Adding support for .vdf files (Linux, from GOG games)

[MatteoAlberghini]

Is your feature request related to a problem? Please describe.
When installing games from GOG, some games have .vdf files (native Linux games). They pretty much tell the OS how to symlink files and what files need certain permissions.

Launchers such as Heroic manage to parse and run this .vdf files, so the user never sees them running.

Describe the solution you'd like
When moving a game into storage, the symlink files need to be excluded (this is pretty easy with rsync commands, but this is besides the point) but when the files are served the .vdf files should be parsed and run to be sure the game can actually run correctly

Describe alternatives you've considered
I made my own script for certain games, for example, from this installscript_linux.vdf (NOTE: this seems to be the default name for Linux games from GOG):

"Installscript"
{
	"version"	"2"
	"symlink"
	{
		"0"
		{
			"link"	"libc++.so.1"
			"target"	"libc++.so.1.0"
		}
		"1"
		{
			"link"	"libc++abi.so.1"
			"target"	"libc++abi.so.1.0"
		}
		"2"
		{
			"link"	"libjpeg.so.8"
			"target"	"libjpeg.so.8.0.2"
		}
		"3"
		{
			"link"	"libpcre.so.3"
			"target"	"libpcre.so.3.13.1"
		}
		"4"
		{
			"link"	"libpng16.so.16"
			"target"	"libpng16.so.16.18.0"
		}
		"5"
		{
			"link"	"libGLEW.so.1.10"
			"target"	"libGLEW.so.1.10.0"
		}
		"6"
		{
			"link"	"libopenal.so.1"
			"target"	"libopenal.so.1.15.1"
		}
		"7"
		{
			"link"	"libXss.so.1"
			"target"	"libXss.so.1.0.0"
		}

	}
	"chmod"
	{
		"0"
		{
			"file"	"EoCApp"
			"mode"	"755"
		}
		"1"
		{
			"file"	"libc++.so.1.0"
			"mode"	"755"
		}
		"2"
		{
			"file"	"libc++abi.so.1.0"
			"mode"	"755"
		}
		"3"
		{
			"file"	"libCoreLib.so"
			"mode"	"755"
		}
		"4"
		{
			"file"	"libGameEngine.so"
			"mode"	"755"
		}
		"5"
		{
			"file"	"libicudata.so.54"
			"mode"	"755"
		}
		"6"
		{
			"file"	"libicuuc.so.54"
			"mode"	"755"
		}
		"7"
		{
			"file"	"libjpeg.so.8.0.2"
			"mode"	"755"
		}
		"8"
		{
			"file"	"libOGLBinding.so"
			"mode"	"755"
		}
		"9"
		{
			"file"	"libosiris.so.2"
			"mode"	"755"
		}
		"10"
		{
			"file"	"libpcre.so.3.13.1"
			"mode"	"755"
		}
		"11"
		{
			"file"	"libpng16.so.16.18.0"
			"mode"	"755"
		}
		"12"
		{
			"file"	"libRenderFramework.so"
			"mode"	"755"
		}
		"13"
		{
			"file"	"libSDL2-2.0.so.1"
			"mode"	"755"
		}
		"14"
		{
			"file"	"libsteam_api.so"
			"mode"	"755"
		}
		"15"
		{
			"file"	"runner.sh"
			"mode"	"755"
		}
		"16"
		{
			"file"	"libGLEW.so.1.10.0"
			"mode"	"755"
		}
		"17"
		{
			"file"	"libopenal.so.1.15.1"
			"mode"	"755"
		}
		"18"
		{
			"file"	"libXss.so.1.0.0"
			"mode"	"755"
		}
		"19"
		{
			"file"	"libbink2.so"
			"mode"	"755"
		}

	}
}

the script would look like:

#!/bin/bash
cd "$(dirname "$0")/game"
ln -sf libc++.so.1.0 libc++.so.1
ln -sf libc++abi.so.1.0 libc++abi.so.1
ln -sf libjpeg.so.8.0.2 libjpeg.so.8
ln -sf libpcre.so.3.13.1 libpcre.so.3
ln -sf libpng16.so.16.18.0 libpng16.so.16
ln -sf libGLEW.so.1.10.0 libGLEW.so.1.10
ln -sf libopenal.so.1.15.1 libopenal.so.1
ln -sf libXss.so.1.0.0 libXss.so.1
chmod 755 EoCApp runner.sh libc++.so.1.0 libc++abi.so.1.0 libCoreLib.so libGameEngine.so libicudata.so.54 libicuuc.so.54 libjpeg.so.8.0.2 libOGLBinding.so libosiris.so.2 libpcre.so.3.13.1 libpng16.so.16.18.0 libRenderFramework.so libSDL2-2.0.so.1 libsteam_api.so libGLEW.so.1.10.0 libopenal.so.1.15.1 libXss.so.1.0.0 libbink2.so

Additional context
I am on the discord if needed, username: 0x6d61646f

[MatteoAlberghini]

I know this might not be priority, but since this is something that needs to run only on the client (since symlinking and chmod need to run on the platform) I can take a look at it.

EDIT: Let me know if its ok if I submit a feature request for it, I have not took a look at the code yet but I might be able this weekend :)

According to some searching (and reading Heroic gogdl) the .vdf file name is not consistent

Idea is (after install and checksums passed):

• Look for .vdf files in the installed folder
• Parse the .vdf file, which should look something like:

"Installscript"
{
    "symlink"
    {
        "0" { "link" "libc++.so.1" "target" "libc++.so.1.0" }
    }
    "chmod"
    {
        "0" { "file" "EoCApp" "mode" "755" }
    }
}

• For each instruction, execute chmod or symlink commands

I would first look at https://github.com/Heroic-Games-Launcher/heroic-gogdl/tree/main/gogdl/dl, unsure where they do the parsing after downloading but it should not be very complicated (famous last words)