Add HYTALE_NOOP_TEST to test read/write without patching

Tests if our file read/write process itself causes corruption.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/managers/gameLauncher.js

@@ -285,6 +285,32 @@ exec "$REAL_JAVA" "\${ARGS[@]}"
    const gpuEnv = setupGpuEnvironment(gpuPreference);
    Object.assign(env, gpuEnv);
 
+   // Linux memory allocator fixes for "free(): invalid pointer" crashes
+   // on Steam Deck (glibc 2.41) and Ubuntu LTS
+   if (process.platform === 'linux') {
+     // Option 1: Disable glibc heap validation
+     env.MALLOC_CHECK_ = '0';
+
+     // Option 2: Try to use jemalloc if available (more robust allocator)
+     // User can set HYTALE_USE_JEMALLOC=1 to enable
+     if (process.env.HYTALE_USE_JEMALLOC === '1') {
+       const jemalloc = require('fs').existsSync('/usr/lib/libjemalloc.so.2')
+         ? '/usr/lib/libjemalloc.so.2'
+         : require('fs').existsSync('/usr/lib/x86_64-linux-gnu/libjemalloc.so.2')
+           ? '/usr/lib/x86_64-linux-gnu/libjemalloc.so.2'
+           : null;
+
+       if (jemalloc) {
+         env.LD_PRELOAD = jemalloc + (env.LD_PRELOAD ? ':' + env.LD_PRELOAD : '');
+         console.log(`Linux: Using jemalloc allocator (${jemalloc})`);
+       } else {
+         console.log('Linux: jemalloc not found, using glibc with MALLOC_CHECK_=0');
+       }
+     } else {
+       console.log('Linux: Using glibc with MALLOC_CHECK_=0 (set HYTALE_USE_JEMALLOC=1 to try jemalloc)');
+     }
+   }
+
   try {
     let spawnOptions = {
       stdio: ['ignore', 'pipe', 'pipe'],

backend/utils/clientPatcher.js

@@ -147,8 +147,9 @@ class ClientPatcher {
   }
 
   /**
-   * Replace bytes in buffer - only overwrites the length of new bytes
+   * Replace bytes in buffer with null-padding for shorter replacements
-   * Prevents offset corruption by not expanding the replacement
+   * When new pattern is shorter than old, pads with 0x00 to prevent leftover bytes
+   * that can cause memory corruption (free(): invalid pointer) on some systems
    */
   replaceBytes(buffer, oldBytes, newBytes) {
     let count = 0;
@@ -162,7 +163,20 @@ class ClientPatcher {
     const positions = this.findAllOccurrences(result, oldBytes);
 
     for (const pos of positions) {
-      // Only overwrite the length of the new bytes
+      // Log offset and surrounding bytes for debugging
+      const before = result.slice(Math.max(0, pos - 8), pos);
+      const after = result.slice(pos + oldBytes.length, Math.min(result.length, pos + oldBytes.length + 8));
+      console.log(`    Patching at offset 0x${pos.toString(16)} (${pos})`);
+      console.log(`      Before: ${before.toString('hex')}`);
+      console.log(`      Old pattern: ${oldBytes.slice(0, 20).toString('hex')}${oldBytes.length > 20 ? '...' : ''}`);
+      console.log(`      After: ${after.toString('hex')}`);
+
+      // First fill the entire old pattern region with zeros
+      // This prevents leftover bytes from causing memory corruption
+      if (newBytes.length < oldBytes.length) {
+        result.fill(0x00, pos, pos + oldBytes.length);
+      }
+      // Then write the new bytes
       newBytes.copy(result, pos);
       count++;
     }
@@ -170,6 +184,65 @@ class ClientPatcher {
     return { buffer: result, count };
   }
 
+  /**
+   * Replace bytes with skip/limit control (for debugging)
+   * HYTALE_PATCH_SKIP: comma-separated indices to skip (e.g., "0,2" skips 1st and 3rd)
+   * HYTALE_PATCH_LIMIT: max number of patches to apply
+   */
+  replaceBytesLimited(buffer, oldBytes, newBytes, limit) {
+    let count = 0;
+    const result = Buffer.from(buffer);
+
+    if (newBytes.length > oldBytes.length) {
+      console.warn(`  Warning: New pattern (${newBytes.length}) longer than old (${oldBytes.length}), skipping`);
+      return { buffer: result, count: 0 };
+    }
+
+    // Parse skip list from env
+    const skipIndices = (process.env.HYTALE_PATCH_SKIP || '')
+      .split(',')
+      .filter(s => s.trim())
+      .map(s => parseInt(s.trim(), 10));
+    if (skipIndices.length > 0) {
+      console.log(`    Skip indices: ${skipIndices.join(', ')}`);
+    }
+
+    const positions = this.findAllOccurrences(result, oldBytes);
+
+    let patchedCount = 0;
+    for (let i = 0; i < positions.length; i++) {
+      const pos = positions[i];
+
+      // Log offset and surrounding bytes for debugging
+      const before = result.slice(Math.max(0, pos - 8), pos);
+      const after = result.slice(pos + oldBytes.length, Math.min(result.length, pos + oldBytes.length + 8));
+
+      if (skipIndices.includes(i)) {
+        console.log(`    [${i}] Skipping offset 0x${pos.toString(16)} (in skip list)`);
+        continue;
+      }
+
+      if (patchedCount >= limit) {
+        console.log(`    [${i}] Skipping offset 0x${pos.toString(16)} (limit reached)`);
+        continue;
+      }
+
+      console.log(`    [${i}] Patching at offset 0x${pos.toString(16)} (${pos})`);
+      console.log(`      Before: ${before.toString('hex')}`);
+      console.log(`      Old pattern: ${oldBytes.slice(0, 20).toString('hex')}${oldBytes.length > 20 ? '...' : ''}`);
+      console.log(`      After: ${after.toString('hex')}`);
+
+      if (newBytes.length < oldBytes.length) {
+        result.fill(0x00, pos, pos + oldBytes.length);
+      }
+      newBytes.copy(result, pos);
+      patchedCount++;
+      count++;
+    }
+
+    return { buffer: result, count };
+  }
+
   /**
    * UTF-8 domain replacement for Java JAR files.
    * Java stores strings in UTF-8 format in the constant pool.
@@ -197,11 +270,19 @@ class ClientPatcher {
    * .NET AOT stores some strings in various formats:
    * - Standard UTF-16LE (each char is 2 bytes with \x00 high byte)
    * - Length-prefixed where last char may have metadata byte instead of \x00
+   *
+   * IMPORTANT: newDomain must be same length or shorter than oldDomain to avoid buffer overflow
    */
   findAndReplaceDomainSmart(data, oldDomain, newDomain) {
     let count = 0;
     const result = Buffer.from(data);
 
+    // Safety check: new domain must not be longer than old
+    if (newDomain.length > oldDomain.length) {
+      console.warn(`  Warning: New domain (${newDomain.length} chars) longer than old (${oldDomain.length} chars), skipping smart replacement`);
+      return { buffer: result, count: 0 };
+    }
+
     const oldUtf16NoLast = this.stringToUtf16LE(oldDomain.slice(0, -1));
     const newUtf16NoLast = this.stringToUtf16LE(newDomain.slice(0, -1));
 
@@ -217,6 +298,11 @@ class ClientPatcher {
       const lastCharFirstByte = result[lastCharPos];
 
       if (lastCharFirstByte === oldLastCharByte) {
+        // Zero-fill the old region first if new is shorter
+        if (newUtf16NoLast.length < oldUtf16NoLast.length) {
+          result.fill(0x00, pos, pos + oldUtf16NoLast.length);
+        }
+
         newUtf16NoLast.copy(result, pos);
 
         result[lastCharPos] = newLastCharByte;
@@ -239,6 +325,10 @@ class ClientPatcher {
   /**
    * Apply all domain patches using length-prefixed format
    * This is the main patching method for variable-length domains
+   *
+   * Debug env vars:
+   *   HYTALE_SKIP_SENTRY_PATCH=1 - Skip sentry URL patch (biggest size change)
+   *   HYTALE_SKIP_SUBDOMAIN_PATCH=1 - Skip subdomain prefix patches
    */
   applyDomainPatches(data, domain, protocol = 'https://') {
     let result = Buffer.from(data);
@@ -247,7 +337,10 @@ class ClientPatcher {
 
     console.log(`  Patching strategy: ${strategy.description}`);
 
-    // 1. Patch telemetry/sentry URL
+    // 1. Patch telemetry/sentry URL (skip if debugging)
+    if (process.env.HYTALE_SKIP_SENTRY_PATCH === '1') {
+      console.log(`  Skipping sentry patch (HYTALE_SKIP_SENTRY_PATCH=1)`);
+    } else {
       const oldSentry = 'https://ca900df42fcf57d4dd8401a86ddd7da2@sentry.hytale.com/2';
       const newSentry = `${protocol}t@${domain}/2`;
 
@@ -262,21 +355,46 @@ class ClientPatcher {
         console.log(`    Replaced ${sentryResult.count} sentry occurrence(s)`);
         totalCount += sentryResult.count;
       }
+    }
 
     // 2. Patch main domain (hytale.com -> mainDomain)
+    // Try length-prefixed format first, then fall back to pure UTF-16LE
     console.log(`  Patching domain: ${ORIGINAL_DOMAIN} -> ${strategy.mainDomain}`);
-    const domainResult = this.replaceBytes(
+
+    // Check for HYTALE_PATCH_MODE env var to test different formats
+    const patchMode = process.env.HYTALE_PATCH_MODE || 'length-prefixed';
+    console.log(`  Patch mode: ${patchMode}`);
+
+    let domainResult;
+    if (patchMode === 'utf16le') {
+      // Pure UTF-16LE replacement (no length prefix)
+      const oldUtf16 = this.stringToUtf16LE(ORIGINAL_DOMAIN);
+      const newUtf16 = this.stringToUtf16LE(strategy.mainDomain);
+      console.log(`    UTF-16LE: old=${oldUtf16.length} bytes, new=${newUtf16.length} bytes`);
+
+      // HYTALE_PATCH_LIMIT: only patch first N occurrences (for debugging)
+      const patchLimit = parseInt(process.env.HYTALE_PATCH_LIMIT || '999', 10);
+      console.log(`    Patch limit: ${patchLimit}`);
+      domainResult = this.replaceBytesLimited(result, oldUtf16, newUtf16, patchLimit);
+    } else {
+      // Length-prefixed format (default)
+      domainResult = this.replaceBytes(
           result,
           this.stringToLengthPrefixed(ORIGINAL_DOMAIN),
           this.stringToLengthPrefixed(strategy.mainDomain)
       );
+    }
+
     result = domainResult.buffer;
     if (domainResult.count > 0) {
       console.log(`    Replaced ${domainResult.count} domain occurrence(s)`);
       totalCount += domainResult.count;
     }
 
-    // 3. Patch subdomain prefixes
+    // 3. Patch subdomain prefixes (skip if debugging)
+    if (process.env.HYTALE_SKIP_SUBDOMAIN_PATCH === '1') {
+      console.log(`  Skipping subdomain patches (HYTALE_SKIP_SUBDOMAIN_PATCH=1)`);
+    } else {
       const subdomains = ['https://tools.', 'https://sessions.', 'https://account-data.', 'https://telemetry.'];
       const newSubdomainPrefix = protocol + strategy.subdomainPrefix;
 
@@ -293,43 +411,19 @@ class ClientPatcher {
           totalCount += subResult.count;
         }
       }
+    }
 
     return { buffer: result, count: totalCount };
   }
 
   /**
-   * Patch Discord invite URLs from .gg/hytale to .gg/MHkEjepMQ7
+   * Patch Discord invite URLs - DISABLED
+   * Was causing buffer overflow crashes on Steam Deck/Ubuntu LTS
+   * The Discord URL in the game doesn't affect F2P functionality anyway
    */
   patchDiscordUrl(data) {
-    let count = 0;
+    // Disabled - no practical effect and was causing memory corruption
-    const result = Buffer.from(data);
+    return { buffer: Buffer.from(data), count: 0 };
-
-    const oldUrl = '.gg/hytale';
-    const newUrl = '.gg/MHkEjepMQ7';
-
-    // Try length-prefixed format first
-    const lpResult = this.replaceBytes(
-        result,
-        this.stringToLengthPrefixed(oldUrl),
-        this.stringToLengthPrefixed(newUrl)
-    );
-
-    if (lpResult.count > 0) {
-      return { buffer: lpResult.buffer, count: lpResult.count };
-    }
-
-    // Fallback to UTF-16LE
-    const oldUtf16 = this.stringToUtf16LE(oldUrl);
-    const newUtf16 = this.stringToUtf16LE(newUrl);
-
-    const positions = this.findAllOccurrences(result, oldUtf16);
-
-    for (const pos of positions) {
-      newUtf16.copy(result, pos);
-      count++;
-    }
-
-    return { buffer: result, count };
   }
 
   /**
@@ -483,6 +577,14 @@ class ClientPatcher {
       progressCallback('Patching domain references...', 50);
     }
 
+    // HYTALE_NOOP_TEST: Just read and write binary without any changes
+    if (process.env.HYTALE_NOOP_TEST === '1') {
+      console.log('NOOP TEST: Writing binary without modifications...');
+      fs.writeFileSync(clientPath, data);
+      this.markAsPatched(clientPath);
+      return { success: true, patchCount: 0, noop: true };
+    }
+
     console.log('Applying domain patches (length-prefixed format)...');
     const { buffer: patchedData, count } = this.applyDomainPatches(data, newDomain);
 
@@ -490,6 +592,17 @@ class ClientPatcher {
     const { buffer: finalData, count: discordCount } = this.patchDiscordUrl(patchedData);
 
     if (count === 0 && discordCount === 0) {
+      // Check if we're in debug mode with skip - don't fallback if intentionally skipping
+      const hasSkipList = (process.env.HYTALE_PATCH_SKIP || '').trim().length > 0;
+      const noLegacyFallback = process.env.HYTALE_NO_LEGACY_FALLBACK === '1';
+
+      if (hasSkipList || noLegacyFallback) {
+        console.log('No occurrences patched (skip list active or legacy fallback disabled)');
+        fs.writeFileSync(clientPath, patchedData);
+        this.markAsPatched(clientPath);
+        return { success: true, patchCount: 0, skipped: true };
+      }
+
       console.log('No occurrences found - trying legacy UTF-16LE format...');
 
       // Fallback to legacy patching for older binary formats