A whoooole lotta 4.0.x fixes.

frontends/web/test_routes.py

@@ -0,0 +1,90 @@
+"""
+Minimal test to isolate the memory corruption crash.
+
+Add this route to your app.py temporarily to test if the crash 
+is in Flask/Pillow or in stegasoo code.
+
+Usage:
+1. Add this code to app.py
+2. Restart the server
+3. Use the /test-capacity endpoint instead of /api/compare-capacity
+4. If it crashes: Flask or Pillow issue
+5. If it works: Stegasoo code issue
+"""
+
+# Add these imports at the top of app.py if not present:
+# from PIL import Image
+# import io
+
+# Add this route to app.py:
+
+@app.route('/test-capacity', methods=['POST'])
+def test_capacity():
+    """
+    Minimal capacity test - no stegasoo code, just PIL.
+    """
+    carrier = request.files.get('carrier')
+    if not carrier:
+        return jsonify({'error': 'No carrier image provided'}), 400
+    
+    try:
+        # Read the file data
+        carrier_data = carrier.read()
+        
+        # Method 1: Just get size from PIL
+        buffer = io.BytesIO(carrier_data)
+        img = Image.open(buffer)
+        width, height = img.size
+        fmt = img.format
+        mode = img.mode
+        img.close()
+        buffer.close()
+        
+        # Simple capacity calculation (no scipy, no numpy)
+        pixels = width * height
+        lsb_bytes = (pixels * 3) // 8
+        blocks = (width // 8) * (height // 8)
+        dct_bytes = (blocks * 16) // 8 - 10
+        
+        return jsonify({
+            'success': True,
+            'width': width,
+            'height': height,
+            'format': fmt,
+            'mode': mode,
+            'lsb': {
+                'capacity_bytes': lsb_bytes,
+                'capacity_kb': round(lsb_bytes / 1024, 1),
+            },
+            'dct': {
+                'capacity_bytes': dct_bytes,
+                'capacity_kb': round(dct_bytes / 1024, 1),
+            }
+        })
+    except Exception as e:
+        import traceback
+        return jsonify({'error': str(e), 'trace': traceback.format_exc()}), 500
+
+
+# Alternative: completely bypass PIL too
+@app.route('/test-capacity-nopil', methods=['POST'])
+def test_capacity_nopil():
+    """
+    Ultra-minimal test - no PIL, no stegasoo.
+    """
+    carrier = request.files.get('carrier')
+    if not carrier:
+        return jsonify({'error': 'No carrier image provided'}), 400
+    
+    try:
+        carrier_data = carrier.read()
+        
+        # Just return size info, no image processing at all
+        return jsonify({
+            'success': True,
+            'data_size': len(carrier_data),
+            'first_bytes': carrier_data[:20].hex() if len(carrier_data) >= 20 else carrier_data.hex(),
+        })
+    except Exception as e:
+        import traceback
+        return jsonify({'error': str(e), 'trace': traceback.format_exc()}), 500