From 698589806abeb50e53c39570a5230b0c92665a20 Mon Sep 17 00:00:00 2001
From: Alexander Medvedev <lilalexmed@proton.me>
Date: Fri, 5 Dec 2025 16:57:41 +0100
Subject: [PATCH] fix: don't crash when failed to lock session.lock

fix: https://github.com/Pumpkin-MC/Pumpkin/issues/1212
fix: https://github.com/Pumpkin-MC/Pumpkin/issues/1194
---
 pumpkin-world/src/lock/anvil.rs | 14 +++++++++++---
 pumpkin-world/src/lock/mod.rs   |  2 ++
 pumpkin/src/server/mod.rs       | 15 ++++++++++-----
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/pumpkin-world/src/lock/anvil.rs b/pumpkin-world/src/lock/anvil.rs
index f314c6bab..029a7d75d 100644
--- a/pumpkin-world/src/lock/anvil.rs
+++ b/pumpkin-world/src/lock/anvil.rs
@@ -1,6 +1,10 @@
 use super::{LevelLocker, LockError};
 
-use std::{fs::File, io::Write, path::Path};
+use std::{
+    fs::{File, TryLockError},
+    io::Write,
+    path::Path,
+};
 
 pub struct AnvilLevelLocker {
     _locked_file: File,
@@ -23,8 +27,12 @@ impl LevelLocker<Self> for AnvilLevelLocker {
         // im not joking, mojang writes a snowman into the lock file
         file.write_all(SNOWMAN)
             .map_err(|_| LockError::FailedWrite)?;
-        file.try_lock()
-            .map_err(|_| LockError::AlreadyLocked(SESSION_LOCK_FILE_NAME.to_string()))?;
+        file.try_lock().map_err(|e| match e {
+            TryLockError::WouldBlock => {
+                LockError::AlreadyLocked(SESSION_LOCK_FILE_NAME.to_string())
+            }
+            TryLockError::Error(io_err) => LockError::Error(io_err),
+        })?;
         Ok(Self { _locked_file: file })
     }
 }
diff --git a/pumpkin-world/src/lock/mod.rs b/pumpkin-world/src/lock/mod.rs
index de43a3339..608ba855b 100644
--- a/pumpkin-world/src/lock/mod.rs
+++ b/pumpkin-world/src/lock/mod.rs
@@ -13,6 +13,8 @@ pub trait LevelLocker<T>: Send + Sync {
 pub enum LockError {
     #[error("Oh no, Level is already locked by {0}")]
     AlreadyLocked(String),
+    #[error("{0}")]
+    Error(std::io::Error),
     #[error("Failed to write into lock file")]
     FailedWrite,
 }
diff --git a/pumpkin/src/server/mod.rs b/pumpkin/src/server/mod.rs
index 0b3ba57da..1f1ed53fe 100644
--- a/pumpkin/src/server/mod.rs
+++ b/pumpkin/src/server/mod.rs
@@ -102,7 +102,7 @@ pub struct Server {
     world_info_writer: Arc<dyn WorldInfoWriter>,
     // Gets unlocked when dropped
     // TODO: Make this a trait
-    _locker: Arc<AnvilLevelLocker>,
+    _locker: Arc<Option<AnvilLevelLocker>>,
 }
 
 impl Server {
@@ -138,10 +138,15 @@ impl Server {
                 fs::copy(dat_path, backup_path).unwrap();
             }
         }
-        // if we fail to lock, lets crash ???. maybe not the best solution when we have a large server with many worlds and one is locked.
-        // So TODO
-        let locker = AnvilLevelLocker::lock(&world_path).expect("Failed to lock level");
-
+        let locker = match AnvilLevelLocker::lock(&world_path) {
+            Ok(l) => Some(l),
+            Err(err) => {
+                log::warn!(
+                    "Could not lock the level file. Data corruption is possible if the world is accessed by multiple processes simultaneously. Error: {err}"
+                );
+                None
+            }
+        };
         let player_data_path = world_path.join("playerdata");
 
         let level_info = level_info.unwrap_or_else(|err| {