Unreal Engine Asset Reader

About

This project contains a set of classes that can be used to read contents of Unreal Engine 4 asset files (.uasset and .uexp).

Not all Unreal Engine property types are currently implemented as the list is rather extensive, however the most common ones are available:

FArrayProperty
FBoolProperty
FFloatProperty
FIntProperty
FObjectProperty
FStrProperty
FStructProperty

To add support for additional properties declare a new property class by extending FProperty and implement an associated method in the UPropertyReader.

Usage

Opening file streams

To read asset files first instantiate a new Stream either by calling

using Stream headerStream = File.OpenRead(pathToHeader);

or by using the helper method available in StreamUtils:

using Stream headerStream = StreamUtils.CreateStreamFromPath(pathToHeader);

Reading package file summary

Once the header stream is successfully created instantiate a header file reader and extract the package file summary:

var headerReader = new UHeaderReader(headerStream);
FPackageFileSummary summary = headerReader.ReadFPackageFileSummary();

Package file summary contains a variety of information about the asset, such as string names used in these files as well as lists of imports and exports contained in the data file (same as the header file in older versions of Unreal Engine).

Populating global lists

Next read the lists of available names, exports and imports and store them globally on the associated manager classes:

UNameManager.NameList = headerReader.ReadFNameEntryList(summary);
UObjectLinker.ExportList = headerReader.ReadFObjectExportList(summary);
List<FObjectImport> exportList = headerReader.ReadFObjectImportList(summary);
UObjectLinker.ImportList = exportList;

Reading exports and their properties

Once package information has been read and name manager and object linker lists have been updated, instantiate a new export reader:

using Stream exportStream = StreamUtils.CreateStreamFromPath(pathToExport);
var exportReader = new UPropertyReader(exportStream, logger);

Finally read properties of every export and store them in the way you prefer, e.g. in tuples:

List<Tuple<FObjectExport, List<FProperty>>> exports = exportList.ConvertAll(
    export =>
    {
        List<FProperty> properties = exportReader.ReadProperties(summary, export);
        return new Tuple<FObjectExport, List<FProperty>>(export, properties);
    });

At this point you can process the list of exports how you like, be it by filtering or serializing to JSON.

Command Line Interface

The included CLI application can used by specifying the source header file path as the --header option:

./UAssetReader --header "/path/to/header/file"

Additionally if the export data file does not reside in the same directory (with the .uexp extension) then you can manually specify its location by including the --export option:

./UAssetReader --header "/path/to/header/file" --export "/path/to/export/file"

As can be seen in the source code of the Program class properties will only be read and will not be printed to the output so it is up to the user to implement such functionality.

codeaid/UAssetReader