feat(nodefs): mmap and msync

add implementation of mmap and msync for NODEFS

src/library_nodefs.js

@@ -292,6 +292,29 @@ mergeInto(LibraryManager.library, {
         }
 
         return position;
+      },
+      mmap: function(stream, buffer, offset, length, position, prot, flags) {
+        if (!FS.isFile(stream.node.mode)) {
+          throw new FS.ErrnoError({{{ cDefine('ENODEV') }}});
+        }
+        var ptr = _malloc(length);
+
+        assert(offset === 0);
+        NODEFS.stream_ops.read(stream, buffer, ptr + offset, length, position);
+
+        return { ptr: ptr, allocated: true };
+      },
+      msync: function(stream, buffer, offset, length, mmapFlags) {
+        if (!FS.isFile(stream.node.mode)) {
+          throw new FS.ErrnoError({{{ cDefine('ENODEV') }}});
+        }
+        if (mmapFlags & {{{ cDefine('MAP_PRIVATE') }}}) {
+          // MAP_PRIVATE calls need not to be synced back to underlying fs
+          return 0;
+        }
+
+        var bytesWritten = NODEFS.stream_ops.write(stream, buffer, 0, length, offset, false);
+        return 0;
       }
     }
   }

tests/fs/test_mmap.c

@@ -21,6 +21,9 @@
 int main() {
   EM_ASM(
     FS.mkdir('yolo');
+    #if NODEFS
+        FS.mount(NODEFS, { root: '.' }, 'yolo');
+    #endif
     FS.writeFile('/yolo/in.txt', 'mmap ftw!');
   );
 
@@ -176,7 +179,7 @@ int main() {
     printf("/yolo/sharedoffset.txt content=%s %d\n", buffer + offset, offset);
     fclose(fd);
   }
-
+#if !defined(NODEFS)
   /**
    * MMAP to an 'over-allocated' file
    * 
@@ -219,6 +222,7 @@ int main() {
 
     close(fd);
   }
+#endif
 
   return 0;
 }

tests/test_core.py

@@ -5320,10 +5320,12 @@ def test_fs_append(self, js_engines=None):
 
   def test_fs_mmap(self):
     orig_compiler_opts = self.emcc_args[:]
-    for fs in ['MEMFS']:
+    for fs in ['MEMFS', 'NODEFS']:
       src = path_from_root('tests', 'fs', 'test_mmap.c')
       out = path_from_root('tests', 'fs', 'test_mmap.out')
       self.emcc_args = orig_compiler_opts + ['-D' + fs]
+      if fs == 'NODEFS':
+        self.emcc_args += ['-lnodefs.js']
       self.do_run_from_file(src, out)
 
   @also_with_noderawfs