Port over stdout implementation to wasmfs.cpp

emcc.py

@@ -1775,6 +1775,12 @@ def default_setting(name, new_default):
     settings.FETCH = 1
     settings.JS_LIBRARIES.append((0, 'library_asmfs.js'))
 
+  if settings.WASMFS:
+    state.forced_stdlibs.append('libwasmfs')
+    settings.FILESYSTEM = 0
+    settings.SYSCALLS_REQUIRE_FILESYSTEM = 0
+    settings.JS_LIBRARIES.append((0, 'library_wasmfs.js'))
+
   # Explicitly drop linking in a malloc implementation if program is not using any dynamic allocation calls.
   if not settings.USES_DYNAMIC_ALLOC:
     settings.MALLOC = 'none'

src/library_wasmfs.js

@@ -0,0 +1,17 @@
+var WasmfsLibrary = {
+  $wasmfsBuffers: [null, [], []],
+  emscripten_wasmfs_printbuffer__deps: ['$wasmfsBuffers'],
+  emscripten_wasmfs_printbuffer: function(stream, ptr, len) {
+    for (var j = 0; j < len; j++) {
+      if (HEAPU8[ptr+j] === 0 || HEAPU8[ptr+j] === 10) {
+        (stream === 1 ? out : err)(UTF8ArrayToString(wasmfsBuffers[stream], 0));
+        wasmfsBuffers[stream].length = 0;
+      } else {
+        wasmfsBuffers[stream].push(HEAPU8[ptr+j]);
+      }
+    }
+
+  }
+}
+
+mergeInto(LibraryManager.library, WasmfsLibrary);

src/modules.js

@@ -110,6 +110,8 @@ var LibraryManager = {
         }
         libraries.push('library_noderawfs.js');
       }
+    } else {
+      libraries.push('library_wasmfs.js');
     }
 
     // Additional JS libraries (without AUTO_JS_LIBRARIES, link to these explicitly via -lxxx.js)

src/preamble.js

@@ -624,7 +624,7 @@ function abort(what) {
 
 #include "memoryprofiler.js"
 
-#if ASSERTIONS && !('$FS' in addedLibraryItems) && !ASMFS
+#if ASSERTIONS && !('$FS' in addedLibraryItems) && !ASMFS && !WASMFS
 // show errors on likely calls to FS when it was not included
 var FS = {
   error: function() {

src/settings.js

@@ -1635,6 +1635,12 @@ var FETCH = 0;
 // [link]
 var ASMFS = 0;
 
+// ATTENTION [WIP]: Experimental feature. Please use at your own risk.
+// This will eventually replace the current JS file system implementation.
+// If set to 1, uses new filesystem implementation.
+// [link]
+var WASMFS = 0;
+
 // If set to 1, embeds all subresources in the emitted file as base64 string
 // literals. Embedded subresources may include (but aren't limited to) wasm,
 // asm.js, and static memory initialization code.

system/lib/wasmfs/wasmfs.cpp

@@ -0,0 +1,54 @@
+// Copyright 2021 The Emscripten Authors.  All rights reserved.
+// Emscripten is available under two separate licenses, the MIT license and the
+// University of Illinois/NCSA Open Source License.  Both these licenses can be
+// found in the LICENSE file.
+// wasmfs.cpp will implement a new file system that replaces the existing JS filesystem.
+// Current Status: Work in Progress.
+// See https://github.com/emscripten-core/emscripten/issues/15041.
+
+#include <emscripten/emscripten.h>
+#include <emscripten/html5.h>
+#include <stdlib.h>
+#include <wasi/api.h>
+
+extern "C" {
+
+int emscripten_wasmfs_printbuffer(__wasi_fd_t fd, const uint8_t* ptr, __wasi_size_t len);
+
+__wasi_errno_t __wasi_fd_write(
+  __wasi_fd_t fd, const __wasi_ciovec_t* iovs, size_t iovs_len, __wasi_size_t* nwritten) {
+  // FD 1 = STDOUT and FD 2 = STDERR.
+  // Temporary hardcoding of filedescriptor values.
+  // TODO: May not want to proxy stderr (fd == 2) to the main thread.
+  // This will not not show in HTML, a console.warn in a worker is suffficient.
+  // This would be a change from the current FS.
+  if (fd == 1 || fd == 2) {
+    __wasi_size_t num = 0;
+    for (size_t i = 0; i < iovs_len; i++) {
+      const uint8_t* ptr = iovs[i].buf;
+      __wasi_size_t len = iovs[i].buf_len;
+      emscripten_wasmfs_printbuffer(fd, ptr, len);
+      num += len;
+    }
+    *nwritten = num;
+  }
+  return 0;
+}
+
+__wasi_errno_t __wasi_fd_seek(
+  __wasi_fd_t fd, __wasi_filedelta_t offset, __wasi_whence_t whence, __wasi_filesize_t* newoffset) {
+  emscripten_console_log("__wasi_fd_seek has been temporarily stubbed and is inert");
+  abort();
+}
+
+__wasi_errno_t __wasi_fd_close(__wasi_fd_t fd) {
+  emscripten_console_log("__wasi_fd_close has been temporarily stubbed and is inert");
+  abort();
+}
+
+__wasi_errno_t __wasi_fd_read(
+  __wasi_fd_t fd, const __wasi_iovec_t* iovs, size_t iovs_len, __wasi_size_t* nread) {
+  emscripten_console_log("__wasi_fd_read has been temporarily stubbed and is inert");
+  abort();
+}
+}

tests/common.py

@@ -541,6 +541,7 @@ def verify_es5(self, filename):
     es_check_env = os.environ.copy()
     es_check_env['PATH'] = os.path.dirname(config.NODE_JS[0]) + os.pathsep + es_check_env['PATH']
     try:
+      # Comment out --quiet if more detailed error logging is needed
       shared.run_process(es_check + ['es5', os.path.abspath(filename), '--quiet'], stderr=PIPE, env=es_check_env)
     except subprocess.CalledProcessError as e:
       print(e.stderr)

tests/test_core.py

@@ -139,6 +139,17 @@ def can_do_standalone(self):
       '-fsanitize=address' not in self.emcc_args
 
 
+def also_with_wasmfs(func):
+  def decorated(self):
+    func(self)
+    print('wasmfs')
+    if self.get_setting('STANDALONE_WASM'):
+      self.skipTest("test currently cannot run both with WASMFS and STANDALONE_WASM")
+    self.set_setting('WASMFS')
+    func(self)
+  return decorated
+
+
 # Impure means a test that cannot run in a wasm VM yet, as it is not 100%
 # standalone. We can still run them with the JS code though.
 def also_with_standalone_wasm(wasm2c=False, impure=False):
@@ -308,6 +319,7 @@ def get_bullet_library(self, use_cmake):
                             cache_name_extra=configure_commands[0])
 
   @also_with_standalone_wasm()
+  @also_with_wasmfs
   def test_hello_world(self):
     self.do_core_test('test_hello_world.c')
     # must not emit this unneeded internal thing

tools/system_libs.py

@@ -1285,6 +1285,16 @@ def can_build(self):
     return True
 
 
+class libwasmfs(MTLibrary):
+  name = 'libwasmfs'
+
+  def get_files(self):
+    return [utils.path_from_root('system/lib/wasmfs/wasmfs.cpp')]
+
+  def can_build(self):
+    return settings.WASMFS
+
+
 class libhtml5(Library):
   name = 'libhtml5'