initial VFS work

4 files changed, 2197 insertions, 43 deletions

diff --git a/src/library.js b/src/library.js
index 0d443adb..1c0e0320 100644
--- a/src/library.js
+++ b/src/library.js
@@ -77,6 +77,7 @@ LibraryManager.library = {
     }
   },
 
+#if USE_OLD_FS
   $FS__deps: ['$FSCOM', '$ERRNO_CODES', '__setErrNo', 'stdin', 'stdout', 'stderr', '_impure_ptr'],
   $FS__postset: 'FS.staticInit();' +
                 '__ATINIT__.unshift({ func: function() { if (!Module["noFSInit"] && !FS.init.initialized) FS.init() } });' +
@@ -688,6 +689,1509 @@ LibraryManager.library = {
       delete path.parentObject.contents[path.name];
     }
   },
+#else
+  $FS__deps: ['$FSCOM', '$ERRNO_CODES', '$ERRNO_MESSAGES', '__setErrNo', '$VFS', '$PATH', '$TTY', '$MEMFS', 'stdin', 'stdout', 'stderr', 'fflush'],
+  $FS__postset: 'FS.staticInit();' +
+                '__ATINIT__.unshift({ func: function() { if (!Module["noFSInit"] && !FS.init.initialized) FS.init() } });' +
+                '__ATMAIN__.push({ func: function() { FS.ignorePermissions = false } });' +
+                '__ATEXIT__.push({ func: function() { FS.quit() } });' +
+                // export some names through closure
+                'Module["FS_createFolder"] = FS.createFolder;' +
+                'Module["FS_createPath"] = FS.createPath;' +
+                'Module["FS_createDataFile"] = FS.createDataFile;' +
+                'Module["FS_createPreloadedFile"] = FS.createPreloadedFile;' +
+                'Module["FS_createLazyFile"] = FS.createLazyFile;' +
+                'Module["FS_createLink"] = FS.createLink;' +
+                'Module["FS_createDevice"] = FS.createDevice;',
+  $FS: {
+    root: null,
+    nodes: [null],
+    devices: [null],
+    streams: [null],
+    nextInode: 1,
+    name_table: new Array(4096),
+    currentPath: '/',
+    initialized: false,
+    // Whether we are currently ignoring permissions. Useful when preparing the
+    // filesystem and creating files inside read-only folders.
+    // This is set to false when the runtime is initialized, allowing you
+    // to modify the filesystem freely before run() is called.
+    ignorePermissions: true,
+    
+    ErrnoError: function (errno) {
+      function ErrnoError(errno) {
+        this.errno = errno;
+        for (var key in ERRNO_CODES) {
+          if (ERRNO_CODES[key] === errno) {
+            this.code = key;
+            break;
+          }
+        }
+        this.message = ERRNO_MESSAGES[errno];
+      };
+      ErrnoError.prototype = Object.create(Error.prototype);
+      ErrnoError.prototype.contructor = ErrnoError;
+      return new ErrnoError(errno);
+    },
+
+    //
+    // nodes
+    //
+    hashName: function (parentid, name) {
+      var hash = 0;
+      for (var i = 0; i < name.length; i++) {
+        hash = ((hash << 5) - hash + name.charCodeAt(i)) | 0;
+      }
+      return (parentid + hash) % FS.name_table.length;
+    },
+    hashAddNode: function (node) {
+      var hash = FS.hashName(node.parent.id, node.name);
+      node.name_next = FS.name_table[hash];
+      FS.name_table[hash] = node;
+    },
+    hashRemoveNode: function (node) {
+      var hash = FS.hashName(node.parent.id, node.name);
+      if (FS.name_table[hash] === node) {
+        FS.name_table[hash] = node.name_next;
+      } else {
+        var current = FS.name_table[hash];
+        while (current) {
+          if (current.name_next === node) {
+            current.name_next = node.name_next;
+            break;
+          }
+          current = current.name_next;
+        }
+      }
+    },
+    lookupNode: function (parent, name) {
+      var err = FS.mayLookup(parent);
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      var hash = FS.hashName(parent.id, name);
+      for (var node = FS.name_table[hash]; node; node = node.name_next) {
+        if (node.parent.id === parent.id && node.name === name) {
+          return node;
+        }
+      }
+      // if we failed to find it in the cache, call into the VFS
+      return VFS.lookup(parent, name);
+    },
+    createNode: function (parent, name, mode, rdev) {
+      var node = {
+        id: FS.nextInode++,
+        name: name,
+        mode: mode,
+        node_ops: {},
+        stream_ops: {},
+        rdev: rdev,
+        parent: null,
+        mount: null
+      };
+      if (!parent) {
+        parent = node;  // root node sets parent to itself
+      }
+      node.parent = parent;
+      node.mount = parent.mount;
+      // compatibility
+      var readMode = {{{ cDefine('S_IRUGO') }}} | {{{ cDefine('S_IXUGO') }}};
+      var writeMode = {{{ cDefine('S_IWUGO') }}};
+      Object.defineProperty(node, 'read', {
+        get: function () { return (node.mode & readMode) === readMode; },
+        set: function (val) { val ? node.mode |= readMode : node.mode &= ~readMode; }
+      });
+      Object.defineProperty(node, 'write', {
+        get: function () { return (node.mode & writeMode) === writeMode; },
+        set: function (val) { val ? node.mode |= writeMode : node.mode &= ~writeMode; }
+      });
+      // TODO add:
+      // isFolder
+      // isDevice
+      FS.hashAddNode(node);
+      return node;
+    },
+    destroyNode: function (node) {
+      FS.hashRemoveNode(node);
+    },
+    isRoot: function (node) {
+      return node === node.parent;
+    },
+    isMountpoint: function (node) {
+      return node.mounted;
+    },
+    isFile: function (mode) {
+      return (mode & {{{ cDefine('S_IFMT') }}}) === {{{ cDefine('S_IFREG') }}};
+    },
+    isDir: function (mode) {
+      return (mode & {{{ cDefine('S_IFMT') }}}) === {{{ cDefine('S_IFDIR') }}};
+    },
+    isLink: function (mode) {
+      return (mode & {{{ cDefine('S_IFMT') }}}) === {{{ cDefine('S_IFLNK') }}};
+    },
+    isChrdev: function (mode) {
+      return (mode & {{{ cDefine('S_IFMT') }}}) === {{{ cDefine('S_IFCHR') }}};
+    },
+    isBlkdev: function (mode) {
+      return (mode & {{{ cDefine('S_IFMT') }}}) === {{{ cDefine('S_IFBLK') }}};
+    },
+    isFIFO: function (mode) {
+      return (mode & {{{ cDefine('S_IFMT') }}}) === {{{ cDefine('S_IFIFO') }}};
+    },
+
+    //
+    // paths
+    //
+    lookupPath: function (path, opts) {
+      path = PATH.resolve(FS.currentPath, path);
+      opts = opts || { recurse_count: 0 };
+
+      if (opts.recurse_count > 8) {  // max recursive lookup of 8
+        throw new FS.ErrnoError(ERRNO_CODES.ELOOP);
+      }
+
+      // split the path
+      var parts = PATH.normalizeArray(path.split('/').filter(function (p) {
+        return !!p;
+      }), false);
+
+      // start at the root
+      var current = FS.root;
+      var current_path = '/';
+
+      for (var i = 0; i < parts.length; i++) {
+        var islast = (i === parts.length-1);
+        if (islast && opts.parent) {
+          // stop resolving
+          break;
+        }
+
+        current = FS.lookupNode(current, parts[i]);
+        current_path = PATH.join(current_path, parts[i]);
+
+        // jump to the mount's root node if this is a mountpoint
+        if (FS.isMountpoint(current)) {
+          current = current.mount.root;
+        }
+
+        // follow symlinks
+        // by default, lookupPath will not follow a symlink if it is the final path component.
+        // setting opts.follow = true will override this behavior.
+        if (!islast || opts.follow) {
+          var count = 0;
+          while (FS.isLink(current.mode)) {
+            var link = VFS.readlink(current_path);
+            current_path = PATH.resolve(PATH.dirname(current_path), link);
+            
+            var lookup = FS.lookupPath(current_path, { recurse_count: opts.recurse_count });
+            current = lookup.node;
+
+            if (count++ > 40) {  // limit max consecutive symlinks to 40 (SYMLOOP_MAX).
+              throw new FS.ErrnoError(ERRNO_CODES.ELOOP);
+            }
+          }
+        }
+      }
+
+      return { path: current_path, node: current };
+    },
+    getPath: function (node) {
+      var path;
+      while (true) {
+        if (FS.isRoot(node)) {
+          return path ? PATH.join(node.mount.mountpoint, path) : node.mount.mountpoint;
+        }
+        path = path ? PATH.join(node.name, path) : node.name;
+        node = node.parent;
+      }
+    },
+
+    //
+    // permissions
+    //
+    flagModes: {
+      '"r"': {{{ cDefine('O_RDONLY') }}},
+      '"rs"': {{{ cDefine('O_RDONLY') }}} | {{{ cDefine('O_SYNC') }}},
+      '"r+"': {{{ cDefine('O_RDWR') }}},
+      '"w"': {{{ cDefine('O_TRUNC') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_WRONLY') }}},
+      '"wx"': {{{ cDefine('O_TRUNC') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_WRONLY') }}} | {{{ cDefine('O_EXCL') }}},
+      '"xw"': {{{ cDefine('O_TRUNC') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_WRONLY') }}} | {{{ cDefine('O_EXCL') }}},
+      '"w+"': {{{ cDefine('O_TRUNC') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_RDWR') }}},
+      '"wx+"': {{{ cDefine('O_TRUNC') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_RDWR') }}} | {{{ cDefine('O_EXCL') }}},
+      '"xw+"': {{{ cDefine('O_TRUNC') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_RDWR') }}} | {{{ cDefine('O_EXCL') }}},
+      '"a"': {{{ cDefine('O_APPEND') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_WRONLY') }}},
+      '"ax"': {{{ cDefine('O_APPEND') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_WRONLY') }}} | {{{ cDefine('O_EXCL') }}},
+      '"xa"': {{{ cDefine('O_APPEND') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_WRONLY') }}} | {{{ cDefine('O_EXCL') }}},
+      '"a+"': {{{ cDefine('O_APPEND') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_RDWR') }}},
+      '"ax+"': {{{ cDefine('O_APPEND') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_RDWR') }}} | {{{ cDefine('O_EXCL') }}},
+      '"xa+"': {{{ cDefine('O_APPEND') }}} | {{{ cDefine('O_CREAT') }}} | {{{ cDefine('O_RDWR') }}} | {{{ cDefine('O_EXCL') }}}
+    },
+    // convert the 'r', 'r+', etc. to it's corresponding set of O_* flags
+    modeStringToFlags: function (str) {
+      var flags = FS.flagModes[str];
+      if (typeof flags === 'undefined') {
+        throw new Error('Unknown file open mode: ' + str);
+      }
+      return flags;
+    },
+    // convert O_* bitmask to a string for nodePermissions
+    flagsToPermissionString: function (flag) {
+      var accmode = flag & {{{ cDefine('O_ACCMODE') }}};
+      var perms = ['r', 'w', 'rw'][accmode];
+      if ((flag & {{{ cDefine('O_TRUNC') }}})) {
+        perms += 'w';
+      }
+      return perms;
+    },
+    nodePermissions: function (node, perms) {
+      if (FS.ignorePermissions) {
+        return 0;
+      }
+      // return 0 if any user, group or owner bits are set.
+      if (perms.indexOf('r') !== -1 && !(node.mode & {{{ cDefine('S_IRUGO') }}})) {
+        return ERRNO_CODES.EACCES;
+      } else if (perms.indexOf('w') !== -1 && !(node.mode & {{{ cDefine('S_IWUGO') }}})) {
+        return ERRNO_CODES.EACCES;
+      } else if (perms.indexOf('x') !== -1 && !(node.mode & {{{ cDefine('S_IXUGO') }}})) {
+        return ERRNO_CODES.EACCES;
+      }
+      return 0;
+    },
+    mayLookup: function (dir) {
+      return FS.nodePermissions(dir, 'x');
+    },
+    mayMknod: function (mode) {
+      switch (mode & {{{ cDefine('S_IFMT') }}}) {
+        case {{{ cDefine('S_IFREG') }}}:
+        case {{{ cDefine('S_IFCHR') }}}:
+        case {{{ cDefine('S_IFBLK') }}}:
+        case {{{ cDefine('S_IFIFO') }}}:
+        case {{{ cDefine('S_IFSOCK') }}}:
+          return 0;
+        default:
+          return ERRNO_CODES.EINVAL;
+      }
+    },
+    mayCreate: function (dir, name) {
+      try {
+        var node = FS.lookupNode(dir, name);
+        return ERRNO_CODES.EEXIST;
+      } catch (e) {
+      }
+      return FS.nodePermissions(dir, 'wx');
+    },
+    mayDelete: function (dir, name, isdir) {
+      var node;
+      try {
+        node = FS.lookupNode(dir, name);
+      } catch (e) {
+        return e.errno;
+      }
+      var err = FS.nodePermissions(dir, 'wx');
+      if (err) {
+        return err;
+      }
+      if (isdir) {
+        if (!FS.isDir(node.mode)) {
+          return ERRNO_CODES.ENOTDIR;
+        }
+        if (FS.isRoot(node) || FS.getPath(node) === FS.currentPath) {
+          return ERRNO_CODES.EBUSY;
+        }
+      } else {
+        if (FS.isDir(node.mode)) {
+          return ERRNO_CODES.EISDIR;
+        }
+      }
+      return 0;
+    },
+    mayOpen: function (node, flags) {
+      if (!node) {
+        return ERRNO_CODES.ENOENT;
+      }
+      if (FS.isLink(node.mode)) {
+        return ERRNO_CODES.ELOOP;
+      } else if (FS.isDir(node.mode)) {
+        if ((flags & {{{ cDefine('O_ACCMODE') }}}) !== {{{ cDefine('O_RDONLY')}}} ||  // opening for write
+            (flags & {{{ cDefine('O_TRUNC') }}})) {
+          return ERRNO_CODES.EISDIR;
+        }
+      }
+      return FS.nodePermissions(node, FS.flagsToPermissionString(flags));
+    },
+
+    //
+    // devices
+    //
+    // each character device consists of a device id + stream operations.
+    // when a character device node is created (e.g. /dev/stdin) it is
+    // assigned a device id that lets us map back to the actual device.
+    // by default, each character device stream (e.g. _stdin) uses chrdev_stream_ops.
+    // however, once opened, the stream's operations are overridden with
+    // the operations of the device its underlying node maps back to.
+    chrdev_stream_ops: {
+      open: function (stream) {
+        var device = FS.getDevice(stream.node.rdev);
+        // override node's stream ops with the device's
+        stream.stream_ops = device.stream_ops;
+        // forward the open call
+        if (stream.stream_ops.open) {
+          stream.stream_ops.open(stream);
+        }
+      },
+      llseek: function () {
+        throw new FS.ErrnoError(ERRNO_CODES.ESPIPE);
+      }
+    },
+    major: function (dev) {
+      return ((dev) >> 8);
+    },
+    minor: function (dev) {
+      return ((dev) & 0xff);
+    },
+    makedev: function (ma, mi) {
+      return ((ma) << 8 | (mi));
+    },
+    registerDevice: function (dev, ops) {
+      FS.devices[dev] = { stream_ops: ops };
+    },
+    getDevice: function (dev) {
+      return FS.devices[dev];
+    },
+
+    //
+    // streams
+    //
+    MAX_OPEN_FDS: 4096,
+    nextfd: function (fd_start, fd_end) {
+      fd_start = fd_start || 1;
+      fd_end = fd_end || FS.MAX_OPEN_FDS;
+      for (var fd = fd_start; fd <= fd_end; fd++) {
+        if (!FS.streams[fd]) {
+          return fd;
+        }
+      }
+      throw new FS.ErrnoError(ERRNO_CODES.EMFILE);
+    },
+    getStream: function (fd) {
+      return FS.streams[fd];
+    },
+    createStream: function (stream, fd_start, fd_end) {
+      var fd = FS.nextfd(fd_start, fd_end);
+      stream.fd = fd;
+      // compatibility
+      Object.defineProperty(stream, 'object', {
+        get: function () { return stream.node; },
+        set: function (val) { stream.node = val; }
+      });
+      Object.defineProperty(stream, 'isRead', {
+        get: function () { return (stream.flags & {{{ cDefine('O_ACCMODE') }}}) !== {{{ cDefine('O_WRONLY') }}}; }
+      });
+      Object.defineProperty(stream, 'isWrite', {
+        get: function () { return (stream.flags & {{{ cDefine('O_ACCMODE') }}}) !== {{{ cDefine('O_RDONLY') }}}; }
+      });
+      Object.defineProperty(stream, 'isAppend', {
+        get: function () { return (stream.flags & {{{ cDefine('O_APPEND') }}}); }
+      });
+      FS.streams[fd] = stream;
+      return stream;
+    },
+    closeStream: function (fd) {
+      FS.streams[fd] = null;
+    },
+
+    //
+    // general
+    //
+    createDefaultDirectories: function () {
+      VFS.mkdir('/tmp', 0777);
+    },
+    createDefaultDevices: function () {
+      // create /dev
+      VFS.mkdir('/dev', 0777);
+      // setup /dev/null
+      FS.registerDevice(FS.makedev(1, 3), {
+        read: function () { return 0; },
+        write: function () { return 0; }
+      });
+      VFS.mkdev('/dev/null', 0666, FS.makedev(1, 3));
+      // setup /dev/tty and /dev/tty1
+      // stderr needs to print output using Module['printErr']
+      // so we register a second tty just for it.
+      TTY.register(FS.makedev(5, 0), TTY.default_tty_ops);
+      TTY.register(FS.makedev(6, 0), TTY.default_tty1_ops);
+      VFS.mkdev('/dev/tty', 0666, FS.makedev(5, 0));
+      VFS.mkdev('/dev/tty1', 0666, FS.makedev(6, 0));
+      // we're not going to emulate the actual shm device,
+      // just create the tmp dirs that reside in it commonly
+      VFS.mkdir('/dev/shm', 0777);
+      VFS.mkdir('/dev/shm/tmp', 0777);
+    },
+    createStandardStreams: function () {
+      // TODO deprecate the old functionality of a single
+      // input / output callback and that utilizes FS.createDevice
+      // and instead require a unique set of stream ops
+
+      // by default, we symlink the standard streams to the
+      // default tty devices. however, if the standard streams
+      // have been overwritten we create a unique device for
+      // them instead.
+      if (Module['stdin']) {
+        FS.createDevice('/dev', 'stdin', Module['stdin']);
+      } else {
+        VFS.symlink('/dev/tty', '/dev/stdin');
+      }
+      if (Module['stdout']) {
+        FS.createDevice('/dev', 'stdout', null, Module['stdout']);
+      } else {
+        VFS.symlink('/dev/tty', '/dev/stdout');
+      }
+      if (Module['stderr']) {
+        FS.createDevice('/dev', 'stderr', null, Module['stderr']);
+      } else {
+        VFS.symlink('/dev/tty1', '/dev/stderr');
+      }
+
+      // open default streams for the stdin, stdout and stderr devices
+      var stdin = VFS.open('/dev/stdin', 'r');
+      {{{ makeSetValue(makeGlobalUse('_stdin'), 0, 'stdin.fd', 'void*') }}};
+      assert(stdin.fd === 1, 'invalid handle for stdin (' + stdin.fd + ')');
+
+      var stdout = VFS.open('/dev/stdout', 'w');
+      {{{ makeSetValue(makeGlobalUse('_stdout'), 0, 'stdout.fd', 'void*') }}};
+      assert(stdout.fd === 2, 'invalid handle for stdout (' + stdout.fd + ')');
+
+      var stderr = VFS.open('/dev/stderr', 'w');
+      {{{ makeSetValue(makeGlobalUse('_stderr'), 0, 'stderr.fd', 'void*') }}};
+      assert(stderr.fd === 3, 'invalid handle for stderr (' + stderr.fd + ')');
+    },
+    staticInit: function () {
+      FS.root = FS.createNode(null, '/', {{{ cDefine('S_IFDIR') }}} | 0777, 0);
+      VFS.mount(MEMFS, {}, '/');
+
+      FS.createDefaultDirectories();
+      FS.createDefaultDevices();
+    },
+    init: function (input, output, error) {
+      assert(!FS.init.initialized, 'FS.init was previously called. If you want to initialize later with custom parameters, remove any earlier calls (note that one is automatically added to the generated code)');
+      FS.init.initialized = true;
+
+      // Allow Module.stdin etc. to provide defaults, if none explicitly passed to us here
+      Module['stdin'] = input || Module['stdin'];
+      Module['stdout'] = output || Module['stdout'];
+      Module['stderr'] = error || Module['stderr'];
+
+      FS.createStandardStreams();
+    },
+    quit: function () {
+      FS.init.initialized = false;
+      for (var i = 0; i < FS.streams.length; i++) {
+        var stream = FS.streams[i];
+        if (!stream) {
+          continue;
+        }
+        VFS.close(stream);
+      }
+    },
+
+    //
+    // compatibility
+    //
+    getMode: function (canRead, canWrite) {
+      var mode = 0;
+      if (canRead) mode |= {{{ cDefine('S_IRUGO') }}} | {{{ cDefine('S_IXUGO') }}};
+      if (canWrite) mode |= {{{ cDefine('S_IWUGO') }}};
+      return mode;
+    },
+    joinPath: function(parts, forceRelative) {
+      var path = PATH.join.apply(null, parts);
+      if (forceRelative && path[0] == '/') path = path.substr(1);
+      return path;
+    },
+    absolutePath: function(relative, base) {
+      return PATH.resolve(base, relative);
+    },
+    findObject: function (path, dontResolveLastLink) {
+      var ret = FS.analyzePath(path, dontResolveLastLink);
+      if (ret.exists) {
+        return ret.object;
+      } else {
+        ___setErrNo(ret.error);
+        return null;
+      }
+    },
+    analyzePath: function (path, dontResolveLastLink) {
+      // operate from within the context of the symlink's target
+      try {
+        var lookup = FS.lookupPath(path, { follow: !dontResolveLastLink });
+        path = lookup.path;
+      } catch (e) {
+      }
+      var ret = {
+        isRoot: false, exists: false, error: 0, name: null, path: null, object: null,
+        parentExists: false, parentPath: null, parentObject: null
+      };
+      try {
+        var lookup = FS.lookupPath(path, { parent: true });
+        ret.parentExists = true;
+        ret.parentPath = lookup.path;
+        ret.parentObject = lookup.node;
+        ret.name = PATH.basename(path);
+        lookup = FS.lookupPath(path, { follow: !dontResolveLastLink });
+        ret.exists = true;
+        ret.path = lookup.path;
+        ret.object = lookup.node;
+        ret.name = lookup.node.name;
+        ret.isRoot = lookup.path === '/';
+      } catch (e) {
+        ret.error = e.errno;
+      };
+      return ret;
+    },
+    createFolder: function (parent, name, canRead, canWrite) {
+      var path = PATH.join(typeof parent === 'string' ? parent : FS.getPath(parent), name);
+      var mode = FS.getMode(canRead, canWrite);
+      return VFS.mkdir(path, mode);
+    },
+    createPath: function (parent, path, canRead, canWrite) {
+      parent = typeof parent === 'string' ? parent : FS.getPath(parent);
+      var parts = path.split('/').reverse();
+      while (parts.length) {
+        var part = parts.pop();
+        if (!part) continue;
+        var current = PATH.join(parent, part);
+        try {
+          VFS.mkdir(current, 0777);
+        } catch (e) {
+          // ignore EEXIST
+        }
+        parent = current;
+      }
+      return current;
+    },
+    createFile: function (parent, name, properties, canRead, canWrite) {
+      var path = PATH.join(typeof parent === 'string' ? parent : FS.getPath(parent), name);
+      var mode = FS.getMode(canRead, canWrite);
+      return VFS.create(path, mode);
+    },
+    createDataFile: function (parent, name, data, canRead, canWrite) {
+      var path = PATH.join(typeof parent === 'string' ? parent : FS.getPath(parent), name);
+      var mode = FS.getMode(canRead, canWrite);
+      var node = VFS.create(path, mode);
+      if (data) {
+        if (typeof data === 'string') {
+          var arr = new Array(data.length);
+          for (var i = 0, len = data.length; i < len; ++i) arr[i] = data.charCodeAt(i);
+          data = arr;
+        }
+        // make sure we can write to the file
+        VFS.chmod(path, mode | {{{ cDefine('S_IWUGO') }}});
+        var stream = VFS.open(path, 'w');
+        VFS.write(stream, data, 0, data.length, 0);
+        VFS.close(stream);
+        VFS.chmod(path, mode);
+      }
+      return node;
+    },
+    createLazyFile: function (parent, name, url, canRead, canWrite) {
+      throw new Error('TODO');
+    },
+    createDevice: function (parent, name, input, output) {
+      var path = PATH.join(typeof parent === 'string' ? parent : FS.getPath(parent), name);
+      var mode = input && output ? 0777 : (input ? 0333 : 0555);
+      if (!FS.createDevice.major) FS.createDevice.major = 64;
+      var dev = FS.makedev(FS.createDevice.major++, 0);
+      // Create a fake device that a set of stream ops to emulate
+      // the old behavior.
+      FS.registerDevice(dev, {
+        open: function (stream) {
+          stream.seekable = false;
+        },
+        close: function (stream) {
+          // flush any pending line data
+          if (output.buffer && output.buffer.length) {
+            output({{{ charCode('\n') }}});
+          }
+        },
+        read: function (stream, buffer, offset, length, pos /* ignored */) {
+          var bytesRead = 0;
+          for (var i = 0; i < length; i++) {
+            var result;
+            try {
+              result = input();
+            } catch (e) {
+              throw new FS.ErrnoError(ERRNO_CODES.EIO);
+            }
+            if (result === undefined && bytesRead === 0) {
+              throw new FS.ErrnoError(ERRNO_CODES.EAGAIN);
+            }
+            if (result === null || result === undefined) break;
+            bytesRead++;
+            buffer[offset+i] = result;
+          }
+          if (bytesRead) {
+            stream.node.timestamp = Date.now();
+          }
+          return bytesRead;
+        },
+        write: function (stream, buffer, offset, length, pos) {
+          for (var i = 0; i < length; i++) {
+            try {
+              output(buffer[offset+i]);
+            } catch (e) {
+              throw new FS.ErrnoError(ERRNO_CODES.EIO);
+            }
+          }
+          if (length) {
+            stream.node.timestamp = Date.now();
+          }
+          return i;
+        }
+      });
+      return VFS.mkdev(path, mode, dev);
+    },
+    createLink: function (parent, name, target, canRead, canWrite) {
+      var path = PATH.join(typeof parent === 'string' ? parent : FS.getPath(parent), name);
+      return VFS.symlink(target, path);
+    },
+    createPreloadedFile: function () {
+      FSCOM.createPreloadedFile.apply(this, arguments);
+    }
+  },
+  
+  $VFS__deps: ['$FS'],
+  $VFS: {
+    mount: function (type, opts, mountpoint) {
+      var mount = {
+        type: type,
+        opts: opts,
+        mountpoint: mountpoint,
+        root: null
+      };
+      var lookup;
+      if (mountpoint) {
+        lookup = FS.lookupPath(mountpoint, { follow: false });
+      }
+      // create a root node for the fs
+      var root = type.mount(mount);
+      root.mount = mount;
+      mount.root = root;
+      // assign the mount info to the mountpoint's node
+      if (lookup) {
+        lookup.node.mount = mount;
+        lookup.node.mounted = true;
+        // compatibility update FS.root if we mount to /
+        if (mountpoint === '/') {
+          FS.root = mount.root;
+        }
+      }
+      return root;
+    },
+    lookup: function (parent, name) {
+      return parent.node_ops.lookup(parent, name);
+    },
+    // generic function for all node creation
+    mknod: function (path, mode, dev) {
+      var lookup = FS.lookupPath(path, { parent: true });
+      var parent = lookup.node;
+      var name = PATH.basename(path);
+      var err = FS.mayCreate(parent, name);
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      if (!parent.node_ops.mknod) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      return parent.node_ops.mknod(parent, name, mode, dev);
+    },
+    // helpers to create specific types of nodes
+    create: function (path, mode) {
+      mode &= {{{ cDefine('S_IALLUGO') }}};
+      mode |= {{{ cDefine('S_IFREG') }}};
+      return VFS.mknod(path, mode, 0);
+    },
+    mkdir: function (path, mode) {
+      mode &= {{{ cDefine('S_IRWXUGO') }}} | {{{ cDefine('S_ISVTX') }}};
+      mode |= {{{ cDefine('S_IFDIR') }}};
+      return VFS.mknod(path, mode, 0);
+    },
+    mkdev: function (path, mode, dev) {
+      mode |= {{{ cDefine('S_IFCHR') }}};
+      return VFS.mknod(path, mode, dev);
+    },
+    symlink: function (oldpath, newpath) {
+      var lookup = FS.lookupPath(newpath, { parent: true });
+      var parent = lookup.node;
+      var newname = PATH.basename(newpath);
+      var err = FS.mayCreate(parent, newname);
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      if (!parent.node_ops.symlink) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      return parent.node_ops.symlink(parent, newname, oldpath);
+    },
+    rename: function (old_path, new_path) {
+      var old_dirname = PATH.dirname(old_path);
+      var new_dirname = PATH.dirname(new_path);
+      var old_name = PATH.basename(old_path);
+      var new_name = PATH.basename(new_path);
+      // parents must exist
+      var lookup, old_dir, new_dir;
+      try {
+        lookup = FS.lookupPath(old_path, { parent: true });
+        old_dir = lookup.node;
+        lookup = FS.lookupPath(new_path, { parent: true });
+        new_dir = lookup.node;
+      } catch (e) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBUSY);
+      }
+      // need to be part of the same mount
+      if (old_dir.mount !== new_dir.mount) {
+        throw new FS.ErrnoError(ERRNO_CODES.EXDEV);
+      }
+      // source must exist
+      var old_node = FS.lookupNode(old_dir, old_name);
+      // old path should not be an ancestor of the new path
+      var relative = PATH.relative(old_path, new_dirname);
+      if (relative.charAt(0) !== '.') {
+        throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
+      }
+      // new path should not be an ancestor of the old path
+      relative = PATH.relative(new_path, old_dirname);
+      if (relative.charAt(0) !== '.') {
+        throw new FS.ErrnoError(ERRNO_CODES.ENOTEMPTY);
+      }
+      // see if the new path alreay exists
+      var new_node;
+      try {
+        new_node = FS.lookupNode(new_dir, new_name);
+      } catch (e) {
+        // not fatal
+      }
+      // early out if nothing needs to changews
+      if (old_node === new_node) {
+        return;
+      }
+      // we'll need to delete the old entry
+      var isdir = FS.isDir(old_node.mode);
+      var err = FS.mayDelete(old_dir, old_name, isdir);
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      // need delete permissions if we'll be overwriting.
+      // need create permissions if new doesn't already exist.
+      err = new_node ?
+        FS.mayDelete(new_dir, new_name, isdir) :
+        FS.mayCreate(new_dir, new_name);
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      if (!old_dir.node_ops.rename) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      if (FS.isMountpoint(old_node) || (new_node && FS.isMountpoint(new_node))) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBUSY);
+      }
+      // if we are going to change the parent, check write permissions
+      if (new_dir !== old_dir) {
+        err = FS.nodePermissions(old_dir, 'w');
+        if (err) {
+          throw new FS.ErrnoError(err);
+        }
+      }
+      // remove the node from the lookup hash
+      FS.hashRemoveNode(old_node);
+      // do the underlying fs rename
+      try {
+        old_node.node_ops.rename(old_node, new_dir, new_name);
+      } catch (e) {
+        throw e;
+      } finally {
+        // add the node back to the hash (in case node_ops.rename
+        // changed its name)
+        FS.hashAddNode(old_node);
+      }
+    },
+    rmdir: function (path) {
+      var lookup = FS.lookupPath(path, { parent: true });
+      var parent = lookup.node;
+      var name = PATH.basename(path);
+      var node = FS.lookupNode(parent, name);
+      var err = FS.mayDelete(parent, name, true);
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      if (!parent.node_ops.rmdir) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      if (FS.isMountpoint(node)) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBUSY);
+      }
+      parent.node_ops.rmdir(parent, name);
+      FS.destroyNode(node);
+    },
+    unlink: function (path) {
+      var lookup = FS.lookupPath(path, { parent: true });
+      var parent = lookup.node;
+      var name = PATH.basename(path);
+      var node = FS.lookupNode(parent, name);
+      var err = FS.mayDelete(parent, name, false);
+      if (err) {
+        // POSIX says unlink should set EPERM, not EISDIR
+        if (err === ERRNO_CODES.EISDIR) err = ERRNO_CODES.EPERM;
+        throw new FS.ErrnoError(err);
+      }
+      if (!parent.node_ops.unlink) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      if (FS.isMountpoint(node)) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBUSY);
+      }
+      parent.node_ops.unlink(parent, name);
+      FS.destroyNode(node);
+    },
+    readlink: function (path) {
+      var lookup = FS.lookupPath(path, { follow: false });
+      var link = lookup.node;
+      if (!link.node_ops.readlink) {
+        throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
+      }
+      return link.node_ops.readlink(link);
+    },
+    stat: function (path, dontFollow) {
+      var lookup = FS.lookupPath(path, { follow: !dontFollow });
+      var node = lookup.node;
+      if (!node.node_ops.getattr) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      return node.node_ops.getattr(node);
+    },
+    lstat: function (path) {
+      return VFS.stat(path, true);
+    },
+    chmod: function (path, mode, dontFollow) {
+      var node;
+      if (typeof path === 'string') {
+        var lookup = FS.lookupPath(path, { follow: !dontFollow });
+        node = lookup.node;
+      } else {
+        node = path;
+      }
+      if (!node.node_ops.setattr) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      node.node_ops.setattr(node, {
+        mode: (mode & {{{ cDefine('S_IALLUGO') }}}) | (node.mode & ~{{{ cDefine('S_IALLUGO') }}}),
+        timestamp: Date.now()
+      });
+    },
+    lchmod: function (path, mode) {
+      VFS.chmod(path, mode, true);
+    },
+    fchmod: function (fd, mode) {
+      var stream = FS.getStream(fd);
+      if (!stream) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBADF);
+      }
+      VFS.chmod(stream.node, mode);
+    },
+    chown: function (path, uid, gid, dontFollow) {
+      var node;
+      if (typeof path === 'string') {
+        var lookup = FS.lookupPath(path, { follow: !dontFollow });
+        node = lookup.node;
+      } else {
+        node = path;
+      }
+      if (!node.node_ops.setattr) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      node.node_ops.setattr(node, {
+        timestamp: Date.now()
+        // we ignore the uid / gid for now
+      });
+    },
+    lchown: function (path, uid, gid) {
+      VFS.chown(path, uid, gid, true);
+    },
+    fchown: function (fd, uid, gid) {
+      var stream = FS.getStream(fd);
+      if (!stream) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBADF);
+      }
+      VFS.chown(stream.node, uid, gid);
+    },
+    truncate: function (path, len) {
+      if (len < 0) {
+        throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
+      }
+      var node;
+      if (typeof path === 'string') {
+        var lookup = FS.lookupPath(path, { follow: true });
+        node = lookup.node;
+      } else {
+        node = path;
+      }
+      if (!node.node_ops.setattr) {
+        throw new FS.ErrnoError(ERRNO_CODES.EPERM);
+      }
+      if (FS.isDir(node.mode)) {
+        throw new FS.ErrnoError(ERRNO_CODES.EISDIR);
+      }
+      if (!FS.isFile(node.mode)) {
+        throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
+      }
+      var err = FS.nodePermissions(node, 'w');
+      if (err) {
+        throw new FS.ErrnoError(err);
+      }
+      node.node_ops.setattr(node, {
+        size: len,
+        timestamp: Date.now()
+      });
+    },
+    ftruncate: function (fd, len) {
+      var stream = FS.getStream(fd);
+      if (!stream) {
+        throw new FS.ErrnoError(ERRNO_CODES.EBADF);
+      }
+      if ((stream.flags & {{{ cDefine('O_ACCMODE') }}}) === {{{ cDefine('O_RDONLY')}}}) {
+        throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
+      }
+      VFS.truncate(stream.node, len);
+    },
+    utime: function (path, atime, mtime) {
+      var lookup = FS.lookupPath(path, { follow: true });
+      var node = lookup.node;
+      node.node_ops.setattr(node, {
+        timestamp: Math.max(atime, mtime)
+      });
+    },
+    open: function (path, flags, mode, fd_start, fd_end) {
+      path = PATH.normalize(path);
+      flags = typeof flags === 'string' ? FS.modeStringToFlags(flags) : flags;
+      if ((flags & {{{ cDefine('O_CREAT') }}})) {
+        mode = (mode & {{{ cDefine('S_IALLUGO') }}}) | {{{ cDefine('S_IFREG') }}};
+      } else {
+        mode = 0;
+      }
+      var node;
+      try {
+        var lookup = FS.lookupPath(path, {
+          follow: !(flags & {{{ cDefine('O_NOFOLLOW') }}})