Local .xz files: parse uncompressed size for better progress reports

debian/changelog

@@ -9,6 +9,7 @@ rpi-imager (1.7.6) unstable; urgency=medium
   * Workaround for ArchLinux's lsblk labeling internal SD card readers
     (mmcblk0) as non-removable storage.
   * Allow drag-dropping image files to Imager.
+  * Local .xz files: parse uncompressed size for better progress reports.
 
  -- Floris Bos <bos@je-eigen-domein.nl>  Sat, 23 Sep 2023 19:47:40 +0200
 

src/CMakeLists.txt

@@ -352,5 +352,5 @@ else()
     install(FILES "${CMAKE_CURRENT_BINARY_DIR}/rpi-imager.metainfo.xml" DESTINATION share/metainfo)
 endif()
 
-include_directories(${CURL_INCLUDE_DIR} ${LibArchive_INCLUDE_DIR} ${OPENSSL_INCLUDE_DIR})
+include_directories(${CURL_INCLUDE_DIR} ${LibArchive_INCLUDE_DIR} ${OPENSSL_INCLUDE_DIR} ${LIBLZMA_INCLUDE_DIR})
 target_link_libraries(${PROJECT_NAME} PRIVATE ${QT}::Core ${QT}::Quick ${QT}::Svg ${CURL_LIBRARIES} ${LibArchive_LIBRARIES} ${OPENSSL_LIBRARIES} ${ATOMIC_LIBRARY} ${EXTRALIBS})

src/imagewriter.cpp

@@ -14,6 +14,7 @@
 #include "wlancredentials.h"
 #include <archive.h>
 #include <archive_entry.h>
+#include <lzma.h>
 #include <random>
 #include <QFileInfo>
 #include <QQmlApplicationEngine>
@@ -242,6 +243,8 @@ void ImageWriter::startWrite()
             _extrLen = _downloadLen;
         else if (lowercaseurl.endsWith(".zip"))
             _parseCompressedFile();
+        else if (lowercaseurl.endsWith(".xz"))
+            _parseXZFile();
     }
 
     if (_devLen && _extrLen > _devLen)
@@ -648,6 +651,47 @@ void ImageWriter::_parseCompressedFile()
     qDebug() << "Parsed .zip file containing" << numFiles << "files, uncompressed size:" << _extrLen;
 }
 
+void ImageWriter::_parseXZFile()
+{
+    QFile f(_src.toLocalFile());
+    lzma_stream_flags opts = { 0 };
+    _extrLen = 0;
+
+    if (f.size() > LZMA_STREAM_HEADER_SIZE && f.open(f.ReadOnly))
+    {
+        f.seek(f.size()-LZMA_STREAM_HEADER_SIZE);
+        QByteArray footer = f.read(LZMA_STREAM_HEADER_SIZE);
+        lzma_ret ret = lzma_stream_footer_decode(&opts, (const uint8_t *) footer.constData());
+
+        if (ret == LZMA_OK && opts.backward_size < 1000000 && opts.backward_size < f.size()-LZMA_STREAM_HEADER_SIZE)
+        {
+            f.seek(f.size()-LZMA_STREAM_HEADER_SIZE-opts.backward_size);
+            QByteArray buf = f.read(opts.backward_size+LZMA_STREAM_HEADER_SIZE);
+            lzma_index *idx;
+            uint64_t memlimit = UINT64_MAX;
+            size_t pos = 0;
+
+            ret = lzma_index_buffer_decode(&idx, &memlimit, NULL, (const uint8_t *) buf.constData(), &pos, buf.size());
+            if (ret == LZMA_OK)
+            {
+                _extrLen = lzma_index_uncompressed_size(idx);
+                qDebug() << "Parsed .xz file. Uncompressed size:" << _extrLen;
+            }
+            else
+            {
+                qDebug() << "Unable to parse index of .xz file";
+            }
+            lzma_index_end(idx, NULL);
+        }
+        else
+        {
+            qDebug() << "Unable to parse footer of .xz file";
+        }
+
+        f.close();
+    }
+}
+
 bool ImageWriter::isOnline()
 {
     return _online || !_embeddedMode;

src/imagewriter.h

@@ -181,6 +181,7 @@ protected:
 #endif
 
     void _parseCompressedFile();
+    void _parseXZFile();
     QString _pubKeyFileName();
     QString _privKeyFileName();
     QString _sshKeyDir();