[nodefs] Return real values for statvfs via __syscall_statfs64

src/library_fs.js

@@ -672,6 +672,31 @@ FS.staticInit();
       }
       return parent.node_ops.mknod(parent, name, mode, dev);
     },
+    statfs(path) {
+
+      // NOTE: None of the defaults here are true. We're just returning safe and
+      //       sane values.
+      var defaults = {
+        bsize: 4096,
+        frsize: 4096,
+        blocks: 1e6,
+        bfree: 5e5,
+        bavail: 5e5,
+        files: FS.nextInode,
+        // Free inodes can not be larger than total inodes so calculate a reasonable value here
+        ffree: () => Math.max(0, Math.floor(this.files * 0.9) - this.files),
+        fsid: 42,
+        flags: 2,
+        namelen: 255,
+      };
+
+      var parent = FS.lookupPath(path, {follow: true}).node;
+      if (typeof parent.node_ops?.statfs !== 'function') {
+        return defaults;
+      }
+
+      return { ...defaults, ...parent.node_ops.statfs(parent.mount.opts.root) };
+    },
     // helpers to create specific types of nodes
     create(path, mode) {
       mode = mode !== undefined ? mode : 438 /* 0666 */;

src/library_nodefs.js

@@ -214,6 +214,13 @@ addToLibrary({
         var path = NODEFS.realPath(node);
         return NODEFS.tryFSOperation(() => fs.readlinkSync(path));
       },
+      statfs(path) {
+        var stats = NODEFS.tryFSOperation(() => fs.statfsSync(path));
+        return {
+          ...stats,
+          frsize: stats.bsize
+        };
+      }
     },
     stream_ops: {
       open(stream) {

src/library_syscall.js

@@ -802,22 +802,20 @@ var SyscallsLibrary = {
   },
 
   __syscall_statfs64: (path, size, buf) => {
-    path = SYSCALLS.getStr(path);
 #if ASSERTIONS
     assert(size === {{{ C_STRUCTS.statfs.__size__ }}});
 #endif
-    // NOTE: None of the constants here are true. We're just returning safe and
-    //       sane values.
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_bsize, '4096', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_frsize, '4096', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_blocks, '1000000', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_bfree, '500000', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_bavail, '500000', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_files, 'FS.nextInode', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_ffree, '1000000', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_fsid, '42', 'i32') }}};
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_flags, '2', 'i32') }}};  // ST_NOSUID
-    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_namelen, '255', 'i32') }}};
+    var defaults = FS.statfs(SYSCALLS.getStr(path));
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_bsize, 'defaults.bsize', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_frsize, 'defaults.bsize', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_blocks, 'defaults.blocks', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_bfree, 'defaults.bfree', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_bavail, 'defaults.bavail', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_files, 'defaults.files', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_ffree, 'defaults.ffree', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_fsid, 'defaults.fsid', 'i32') }}};
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_flags, 'defaults.flags', 'i32') }}};  // ST_NOSUID
+    {{{ makeSetValue('buf', C_STRUCTS.statfs.f_namelen, 'defaults.namelen', 'i32') }}};
     return 0;
   },
   __syscall_fstatfs64__deps: ['__syscall_statfs64'],

test/core/test_statvfs.c

@@ -8,10 +8,13 @@
 #include <stdio.h>
 #include <errno.h>
 #include <sys/statvfs.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 int main() {
   struct statvfs s;
 
+  mkdir("/test", S_IRWXU | S_IRWXG | S_IRWXO);
   printf("result: %d\n", statvfs("/test", &s));
   printf("errno: %d\n", errno);
 

test/fs/test_nodefs_statfs.c

@@ -0,0 +1,37 @@
+#include <assert.h>
+#include <stdio.h>
+#include <sys/statvfs.h>
+#include <emscripten.h>
+
+void test_statfs(const char *path) {
+    printf("Testing statfs for path: %s\n", path);
+    struct statvfs st;
+    int result = statvfs(path, &st);
+
+    assert(result == 0 && "statvfs should succeed");
+
+
+
+    // Basic sanity checks
+    assert(st.f_bsize > 0 && "Block size should be positive");
+    assert(st.f_blocks > 0 && "Total blocks should be positive");
+    assert(st.f_bfree <= st.f_blocks && "Free blocks should not exceed total blocks");
+    assert(st.f_bavail <= st.f_bfree && "Available blocks should not exceed free blocks");
+    assert(st.f_files > 0 && "Total inodes should be positive");
+    assert(st.f_ffree <= st.f_files && "Free inodes should not exceed total inodes");
+}
+
+int main() {
+    // Test the root filesystem (which should be MEMFS by default)
+    test_statfs("/");
+
+    // Mount NODEFS and test it
+    EM_ASM(
+        FS.mkdir('/working');
+        FS.mount(NODEFS, { root: '.' }, '/working');
+    );
+
+    test_statfs("/working");
+
+    puts("success");
+}

test/test_core.py

@@ -5779,6 +5779,15 @@ def test_fs_nodefs_readdir(self):
     self.emcc_args += ['-lnodefs.js']
     self.do_runf('fs/test_nodefs_readdir.c', 'success')
 
+  @requires_node
+  def test_fs_nodefs_statfs(self):
+    # externally setup an existing folder structure: existing/a
+    if self.get_setting('WASMFS'):
+      self.set_setting('FORCE_FILESYSTEM')
+    os.makedirs(os.path.join(self.working_dir, 'existing', 'a'))
+    self.emcc_args += ['-lnodefs.js']
+    self.do_runf('fs/test_nodefs_statfs.c', 'success')
+
   @no_windows('no symlink support on windows')
   @requires_node
   def test_fs_noderawfs_nofollow(self):