Unkown FPropertyType: TextProperty

[JasonGilley]

Just got your project and ran it with this file:

SaveGame1.zip

I don't know enough about the structure, or have documentation to debug it easily. Can you shed some light? Thanks.

[SparkyTD]

Your save file is 19 megabytes, and it's full of data structures that seem to be non-standard. Most saves that I've tested this on are less than 100 KB in size.

I'll look into it, but I can't promise anything. This would be the ultimate stress-test for this project.

May I ask what game it's from?

[JasonGilley]

It’s from BreathEdge. I think most of the data is locations for objects you’ve moved around in the game. No worries. The reason I needed your code was to fix a save game file. I’ve since resolved the problem, but don’t know if something like it would creep up again. A general purpose Unreal Engine save game editor, though, would be handy. Looks like no one has yet to make one successfully. If I’m forced to, I could probably figure it out via the UE source code, but figured someone probably had already done it. Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows From: ***@***.***> Sent: Saturday, February 19, 2022 5:16 PM To: ***@***.***> Cc: ***@***.***>; ***@***.***> Subject: Re: [SparkyTD/UnrealEngine.Gvas] Unkown FPropertyType: TextProperty (Issue #1) Your save file is 19 megabytes, and it's full of data structures that seem to be non-standard. Most saves that I've tested this on are less than 100 KB in size. I'll look into it, but I can't promise anything. This would be the ultimate stress-test for this project. May I ask what game it's from? — Reply to this email directly, view it on GitHub<#1 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AC2C4N7COMLTMIKMEDZG2HTU4AQFZANCNFSM5O3OQ4HA>. Triage notifications on the go with GitHub Mobile for iOS<https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android<https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[SparkyTD]

I've tried other projects that are supposed to parse UE4 saves, but as far as I can tell, mine is the most complete. As the readme states, it can fully parse, edit and save GVAS files from 5 different games, without any problems. (more specifically, it can read the file, parse it, write it back to the disk, and the hash of this new file will match the original if no edits were made).

I'll definitely try to make your files work when I have time. In the meantime, if you would like to try it yourself, use this project as a base, PRs are welcome. The way it works is pretty simple: For each UE4 data type there is a corresponding class in the FProperties folder (e.g. TextProperty -> FTextProperty.cs). When the parser is reading a data field, it tries to locate the class with the matching name. So if you want to implement a new data type, you just have to create a new class for it in the FProperties folder, everything else is handled automatically. Most of the reading/parsing logic is in the FProperty class.

So far I've found two issues with your save file:

• The TextProperty type does not exist. Strangely, none of the games I've tried this with use this data type. This seems like more than just a string, and I don't yet fully understand the data format. I've implemented a very basic parser for it just to get rid of the exception, and I'll push the commit in a minute, but there are data fields in it that I don't understand. UE4 source code wasn't helpful either.
• There is a StackOverflowException in the main property reader method due to an infinite recursion, after it tries to read a StructProeprty. I don't know why this happens, it probably fails to detect the end of a complex struct object, and it keeps reading it recursively. Kind of hard to debug, because I don't know the overall structure of your save file.

Here's a rough overview of what a single property looks like, in case you want to help:

• Property Name (FString, e.g. "GameVersion")
• Property Type (FString, e.g. "StrProperty")
• Field Length (uint64, the length of the data)
• Has GUID? (uint8/bool, some data types might store a GUID before the data, but only if this bool is true)
• GUID (16 bytes, optional, only present if previous byte is 1)
• Data (this depends on the data type. In case of the GameVersion, it's an FString with the value "1.0.0.0")

There are of course more complex types like Arrays, Maps and Structs that can have multiple fields.

Note, that the UE source code is insanely complex, trying to reverse-engineer the file itself is much easier than trying to understand the code in my opinion. If you still want to try using the UE4 code, than you'll want to look at the FArchive class, as it represents the data section of a save file. You can create an FArchive object, add data fields to it, write it to a file or the console in hex, and analyze the data.

[funjoker]

Longvinter Placeable.sav
Also unparseable atm.