Fix a crash on startup or during backup when backup data is corrupted (#5)

Author: tier940

CHANGELOG.md

@@ -1,5 +1,10 @@
+# 1.0.6
+- Fix a crash on startup or during backup when backup data is corrupted. ([HeatherComputer/AdvancedBackups#110](https://github.com/HeatherComputer/AdvancedBackups/issues/110))
+
+* * *
+
 # 1.0.5
-- Fix a rare crash when entering a singleplayer world. ([HeatherComputer/AdvancedBackups#110](https://github.com/HeatherComputer/AdvancedBackups/issues/110))
+- Fix a rare crash when entering a singleplayer world. ([HeatherComputer/AdvancedBackups#87](https://github.com/HeatherComputer/AdvancedBackups/issues/87))
 - Fix a potential crash during backup when a backup directory is missing.
 - Fix a potential crash when cleaning up old backup files.
 

src/main/java/com/github/gtexpert/advancedbackupspatch/mixin/ABCoreMixin.java

@@ -0,0 +1,42 @@
+package com.github.gtexpert.advancedbackupspatch.mixin;
+
+import computer.heather.advancedbackups.core.ABCore;
+import computer.heather.advancedbackups.core.backups.gson.BackupManifest;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonParseException;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+@Mixin(value = ABCore.class, remap = false)
+public abstract class ABCoreMixin {
+
+    /**
+     * Prevent NPE when parsing a corrupted backup manifest in setActivity.
+     * <p>
+     * The JAR v3.7.1 only catches {@link JsonParseException}, but {@code gson.fromJson()}
+     * can return null or a manifest with null fields for certain malformed JSON,
+     * causing a {@link NullPointerException} when accessing {@code manifest.general.activity}.
+     * <p>
+     * This redirect converts the null case into a {@link JsonParseException},
+     * which is already caught and handled by the existing recovery logic.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/110">Issue #110</a>
+     */
+    @Redirect(method = "setActivity",
+            at = @At(value = "INVOKE",
+                    target = "Lcom/google/gson/Gson;fromJson(Ljava/lang/String;Ljava/lang/Class;)Ljava/lang/Object;"))
+    private static Object safeFromJson(Gson gson, String json, Class<?> classOfT) {
+        Object result = gson.fromJson(json, classOfT);
+        if (result == null) {
+            throw new JsonParseException("Backup manifest parsed as null");
+        }
+        BackupManifest manifest = (BackupManifest) result;
+        if (manifest.general == null) {
+            throw new JsonParseException("Backup manifest 'general' field is null");
+        }
+        return result;
+    }
+}

src/main/java/com/github/gtexpert/advancedbackupspatch/mixin/AdvancedBackupsMixin.java

@@ -32,6 +32,8 @@ public abstract class AdvancedBackupsMixin {
     /**
      * Disable EVENT_BUS.register(this) in the constructor.
      * The mod container is not yet established at construction time, so defer to preInit.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/87">Issue #87</a>
      */
     @Redirect(method = "<init>",
             at = @At(value = "INVOKE",
@@ -43,6 +45,8 @@ private void redirectEventBusRegister(EventBus bus, Object target) {
     /**
      * Disable NetworkHandler.registerMessages() in the constructor.
      * Defer network channel registration until the mod container is established.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/87">Issue #87</a>
      */
     @Redirect(method = "<init>",
             at = @At(value = "INVOKE",
@@ -54,6 +58,8 @@ private void redirectNetworkRegister() {
     /**
      * Register the event bus and network messages at the beginning of preInit,
      * where the mod container is properly established.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/87">Issue #87</a>
      */
     @Inject(method = "preInit", at = @At("HEAD"))
     private void onPreInit(FMLPreInitializationEvent event, CallbackInfo ci) {
@@ -65,6 +71,8 @@ private void onPreInit(FMLPreInitializationEvent event, CallbackInfo ci) {
      * Set ABCore loggers after preInit sets them on AdvancedBackups.
      * Without this, ABCore.infoLogger is null on the client side (only set in onServerStarting),
      * causing NPE in ClientConfigManager when receiving PacketToastTest.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/87">Issue #87</a>
      */
     @Inject(method = "preInit", at = @At("TAIL"))
     private void onPreInitTail(FMLPreInitializationEvent event, CallbackInfo ci) {

src/main/java/com/github/gtexpert/advancedbackupspatch/mixin/BackupWrapperMixin.java

@@ -3,6 +3,10 @@
 import java.io.File;
 
 import computer.heather.advancedbackups.core.backups.BackupWrapper;
+import computer.heather.advancedbackups.core.backups.gson.BackupManifest;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonParseException;
 
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
@@ -22,4 +26,32 @@ private static File[] safeListFiles(File directory) {
         File[] result = directory.listFiles();
         return result != null ? result : new File[0];
     }
+
+    /**
+     * Prevent NPE when parsing a corrupted backup manifest in checkStartupBackups.
+     * <p>
+     * The JAR v3.7.1 only catches {@link JsonParseException}, but {@code gson.fromJson()}
+     * can return null (or a manifest with null fields) for certain malformed JSON,
+     * causing a {@link NullPointerException} when accessing {@code manifest.general.activity}.
+     * <p>
+     * This redirect converts the null case into a {@link JsonParseException},
+     * which is already caught and handled by the existing recovery logic
+     * (creates default manifest and writes it back to disk).
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/110">Issue #110</a>
+     */
+    @Redirect(method = "checkStartupBackups",
+            at = @At(value = "INVOKE",
+                    target = "Lcom/google/gson/Gson;fromJson(Ljava/lang/String;Ljava/lang/Class;)Ljava/lang/Object;"))
+    private static Object safeFromJson(Gson gson, String json, Class<?> classOfT) {
+        Object result = gson.fromJson(json, classOfT);
+        if (result == null) {
+            throw new JsonParseException("Backup manifest parsed as null");
+        }
+        BackupManifest manifest = (BackupManifest) result;
+        if (manifest.general == null) {
+            throw new JsonParseException("Backup manifest 'general' field is null");
+        }
+        return result;
+    }
 }

src/main/java/com/github/gtexpert/advancedbackupspatch/mixin/ClientConfigManagerMixin.java

@@ -25,6 +25,8 @@ public abstract class ClientConfigManagerMixin {
      * which may not see logger writes from the IntegratedServer thread
      * due to the Java Memory Model (non-volatile fields).
      * This provides a fallback to prevent NPE.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/87">Issue #87</a>
      */
     @Inject(method = "loadOrCreateConfig", at = @At("HEAD"))
     private static void ensureLoggers(CallbackInfo ci) {

src/main/java/com/github/gtexpert/advancedbackupspatch/mixin/CoreCommandSystemMixin.java

@@ -0,0 +1,42 @@
+package com.github.gtexpert.advancedbackupspatch.mixin;
+
+import computer.heather.advancedbackups.core.CoreCommandSystem;
+import computer.heather.advancedbackups.core.backups.gson.BackupManifest;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonParseException;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+@Mixin(value = CoreCommandSystem.class, remap = false)
+public abstract class CoreCommandSystemMixin {
+
+    /**
+     * Prevent NPE when parsing a corrupted backup manifest in resetChainLength.
+     * <p>
+     * The JAR v3.7.1 only catches {@link JsonParseException}, but {@code gson.fromJson()}
+     * can return null or a manifest with null fields for certain malformed JSON,
+     * causing a {@link NullPointerException} when accessing manifest fields.
+     * <p>
+     * This redirect converts the null case into a {@link JsonParseException},
+     * which is already caught and handled by the existing recovery logic.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/110">Issue #110</a>
+     */
+    @Redirect(method = "resetChainLength",
+            at = @At(value = "INVOKE",
+                    target = "Lcom/google/gson/Gson;fromJson(Ljava/lang/String;Ljava/lang/Class;)Ljava/lang/Object;"))
+    private static Object safeFromJson(Gson gson, String json, Class<?> classOfT) {
+        Object result = gson.fromJson(json, classOfT);
+        if (result == null) {
+            throw new JsonParseException("Backup manifest parsed as null");
+        }
+        BackupManifest manifest = (BackupManifest) result;
+        if (manifest.incremental == null || manifest.differential == null) {
+            throw new JsonParseException("Backup manifest chain fields are null");
+        }
+        return result;
+    }
+}

src/main/java/com/github/gtexpert/advancedbackupspatch/mixin/ThreadedBackupMixin.java

@@ -3,6 +3,10 @@
 import java.io.File;
 
 import computer.heather.advancedbackups.core.backups.ThreadedBackup;
+import computer.heather.advancedbackups.core.backups.gson.BackupManifest;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonParseException;
 
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
@@ -14,6 +18,8 @@ public abstract class ThreadedBackupMixin {
     /**
      * Prevent NPE when File.list() returns null in performRename.
      * This happens when the directory does not exist or an I/O error occurs.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/103">Issue #103</a>
      */
     @Redirect(method = "performRename",
             at = @At(value = "INVOKE",
@@ -26,6 +32,8 @@ private String[] safeListInRename(File file) {
     /**
      * Prevent NPE when File.list() returns null in performDelete.
      * This happens when the directory does not exist or an I/O error occurs.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/103">Issue #103</a>
      */
     @Redirect(method = "performDelete",
             at = @At(value = "INVOKE",
@@ -34,4 +42,28 @@ private String[] safeListInDelete(File file) {
         String[] result = file.list();
         return result != null ? result : new String[0];
     }
+
+    /**
+     * Prevent NPE when parsing a corrupted backup manifest in makeDifferentialOrIncrementalBackup.
+     * <p>
+     * Same issue as in {@code BackupWrapper.checkStartupBackups()} — the JAR v3.7.1
+     * only catches {@link JsonParseException}, but {@code gson.fromJson()} can return null
+     * or a manifest with null fields, causing a {@link NullPointerException}.
+     *
+     * @see <a href="https://github.com/HeatherComputer/AdvancedBackups/issues/110">Issue #110</a>
+     */
+    @Redirect(method = "makeDifferentialOrIncrementalBackup",
+            at = @At(value = "INVOKE",
+                    target = "Lcom/google/gson/Gson;fromJson(Ljava/lang/String;Ljava/lang/Class;)Ljava/lang/Object;"))
+    private Object safeFromJson(Gson gson, String json, Class<?> classOfT) {
+        Object result = gson.fromJson(json, classOfT);
+        if (result == null) {
+            throw new JsonParseException("Backup manifest parsed as null");
+        }
+        BackupManifest manifest = (BackupManifest) result;
+        if (manifest.differential == null || manifest.incremental == null) {
+            throw new JsonParseException("Backup manifest fields are null");
+        }
+        return result;
+    }
 }

src/main/resources/mixins.advancedbackupspatch.json

@@ -3,9 +3,11 @@
   "package": "com.github.gtexpert.advancedbackupspatch.mixin",
   "compatibilityLevel": "JAVA_8",
   "mixins": [
+    "ABCoreMixin",
     "AdvancedBackupsMixin",
     "BackupWrapperMixin",
     "ClientConfigManagerMixin",
+    "CoreCommandSystemMixin",
     "ThreadedBackupMixin"
   ]
 }