modified appinfo.vdf is rejected by Steam

[magiruuvelvet]

During a research how the appinfo.vdf file works I found your project. I started playing around with it as I plan to rename some game titles in my local library. But the problem is Steam rejects the newly created appinfo.vdf and just deletes it and starts a sync from the Steam cloud. Also adding the immutable flag (chattr +i) to the file doesn't help; Steam just ignores it and loads a temporary appinfo into memory. :/

The console output of the Steam client never mentions the file or any other meaningful information.

Here is the snippet I'm currently trying:

from collections import OrderedDict;
from steamfiles import appinfo;

with open("/ssd/steam/appcache/appinfo.vdf~", "rb") as f:
    data = appinfo.load(f, wrapper=OrderedDict);

with open("/ssd/steam/appcache/appinfo.vdf", "wb") as f:
    appinfo.dump(data, f);

I don't change anything and save back the data immediately to no avail.

Reading data from it works though. A snippet to list all games in the library:

for k,v in data.items():
    try:
        appinfo2 = v["sections"][b"appinfo"][b"common"];
        if (appinfo2[b"type"] == b"Game"):
            name = appinfo2[b"name"].decode("utf-8");
            print(k, name);

    except:
        # silently skip incompatible entries
        continue;

The file hash changes every time when Steam syncs back the file from Steam cloud. The file saved from your tool also have a different hash each time.

Do you have any idea what could be wrong; or am I missing something?

EDIT: I'm using the latest Steam Client Beta on Linux

EDIT2: Here are the 2 appinfo.vdf files, the original the Steam client created and the "unchanged" modified appinfo from the snippet above. appinfo.zip

[leovp]

@magiruuvelvet After a brief investigation of the original VDF, I found out that in [app_id = 17500]['sections'][b'appinfo'][b'extended'], the key-value pair {"serverbrowsername": "Zombie Panic! Source'"} repeats twice. So 1 byte for the type of value, plus lengths of these two null-terminated strings is 40. And the difference between two VDF files is 40 bytes...

Not sure yet what to do with this. Sounds like two different problems: what to do when our assumption about non-repeating keys breaks, and Steam rejecting the changed file.

I'll play around with issue 1 and try to find other files with the same problem. As for point 2, it was never a guarantee that Steam won't outright reject the file with even minor changes.. I'd say it makes sense, even.

[Ajax001by7]

Hi magiruuvelvet, can you tell me about how the appinfo.vdf file works?

[Ajax001by7]

What is changing in the appinfo.vdf file? What is it there for? How is Steam using it? What is its importance?

[mirh]

Appinfo is where the "configuration" of all games is stored, from launch parameters to supported languages and features, to even just the name of appids itself. I can also report like OP that "blindly editing the file" is reset as soon as possible... Though SteamEdit seems able to do that just fine. EDIT: maybe there's the size of the data area to respect/fix?

[pdfrod]

When the section data changes, the checksum of the section needs to recomputed (as explained here, otherwise Steam will consider the file as invalid and throw it away.