[WasmFS] Ensure error codes are positive in _wasmfs_node_* APIs (#26616)

Follow-up to #26598.

Author: kleisauke

src/lib/libwasmfs_node.js

@@ -159,14 +159,14 @@ var wasmFSNodeLibrary = {
   _wasmfs_node_truncate__i53abi: true,
   _wasmfs_node_truncate__deps: ['$wasmfsTry'],
   _wasmfs_node_truncate: (path_p, len) => {
-    if (isNaN(len)) return -{{{ cDefs.EOVERFLOW }}};
+    if (isNaN(len)) return {{{ cDefs.EOVERFLOW }}};
     return wasmfsTry(() => fs.truncateSync(UTF8ToString(path_p), len));
   },
 
   _wasmfs_node_ftruncate__i53abi: true,
   _wasmfs_node_ftruncate__deps: ['$wasmfsTry'],
   _wasmfs_node_ftruncate: (fd, len) => {
-    if (isNaN(len)) return -{{{ cDefs.EOVERFLOW }}};
+    if (isNaN(len)) return {{{ cDefs.EOVERFLOW }}};
     return wasmfsTry(() => fs.ftruncateSync(fd, len));
   },
 

system/lib/wasmfs/backends/node_backend.cpp

@@ -124,9 +124,9 @@ class NodeFile : public DataFile {
 
   int setSize(off_t size) override {
     if (state.isOpen()) {
-      return _wasmfs_node_ftruncate(state.getFD(), size);
+      return -_wasmfs_node_ftruncate(state.getFD(), size);
     }
-    return _wasmfs_node_truncate(state.path.c_str(), size);
+    return -_wasmfs_node_truncate(state.path.c_str(), size);
   }
 
   int open(oflags_t flags) override { return state.open(flags); }