FS attribute changes:

	removed unused `no_buffer_resize`
	renamed `no_async` to `no_async_preload`
	added `no_atime`, `no_suid`, `sync`
Changed `InodeFlags` to follow `S_*` instead of `FS_*_FL`
Added `FileFlag` (for `FS_*_FL`) to ioctl.ts
Improved read test slightly

Author: james-pre

src/backends/store/fs.ts

@@ -100,6 +100,7 @@ export class StoreFS<T extends Store = Store> extends FileSystem {
 		super(store.type ?? 0x6b766673, store.name);
 		store._fs = this;
 		this._uuid = store.uuid ?? this.uuid;
+		this.label = store.label;
 		debug(this.name + ': supports features: ' + this.store.flags?.join(', '));
 	}
 

src/backends/store/store.ts

@@ -1,5 +1,5 @@
 import { withErrno } from 'kerium';
-import { err, warn } from 'kerium/log';
+import { warn } from 'kerium/log';
 import type { UUID } from 'node:crypto';
 import { Resource } from 'utilium/cache.js';
 import type { UsageInfo } from '../../internal/filesystem.js';

src/config.ts

@@ -65,7 +65,7 @@ export async function resolveMountConfig<T extends Backend>(configuration: Mount
 
 	checkOptions(backend, configuration);
 	const mount = (await backend.create(configuration)) as FilesystemOf<T>;
-	if (configuration.disableAsyncCache) mount.attributes.set('no_async');
+	if (configuration.disableAsyncCache) mount.attributes.set('no_async_preload');
 	await mount.ready();
 	return mount;
 }

src/internal/filesystem.ts

@@ -42,25 +42,24 @@ export interface UsageInfo {
  * @internal
  */
 export type FileSystemAttributes = {
-	/** If set, disables `PreloadFile` from using a resizable array buffer. */
-	no_buffer_resize: void;
-
 	/**
 	 * If set disables async file systems from preloading their contents.
 	 * This means *sync operations will not work* (unless the contents are cached)
 	 * It has no affect on sync file systems.
 	 */
-	no_async: void;
+	no_async_preload: void;
 
 	/**
 	 * Currently unused. In the future, this will disable caching.
-	 * Not recommended due to performance impact.
+	 * Analogous to `S_DAX` on every file.
 	 */
 	no_cache: void;
 
 	/**
 	 * If set, the file system should not be written to.
 	 * This should be set for read-only file systems.
+	 * Note this does NOT trigger EROFS errors;
+	 * writes will silently be dropped.
 	 */
 	no_write: void;
 
@@ -75,6 +74,24 @@ export type FileSystemAttributes = {
 	 * @internal
 	 */
 	default_stream_write: void;
+
+	/**
+	 * Do not update access times.
+	 */
+	no_atime: void;
+
+	/**
+	 * Ignore suid and sgid bits.
+	 * @todo Implement
+	 * @experimental
+	 */
+	no_suid: void;
+
+	/**
+	 * Writes are synced at once
+	 * @experimental
+	 */
+	sync: void;
 };
 
 /**

src/internal/inode.ts

@@ -214,79 +214,53 @@ export const _inode_fields = [
  * 2. 66 bytes. Renamed the first member from `ino` to `data` and added a separate `ino` field
  * 3. 72 bytes. Changed the ID fields from 64 to 32 bits and added `flags`.
  * 4. >= 128 bytes. Added extended attributes.
- * 5. (current) 4 KiB. Changed to a fixed size to make a lot of size-related stuff easier.
+ * 5. (current) 4 KiB. Changed flags
  * @internal @hidden
  */
 export const _inode_version = 5;
 
 /**
- * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
- * @see `FS_*_FL` in `include/uapi/linux/fs.h` (around L250)
+ * Inode flags
+ * @see `S_*` in `include/linux/fs.h` (around L2325)
  * @experimental
  */
 export enum InodeFlags {
-	/** Secure deletion */
-	SecureRm = 0x00000001,
-	/** Undelete */
-	Undelete = 0x00000002,
-	/** Compress file */
-	Compress = 0x00000004,
-	/** Synchronous updates */
-	Sync = 0x00000008,
+	/** Writes are synced at once */
+	Sync = 1 << 0,
+	/** Do not update access times */
+	NoAtime = 1 << 1,
+	/** Append-only file */
+	Append = 1 << 2,
 	/** Immutable file */
-	Immutable = 0x00000010,
-	/** Writes to file may only append */
-	Append = 0x00000020,
-	/** do not dump file */
-	NoDump = 0x00000040,
-	/** do not update atime */
-	NoAtime = 0x00000080,
-	// Reserved for compression usage...
-	Dirty = 0x00000100,
-	/** One or more compressed clusters */
-	CompressBlk = 0x00000200,
-	/** Don't compress */
-	NoCompress = 0x00000400,
-	// End compression flags --- maybe not all used
-	/** Encrypted file */
-	Encrypt = 0x00000800,
-	/** btree format dir */
-	Btree = 0x00001000,
-	/** hash-indexed directory */
-	// eslint-disable-next-line @typescript-eslint/no-duplicate-enum-values
-	Index = 0x00001000,
-	/** AFS directory */
-	IMagic = 0x00002000,
-	/** Reserved for ext3 */
-	JournalData = 0x00004000,
-	/** file tail should not be merged */
-	NoTail = 0x00008000,
-	/** dirsync behaviour (directories only) */
-	DirSync = 0x00010000,
-	/** Top of directory hierarchies*/
-	TopDir = 0x00020000,
-	/** Reserved for ext4 */
-	HugeFile = 0x00040000,
-	/** Extents */
-	Extent = 0x00080000,
-	/** Verity protected inode */
-	Verity = 0x00100000,
-	/** Inode used for large EA */
-	EaInode = 0x00200000,
-	/** Reserved for ext4 */
-	EofBlocks = 0x00400000,
-	/** Do not cow file */
-	NoCow = 0x00800000,
-	/** Inode is DAX */
-	Dax = 0x02000000,
-	/** Reserved for ext4 */
-	InlineData = 0x10000000,
-	/** Create with parents projid */
-	ProjInherit = 0x20000000,
-	/** Folder is case insensitive */
-	CaseFold = 0x40000000,
-	/** reserved for ext2 lib */
-	Reserved = 0x80000000,
+	Immutable = 1 << 3,
+	/** removed, but still open directory */
+	Dead = 1 << 4,
+	/** Inode is not counted to quota */
+	NoQuota = 1 << 5,
+	/** Directory modifications are synchronous */
+	Dirsync = 1 << 6,
+	/** Do not update file c/mtime */
+	NoCMtime = 1 << 7,
+	/** Do not truncate: swapon got its bmaps */
+	SwapFile = 1 << 8,
+	/** Inode is fs-internal */
+	Private = 1 << 9,
+	/** Inode has an associated IMA struct */
+	IMA = 1 << 10,
+	/** Automount/referral quasi-directory */
+	AutoMount = 1 << 11,
+	/** no suid or xattr security attributes */
+	NoSec = 1 << 12,
+	/** Direct Access, avoiding the page cache */
+	DAX = 1 << 13,
+	/** Encrypted file (using fs/crypto/) */
+	Encrypted = 1 << 14,
+	/** Casefolded file */
+	CaseFold = 1 << 15,
+	/** Verity file (using fs/verity/) */
+	Verity = 1 << 16,
+	/** File is in use by the kernel (eg. fs/cachefiles) */
+	KernelFile = 1 << 17,
 }
 
 /** User visible flags */

src/mixins/async.ts

@@ -69,7 +69,7 @@ export function Async<const T extends abstract new (...args: any[]) => FileSyste
 		public async ready(): Promise<void> {
 			await super.ready();
 			await this.queueDone();
-			if (this._isInitialized || this.attributes.has('no_async')) return;
+			if (this._isInitialized || this.attributes.has('no_async_preload')) return;
 
 			this.checkSync();
 
@@ -102,7 +102,7 @@ export function Async<const T extends abstract new (...args: any[]) => FileSyste
 		}
 
 		protected checkSync(): asserts this is { _sync: FileSystem } {
-			if (this.attributes.has('no_async')) {
+			if (this.attributes.has('no_async_preload')) {
 				throw withErrno('ENOTSUP', 'Sync preloading has been disabled for this async file system');
 			}
 			if (!this._sync) {

src/vfs/file.ts

@@ -69,7 +69,7 @@ export class SyncHandle {
 	}
 
 	private get _isSync(): boolean {
-		return !!(this.flag & c.O_SYNC || this.inode.flags! & InodeFlags.Sync);
+		return !!(this.flag & c.O_SYNC || this.inode.flags! & InodeFlags.Sync || this.fs.attributes.has('sync'));
 	}
 
 	public sync(): void {
@@ -112,8 +112,11 @@ export class SyncHandle {
 	}
 
 	public truncate(length: number): void {
+		if (length < 0) throw UV('EINVAL', 'truncate', this.path);
 		if (this.closed) throw UV('EBADF', 'truncate', this.path);
-		if (!(this.flag & c.O_WRONLY || this.flag & c.O_RDWR)) throw UV('EBADF', 'write', this.path);
+		if (!(this.flag & c.O_WRONLY || this.flag & c.O_RDWR)) throw UV('EBADF', 'truncate', this.path);
+		if (this.fs.attributes.has('readonly')) throw UV('EROFS', 'truncate', this.path);
+		if (this.inode.flags! & InodeFlags.Immutable) throw UV('EPERM', 'truncate', this.path);
 
 		this.dirty = true;
 		this.inode.mtimeMs = Date.now();
@@ -135,6 +138,7 @@ export class SyncHandle {
 	public write(buffer: Uint8Array, offset: number = 0, length: number = buffer.byteLength - offset, position: number = this.position): number {
 		if (this.closed) throw UV('EBADF', 'write', this.path);
 		if (!(this.flag & c.O_WRONLY || this.flag & c.O_RDWR)) throw UV('EBADF', 'write', this.path);
+		if (this.fs.attributes.has('readonly')) throw UV('EROFS', 'write', this.path);
 		if (this.inode.flags! & InodeFlags.Immutable) throw UV('EPERM', 'write', this.path);
 
 		this.dirty = true;
@@ -167,7 +171,7 @@ export class SyncHandle {
 		if (this.closed) throw UV('EBADF', 'read', this.path);
 		if (this.flag & c.O_WRONLY) throw UV('EBADF', 'read', this.path);
 
-		if (!(this.inode.flags! & InodeFlags.NoAtime)) {
+		if (!(this.inode.flags! & InodeFlags.NoAtime) && !this.fs.attributes.has('no_atime')) {
 			this.dirty = true;
 			this.inode.atimeMs = Date.now();
 		}
@@ -224,6 +228,7 @@ export class SyncHandle {
 	public streamWrite(options: StreamOptions): WritableStream {
 		if (this.closed) throw UV('EBADF', 'write', this.path);
 		if (this.inode.flags! & InodeFlags.Immutable) throw UV('EPERM', 'write', this.path);
+		if (this.fs.attributes.has('readonly')) throw UV('EROFS', 'write', this.path);
 		return this.fs.streamWrite(this.internalPath, options);
 	}
 }

src/vfs/ioctl.ts

@@ -83,6 +83,76 @@ class fsxattr extends BufferView {
 	}
 }
 
+/**
+ * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
+ * @see `FS_*_FL` in `include/uapi/linux/fs.h` (around L250)
+ * @experimental
+ */
+enum FileFlag {
+	/** Secure deletion */
+	SecureRm = 0x00000001,
+	/** Undelete */
+	Undelete = 0x00000002,
+	/** Compress file */
+	Compress = 0x00000004,
+	/** Synchronous updates */
+	Sync = 0x00000008,
+	/** Immutable file */
+	Immutable = 0x00000010,
+	/** Writes to file may only append */
+	Append = 0x00000020,
+	/** do not dump file */
+	NoDump = 0x00000040,
+	/** do not update atime */
+	NoAtime = 0x00000080,
+	// Reserved for compression usage...
+	Dirty = 0x00000100,
+	/** One or more compressed clusters */
+	CompressBlk = 0x00000200,
+	/** Don't compress */
+	NoCompress = 0x00000400,
+	// End compression flags --- maybe not all used
+	/** Encrypted file */
+	Encrypt = 0x00000800,
+	/** btree format dir */
+	Btree = 0x00001000,
+	/** hash-indexed directory */
+	// eslint-disable-next-line @typescript-eslint/no-duplicate-enum-values
+	Index = 0x00001000,
+	/** AFS directory */
+	IMagic = 0x00002000,
+	/** Reserved for ext3 */
+	JournalData = 0x00004000,
+	/** file tail should not be merged */
+	NoTail = 0x00008000,
+	/** dirsync behaviour (directories only) */
+	DirSync = 0x00010000,
+	/** Top of directory hierarchies*/
+	TopDir = 0x00020000,
+	/** Reserved for ext4 */
+	HugeFile = 0x00040000,
+	/** Extents */
+	Extent = 0x00080000,
+	/** Verity protected inode */
+	Verity = 0x00100000,
+	/** Inode used for large EA */
+	EaInode = 0x00200000,
+	/** Reserved for ext4 */
+	EofBlocks = 0x00400000,
+	/** Do not cow file */
+	NoCow = 0x00800000,
+	/** Inode is DAX */
+	Dax = 0x02000000,
+	/** Reserved for ext4 */
+	InlineData = 0x10000000,
+	/** Create with parents projid */
+	ProjInherit = 0x20000000,
+	/** Folder is case insensitive */
+	CaseFold = 0x40000000,
+	/** reserved for ext2 lib */
+	Reserved = 0x80000000,
+}
+
 /**
  * `FS_IOC_*` commands for {@link ioctl | `ioctl`}
  * @remarks

src/vfs/promises.ts

@@ -147,6 +147,9 @@ export class FileHandle implements promises.FileHandle {
 	public async truncate(length: number = 0): Promise<void> {
 		if (this.closed) throw UV('EBADF', 'truncate', this.path);
 		if (length < 0) throw UV('EINVAL', 'truncate', this.path);
+		if (!(this.flag & constants.O_WRONLY || this.flag & constants.O_RDWR)) throw UV('EBADF', 'truncate', this.path);
+		if (this.fs.attributes.has('readonly')) throw UV('EROFS', 'truncate', this.path);
+		if (this.inode.flags! & InodeFlags.Immutable) throw UV('EPERM', 'truncate', this.path);
 
 		this.dirty = true;
 		if (!(this.flag & constants.O_WRONLY || this.flag & constants.O_RDWR)) throw UV('EBADF', 'truncate', this.path);
@@ -211,7 +214,7 @@ export class FileHandle implements promises.FileHandle {
 		if (this.closed) throw UV('EBADF', 'read', this.path);
 		if (this.flag & constants.O_WRONLY) throw UV('EBADF', 'read', this.path);
 
-		if (!(this.inode.flags! & InodeFlags.NoAtime)) {
+		if (!(this.inode.flags! & InodeFlags.NoAtime) && !this.fs.attributes.has('no_atime')) {
 			this.dirty = true;
 			this.inode.atimeMs = Date.now();
 		}
@@ -356,10 +359,9 @@ export class FileHandle implements promises.FileHandle {
 		position: number = this.position
 	): Promise<number> {
 		if (this.closed) throw UV('EBADF', 'write', this.path);
-
 		if (this.inode.flags! & InodeFlags.Immutable) throw UV('EPERM', 'write', this.path);
-
 		if (!(this.flag & constants.O_WRONLY || this.flag & constants.O_RDWR)) throw UV('EBADF', 'write', this.path);
+		if (this.fs.attributes.has('readonly')) throw UV('EROFS', 'write', this.path);
 
 		this.dirty = true;
 		const end = position + length;
@@ -503,6 +505,7 @@ export class FileHandle implements promises.FileHandle {
 	public createWriteStream(options: promises.CreateWriteStreamOptions = {}): WriteStream {
 		if (this.closed) throw UV('EBADF', 'createWriteStream', this.path);
 		if (this.inode.flags! & InodeFlags.Immutable) throw UV('EPERM', 'createWriteStream', this.path);
+		if (this.fs.attributes.has('readonly')) throw UV('EROFS', 'createWriteStream', this.path);
 		return new WriteStream(options, this);
 	}
 }