WasmFS JS API: Implement mknod and create (#19536)

Author: jameshu15869

emcc.py

@@ -2324,6 +2324,7 @@ def phase_linker_setup(options, state, newargs):
         '_wasmfs_mkdir',
         '_wasmfs_unlink',
         '_wasmfs_chdir',
+        '_wasmfs_mknod',
         '_wasmfs_rmdir',
         '_wasmfs_read',
         '_wasmfs_pread',

src/library_wasmfs.js

@@ -108,14 +108,12 @@ FS.createPreloadedFile = FS_createPreloadedFile;
       });
     },
     // TODO: mkdirTree
-    // TDOO: rmdir
     rmdir: (path) => {
       return withStackSave(() => {
         var buffer = stringToUTF8OnStack(path);
         return __wasmfs_rmdir(buffer);
       })
     },
-    // TODO: open
     open: (path, flags, mode) => {
       flags = typeof flags == 'string' ? FS_modeStringToFlags(flags) : flags;
       mode = typeof mode == 'undefined' ? 438 /* 0666 */ : mode;
@@ -125,8 +123,13 @@ FS.createPreloadedFile = FS_createPreloadedFile;
         return { fd : fd };
       });
     },
-    // TODO: create
-    // TODO: close
+    create: (path, mode) => {
+      // Default settings copied from the legacy JS FS API.
+      mode = mode !== undefined ? mode : 438 /* 0666 */;
+      mode &= {{{ cDefs.S_IALLUGO }}};
+      mode |= {{{ cDefs.S_IFREG }}};
+      return FS.mknod(path, mode, 0);
+    },
     close: (stream) => {
       return FS.handleError(-__wasmfs_close(stream.fd));
     },
@@ -261,14 +264,12 @@ FS.createPreloadedFile = FS_createPreloadedFile;
         return __wasmfs_chmod(buffer, mode);
       }));
     },
-    // TODO: lchmod
     lchmod: (path, mode) => {
       return FS.handleError(withStackSave(() => {
         var buffer = stringToUTF8OnStack(path);
         return __wasmfs_lchmod(buffer, mode);
       }));
     },
-    // TODO: fchmod
     fchmod: (fd, mode) => {
       return FS.handleError(__wasmfs_fchmod(fd, mode));
     },
@@ -308,7 +309,12 @@ FS.createPreloadedFile = FS_createPreloadedFile;
     // TODO: mount
     // TODO: unmount
     // TODO: lookup
-    // TODO: mknod
+    mknod: (path, mode, dev) => {
+      return FS.handleError(withStackSave(() => {
+        var pathBuffer = stringToUTF8OnStack(path);
+        return __wasmfs_mknod(pathBuffer, mode, dev);
+      }));
+    },
     // TODO: mkdev
     rename: (oldPath, newPath) => {
       return FS.handleError(withStackSave(() => {

system/lib/wasmfs/js_api.cpp

@@ -133,6 +133,14 @@ int _wasmfs_open(char* path, int flags, mode_t mode) {
   return err;
 }
 
+int _wasmfs_mknod(char* path, mode_t mode, dev_t dev) {
+  int err = __syscall_mknodat(AT_FDCWD, (intptr_t)path, mode, dev);
+  if (err == -1) {
+    return errno;
+  }
+  return err;
+}
+
 int _wasmfs_unlink(char* path) {
   return __syscall_unlinkat(AT_FDCWD, (intptr_t)path, 0);
 }

test/fs/test_fs_js_api.c

@@ -1,5 +1,8 @@
 #include <emscripten/emscripten.h>
 #include <stdio.h>
+#include <sys/stat.h>
+#include <assert.h>
+#include <fcntl.h>
 
 int main() {
     /********** test FS.open() **********/
@@ -130,6 +133,24 @@ int main() {
         assert(ex.name === "ErrnoError" && ex.errno === 8 /* EBADF */)
     );
 
+    /********** test FS.mknod() **********/
+    EM_ASM(
+        FS.mknod("mknodtest", 0100000 | 0777); /* S_IFREG | S_RWXU | S_RWXG | S_RWXO */
+
+        FS.create("createtest", 0400); /* S_IRUSR */
+    );
+    struct stat stats;
+    stat("mknodtest", &stats);
+
+    assert(S_ISREG(stats.st_mode));
+    assert(stats.st_mode & 0777);
+
+    stat("createtest", &stats);
+    assert(S_ISREG(stats.st_mode));
+    assert(stats.st_mode & 0400);
+
+    remove("mknodtest");
+    remove("createtest");
     remove("testfile");
     remove("renametestfile");
     remove("readtestfile");