Update Upstream (Folia)

* Add an option to crash on broken Linear symlink

* Refactoring Crash on broken symlink

---------

Co-authored-by: Sofiane H. Djerbi <46628754+kugge@users.noreply.github.com>

README.md

@@ -12,13 +12,36 @@
 
 ## Features
 
-### Additions
-- **Xymb Linear Format**: Saves about 50% of disk space in OW and Nether and 95% in The End.
-- **Auto update**: Update upstream everyday.
+### Main additions
+- **Xymb Linear Format**: Saves about 50% of disk space in OW/Nether and 95% in The End.
+- **Auto update**: Automatic upstream updates.
+
+### Configuration
+
+```yaml
+region-format:
+  debug: false
+network:
+  send-null-entity-packets: true
+  alternate-keepalive: false
+gameplay:
+  server-mod-name: Kaiiju
+world-settings:
+  default:
+    region-format:
+      format: LINEAR
+      linear:
+        compression-level: 1
+        crash-on-broken-symlink: true
+    gameplay:
+      shulker-box-drop-contents-when-destroyed: true
+```
 
 ### Roadmap
-- **Static view distance**: Reduce RAM usage with a "cached" view distance.
-- **Native world conversion**: Convert region file format at startup
+- **Static view distance**: Reduce RAM usage / Region size with a "static" view distance.
+- **Linear timestamps**: Add chunk timestamps to linear region files.
+- **Native world conversion**: Convert region file format at startup.
+- **Stash deduplication**: Make giant dupe stashes possible and lagless.
 
 ## Building
 
@@ -29,5 +52,3 @@
 
 ## License
 Original patches are licensed under GPL-3.0.
-
-Made with <span style="color: #e25555;">&#9829;</span> on Earth.

build.gradle.kts

@@ -3,8 +3,8 @@ import io.papermc.paperweight.util.constants.*
 
 plugins {
     java
-    id("com.github.johnrengelman.shadow") version "7.1.2"
-    id("io.papermc.paperweight.patcher") version "1.5.1"
+    id("com.github.johnrengelman.shadow") version "8.1.1"
+    id("io.papermc.paperweight.patcher") version "1.5.4"
 }
 
 allprojects {
@@ -30,8 +30,8 @@ repositories {
 
 dependencies {
     remapper("net.fabricmc:tiny-remapper:0.8.6:fat")
-    decompiler("net.minecraftforge:forgeflower:2.0.627.2")
-    paperclip("io.papermc:paperclip:3.0.2")
+    decompiler("net.minecraftforge:forgeflower:2.0.629.0")
+    paperclip("io.papermc:paperclip:3.0.3")
 }
 
 subprojects {
@@ -72,36 +72,35 @@ paperweight {
             serverOutputDir.set(layout.projectDirectory.dir("kaiiju-server"))
         }
     }
+}
 
-    tasks.register("foliaRefLatest") {
-        // Update the foliaRef in gradle.properties to be the latest commit.
-        val tempDir = layout.cacheDir("foliaRefLatest");
-        val file = "gradle.properties";
+tasks.register("foliaRefLatest") {
+    // Update the foliaRef in gradle.properties to be the latest commit.
+    val tempDir = layout.cacheDir("foliaRefLatest");
+    val file = "gradle.properties";
         
-        doFirst {
-            data class GithubCommit(
-                    val sha: String
-            )
+    doFirst {
+        data class GithubCommit(
+                val sha: String
+        )
 
-            val foliaLatestCommitJson = layout.cache.resolve("foliaLatestCommit.json");
-            download.get().download("https://api.github.com/repos/PaperMC/Folia/commits/master", foliaLatestCommitJson);
-            val foliaLatestCommit = gson.fromJson<paper.libs.com.google.gson.JsonObject>(foliaLatestCommitJson)["sha"].asString;
+        val foliaLatestCommitJson = layout.cache.resolve("foliaLatestCommit.json");
+        download.get().download("https://api.github.com/repos/PaperMC/Folia/commits/master", foliaLatestCommitJson);
+        val foliaLatestCommit = gson.fromJson<paper.libs.com.google.gson.JsonObject>(foliaLatestCommitJson)["sha"].asString;
 
-            copy {
-                from(file)
-                into(tempDir)
-                filter { line: String ->
-                    line.replace("foliaRef = .*".toRegex(), "foliaRef = $foliaLatestCommit")
-                }
-            }
-        }
-
-        doLast {
-            copy {
-                from(tempDir.file("gradle.properties"))
-                into(project.file(file).parent)
+        copy {
+            from(file)
+            into(tempDir)
+            filter { line: String ->
+                line.replace("foliaRef = .*".toRegex(), "foliaRef = $foliaLatestCommit")
             }
         }
     }
-}
 
+    doLast {
+        copy {
+            from(tempDir.file("gradle.properties"))
+            into(project.file(file).parent)
+        }
+    }
+}

gradle.properties

@@ -2,7 +2,7 @@ group = dev.kaiijumc.kaiiju
 version = 1.19.4-R0.1-SNAPSHOT
 mcVersion = 1.19.4
 
-foliaRef = 25e0cbdae46912d227a31703869594538b731931
+foliaRef = ce49776448d6fbd3c3bd399721e238efb2c6ab2e
 
 org.gradle.caching=true
 org.gradle.parallel=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.0.2-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.1-bin.zip
+networkTimeout=10000
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -1,7 +1,7 @@
-#!/usr/bin/env sh
+#!/bin/sh
 
 #
-# Copyright 2015 the original author or authors.
+# Copyright © 2015-2021 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -17,67 +17,98 @@
 #
 
 ##############################################################################
-##
-##  Gradle start up script for UN*X
-##
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
 ##############################################################################
 
 # Attempt to set APP_HOME
+
 # Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
 done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
 
-APP_NAME="Gradle"
-APP_BASE_NAME=`basename "$0"`
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD="maximum"
+MAX_FD=maximum
 
 warn () {
     echo "$*"
-}
+} >&2
 
 die () {
     echo
     echo "$*"
     echo
     exit 1
-}
+} >&2
 
 # OS specific support (must be 'true' or 'false').
 cygwin=false
 msys=false
 darwin=false
 nonstop=false
-case "`uname`" in
-  CYGWIN* )
-    cygwin=true
-    ;;
-  Darwin* )
-    darwin=true
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
 esac
 
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
@@ -87,9 +118,9 @@ CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 if [ -n "$JAVA_HOME" ] ; then
     if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
         # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD="$JAVA_HOME/jre/sh/java"
+        JAVACMD=$JAVA_HOME/jre/sh/java
     else
-        JAVACMD="$JAVA_HOME/bin/java"
+        JAVACMD=$JAVA_HOME/bin/java
     fi
     if [ ! -x "$JAVACMD" ] ; then
         die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
@@ -98,7 +129,7 @@ Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
     fi
 else
-    JAVACMD="java"
+    JAVACMD=java
     which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
@@ -106,80 +137,109 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
-    if [ $? -eq 0 ] ; then
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
-            MAX_FD="$MAX_FD_LIMIT"
-        fi
-        ulimit -n $MAX_FD
-        if [ $? -ne 0 ] ; then
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
-        fi
-    else
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
-    fi
-fi
-
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
-
-# For Cygwin or MSYS, switch paths to Windows format before running java
-if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
-        fi
-        i=`expr $i + 1`
-    done
-    case $i in
-        0) set -- ;;
-        1) set -- "$args0" ;;
-        2) set -- "$args0" "$args1" ;;
-        3) set -- "$args0" "$args1" "$args2" ;;
-        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
 fi
 
-# Escape application args
-save () {
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
-    echo " "
-}
-APP_ARGS=`save "$@"`
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
 
-# Collect all arguments for the java command, following the shell quoting and substitution rules
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
 
 exec "$JAVACMD" "$@"

gradlew.bat

@@ -14,7 +14,7 @@
 @rem limitations under the License.
 @rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +25,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,7 +41,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -75,13 +76,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal

patches/server/0004-Kaiiju-RegionFormat-Linear.patch

@@ -109,10 +109,10 @@ index 0000000000000000000000000000000000000000..dcfbabf54b19a4c29d5c95830242c5c2
 +}
 diff --git a/src/main/java/dev/kaiijumc/kaiiju/region/LinearRegionFile.java b/src/main/java/dev/kaiijumc/kaiiju/region/LinearRegionFile.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696d4cdd0cc
+index 0000000000000000000000000000000000000000..245e3b1801c5f92054d9c0d0d8fc2a8fcfd6a1d4
 --- /dev/null
 +++ b/src/main/java/dev/kaiijumc/kaiiju/region/LinearRegionFile.java
-@@ -0,0 +1,336 @@
+@@ -0,0 +1,328 @@
 +package dev.kaiijumc.kaiiju.region;
 +
 +import com.github.luben.zstd.ZstdInputStream;
@@ -133,15 +133,25 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +import java.nio.file.Path;
 +import java.nio.file.StandardCopyOption;
 +import java.util.ArrayList;
++import java.util.Arrays;
 +import java.util.concurrent.locks.ReentrantLock;
 +
 +public class LinearRegionFile extends Thread implements AbstractRegionFile {
++    private static long SUPERBLOCK = -4323716122432332390L;
++    private static byte VERSION = 1;
++    private static int HEADER_SIZE = 32;
++    private static int FOOTER_SIZE = 8;
 +    private static final Logger LOGGER = LogUtils.getLogger();
-+    private final byte[][] buffer = new byte[32*32][];
-+    private final int[] bufferUncompressedSize = new int[32*32];
++
++
++    private final byte[][] buffer = new byte[1024][];
++    private final int[] bufferUncompressedSize = new int[1024];
 +
 +    private final Object markedToSaveLock = new Object();
-+    private final ChunkStatus[] statuses = new ChunkStatus[32 * 32];
++    private final ChunkStatus[] statuses = new ChunkStatus[1024];
++
++    private final LZ4Compressor compressor;
++    private final LZ4FastDecompressor decompressor;
 +
 +    private boolean markedToSave = false;
 +    private boolean close = false;
@@ -162,69 +172,60 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +    public LinearRegionFile(Path file, int compression) throws IOException {
 +        this.regionFile = file;
 +        this.compressionLevel = compression;
++
++        this.compressor = LZ4Factory.fastestInstance().fastCompressor();
++        this.decompressor = LZ4Factory.fastestInstance().fastDecompressor();
++
 +        File regionFile = new File(this.regionFile.toString());
 +
-+        LZ4Compressor compressor = LZ4Factory.fastestInstance().fastCompressor();
-+
-+        for (int i = 0; i < 32 * 32; i++)
-+            this.bufferUncompressedSize[i] = 0;
++        Arrays.fill(this.bufferUncompressedSize, 0);
 +
 +        if(regionFile.canRead()) {
-+            long fileLength = file.toFile().length();
 +            FileInputStream fileStream = new FileInputStream(regionFile);
 +            DataInputStream rawDataStream = new DataInputStream(fileStream);
 +
-+            long SUPERBLOCK = -4323716122432332390L;
-+            byte VERSION = 1;
-+            int HEADER_SIZE = 32;
-+            int FOOTER_SIZE = 8;
-+
 +            long superBlock = rawDataStream.readLong();
-+
 +            if (superBlock != SUPERBLOCK)
 +                throw new RuntimeException("Superblock invalid: " + superBlock + " file " + file);
 +
 +            byte version = rawDataStream.readByte();
-+
 +            if (version != VERSION)
 +                throw new RuntimeException("Version invalid: " + version + " file " + file);
 +
-+            rawDataStream.readLong(); // newestTimestamp
-+            rawDataStream.readByte(); // Compression level
-+            rawDataStream.readShort(); // Chunk count
-+            int dataCount = rawDataStream.readInt();
++            // Skip newestTimestamp (Long) + Compression level (Byte) + Chunk count (Short): Unused.
++            rawDataStream.skipBytes(11);
 +
++            int dataCount = rawDataStream.readInt();
++            long fileLength = file.toFile().length();
 +            if (fileLength != HEADER_SIZE + dataCount + FOOTER_SIZE)
 +                throw new IOException("File length invalid " + this.regionFile + " " + fileLength + " " + (HEADER_SIZE + dataCount + FOOTER_SIZE));
 +
-+            rawDataStream.readLong(); // Data Hash
-+            byte[] rawCompressed = new byte[dataCount];
++            rawDataStream.skipBytes(8); // Skip data hash (Long): Unused.
 +
++            byte[] rawCompressed = new byte[dataCount];
 +            rawDataStream.readFully(rawCompressed, 0, dataCount);
 +
 +            superBlock = rawDataStream.readLong();
-+
-+            if (superBlock != SUPERBLOCK) {
++            if (superBlock != SUPERBLOCK)
 +                throw new IOException("Footer superblock invalid " + this.regionFile);
-+            }
 +
 +            DataInputStream dataStream = new DataInputStream(new ZstdInputStream(new ByteArrayInputStream(rawCompressed)));
 +
-+            int[] starts = new int[32 * 32];
-+            for(int i = 0 ; i < 32 * 32 ; i++) {
++            int[] starts = new int[1024];
++            for(int i = 0; i < 1024; i++) {
 +                starts[i] = dataStream.readInt();
-+                dataStream.readInt(); // Skip timestamps
++                dataStream.skipBytes(4); // Skip timestamps (Int): Unimplemented TODO: Implement per-chunk timestamps
 +            }
 +
-+            for(int i = 0 ; i < 32 * 32 ; i++) {
++            for(int i = 0; i < 1024; i++) {
 +                if(starts[i] > 0) {
 +                    int size = starts[i];
 +                    byte[] b = new byte[size];
 +                    dataStream.readFully(b, 0, size);
 +
-+                    int maxCompressedLength = compressor.maxCompressedLength(size);
++                    int maxCompressedLength = this.compressor.maxCompressedLength(size);
 +                    byte[] compressed = new byte[maxCompressedLength];
-+                    int compressedLength = compressor.compress(b, 0, size, compressed, 0, maxCompressedLength);
++                    int compressedLength = this.compressor.compress(b, 0, size, compressed, 0, maxCompressedLength);
 +                    b = new byte[compressedLength];
 +                    System.arraycopy(compressed, 0, b, 0, compressedLength);
 +
@@ -264,9 +265,7 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +                }
 +                for(int i = 0 ; i < 100 ; i++) {
 +                    Thread.sleep(100);
-+                    if(close) {
-+                        return;
-+                    }
++                    if(close) return;
 +                }
 +            }
 +        } catch(InterruptedException ignored) {}
@@ -277,11 +276,8 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +    }
 +
 +    public synchronized void flush() throws IOException {
-+        if(!isMarkedToSave())
-+            return;
++        if(!isMarkedToSave()) return;
 +
-+        long SUPERBLOCK = -4323716122432332390L;
-+        byte VERSION = 1;
 +        long timestamp = System.currentTimeMillis() / 1000L;
 +        short chunkCount = 0;
 +
@@ -299,23 +295,21 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +        dataStream.writeLong(timestamp);
 +        dataStream.writeByte(this.compressionLevel);
 +
-+        LZ4FastDecompressor decompressor = LZ4Factory.fastestInstance().fastDecompressor();
-+
 +        ArrayList<byte[]> byteBuffers = new ArrayList<>();
-+        for(int i = 0 ; i < 32 * 32 ; i++) {
++        for(int i = 0; i < 1024; i++) {
 +            if(this.bufferUncompressedSize[i] != 0) {
 +                chunkCount += 1;
 +                byte[] content = new byte[bufferUncompressedSize[i]];
-+                decompressor.decompress(buffer[i], 0, content, 0, bufferUncompressedSize[i]);
++                this.decompressor.decompress(buffer[i], 0, content, 0, bufferUncompressedSize[i]);
 +
 +                byteBuffers.add(content);
 +            } else byteBuffers.add(null);
 +        }
-+        for(int i = 0 ; i < 32 * 32 ; i++) {
++        for(int i = 0; i < 1024; i++) {
 +            zstdDataStream.writeInt(this.bufferUncompressedSize[i]);
-+            zstdDataStream.writeInt(0);
++            zstdDataStream.writeInt(0); // TODO: IMPLEMENT PER CHUNK TIMESTAMPS
 +        }
-+        for(int i = 0 ; i < 32 * 32 ; i++) {
++        for(int i = 0; i < 1024; i++) {
 +            if(byteBuffers.get(i) != null)
 +                zstdDataStream.write(byteBuffers.get(i), 0, byteBuffers.get(i).length);
 +        }
@@ -345,14 +339,13 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +    }
 +
 +    public synchronized void write(ChunkPos pos, ByteBuffer buffer) {
-+        LZ4Compressor compressor = LZ4Factory.fastestInstance().fastCompressor();
 +        try {
 +            byte[] b = toByteArray(new ByteArrayInputStream(buffer.array()));
 +            int uncompressedSize = b.length;
 +
-+            int maxCompressedLength = compressor.maxCompressedLength(b.length);
++            int maxCompressedLength = this.compressor.maxCompressedLength(b.length);
 +            byte[] compressed = new byte[maxCompressedLength];
-+            int compressedLength = compressor.compress(b, 0, b.length, compressed, 0, maxCompressedLength);
++            int compressedLength = this.compressor.compress(b, 0, b.length, compressed, 0, maxCompressedLength);
 +            b = new byte[compressedLength];
 +            System.arraycopy(compressed, 0, b, 0, compressedLength);
 +
@@ -399,9 +392,8 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +    @Nullable
 +    public synchronized DataInputStream getChunkDataInputStream(ChunkPos pos) {
 +        if(this.bufferUncompressedSize[getChunkIndex(pos.x, pos.z)] != 0) {
-+            LZ4FastDecompressor decompressor = LZ4Factory.fastestInstance().fastDecompressor();
 +            byte[] content = new byte[bufferUncompressedSize[getChunkIndex(pos.x, pos.z)]];
-+            decompressor.decompress(this.buffer[getChunkIndex(pos.x, pos.z)], 0, content, 0, bufferUncompressedSize[getChunkIndex(pos.x, pos.z)]);
++            this.decompressor.decompress(this.buffer[getChunkIndex(pos.x, pos.z)], 0, content, 0, bufferUncompressedSize[getChunkIndex(pos.x, pos.z)]);
 +            return new DataInputStream(new ByteArrayInputStream(content));
 +        }
 +        return null;
@@ -432,7 +424,7 @@ index 0000000000000000000000000000000000000000..32213e1f2432a2ee0c27331e83a04696
 +    }
 +
 +    private static int getChunkIndex(int x, int z) {
-+        return (x & 31) + (z & 31) * 32;
++        return (x & 31) + ((z & 31) << 5);
 +    }
 +
 +    public boolean recalculateHeader() {
@@ -537,7 +529,7 @@ index 513833c2ea23df5b079d157bc5cb89d5c9754c0b..a62a1b281bd0b6ad7d59b45b9470d84f
          long expectedChunks = (long)regionFiles.length * (32L * 32L);
  
 diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
-index 6f12d91f73e04c25fb0bc9054dc7d49de16e614a..43503974433c4d1808b2acb2b79f46d640725dc0 100644
+index c8bc7db4c22f48047aa409f0bcff3ef8c4034781..5ad209fed6aef1992af0472ac0af0911d178a260 100644
 --- a/src/main/java/net/minecraft/server/level/ChunkMap.java
 +++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
 @@ -272,7 +272,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
@@ -558,7 +550,7 @@ index 6f12d91f73e04c25fb0bc9054dc7d49de16e614a..43503974433c4d1808b2acb2b79f46d6
          this.setViewDistance(viewDistance);
          // Paper start
          this.dataRegionManager = new io.papermc.paper.chunk.SingleThreadChunkRegionManager(this.level, 2, (1.0 / 3.0), 1, 6, "Data", DataRegionData::new, DataRegionSectionData::new);
-@@ -849,13 +849,13 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
+@@ -853,13 +853,13 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
  
      // Paper start - chunk status cache "api"
      public ChunkStatus getChunkStatusOnDiskIfCached(ChunkPos chunkPos) {
@@ -574,7 +566,7 @@ index 6f12d91f73e04c25fb0bc9054dc7d49de16e614a..43503974433c4d1808b2acb2b79f46d6
  
          if (regionFile == null || !regionFileCache.chunkExists(chunkPos)) {
              return null;
-@@ -873,7 +873,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
+@@ -877,7 +877,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
      }
  
      public void updateChunkStatusOnDisk(ChunkPos chunkPos, @Nullable CompoundTag compound) throws IOException {

patches/server/0011-Kaiiju-Linear-CrashOnBrokenSymlink.patch

@@ -0,0 +1,228 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Xymb <xymb@endcrystal.me>
+Date: Fri, 14 Apr 2023 02:12:58 +0200
+Subject: [PATCH] Kaiiju Linear CrashOnBrokenSymlink
+
+
+diff --git a/src/main/java/dev/kaiijumc/kaiiju/KaiijuWorldConfig.java b/src/main/java/dev/kaiijumc/kaiiju/KaiijuWorldConfig.java
+index bac11b0e30a86d0689693ff129b53bcad7c2034c..0f0cfd958f7d2c6d2ca4192be1b986900a2bfa53 100644
+--- a/src/main/java/dev/kaiijumc/kaiiju/KaiijuWorldConfig.java
++++ b/src/main/java/dev/kaiijumc/kaiiju/KaiijuWorldConfig.java
+@@ -127,6 +127,7 @@ public class KaiijuWorldConfig {
+ 
+     public List<String> regionFormatList = Arrays.asList("ANVIL", "LINEAR");
+     public String regionFormatName = "ANVIL";
++    public boolean linearCrashOnBrokenSymlink = true;
+     public int regionFormatLinearCompressionLevel = 1;
+ 
+     private void regionFormatSettings() {
+@@ -142,6 +143,7 @@ public class KaiijuWorldConfig {
+             log(Level.SEVERE, "Falling back to compression level 1.");
+             regionFormatLinearCompressionLevel = 1;
+         }
++        linearCrashOnBrokenSymlink = getBoolean("region-format.linear.crash-on-broken-symlink", linearCrashOnBrokenSymlink);
+     }
+ 
+     public boolean shulkerBoxDropContentsWhenDestroyed = true;
+diff --git a/src/main/java/io/papermc/paper/world/ThreadedWorldUpgrader.java b/src/main/java/io/papermc/paper/world/ThreadedWorldUpgrader.java
+index a62a1b281bd0b6ad7d59b45b9470d84f496f6539..7f87dfa131ab7d40a94cf6355765478f2961342e 100644
+--- a/src/main/java/io/papermc/paper/world/ThreadedWorldUpgrader.java
++++ b/src/main/java/io/papermc/paper/world/ThreadedWorldUpgrader.java
+@@ -86,10 +86,11 @@ public class ThreadedWorldUpgrader {
+         // Kaiiju start
+         String formatName = ((org.bukkit.craftbukkit.CraftWorld) org.bukkit.Bukkit.getWorld(worldName)).getHandle().kaiijuConfig.regionFormatName;
+         int linearCompression = ((org.bukkit.craftbukkit.CraftWorld) org.bukkit.Bukkit.getWorld(worldName)).getHandle().kaiijuConfig.regionFormatLinearCompressionLevel;
++        boolean linearCrashOnBrokenSymlink = ((org.bukkit.craftbukkit.CraftWorld) org.bukkit.Bukkit.getWorld(worldName)).getHandle().kaiijuConfig.linearCrashOnBrokenSymlink;
+         LOGGER.info("Using format " + formatName + " (" + linearCompression + ")");
+         // Kaiiju end
+         final WorldInfo info = new WorldInfo(() -> worldPersistentData,
+-                new ChunkStorage(formatName, linearCompression, regionFolder.toPath(), this.dataFixer, false), this.removeCaches, this.dimensionType, this.generatorKey); // Kaiiju
++                new ChunkStorage(formatName, linearCompression, linearCrashOnBrokenSymlink, regionFolder.toPath(), this.dataFixer, false), this.removeCaches, this.dimensionType, this.generatorKey); // Kaiiju
+ 
+         long expectedChunks = (long)regionFiles.length * (32L * 32L);
+ 
+diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
+index 43503974433c4d1808b2acb2b79f46d640725dc0..73ac94eaebdeaa94c83f1f23b53e686d867e6f98 100644
+--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
++++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
+@@ -272,7 +272,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
+     // Paper end
+ 
+     public ChunkMap(ServerLevel world, LevelStorageSource.LevelStorageAccess session, DataFixer dataFixer, StructureTemplateManager structureTemplateManager, Executor executor, BlockableEventLoop<Runnable> mainThreadExecutor, LightChunkGetter chunkProvider, ChunkGenerator chunkGenerator, ChunkProgressListener worldGenerationProgressListener, ChunkStatusUpdateListener chunkStatusChangeListener, Supplier<DimensionDataStorage> persistentStateManagerFactory, int viewDistance, boolean dsync) {
+-        super(world.getLevel().kaiijuConfig.regionFormatName, world.getLevel().kaiijuConfig.regionFormatLinearCompressionLevel, session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync); // Kaiiju
++        super(world.getLevel().kaiijuConfig.regionFormatName, world.getLevel().kaiijuConfig.regionFormatLinearCompressionLevel, world.getLevel().kaiijuConfig.linearCrashOnBrokenSymlink, session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync); // Kaiiju
+         // Paper - rewrite chunk system
+         this.tickingGenerated = new AtomicInteger();
+         //this.playerMap = new PlayerMap(); // Folia - region threading
+@@ -317,7 +317,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
+         this.lightEngine = new ThreadedLevelLightEngine(chunkProvider, this, this.level.dimensionType().hasSkyLight(), null, null); // Paper - rewrite chunk system
+         this.distanceManager = new ChunkMap.ChunkDistanceManager(executor, mainThreadExecutor);
+         this.overworldDataStorage = persistentStateManagerFactory;
+-        this.poiManager = new PoiManager(this.level.kaiijuConfig.regionFormatName, this.level.kaiijuConfig.regionFormatLinearCompressionLevel, path.resolve("poi"), dataFixer, dsync, iregistrycustom, world); // Kaiiju
++        this.poiManager = new PoiManager(this.level.kaiijuConfig.regionFormatName, this.level.kaiijuConfig.regionFormatLinearCompressionLevel, this.level.kaiijuConfig.linearCrashOnBrokenSymlink, path.resolve("poi"), dataFixer, dsync, iregistrycustom, world); // Kaiiju
+         this.setViewDistance(viewDistance);
+         // Paper start
+         this.dataRegionManager = new io.papermc.paper.chunk.SingleThreadChunkRegionManager(this.level, 2, (1.0 / 3.0), 1, 6, "Data", DataRegionData::new, DataRegionSectionData::new);
+diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
+index 20359c63b19c7e0c703ef1562fb774803d631c41..35ae624be25b66d5615dc19cbe7eb8785c7029b5 100644
+--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
++++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
+@@ -425,8 +425,8 @@ public class ServerLevel extends Level implements WorldGenLevel {
+     private final EntityRegionFileStorage entityStorage;
+ 
+     private static final class EntityRegionFileStorage extends net.minecraft.world.level.chunk.storage.RegionFileStorage {
+-        public EntityRegionFileStorage(String format, int linearCompression, Path directory, boolean dsync) { // Kaiiju
+-            super(format, linearCompression, directory, dsync); // Kaiiju
++        public EntityRegionFileStorage(String format, int linearCompression, boolean linearCrashOnBrokenSymlink, Path directory, boolean dsync) { // Kaiiju
++            super(format, linearCompression, linearCrashOnBrokenSymlink, directory, dsync); // Kaiiju
+         }
+ 
+         protected void write(ChunkPos pos, net.minecraft.nbt.CompoundTag nbt) throws IOException {
+@@ -632,7 +632,7 @@ public class ServerLevel extends Level implements WorldGenLevel {
+         // CraftBukkit end
+         boolean flag2 = minecraftserver.forceSynchronousWrites();
+         DataFixer datafixer = minecraftserver.getFixerUpper();
+-        this.entityStorage = new EntityRegionFileStorage(this.getLevel().kaiijuConfig.regionFormatName, this.getLevel().kaiijuConfig.regionFormatLinearCompressionLevel, convertable_conversionsession.getDimensionPath(resourcekey).resolve("entities"), flag2); // Paper - rewrite chunk system  //EntityPersistentStorage<Entity> entitypersistentstorage = new EntityStorage(this, convertable_conversionsession.getDimensionPath(resourcekey).resolve("entities"), datafixer, flag2, minecraftserver); // Kaiiju
++        this.entityStorage = new EntityRegionFileStorage(this.getLevel().kaiijuConfig.regionFormatName, this.getLevel().kaiijuConfig.regionFormatLinearCompressionLevel, this.getLevel().kaiijuConfig.linearCrashOnBrokenSymlink, convertable_conversionsession.getDimensionPath(resourcekey).resolve("entities"), flag2); // Paper - rewrite chunk system  //EntityPersistentStorage<Entity> entitypersistentstorage = new EntityStorage(this, convertable_conversionsession.getDimensionPath(resourcekey).resolve("entities"), datafixer, flag2, minecraftserver); // Kaiiju
+ 
+         // this.entityManager = new PersistentEntitySectionManager<>(Entity.class, new ServerLevel.EntityCallbacks(), entitypersistentstorage, this.entitySliceManager); // Paper // Paper - rewrite chunk system
+         StructureTemplateManager structuretemplatemanager = minecraftserver.getStructureManager();
+diff --git a/src/main/java/net/minecraft/util/worldupdate/WorldUpgrader.java b/src/main/java/net/minecraft/util/worldupdate/WorldUpgrader.java
+index 469802b9c454c5e98c0a55ba89559d9d8ba0c4c0..1652398c211c4366dde1d973bdb8e9d2c5c67ff4 100644
+--- a/src/main/java/net/minecraft/util/worldupdate/WorldUpgrader.java
++++ b/src/main/java/net/minecraft/util/worldupdate/WorldUpgrader.java
+@@ -119,7 +119,8 @@ public class WorldUpgrader {
+                 String worldName = this.levelStorage.getLevelId();
+                 String formatName = ((org.bukkit.craftbukkit.CraftWorld) org.bukkit.Bukkit.getWorld(worldName)).getHandle().kaiijuConfig.regionFormatName;
+                 int linearCompression = ((org.bukkit.craftbukkit.CraftWorld) org.bukkit.Bukkit.getWorld(worldName)).getHandle().kaiijuConfig.regionFormatLinearCompressionLevel;
+-                builder1.put(resourcekey1, new ChunkStorage(formatName, linearCompression, path.resolve("region"), this.dataFixer, true));
++                boolean linearCrashOnBrokenSymlink = ((org.bukkit.craftbukkit.CraftWorld) org.bukkit.Bukkit.getWorld(worldName)).getHandle().kaiijuConfig.linearCrashOnBrokenSymlink;
++                builder1.put(resourcekey1, new ChunkStorage(formatName, linearCompression, linearCrashOnBrokenSymlink, path.resolve("region"), this.dataFixer, true));
+                 // Kaiiju end
+             }
+ 
+diff --git a/src/main/java/net/minecraft/world/entity/ai/village/poi/PoiManager.java b/src/main/java/net/minecraft/world/entity/ai/village/poi/PoiManager.java
+index f560aa13c6c8ffecb456f478687dc6a9eb5e8017..f0354203f974a8d7440407a5561ffa0fcb63182d 100644
+--- a/src/main/java/net/minecraft/world/entity/ai/village/poi/PoiManager.java
++++ b/src/main/java/net/minecraft/world/entity/ai/village/poi/PoiManager.java
+@@ -59,8 +59,8 @@ public class PoiManager extends SectionStorage<PoiSection> {
+     // Paper end - rewrite chunk system
+ 
+ 
+-    public PoiManager(String formatName, int linearCompression, Path path, DataFixer dataFixer, boolean dsync, RegistryAccess registryManager, LevelHeightAccessor world) { // Kaiiju
+-        super(formatName, linearCompression, path, PoiSection::codec, PoiSection::new, dataFixer, DataFixTypes.POI_CHUNK, dsync, registryManager, world); // Kaiiju
++    public PoiManager(String formatName, int linearCompression, boolean linearCrashOnBrokenSymlink, Path path, DataFixer dataFixer, boolean dsync, RegistryAccess registryManager, LevelHeightAccessor world) { // Kaiiju
++        super(formatName, linearCompression, linearCrashOnBrokenSymlink, path, PoiSection::codec, PoiSection::new, dataFixer, DataFixTypes.POI_CHUNK, dsync, registryManager, world); // Kaiiju
+         this.world = (net.minecraft.server.level.ServerLevel)world; // Paper - rewrite chunk system
+     }
+ 
+diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/ChunkStorage.java b/src/main/java/net/minecraft/world/level/chunk/storage/ChunkStorage.java
+index 52c2e0fe73a5af18535a2b0b9a506919e3f93003..ea54af3f68c6534ff5a71ca0b7a99d126557868e 100644
+--- a/src/main/java/net/minecraft/world/level/chunk/storage/ChunkStorage.java
++++ b/src/main/java/net/minecraft/world/level/chunk/storage/ChunkStorage.java
+@@ -37,12 +37,12 @@ public class ChunkStorage implements AutoCloseable {
+     public final RegionFileStorage regionFileCache;
+     // Paper end - async chunk loading
+ 
+-    public ChunkStorage(String format, int linearCompression, Path directory, DataFixer dataFixer, boolean dsync) { // Kaiiju
++    public ChunkStorage(String format, int linearCompression, boolean linearCrashOnBrokenSymlink, Path directory, DataFixer dataFixer, boolean dsync) { // Kaiiju
+         this.fixerUpper = dataFixer;
+ 
+         // Paper start - async chunk io
+         // remove IO worker
+-        this.regionFileCache = new RegionFileStorage(format, linearCompression, directory, dsync, true); // Paper - nuke IOWorker // Paper
++        this.regionFileCache = new RegionFileStorage(format, linearCompression, linearCrashOnBrokenSymlink, directory, dsync, true); // Paper - nuke IOWorker // Paper
+         // Paper end - async chunk io
+     }
+ 
+diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
+index c9fbba6f709ed0540dcc22b41e50ce9d01a6381c..70e3ee306283263cdcdb7a66c80fc23484385aac 100644
+--- a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
++++ b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
+@@ -20,6 +20,7 @@ import net.minecraft.world.level.ChunkPos;
+ 
+ public class RegionFileStorage implements AutoCloseable {
+ 
++    private static final org.slf4j.Logger LOGGER = com.mojang.logging.LogUtils.getLogger(); // Kaiiju
+     public static final String ANVIL_EXTENSION = ".mca";
+     private static final int MAX_CACHE_SIZE = 256;
+     public final Long2ObjectLinkedOpenHashMap<dev.kaiijumc.kaiiju.region.AbstractRegionFile> regionCache = new Long2ObjectLinkedOpenHashMap(); // Kaiiju
+@@ -28,6 +29,7 @@ public class RegionFileStorage implements AutoCloseable {
+     // Kaiiju start - Per world chunk format
+     public final String format;
+     public final int linearCompression;
++    public final boolean linearCrashOnBrokenSymlink;
+     // Kaiiju end
+ 
+     private final boolean isChunkData; // Paper
+@@ -61,14 +63,15 @@ public class RegionFileStorage implements AutoCloseable {
+     }
+     // Paper end - cache regionfile does not exist state
+ 
+-    protected RegionFileStorage(String format, int linearCompression, Path directory, boolean dsync) { // Paper - protected constructor
++    protected RegionFileStorage(String format, int linearCompression, boolean linearCrashOnBrokenSymlink, Path directory, boolean dsync) { // Paper - protected constructor
+         // Paper start - add isChunkData param
+-        this(format, linearCompression, directory, dsync, false);
++        this(format, linearCompression, linearCrashOnBrokenSymlink, directory, dsync, false);
+     }
+-    RegionFileStorage(String format, int linearCompression, Path directory, boolean dsync, boolean isChunkData) { // Kaiiju
++    RegionFileStorage(String format, int linearCompression, boolean linearCrashOnBrokenSymlink, Path directory, boolean dsync, boolean isChunkData) { // Kaiiju
+         // Kaiiju start
+         this.format = format;
+         this.linearCompression = linearCompression;
++        this.linearCrashOnBrokenSymlink = linearCrashOnBrokenSymlink;
+         // Kaiiju end
+         this.isChunkData = isChunkData;
+         // Paper end - add isChunkData param
+@@ -109,6 +112,20 @@ public class RegionFileStorage implements AutoCloseable {
+         return regionfile != null ? regionfile.hasChunk(pos) : false;
+     }
+ 
++    // Kaiiju start
++    private void guardAgainstBrokenSymlinks(Path path) throws IOException {
++        if (!linearCrashOnBrokenSymlink) return;
++        if (!this.format.equals("LINEAR")) return;
++        if (!java.nio.file.Files.isSymbolicLink(path)) return;
++        Path link = java.nio.file.Files.readSymbolicLink(path);
++        if (!java.nio.file.Files.exists(link) || !java.nio.file.Files.isReadable(link)) {
++            LOGGER.error("Linear region file {} is a broken symbolic link, crashing to prevent data loss", path);
++            net.minecraft.server.MinecraftServer.getServer().halt(false);
++            throw new IOException("Linear region file " + path + " is a broken symbolic link, crashing to prevent data loss");
++        }
++    }
++    // Kaiiju end
++
+     public synchronized dev.kaiijumc.kaiiju.region.AbstractRegionFile getRegionFile(ChunkPos chunkcoordintpair, boolean existingOnly) throws IOException { // CraftBukkit // Kaiiju
+         return this.getRegionFile(chunkcoordintpair, existingOnly, false);
+     }
+@@ -144,6 +161,7 @@ public class RegionFileStorage implements AutoCloseable {
+             if (existingOnly) {
+                 Path anvil = path.resolve("r." + j + "." + chunkcoordintpair.getRegionZ() + ".mca");
+                 Path linear = path.resolve("r." + j + "." + chunkcoordintpair.getRegionZ() + ".linear");
++                guardAgainstBrokenSymlinks(linear);
+                 if (java.nio.file.Files.exists(anvil)) path1 = anvil;
+                 else if (java.nio.file.Files.exists(linear)) path1 = linear;
+                 else {
+@@ -156,6 +174,7 @@ public class RegionFileStorage implements AutoCloseable {
+                     default -> "mca";
+                 };
+                 path1 = path.resolve("r." + j + "." + chunkcoordintpair.getRegionZ() + "." + extension);
++                guardAgainstBrokenSymlinks(path1);
+                 this.createRegionFile(regionPos);
+             }
+             if (dev.kaiijumc.kaiiju.KaiijuConfig.regionFormatDebug)
+diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/SectionStorage.java b/src/main/java/net/minecraft/world/level/chunk/storage/SectionStorage.java
+index 414aa3ae00c2d28e754235e3e93b6b623d4fd180..15e376fac063430e4355c6ffcd25c35a8ce20c5b 100644
+--- a/src/main/java/net/minecraft/world/level/chunk/storage/SectionStorage.java
++++ b/src/main/java/net/minecraft/world/level/chunk/storage/SectionStorage.java
+@@ -47,8 +47,8 @@ public class SectionStorage<R> extends RegionFileStorage implements AutoCloseabl
+     public final RegistryAccess registryAccess; // Paper - rewrite chunk system
+     protected final LevelHeightAccessor levelHeightAccessor;
+ 
+-    public SectionStorage(String format, int linearCompression, Path path, Function<Runnable, Codec<R>> codecFactory, Function<Runnable, R> factory, DataFixer dataFixer, DataFixTypes dataFixTypes, boolean dsync, RegistryAccess dynamicRegistryManager, LevelHeightAccessor world) { // Kaiiju
+-        super(format, linearCompression, path, dsync); // Paper - remove mojang I/O thread // Kaiiju
++    public SectionStorage(String format, int linearCompression, boolean linearCrashOnBrokenSymlink, Path path, Function<Runnable, Codec<R>> codecFactory, Function<Runnable, R> factory, DataFixer dataFixer, DataFixTypes dataFixTypes, boolean dsync, RegistryAccess dynamicRegistryManager, LevelHeightAccessor world) { // Kaiiju
++        super(format, linearCompression, linearCrashOnBrokenSymlink, path, dsync); // Paper - remove mojang I/O thread // Kaiiju
+         this.codec = codecFactory;
+         this.factory = factory;
+         this.fixerUpper = dataFixer;