Version v0.2.66 - Fixed cross-filesystem pad generation with copy fallback for USB drives

otp.c

@@ -1127,10 +1127,39 @@ int generate_pad_with_entropy(uint64_t size_bytes, int display_progress, int use
     // Get final paths in pads directory
     get_pad_path(chksum_hex, pad_path, state_path);
     
+    // Try rename first (works for same filesystem)
     if (rename(temp_filename, pad_path) != 0) {
-        printf("Error: Cannot move pad file to pads directory\n");
+        // If rename fails, try copy and delete (works across filesystems)
+        FILE* temp_file = fopen(temp_filename, "rb");
+        FILE* dest_file = fopen(pad_path, "wb");
+        
+        if (!temp_file || !dest_file) {
+            printf("Error: Cannot copy pad file to pads directory\n");
+            if (temp_file) fclose(temp_file);
+            if (dest_file) fclose(dest_file);
+            unlink(temp_filename);
+            return 1;
+        }
+        
+        // Copy file in chunks
+        unsigned char copy_buffer[64 * 1024];
+        size_t bytes_read;
+        while ((bytes_read = fread(copy_buffer, 1, sizeof(copy_buffer), temp_file)) > 0) {
+            if (fwrite(copy_buffer, 1, bytes_read, dest_file) != bytes_read) {
+                printf("Error: Failed to copy pad file to pads directory\n");
+                fclose(temp_file);
+                fclose(dest_file);
+                unlink(temp_filename);
+                unlink(pad_path);
+                return 1;
+            }
+        }
+        
+        fclose(temp_file);
+        fclose(dest_file);
+        
+        // Remove temporary file after successful copy
         unlink(temp_filename);
-        return 1;
     }
     
     // Set pad file to read-only