WasmFS JS API: Implement rename (#19535)

Author: jameshu15869

emcc.py

@@ -2318,6 +2318,7 @@ def phase_linker_setup(options, state, newargs):
         '_wasmfs_write_file',
         '_wasmfs_open',
         '_wasmfs_close',
+        '_wasmfs_rename',
         '_wasmfs_mkdir',
         '_wasmfs_unlink',
         '_wasmfs_chdir',

src/library_wasmfs.js

@@ -284,13 +284,19 @@ FS.createPreloadedFile = FS_createPreloadedFile;
         __wasmfs_readdir_finish(state);
         return entries;
       });
-    }
+    },
     // TODO: mount
     // TODO: unmount
     // TODO: lookup
     // TODO: mknod
     // TODO: mkdev
-    // TODO: rename
+    rename: (oldPath, newPath) => {
+      return FS.handleError(withStackSave(() => {
+        var oldPathBuffer = stringToUTF8OnStack(oldPath);
+        var newPathBuffer = stringToUTF8OnStack(newPath);
+        return __wasmfs_rename(oldPathBuffer, newPathBuffer);
+      }));
+    },
     // TODO: syncfs
     // TODO: llseek
     // TODO: ioctl

system/lib/wasmfs/js_api.cpp

@@ -155,6 +155,14 @@ int _wasmfs_lchmod(char* path, mode_t mode) {
   return __syscall_fchmodat(AT_FDCWD, (intptr_t)path, mode, AT_SYMLINK_NOFOLLOW);
 }
 
+int _wasmfs_rename(char* oldpath, char* newpath) {
+  int err = __syscall_renameat(AT_FDCWD, (intptr_t)oldpath, AT_FDCWD, (intptr_t)newpath);
+  if (err == -1) {
+    return errno;
+  }
+  return err;
+};
+
 int _wasmfs_read(int fd, void *buf, size_t count) {
   __wasi_iovec_t iovs[1];
   iovs[0].buf = (uint8_t *)buf;

test/fs/test_fs_js_api.c

@@ -37,6 +37,41 @@ int main() {
 #endif
     );
 
+    /********** test FS.rename() **********/
+    EM_ASM(
+        FS.mkdir('renamedir');
+        FS.writeFile('renamedir/renametestfile', "");
+
+        FS.rename('renamedir/renametestfile', 'renamedir/newname');
+        var newnameStream = FS.open('renamedir/newname', 'r');
+        assert(newnameStream);
+
+        var ex;
+        try {
+            FS.open('renamedir/renametestfile', 'r');
+        } catch (err) {
+            ex = err;
+        }
+        assert(ex.name === "ErrnoError" && ex.errno === 44 /* ENOENT */);
+
+        
+        try {
+            FS.rename('renamedir', 'renamedir/newdirname');
+        } catch (err) {
+            ex = err;
+        }
+        // The old path should not be an ancestor of the new path.
+        assert(ex.name === "ErrnoError" && ex.errno === 28 /* EINVAL */);
+
+        FS.writeFile('toplevelfile', "");
+        try {
+            FS.rename('renamedir', 'toplevelfile');
+        } catch (err) {
+            ex = err;
+        }
+        assert(ex.name === "ErrnoError" && ex.errno === 54 /* ENOTDIR */);
+    );
+    
     /********** test FS.read() **********/
     EM_ASM(
         FS.writeFile("readtestfile", 'a=1_b=2_');
@@ -104,5 +139,10 @@ int main() {
         assert(ex.name === "ErrnoError" && ex.errno === 8 /* EBADF */)
     );
 
+    remove("testfile");
+    remove("renametestfile");
+    remove("readtestfile");
+    remove("closetestfile");
+
     puts("success");
 }