-                    // we use a Task helper to extract tarballs incrementally.
+                        // we use a Task helper to extract tarballs incrementally.
-                    // without this, archive extraction blocks here, which
+                        // without this, archive extraction blocks here, which
-                    // prevents other repositories downloading / updating.
+                        // prevents other repositories downloading / updating.
-                    // Unfortunately due Windows AV (Defender, etc) we cna block
+                        // Unfortunately due Windows AV (Defender, etc) we cna block
-                    // here for many minutes.
+                        // here for many minutes.
 
-                    // use a lambda to own this shared_ptr; this means when the
+                        // use a lambda to own this shared_ptr; this means when the
-                    // lambda is destroyed, the ArchiveExtraTask will get
+                        // lambda is destroyed, the ArchiveExtraTask will get
-                    // cleaned up.
+                        // cleaned up.
-                    ArchiveExtractTaskPtr t =
+                        ArchiveExtractTaskPtr t =
-                        std::make_shared<ArchiveExtractTask>(p, _relativePath);
+                            std::make_shared<ArchiveExtractTask>(p, _relativePath);
-                    auto cb = [t](HTTPRepoPrivate *repo) {
+                        auto cb = [t](HTTPRepoPrivate* repo) {
-                      return t->run(repo);
+                            return t->run(repo);
-                    };
+                        };
 
-                    _repository->addTask(cb);
+                        _repository->addTask(cb);
-                  } else {
+                    } else {
-                    SG_LOG(SG_TERRASYNC, SG_ALERT, "Unable to remove old file/directory " << removePath);
+                        SG_LOG(SG_TERRASYNC, SG_ALERT, "Unable to remove old file/directory " << removePath);
-                  } // of pathAvailable
+                    } // of pathAvailable
-                } // of handling tgz files
+                }     // of handling archive files
             } // of hash matches
         } // of found in child list
     }
@@ -736,11 +753,9 @@ private:
     std::string hashForChild(const ChildInfo& child) const
     {
       SGPath p(child.path);
-      if (child.type == HTTPRepository::DirectoryType)
+      if (child.type == HTTPRepository::DirectoryType) {
-        p.append(".dirindex");
+          p.append(".dirindex");
-      if (child.type == HTTPRepository::TarballType)
+      }
-        p.concat(
-            ".tgz"); // For tarballs the hash is against the tarball file itself
       return hashForPath(p);
     }
 

simgear/io/test_untar.cxx

@@ -32,7 +32,7 @@ void testTarGz()
     uint8_t* buf = (uint8_t*) alloca(8192);
     size_t bufSize = f.read((char*) buf, 8192);
 
-    SG_VERIFY(ArchiveExtractor::determineType(buf, bufSize) == ArchiveExtractor::TarData);
+    SG_VERIFY(ArchiveExtractor::determineType(buf, bufSize) == ArchiveExtractor::GZData);
 
     f.close();
 }
@@ -174,6 +174,34 @@ void testPAXAttributes()
 
 }
 
+void testExtractXZ()
+{
+    SGPath p = SGPath(SRC_DIR);
+    p.append("test.tar.xz");
+
+    SGBinaryFile f(p);
+    f.open(SG_IO_IN);
+
+    SGPath extractDir = simgear::Dir::current().path() / "test_extract_xz";
+    simgear::Dir pd(extractDir);
+    pd.removeChildren();
+
+    ArchiveExtractor ex(extractDir);
+
+    uint8_t* buf = (uint8_t*)alloca(128);
+    while (!f.eof()) {
+        size_t bufSize = f.read((char*)buf, 128);
+        ex.extractBytes(buf, bufSize);
+    }
+
+    ex.flush();
+    SG_VERIFY(ex.isAtEndOfArchive());
+    SG_VERIFY(ex.hasError() == false);
+
+    SG_VERIFY((extractDir / "testDir/hello.c").exists());
+    SG_VERIFY((extractDir / "testDir/foo.txt").exists());
+}
+
 int main(int ac, char ** av)
 {
     testTarGz();
@@ -181,7 +209,8 @@ int main(int ac, char ** av)
     testFilterTar();
 	testExtractStreamed();
 	testExtractZip();
-   
+    testExtractXZ();
+
     // disabled to avoiding checking in large PAX archive
     // testPAXAttributes();
     

simgear/io/untar.cxx

@@ -38,82 +38,11 @@
 #include <simgear/package/unzip.h>
 #include <simgear/structure/exception.hxx>
 
+#include "ArchiveExtractor_private.hxx"
+
 namespace simgear
 {
 
-	class ArchiveExtractorPrivate
-	{
-	public:
-		ArchiveExtractorPrivate(ArchiveExtractor* o) :
-			outer(o)
-		{
-			assert(outer);
-		}
-
-        virtual ~ArchiveExtractorPrivate() = default;
-        
-		typedef enum {
-			INVALID = 0,
-			READING_HEADER,
-			READING_FILE,
-			READING_PADDING,
-            READING_PAX_GLOBAL_ATTRIBUTES,
-            READING_PAX_FILE_ATTRIBUTES,
-			PRE_END_OF_ARCHVE,
-			END_OF_ARCHIVE,
-			ERROR_STATE, ///< states above this are error conditions
-			BAD_ARCHIVE,
-			BAD_DATA,
-			FILTER_STOPPED
-		} State;
-
-		State state = INVALID;
-		ArchiveExtractor* outer = nullptr;
-
-		virtual void extractBytes(const uint8_t* bytes, size_t count) = 0;
-
-		virtual void flush() = 0;
-
-		SGPath extractRootPath()
-		{
-			return outer->_rootPath;
-		}
-
-		ArchiveExtractor::PathResult filterPath(std::string& pathToExtract)
-		{
-			return outer->filterPath(pathToExtract);
-		}
-
-
-		bool isSafePath(const std::string& p) const
-		{
-			if (p.empty()) {
-				return false;
-			}
-
-			// reject absolute paths
-			if (p.at(0) == '/') {
-				return false;
-			}
-
-			// reject paths containing '..'
-			size_t doubleDot = p.find("..");
-			if (doubleDot != std::string::npos) {
-				return false;
-			}
-
-			// on POSIX could use realpath to sanity check
-			return true;
-		}
-	};
-
-///////////////////////////////////////////////////////////////////////////////////////////////////
-
-const int ZLIB_DECOMPRESS_BUFFER_SIZE = 32 * 1024;
-const int ZLIB_INFLATE_WINDOW_BITS = MAX_WBITS;
-const int ZLIB_DECODE_GZIP_HEADER = 16;
-
-/* tar Header Block, from POSIX 1003.1-1990.  */
 
 typedef struct
 {
@@ -153,320 +82,410 @@ typedef struct
 #define FIFOTYPE '6'            /* FIFO special */
 #define CONTTYPE '7'            /* reserved */
 
-	const char PAX_GLOBAL_HEADER = 'g';
+    const char PAX_GLOBAL_HEADER = 'g';
-	const char PAX_FILE_ATTRIBUTES = 'x';
+    const char PAX_FILE_ATTRIBUTES = 'x';
 
 
-class TarExtractorPrivate : public ArchiveExtractorPrivate
+    ///////////////////////////////////////////////////////////////////////////////////////////////////
+
+    const int ZLIB_DECOMPRESS_BUFFER_SIZE = 32 * 1024;
+    const int ZLIB_INFLATE_WINDOW_BITS = MAX_WBITS;
+    const int ZLIB_DECODE_GZIP_HEADER = 16;
+
+    /* tar Header Block, from POSIX 1003.1-1990.  */
+
+
+    class TarExtractorPrivate : public ArchiveExtractorPrivate
+    {
+    public:
+        union {
+            UstarHeaderBlock header;
+            uint8_t headerBytes[TAR_HEADER_BLOCK_SIZE];
+        };
+
+        size_t bytesRemaining;
+        std::unique_ptr<SGFile> currentFile;
+        size_t currentFileSize;
+
+        uint8_t* headerPtr;
+        bool skipCurrentEntry = false;
+        std::string paxAttributes;
+        std::string paxPathName;
+
+        TarExtractorPrivate(ArchiveExtractor* o) : ArchiveExtractorPrivate(o)
+        {
+            setState(TarExtractorPrivate::READING_HEADER);
+        }
+
+        ~TarExtractorPrivate() = default;
+
+        void readPaddingIfRequired()
+        {
+            size_t pad = currentFileSize % TAR_HEADER_BLOCK_SIZE;
+            if (pad) {
+                bytesRemaining = TAR_HEADER_BLOCK_SIZE - pad;
+                setState(READING_PADDING);
+            } else {
+                setState(READING_HEADER);
+            }
+        }
+
+        void checkEndOfState()
+        {
+            if (bytesRemaining > 0) {
+                return;
+            }
+
+            if (state == READING_FILE) {
+                if (currentFile) {
+                    currentFile->close();
+                    currentFile.reset();
+                }
+                readPaddingIfRequired();
+            } else if (state == READING_HEADER) {
+                processHeader();
+            } else if (state == PRE_END_OF_ARCHVE) {
+                if (headerIsAllZeros()) {
+                    setState(END_OF_ARCHIVE);
+                } else {
+                    // what does the spec say here?
+                }
+            } else if (state == READING_PAX_GLOBAL_ATTRIBUTES) {
+                parsePAXAttributes(true);
+                readPaddingIfRequired();
+            } else if (state == READING_PAX_FILE_ATTRIBUTES) {
+                parsePAXAttributes(false);
+                readPaddingIfRequired();
+            } else if (state == READING_PADDING) {
+                setState(READING_HEADER);
+            }
+        }
+
+        void setState(State newState)
+        {
+            if ((newState == READING_HEADER) || (newState == PRE_END_OF_ARCHVE)) {
+                bytesRemaining = TAR_HEADER_BLOCK_SIZE;
+                headerPtr = headerBytes;
+            }
+
+            state = newState;
+        }
+
+        void extractBytes(const uint8_t* bytes, size_t count) override
+        {
+            // uncompressed, just pass through directly
+            processBytes((const char*)bytes, count);
+        }
+
+        void flush() override
+        {
+            // no-op for tar files, we process everything greedily
+        }
+
+        void processHeader()
+        {
+            if (headerIsAllZeros()) {
+                if (state == PRE_END_OF_ARCHVE) {
+                    setState(END_OF_ARCHIVE);
+                } else {
+                    setState(PRE_END_OF_ARCHVE);
+                }
+                return;
+            }
+
+            if (strncmp(header.magic, TMAGIC, TMAGLEN) != 0) {
+                SG_LOG(SG_IO, SG_WARN, "Untar: magic is wrong");
+                state = BAD_ARCHIVE;
+                return;
+            }
+
+            skipCurrentEntry = false;
+            std::string tarPath = std::string(header.prefix) + std::string(header.fileName);
+            if (!paxPathName.empty()) {
+                tarPath = paxPathName;
+                paxPathName.clear(); // clear for next file
+            }
+
+            if (!isSafePath(tarPath)) {
+                SG_LOG(SG_IO, SG_WARN, "unsafe tar path, skipping::" << tarPath);
+                skipCurrentEntry = true;
+            }
+
+            auto result = filterPath(tarPath);
+            if (result == ArchiveExtractor::Stop) {
+                setState(FILTER_STOPPED);
+                return;
+            } else if (result == ArchiveExtractor::Skipped) {
+                skipCurrentEntry = true;
+            }
+
+            SGPath p = extractRootPath() / tarPath;
+            if (header.typeflag == DIRTYPE) {
+                if (!skipCurrentEntry) {
+                    Dir dir(p);
+                    dir.create(0755);
+                }
+                setState(READING_HEADER);
+            } else if ((header.typeflag == REGTYPE) || (header.typeflag == AREGTYPE)) {
+                currentFileSize = ::strtol(header.size, NULL, 8);
+                bytesRemaining = currentFileSize;
+                if (!skipCurrentEntry) {
+                    currentFile.reset(new SGBinaryFile(p));
+                    currentFile->open(SG_IO_OUT);
+                }
+                setState(READING_FILE);
+            } else if (header.typeflag == PAX_GLOBAL_HEADER) {
+                setState(READING_PAX_GLOBAL_ATTRIBUTES);
+                currentFileSize = ::strtol(header.size, NULL, 8);
+                bytesRemaining = currentFileSize;
+                paxAttributes.clear();
+            } else if (header.typeflag == PAX_FILE_ATTRIBUTES) {
+                setState(READING_PAX_FILE_ATTRIBUTES);
+                currentFileSize = ::strtol(header.size, NULL, 8);
+                bytesRemaining = currentFileSize;
+                paxAttributes.clear();
+            } else if ((header.typeflag == SYMTYPE) || (header.typeflag == LNKTYPE)) {
+                SG_LOG(SG_IO, SG_WARN, "Tarball contains a link or symlink, will be skipped:" << tarPath);
+                skipCurrentEntry = true;
+                setState(READING_HEADER);
+            } else {
+                SG_LOG(SG_IO, SG_WARN, "Unsupported tar file type:" << header.typeflag);
+                state = BAD_ARCHIVE;
+            }
+        }
+
+        void processBytes(const char* bytes, size_t count)
+        {
+            if ((state >= ERROR_STATE) || (state == END_OF_ARCHIVE)) {
+                return;
+            }
+
+            size_t curBytes = std::min(bytesRemaining, count);
+            if (state == READING_FILE) {
+                if (currentFile) {
+                    currentFile->write(bytes, curBytes);
+                }
+                bytesRemaining -= curBytes;
+            } else if ((state == READING_HEADER) || (state == PRE_END_OF_ARCHVE) || (state == END_OF_ARCHIVE)) {
+                memcpy(headerPtr, bytes, curBytes);
+                bytesRemaining -= curBytes;
+                headerPtr += curBytes;
+            } else if (state == READING_PADDING) {
+                bytesRemaining -= curBytes;
+            } else if ((state == READING_PAX_FILE_ATTRIBUTES) || (state == READING_PAX_GLOBAL_ATTRIBUTES)) {
+                bytesRemaining -= curBytes;
+                paxAttributes.append(bytes, curBytes);
+            }
+
+            checkEndOfState();
+            if (count > curBytes) {
+                // recurse with unprocessed bytes
+                processBytes(bytes + curBytes, count - curBytes);
+            }
+        }
+
+        bool headerIsAllZeros() const
+        {
+            char* headerAsChar = (char*)&header;
+            for (size_t i = 0; i < offsetof(UstarHeaderBlock, magic); ++i) {
+                if (*headerAsChar++ != 0) {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        // https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.3.0/com.ibm.zos.v2r3.bpxa500/paxex.htm#paxex
+        void parsePAXAttributes(bool areGlobal)
+        {
+            auto lineStart = 0;
+            for (;;) {
+                auto firstSpace = paxAttributes.find(' ', lineStart);
+                auto firstEq = paxAttributes.find('=', lineStart);
+                if ((firstEq == std::string::npos) || (firstSpace == std::string::npos)) {
+                    SG_LOG(SG_IO, SG_WARN, "Malfroemd PAX attributes in tarfile");
+                    break;
+                }
+
+                uint32_t lengthBytes = std::stoul(paxAttributes.substr(lineStart, firstSpace));
+                uint32_t dataBytes = lengthBytes - (firstEq + 1);
+                std::string name = paxAttributes.substr(firstSpace + 1, firstEq - (firstSpace + 1));
+
+                // dataBytes - 1 here to trim off the trailing newline
+                std::string data = paxAttributes.substr(firstEq + 1, dataBytes - 1);
+
+                processPAXAttribute(areGlobal, name, data);
+
+                lineStart += lengthBytes;
+            }
+        }
+
+        void processPAXAttribute(bool isGlobalAttr, const std::string& attrName, const std::string& data)
+        {
+            if (!isGlobalAttr && (attrName == "path")) {
+                // data is UTF-8 encoded path name
+                paxPathName = data;
+            }
+        }
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+
+class GZTarExtractor : public TarExtractorPrivate
 {
 public:
-    
+    GZTarExtractor(ArchiveExtractor* outer) : TarExtractorPrivate(outer)
-    union {
-        UstarHeaderBlock header;
-        uint8_t headerBytes[TAR_HEADER_BLOCK_SIZE];
-    };
-
-    size_t bytesRemaining;
-    std::unique_ptr<SGFile> currentFile;
-    size_t currentFileSize;
-    z_stream zlibStream;
-    uint8_t* zlibOutput;
-    bool haveInitedZLib = false;
-    bool uncompressedData = false; // set if reading a plain .tar (not tar.gz)
-    uint8_t* headerPtr;
-    bool skipCurrentEntry = false;
-    std::string paxAttributes;
-    std::string paxPathName;
-    
-    TarExtractorPrivate(ArchiveExtractor* o) :
-		ArchiveExtractorPrivate(o)
     {
-		memset(&zlibStream, 0, sizeof(z_stream));
+        memset(&zlibStream, 0, sizeof(z_stream));
-		zlibOutput = (unsigned char*)malloc(ZLIB_DECOMPRESS_BUFFER_SIZE);
+        zlibOutput = (unsigned char*)malloc(ZLIB_DECOMPRESS_BUFFER_SIZE);
-		zlibStream.zalloc = Z_NULL;
+        zlibStream.zalloc = Z_NULL;
-		zlibStream.zfree = Z_NULL;
+        zlibStream.zfree = Z_NULL;
-		zlibStream.avail_out = ZLIB_DECOMPRESS_BUFFER_SIZE;
+        zlibStream.avail_out = ZLIB_DECOMPRESS_BUFFER_SIZE;
-		zlibStream.next_out = zlibOutput;
+        zlibStream.next_out = zlibOutput;
     }
 
-    ~TarExtractorPrivate()
+    ~GZTarExtractor()
     {
         free(zlibOutput);
     }
 
-    void readPaddingIfRequired()
+    void extractBytes(const uint8_t* bytes, size_t count) override
     {
-        size_t pad = currentFileSize % TAR_HEADER_BLOCK_SIZE;
+        zlibStream.next_in = (uint8_t*)bytes;
-        if (pad) {
+        zlibStream.avail_in = count;
-            bytesRemaining = TAR_HEADER_BLOCK_SIZE - pad;
-            setState(READING_PADDING);
-        } else {
-            setState(READING_HEADER);
-        }
-    }
-    
-    void checkEndOfState()
-    {
-        if (bytesRemaining > 0) {
-            return;
-        }
 
-        if (state == READING_FILE) {
+        if (!haveInitedZLib) {
-            if (currentFile) {
+            // now we have data, see if we're dealing with GZ-compressed data or not
-                currentFile->close();
+            if ((bytes[0] == 0x1f) && (bytes[1] == 0x8b)) {
-                currentFile.reset();
+                // GZIP identification bytes
-            }
+                if (inflateInit2(&zlibStream, ZLIB_INFLATE_WINDOW_BITS | ZLIB_DECODE_GZIP_HEADER) != Z_OK) {
-            readPaddingIfRequired();
+                    SG_LOG(SG_IO, SG_WARN, "inflateInit2 failed");
-        } else if (state == READING_HEADER) {
+                    state = TarExtractorPrivate::BAD_DATA;
-            processHeader();
+                    return;
-        } else if (state == PRE_END_OF_ARCHVE) {
+                }
-            if (headerIsAllZeros()) {
-                setState(END_OF_ARCHIVE);
             } else {
-                // what does the spec say here?
+                // set error state
+                state = TarExtractorPrivate::BAD_DATA;
+                return;
             }
-        } else if (state == READING_PAX_GLOBAL_ATTRIBUTES) {
-            parsePAXAttributes(true);
-            readPaddingIfRequired();
-        } else if (state == READING_PAX_FILE_ATTRIBUTES) {
-            parsePAXAttributes(false);
-            readPaddingIfRequired();
-        } else if (state == READING_PADDING) {
-            setState(READING_HEADER);
-        }
-    }
 
-    void setState(State newState)
+            haveInitedZLib = true;
-    {
+            setState(TarExtractorPrivate::READING_HEADER);
-        if ((newState == READING_HEADER) || (newState == PRE_END_OF_ARCHVE)) {
+        } // of init on first-bytes case
-            bytesRemaining = TAR_HEADER_BLOCK_SIZE;
-            headerPtr = headerBytes;
-        }
 
-        state = newState;
+        size_t writtenSize;
-    }
+        // loop, running zlib() inflate and sending output bytes to
+        // our request body handler. Keep calling inflate until no bytes are
+        // written, and ZLIB has consumed all available input
+        do {
+            zlibStream.next_out = zlibOutput;
+            zlibStream.avail_out = ZLIB_DECOMPRESS_BUFFER_SIZE;
+            int result = inflate(&zlibStream, Z_NO_FLUSH);
+            if (result == Z_OK || result == Z_STREAM_END) {
+                // nothing to do
 
-	void extractBytes(const uint8_t* bytes, size_t count) override
+            } else if (result == Z_BUF_ERROR) {
-	{
+                // transient error, fall through
-		zlibStream.next_in = (uint8_t*) bytes;
-		zlibStream.avail_in = count;
-
-		if (!haveInitedZLib) {
-			// now we have data, see if we're dealing with GZ-compressed data or not
-			if ((bytes[0] == 0x1f) && (bytes[1] == 0x8b)) {
-				// GZIP identification bytes
-				if (inflateInit2(&zlibStream, ZLIB_INFLATE_WINDOW_BITS | ZLIB_DECODE_GZIP_HEADER) != Z_OK) {
-					SG_LOG(SG_IO, SG_WARN, "inflateInit2 failed");
-					state = TarExtractorPrivate::BAD_DATA;
-					return;
-				}
-			} else {
-				UstarHeaderBlock* header = (UstarHeaderBlock*)bytes;
-				if (strncmp(header->magic, TMAGIC, TMAGLEN) != 0) {
-					SG_LOG(SG_IO, SG_WARN, "didn't find tar magic in header");
-					state = TarExtractorPrivate::BAD_DATA;
-					return;
-				}
-
-				uncompressedData = true;
-			}
-
-			haveInitedZLib = true;
-			setState(TarExtractorPrivate::READING_HEADER);
-		} // of init on first-bytes case
-
-		if (uncompressedData) {
-			processBytes((const char*) bytes, count);
-		} else {
-			size_t writtenSize;
-			// loop, running zlib() inflate and sending output bytes to
-			// our request body handler. Keep calling inflate until no bytes are
-			// written, and ZLIB has consumed all available input
-			do {
-				zlibStream.next_out = zlibOutput;
-				zlibStream.avail_out = ZLIB_DECOMPRESS_BUFFER_SIZE;
-				int result = inflate(&zlibStream, Z_NO_FLUSH);
-				if (result == Z_OK || result == Z_STREAM_END) {
-					// nothing to do
-
-				}
-				else if (result == Z_BUF_ERROR) {
-					// transient error, fall through
-				}
-				else {
-					//  _error = result;
-					SG_LOG(SG_IO, SG_WARN, "Permanent ZLib error:" << zlibStream.msg);
-					state = TarExtractorPrivate::BAD_DATA;
-					return;
-				}
-
-				writtenSize = ZLIB_DECOMPRESS_BUFFER_SIZE - zlibStream.avail_out;
-				if (writtenSize > 0) {
-					processBytes((const char*) zlibOutput, writtenSize);
-				}
-
-				if (result == Z_STREAM_END) {
-					break;
-				}
-			} while ((zlibStream.avail_in > 0) || (writtenSize > 0));
-		} // of Zlib-compressed data
-	}
-
-	void flush() override
-	{
-		// no-op for tar files, we process everything greedily
-	}
-
-    void processHeader()
-    {
-        if (headerIsAllZeros()) {
-            if (state == PRE_END_OF_ARCHVE) {
-                setState(END_OF_ARCHIVE);
             } else {
-                setState(PRE_END_OF_ARCHVE);
+                //  _error = result;
+                SG_LOG(SG_IO, SG_WARN, "Permanent ZLib error:" << zlibStream.msg);
+                state = TarExtractorPrivate::BAD_DATA;
+                return;
             }
-            return;
-        }
 
-        if (strncmp(header.magic, TMAGIC, TMAGLEN) != 0) {
+            writtenSize = ZLIB_DECOMPRESS_BUFFER_SIZE - zlibStream.avail_out;
-            SG_LOG(SG_IO, SG_WARN, "Untar: magic is wrong");
+            if (writtenSize > 0) {
-            state = BAD_ARCHIVE;
+                processBytes((const char*)zlibOutput, writtenSize);
-            return;
-        }
-
-        skipCurrentEntry = false;
-        std::string tarPath = std::string(header.prefix) + std::string(header.fileName);
-        if (!paxPathName.empty()) {
-            tarPath = paxPathName;
-            paxPathName.clear(); // clear for next file
-        }
-        
-        if (!isSafePath(tarPath)) {
-            SG_LOG(SG_IO, SG_WARN, "unsafe tar path, skipping::" << tarPath);
-            skipCurrentEntry = true;
-        }
-
-        auto result = filterPath(tarPath);
-        if (result == ArchiveExtractor::Stop) {
-            setState(FILTER_STOPPED);
-            return;
-        } else if (result == ArchiveExtractor::Skipped) {
-            skipCurrentEntry = true;
-        }
-        
-        SGPath p = extractRootPath() / tarPath;
-        if (header.typeflag == DIRTYPE) {
-            if (!skipCurrentEntry) {
-                Dir dir(p);
-                dir.create(0755);
             }
-            setState(READING_HEADER);
-        } else if ((header.typeflag == REGTYPE) || (header.typeflag == AREGTYPE)) {
-            currentFileSize = ::strtol(header.size, NULL, 8);
-            bytesRemaining = currentFileSize;
-            if (!skipCurrentEntry) {
-                currentFile.reset(new SGBinaryFile(p));
-                currentFile->open(SG_IO_OUT);
-            }
-            setState(READING_FILE);
-        } else if (header.typeflag == PAX_GLOBAL_HEADER) {
-            setState(READING_PAX_GLOBAL_ATTRIBUTES);
-            currentFileSize = ::strtol(header.size, NULL, 8);
-            bytesRemaining = currentFileSize;
-            paxAttributes.clear();
-        } else if (header.typeflag == PAX_FILE_ATTRIBUTES) {
-            setState(READING_PAX_FILE_ATTRIBUTES);
-            currentFileSize = ::strtol(header.size, NULL, 8);
-            bytesRemaining = currentFileSize;
-            paxAttributes.clear();
-        } else if ((header.typeflag == SYMTYPE) || (header.typeflag == LNKTYPE)) {
-            SG_LOG(SG_IO, SG_WARN, "Tarball contains a link or symlink, will be skipped:" << tarPath);
-            skipCurrentEntry = true;
-            setState(READING_HEADER);
-        } else {
-            SG_LOG(SG_IO, SG_WARN, "Unsupported tar file type:" << header.typeflag);
-            state = BAD_ARCHIVE;
-        }
-    }
 
-    void processBytes(const char* bytes, size_t count)
+            if (result == Z_STREAM_END) {
-    {
-        if ((state >= ERROR_STATE) || (state == END_OF_ARCHIVE)) {
-            return;
-        }
-
-        size_t curBytes = std::min(bytesRemaining, count);
-        if (state == READING_FILE) {
-            if (currentFile) {
-                currentFile->write(bytes, curBytes);
-            }
-            bytesRemaining -= curBytes;
-        } else if ((state == READING_HEADER) || (state == PRE_END_OF_ARCHVE) || (state == END_OF_ARCHIVE)) {
-            memcpy(headerPtr, bytes, curBytes);
-            bytesRemaining -= curBytes;
-            headerPtr += curBytes;
-        } else if (state == READING_PADDING) {
-            bytesRemaining -= curBytes;
-        } else if ((state == READING_PAX_FILE_ATTRIBUTES) || (state == READING_PAX_GLOBAL_ATTRIBUTES)) {
-            bytesRemaining -= curBytes;
-            paxAttributes.append(bytes, curBytes);
-        }
-
-        checkEndOfState();
-        if (count > curBytes) {
-            // recurse with unprocessed bytes
-            processBytes(bytes + curBytes, count - curBytes);
-        }
-    }
-
-    bool headerIsAllZeros() const
-    {
-        char* headerAsChar = (char*) &header;
-        for (size_t i=0; i < offsetof(UstarHeaderBlock, magic); ++i) {
-            if (*headerAsChar++ != 0) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    // https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.3.0/com.ibm.zos.v2r3.bpxa500/paxex.htm#paxex
-    void parsePAXAttributes(bool areGlobal)
-    {
-        auto lineStart = 0;
-        for (;;) {
-            auto firstSpace = paxAttributes.find(' ', lineStart);
-            auto firstEq = paxAttributes.find('=', lineStart);
-            if ((firstEq == std::string::npos) || (firstSpace == std::string::npos)) {
-                SG_LOG(SG_IO, SG_WARN, "Malfroemd PAX attributes in tarfile");
                 break;
             }
-            
+        } while ((zlibStream.avail_in > 0) || (writtenSize > 0));
-            uint32_t lengthBytes = std::stoul(paxAttributes.substr(lineStart, firstSpace));
-            uint32_t dataBytes = lengthBytes - (firstEq + 1);
-            std::string name = paxAttributes.substr(firstSpace+1, firstEq - (firstSpace + 1));
-            
-            // dataBytes - 1 here to trim off the trailing newline
-            std::string data = paxAttributes.substr(firstEq+1, dataBytes - 1);
-            
-            processPAXAttribute(areGlobal, name, data);
-            
-            lineStart += lengthBytes;
-        }
-    }
-    
-    void processPAXAttribute(bool isGlobalAttr, const std::string& attrName, const std::string& data)
-    {
-        if (!isGlobalAttr && (attrName == "path")) {
-            // data is UTF-8 encoded path name
-            paxPathName = data;
-        }
     }
+
+private:
+    z_stream zlibStream;
+    uint8_t* zlibOutput;
+    bool haveInitedZLib = false;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#if 1 || defined(HAVE_XZ)
+
+#include <lzma.h>
+
+class XZTarExtractor : public TarExtractorPrivate
+{
+public:
+    XZTarExtractor(ArchiveExtractor* outer) : TarExtractorPrivate(outer)
+    {
+        _xzStream = LZMA_STREAM_INIT;
+        _outputBuffer = (uint8_t*)malloc(ZLIB_DECOMPRESS_BUFFER_SIZE);
+
+
+        auto ret = lzma_stream_decoder(&_xzStream, UINT64_MAX, LZMA_TELL_ANY_CHECK);
+        if (ret != LZMA_OK) {
+            setState(BAD_ARCHIVE);
+            return;
+        }
+    }
+
+    ~XZTarExtractor()
+    {
+        free(_outputBuffer);
+    }
+
+    void extractBytes(const uint8_t* bytes, size_t count) override
+    {
+        lzma_action action = LZMA_RUN;
+        _xzStream.next_in = bytes;
+        _xzStream.avail_in = count;
+
+        size_t writtenSize;
+        do {
+            _xzStream.avail_out = ZLIB_DECOMPRESS_BUFFER_SIZE;
+            _xzStream.next_out = _outputBuffer;
+
+            const auto ret = lzma_code(&_xzStream, action);
+
+            writtenSize = ZLIB_DECOMPRESS_BUFFER_SIZE - _xzStream.avail_out;
+            if (writtenSize > 0) {
+                processBytes((const char*)_outputBuffer, writtenSize);
+            }
+
+            if (ret == LZMA_GET_CHECK) {
+                //
+            } else if (ret == LZMA_STREAM_END) {
+                setState(END_OF_ARCHIVE);
+                break;
+            } else if (ret != LZMA_OK) {
+                setState(BAD_ARCHIVE);
+                break;
+            }
+        } while ((_xzStream.avail_in > 0) || (writtenSize > 0));
+    }
+
+    void flush() override
+    {
+        const auto ret = lzma_code(&_xzStream, LZMA_FINISH);
+        if (ret != LZMA_STREAM_END) {
+            setState(BAD_ARCHIVE);
+        }
+    }
+
+private:
+    lzma_stream _xzStream;
+    uint8_t* _outputBuffer = nullptr;
+};
+
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+
 extern "C" {
 	void fill_memory_filefunc(zlib_filefunc_def*);
 }
@@ -637,17 +656,19 @@ void ArchiveExtractor::extractBytes(const uint8_t* bytes, size_t count)
 
 		if (r == TarData) {
 			d.reset(new TarExtractorPrivate(this));
-		}
+        } else if (r == GZData) {
-		else if (r == ZipData) {
+            d.reset(new GZTarExtractor(this));
-			d.reset(new ZipExtractorPrivate(this));
+        } else if (r == XZData) {
-		}
+            d.reset(new XZTarExtractor(this));
-		else {
+        } else if (r == ZipData) {
-			SG_LOG(SG_IO, SG_WARN, "Invalid archive type");
+            d.reset(new ZipExtractorPrivate(this));
+        } else {
+            SG_LOG(SG_IO, SG_WARN, "Invalid archive type");
 			_invalidDataType = true;
 			return;
-		}
+        }
 
-		// if hit here, we created the extractor. Feed the prefbuffer
+        // if hit here, we created the extractor. Feed the prefbuffer
 		// bytes through it
 		d->extractBytes((uint8_t*) _prebuffer.data(), _prebuffer.size());
 		_prebuffer.clear();
@@ -699,9 +720,18 @@ ArchiveExtractor::DetermineResult ArchiveExtractor::determineType(const uint8_t*
 		return ZipData;
 	}
 
-	auto r = isTarData(bytes, count);
+    if (count < 6) {
-	if ((r == TarData) || (r == InsufficientData))
+        return InsufficientData;
-		return r;
+    }
+
+    const uint8_t XZ_HEADER[6] = {0xFD, '7', 'z', 'X', 'Z', 0x00};
+    if (memcmp(bytes, XZ_HEADER, 6) == 0) {
+        return XZData;
+    }
+
+    auto r = isTarData(bytes, count);
+    if ((r == TarData) || (r == InsufficientData) || (r == GZData))
+        return r;
 
 	return Invalid;
 }
@@ -714,6 +744,8 @@ ArchiveExtractor::DetermineResult ArchiveExtractor::isTarData(const uint8_t* byt
     }
 
     UstarHeaderBlock* header = 0;
+    DetermineResult result = InsufficientData;
+
     if ((bytes[0] == 0x1f) && (bytes[1] == 0x8b)) {
         // GZIP identification bytes
         z_stream z;
@@ -731,11 +763,11 @@ ArchiveExtractor::DetermineResult ArchiveExtractor::isTarData(const uint8_t* byt
             return Invalid;
         }
 
-        int result = inflate(&z, Z_SYNC_FLUSH);
+        int zResult = inflate(&z, Z_SYNC_FLUSH);
-        if ((result == Z_OK) || (result == Z_STREAM_END)) {
+        if ((zResult == Z_OK) || (zResult == Z_STREAM_END)) {
             // all good
         } else {
-            SG_LOG(SG_IO, SG_WARN, "isTarData: Zlib inflate failed:" << result);
+            SG_LOG(SG_IO, SG_WARN, "isTarData: Zlib inflate failed:" << zResult);
             inflateEnd(&z);
             return Invalid; // not tar data
         }
@@ -748,6 +780,7 @@ ArchiveExtractor::DetermineResult ArchiveExtractor::isTarData(const uint8_t* byt
 
         header = reinterpret_cast<UstarHeaderBlock*>(zlibOutput);
         inflateEnd(&z);
+        result = GZData;
     } else {
         // uncompressed tar
         if (count < TAR_HEADER_BLOCK_SIZE) {
@@ -755,13 +788,14 @@ ArchiveExtractor::DetermineResult ArchiveExtractor::isTarData(const uint8_t* byt
         }
 
         header = (UstarHeaderBlock*) bytes;
+        result = TarData;
     }
 
     if (strncmp(header->magic, TMAGIC, TMAGLEN) != 0) {
         return Invalid;
     }
 
-    return TarData;
+    return result;
 }
 
 void ArchiveExtractor::extractLocalFile(const SGPath& archiveFile)

simgear/io/untar.hxx

@@ -36,15 +36,16 @@ public:
 	ArchiveExtractor(const SGPath& rootPath);
 	virtual ~ArchiveExtractor();
 
-	enum DetermineResult
+    enum DetermineResult {
-	{
+        Invalid,
-		Invalid,
+        InsufficientData,
-		InsufficientData,
+        TarData,
-		TarData,
+        ZipData,
-		ZipData
+        GZData, // Gzipped-tar
-	};
+        XZData  // XZ (aka LZMA) tar
+    };
 
-	static DetermineResult determineType(const uint8_t* bytes, size_t count);
+    static DetermineResult determineType(const uint8_t* bytes, size_t count);
 
 	/**
 	 * @brief API to extract a local zip or tar.gz