Gvas: add support for UE5 saves.

Fuckers at Epic added four more bytes to the file header, and not
even equivalent Rust libraries know what those bytes are for.

src/Gvas/File.cpp

@@ -95,16 +95,39 @@ File::saveToFile() {
         return false;
     }
 
-    if(!writer.writeArray(arrayView(_magicBytes)) ||
-       !writer.writeUint32(_saveVersion)          ||
-       !writer.writeUint32(_packageVersion)       ||
-       !writer.writeUint16(_engineVersion.major)  ||
+    if(!writer.writeArray(arrayView(_magicBytes))) {
+        _lastError = "Couldn't write the magic bytes."_s;
+        LOG_ERROR(_lastError);
+        return false;
+    }
+
+    if(!writer.writeUint32(_saveVersion)) {
+        _lastError = "Couldn't write the save version."_s;
+        LOG_ERROR(_lastError);
+        return false;
+    }
+
+    if(!writer.writeUint32(_packageVersion)) {
+        _lastError = "Couldn't write the package version."_s;
+        LOG_ERROR(_lastError);
+        return false;
+    }
+
+    if(_saveVersion == 3) {
+        if(!writer.writeUint32(_unknown)) {
+            _lastError = "Couldn't write some unknown bytes."_s;
+            LOG_ERROR(_lastError);
+            return false;
+        }
+    }
+
+    if(!writer.writeUint16(_engineVersion.major) ||
        !writer.writeUint16(_engineVersion.minor) ||
        !writer.writeUint16(_engineVersion.patch) ||
        !writer.writeUint32(_engineVersion.build) ||
        !writer.writeUEString(_engineVersion.buildId))
     {
-        _lastError = "Couldn't write the header."_s;
+        _lastError = "Couldn't write the engine version."_s;
         LOG_ERROR(_lastError);
         return false;
     }
@@ -198,15 +221,53 @@ File::loadData() {
         return;
     }
 
-    if(!reader.readUint32(_saveVersion)         ||
-       !reader.readUint32(_packageVersion)      ||
-       !reader.readUint16(_engineVersion.major) ||
-       !reader.readUint16(_engineVersion.minor) ||
-       !reader.readUint16(_engineVersion.patch) ||
-       !reader.readUint32(_engineVersion.build) ||
-       !reader.readUEString(_engineVersion.buildId))
+    if(!reader.readUint32(_saveVersion)) {
+        _lastError = "Couldn't read save version.";
+        LOG_ERROR(_lastError);
+        return;
+    }
+
+    if(!reader.readUint32(_packageVersion)) {
+        _lastError = "Couldn't read package version.";
+        LOG_ERROR(_lastError);
+        return;
+    }
+
+    if(_saveVersion == 3) {
+        if(!reader.readUint32(_unknown)) {
+            _lastError = "Couldn't read some unknown bytes.";
+            LOG_ERROR(_lastError);
+            return;
+        }
+    }
+
+    if(!reader.readUint16(_engineVersion.major)) {
+        _lastError = "Couldn't read major engine version.";
+        LOG_ERROR(_lastError);
+        return;
+    }
+
+    if(!reader.readUint16(_engineVersion.minor)) {
+        _lastError = "Couldn't read minor engine version.";
+        LOG_ERROR(_lastError);
+        return;
+    }
+
+    if(!reader.readUint16(_engineVersion.patch)) {
+        _lastError = "Couldn't read patch engine version.";
+        LOG_ERROR(_lastError);
+        return;
+    }
+
+    if(!reader.readUint32(_engineVersion.build)) {
+        _lastError = "Couldn't read engine build.";
+        LOG_ERROR(_lastError);
+        return;
+    }
+
+    if(!reader.readUEString(_engineVersion.buildId))
     {
-        _lastError = "Couldn't read version data.";
+        _lastError = "Couldn't read engine build ID string.";
         LOG_ERROR(_lastError);
         return;
     }

src/Gvas/File.h

@@ -17,7 +17,6 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 #include <Corrade/Containers/ArrayView.h>
-#include <Corrade/Containers/GrowableArray.h>
 #include <Corrade/Containers/Reference.h>
 #include <Corrade/Containers/StaticArray.h>
 #include <Corrade/Containers/String.h>
@@ -73,6 +72,7 @@ class File {
 
         std::uint32_t _saveVersion = 0;
         std::uint32_t _packageVersion = 0;
+        std::uint32_t _unknown = 0;
         struct {
             std::uint16_t      major = 0;
             std::uint16_t      minor = 0;