[WasmFS] Remove ProxiedFileBackend (#18249)

This was an experimental backend for showing that proxying could work. It's not
actually useful, though, since backends that require proxying will do their own
proxying internally. Since this code isn't useful, remove it to reduce our
maintenance burden in future refactorings.

Author: tlively

system/include/emscripten/wasmfs.h

@@ -40,10 +40,6 @@ backend_t wasmfs_create_js_file_backend(void);
 // A function that receives a void* and returns a backend.
 typedef backend_t (*backend_constructor_t)(void*);
 
-// Creates a Proxied Backend in the new file system.
-backend_t wasmfs_create_proxied_backend(backend_constructor_t create_backend,
-                                        void* arg);
-
 backend_t wasmfs_create_fetch_backend(const char* base_url);
 
 backend_t wasmfs_create_node_backend(const char* root);

system/lib/wasmfs/backends/proxied_file_backend.cpp

@@ -12214,14 +12214,6 @@ def test_wasmfs_jsfile(self):
     self.set_setting('WASMFS')
     self.do_run_in_out_file_test('wasmfs/wasmfs_jsfile.c')
 
-  @node_pthreads
-  def test_wasmfs_jsfile_proxying_backend(self):
-    self.emcc_args.append('-DPROXYING')
-    self.set_setting('USE_PTHREADS')
-    self.set_setting('PROXY_TO_PTHREAD')
-    self.set_setting('EXIT_RUNTIME')
-    self.test_wasmfs_jsfile()
-
   def test_wasmfs_before_preload(self):
     self.set_setting('WASMFS')
     os.mkdir('js_backend_files')

test/test_other.py

@@ -36,12 +36,7 @@ static backend_t make_js_file_backend(void* arg) {
 }
 
 int main() {
-  backend_t backend;
-#ifndef PROXYING
-  backend = make_js_file_backend(NULL);
-#else
-  backend = wasmfs_create_proxied_backend(make_js_file_backend, NULL);
-#endif
+  backend_t backend = make_js_file_backend(NULL);
 
   // Create a new backend file under root.
   int fd = wasmfs_create_file("/testfile", 0777, backend);

test/wasmfs/wasmfs_jsfile.c

@@ -1735,8 +1735,7 @@ def get_files(self):
                    'js_file_backend.cpp',
                    'memory_backend.cpp',
                    'node_backend.cpp',
-                   'opfs_backend.cpp',
-                   'proxied_file_backend.cpp'])
+                   'opfs_backend.cpp'])
     return backends + files_in_path(
         path='system/lib/wasmfs',
         filenames=['file.cpp',