[WasmFS] Implement FS.unlink (#18315)

Author: kleisauke

emcc.py

@@ -2172,6 +2172,7 @@ def phase_linker_setup(options, state, newargs):
       settings.REQUIRED_EXPORTS += [
         '_wasmfs_write_file',
         '_wasmfs_mkdir',
+        '_wasmfs_unlink',
         '_wasmfs_chdir',
         '_wasmfs_symlink',
         '_wasmfs_chmod',

src/library_wasmfs.js

@@ -125,7 +125,12 @@ mergeInto(LibraryManager.library, {
     // TODO: open
     // TODO: create
     // TODO: close
-    // TODO: unlink
+    unlink: (path) => {
+      return withStackSave(() => {
+        var buffer = allocateUTF8OnStack(path);
+        return __wasmfs_unlink(buffer);
+      });
+    },
     chdir: (path) => {
       return withStackSave(() => {
         var buffer = allocateUTF8OnStack(path);

system/lib/wasmfs/js_api.cpp

@@ -100,6 +100,10 @@ int _wasmfs_mkdir(char* path, int mode) {
   return __syscall_mkdirat(AT_FDCWD, (intptr_t)path, mode);
 }
 
+int _wasmfs_unlink(char* path) {
+  return __syscall_unlinkat(AT_FDCWD, (intptr_t)path, 0);
+}
+
 int _wasmfs_chdir(char* path) { return __syscall_chdir((intptr_t)path); }
 
 int _wasmfs_symlink(char* old_path, char* new_path) {

test/test_other.py

@@ -12206,10 +12206,12 @@ def test_wasmfs_getdents(self):
 
   @wasmfs_all_backends
   def test_wasmfs_readfile(self):
+    self.set_setting('FORCE_FILESYSTEM')
     self.do_run_in_out_file_test(test_file('wasmfs/wasmfs_readfile.c'))
 
   @wasmfs_all_backends
   def test_wasmfs_readfile_bigint(self):
+    self.set_setting('FORCE_FILESYSTEM')
     self.set_setting('WASM_BIGINT')
     self.node_args += shared.node_bigint_flags()
     self.do_run_in_out_file_test(test_file('wasmfs/wasmfs_readfile.c'))

test/wasmfs/wasmfs_readfile.c

@@ -33,6 +33,8 @@ int main() {
     var output = FS.readFile("/root/test");
     out(UTF8ArrayToString(output, 0));
     out("Length: " + output.byteLength);
+    var err = FS.unlink("/root/test");
+    out("FS.unlink: " + err);
   });
 
   EM_ASM({
@@ -44,7 +46,8 @@ int main() {
 
   EM_ASM({
     try {
-      var output = FS.readFile("", {encoding : 'utf8'});
+      // Already unlinked above, file should not exist anymore
+      var output = FS.readFile("/root/test", {encoding : 'utf8'});
     } catch (err) {
     }
   });

test/wasmfs/wasmfs_readfile.out

@@ -1,6 +1,7 @@
 Success
 
 Length: 8
+FS.unlink: 0
 Fatal error in FS.readFile
 Aborted(native code called abort())
 Fatal error in FS.readFile