feature: add --executable flag

Some mods are launched through a executable different from
`eldenring.exe` or `launch_game_protected.exe`. Because of that
its useful to be able to explicitly specify the path.

Also fixes some linter warnings.

README.md

@@ -16,6 +16,7 @@ A tool aimed at enhancing the experience when playing the game on linux through
 1. Copy the file `er-patcher` to the game directory.
 2. In steam, set the game launch options to `python er-patcher ARGS -- %command%` See [Features](#features) for available options.
   - Example: `python er-patcher --all --rate 30 --disable-rune-loss -- %command%`
+  - Example using the [seamless co-op](https://www.nexusmods.com/eldenring/mods/510) mod: `python er-patcher --all --executable launch_elden_ring_seamlesscoop.exe -- %command%`
   - Example using [MangoHud](https://github.com/flightlessmango/MangoHud) and wine fullscreen FSR: `python er-patcher --rate 144 -uvca -- env WINE_FULLSCREEN_FSR=1 MANGOHUD=1 MANGOHUD_CONFIG=histogram %command%`
 3. Launch the game through steam. `er-patcher` automatically launches a patched version of `eldenring.exe` with EAC disabled.
 
@@ -26,9 +27,10 @@ Note: There might be some distros (e.g. older Ubuntu releases) that launch pytho
 | Argument                                | Description                                                                                               |
 | --------------------------------------- | --------------------------------------------------------------------------------------------------------- |
 | `-r RATE` or `--rate RATE`              | Set a custom framerate limit (default: 60).                                                               |
-| `--with-eac`                            | Run game with EAC (Use it at your own risk)                                                               |
+| `-x EXE` or `--executable EXE`          | The executable to launch, relative to the games folder.<br>Mutually exclusive with `--with-eac`.          |
+| `--with-eac`                            | Run game with EAC (Use it at your own risk).<br>Mutually exclusive with `--executable`.                   |
 | `--disable-rune-loss`                   | Disable losing runes upon death.                                                                          |
-| `--all`                                 | Enable all options except `--rate` and<br>gameplay changes like `--disable-rune-loss`.                    |
+| `--all`                                 | Enable all options except `--rate`, `--executable`, and<br>gameplay changes like `--disable-rune-loss`.   |
 | `-u` or `--ultrawide`                   | Remove black bars.                                                                                        |
 | `-v` or `--disable-vigniette`           | Remove the vigniette overlay.                                                                             |
 | `-c` or `--disable-ca`                  | Disable chromatic abberation.                                                                             |

er-patcher

@@ -1,6 +1,5 @@
 #!/usr/bin/env python3
 
-import os
 import sys
 import subprocess
 import argparse
@@ -17,6 +16,7 @@ if __name__ == "__main__":
     parser = argparse.ArgumentParser(description="Patch Elden Ring executable and launch it without EAC.")
 
     parser.add_argument("-r", "--rate", type=int, default=60, help="Modify the frame rate limit (e.g. 30, 120, 165 or whatever).")
+    parser.add_argument("-x", "--executable", action='store', type=str, default="eldenring.exe", help="The executable to launch, relative to the games folder.")
     parser.add_argument("--with-eac", action='store_true', help="Run game with EAC (Use at own your risk)")
     parser.add_argument("--disable-rune-loss", action='store_true', help="Disable losing runes upon death.")
     parser.add_argument("--all", action='store_true', help="Enable all options except rate adjustment and gamplay changes like `--disable-rune-loss`.")
@@ -28,6 +28,10 @@ if __name__ == "__main__":
     parser.add_argument("-f", "--remove-60hz-fullscreen", action='store_true', help="Remove 60hz lock in fullscreen.")
     patch = parser.parse_args(patcher_args)
 
+    if patch.with_eac and patch.executable != "eldenring.exe":
+        print("er-patcher: --with-eac is mutually exclusive with --executable")
+        sys.exit(1)
+
     game_dir = Path(".")
     with open(game_dir / "eldenring.exe", "rb") as f:
         exe_hex = f.read().hex()
@@ -134,7 +138,7 @@ if __name__ == "__main__":
 
     # start patched exe directly to avoid EAC
     steam_cmd = sys.argv[1 + sys.argv.index("--"):]
-    steam_cmd[-1] = Path(steam_cmd[-1]).parent.absolute() / game_dir_patched / ("start_protected_game.exe" if patch.with_eac else "eldenring.exe")
+    steam_cmd[-1] = Path(steam_cmd[-1]).parent.absolute() / game_dir_patched / ("start_protected_game.exe" if patch.with_eac else patch.executable)
     subprocess.run(steam_cmd, cwd=steam_cmd[-1].parent.absolute())
 
     # cleanup