lib/filesystem.js - emulators/v86 - Rivoreo Source Code Repositories

 // -------------------------------------------------
 // ----------------- FILESYSTEM---------------------
 // -------------------------------------------------
 // Implementation of a unix filesystem in memory.

 "use strict";

 var S_IRWXUGO = 0x1FF;
 var S_IFMT = 0xF000;
 var S_IFSOCK = 0xC000;
 var S_IFLNK = 0xA000;
 var S_IFREG = 0x8000;
 var S_IFBLK = 0x6000;
 var S_IFDIR = 0x4000;
 var S_IFCHR = 0x2000;

 //var S_IFIFO  0010000
 //var S_ISUID  0004000
 //var S_ISGID  0002000
 //var S_ISVTX  0001000

 var O_RDONLY = 0x0000; // open for reading only
 var O_WRONLY = 0x0001; // open for writing only
 var O_RDWR = 0x0002; // open for reading and writing
 var O_ACCMODE = 0x0003; // mask for above modes

 var STATUS_INVALID = -0x1;
 var STATUS_OK = 0x0;
 var STATUS_OPEN = 0x1;
 var STATUS_ON_SERVER = 0x2;
 var STATUS_LOADING = 0x3;
 var STATUS_UNLINKED = 0x4;


 /** @const */ var JSONFS_VERSION = 2;


 /** @const */ var JSONFS_IDX_NAME = 0
 /** @const */ var JSONFS_IDX_SIZE = 1
 /** @const */ var JSONFS_IDX_MTIME = 2
 /** @const */ var JSONFS_IDX_MODE = 3
 /** @const */ var JSONFS_IDX_UID = 4
 /** @const */ var JSONFS_IDX_GID = 5
 /** @const */ var JSONFS_IDX_TARGET = 6


 /** @constructor */
 function FS(baseurl) {
     /** @type {Array.<Inode>} */
     this.inodes = [];
     this.events = [];

     this.baseurl = baseurl;

     this.qidnumber = 0x0;
     this.filesinloadingqueue = 0;
     this.OnLoaded = function() {};

     //this.tar = new TAR(this);

     this.inodedata = {};

     this.total_size = 256 * 1024 * 1024 * 1024;
     this.used_size = 0;

     //RegisterMessage("LoadFilesystem", this.LoadFilesystem.bind(this) );
     //RegisterMessage("MergeFile", this.MergeFile.bind(this) );
     //RegisterMessage("tar",
     //    function(data) {
     //        SendToMaster("tar", this.tar.Pack(data));
     //    }.bind(this)
     //);
     //RegisterMessage("sync",
     //    function(data) {
     //        SendToMaster("sync", this.tar.Pack(data));
     //    }.bind(this)
     //);

     // root entry
     this.CreateDirectory("", -1);
 }


 // -----------------------------------------------------

 FS.prototype.AddEvent = function(id, OnEvent) {
     var inode = this.GetInode(id);
     if (inode.status == STATUS_OK) {
         OnEvent();
         return;
     }
     this.events.push({id: id, OnEvent: OnEvent});
 }

 FS.prototype.HandleEvent = function(id) {

     if (this.filesinloadingqueue == 0) {
         this.OnLoaded();
         this.OnLoaded = function() {}
     }
     //message.Debug("number of events: " + this.events.length);
     var newevents = [];
     for(var i=0; i<this.events.length; i++) {
         if (this.events[i].id == id) {
             this.events[i].OnEvent();
         } else {
             newevents.push(this.events[i]);
         }
     }
     this.events = newevents;
 }

 FS.prototype.OnJSONLoaded = function(fs)
 {
     if(DEBUG)
     {
         console.assert(fs, "Invalid fs passed to OnJSONLoaded");
     }

     //console.time("parse");
     var fsdata = JSON.parse(fs);
     //console.timeEnd("parse");

     if(fsdata["version"] !== JSONFS_VERSION)
     {
         throw "The filesystem JSON format has changed. " +
               "Please update your fs2json (https://github.com/copy/fs2json) and recreate the filesystem JSON.";
     }

     var fsroot = fsdata["fsroot"];
     this.used_size = fsdata["size"];

     var me = this;

     setTimeout(function()
     {
         //console.time("Load");
         //console.profile("Load");
         for(var i = 0; i < fsroot.length; i++) {
             me.LoadRecursive(fsroot[i], 0);
         }
         //console.profileEnd("Load");
         //console.timeEnd("Load");

         //if(DEBUG)
         //{
         //    console.time("Check");
         //    me.Check();
         //    console.timeEnd("Check");
         //}

         me.OnLoaded();
         me.OnLoaded = function() {};
     }, 0);
 };

 FS.prototype.LoadRecursive = function(data, parentid)
 {
     var inode = this.CreateInode();

     inode.name = data[JSONFS_IDX_NAME]
     inode.size = data[JSONFS_IDX_SIZE];
     inode.mtime = data[JSONFS_IDX_MTIME];
     inode.ctime = inode.mtime;
     inode.atime = inode.mtime;
     inode.mode = data[JSONFS_IDX_MODE];
     inode.uid = data[JSONFS_IDX_UID];
     inode.gid = data[JSONFS_IDX_GID];

     inode.parentid = parentid;
     this.inodes[inode.parentid].nlinks++;

     var ifmt = inode.mode & S_IFMT;

     if(ifmt === S_IFDIR)
     {
         this.LoadDir(inode, data[JSONFS_IDX_TARGET]);
     }
     else if(ifmt === S_IFREG)
     {
         inode.status = STATUS_ON_SERVER;
         this.PushInode(inode);
     }
     else if(ifmt === S_IFLNK)
     {
         inode.symlink = data[JSONFS_IDX_TARGET];
         this.PushInode(inode);
     }
     else if(ifmt === S_IFSOCK)
     {
         // socket: ignore
     }
     else
     {
         dbg_log("Unexpected ifmt: " + h(ifmt) + " (" + inode.name + ")");
     }
 }

 FS.prototype.LoadDir = function(inode, children)
 {
     inode.updatedir = true;
     inode.nlinks = 2; // . and ..

     var p = this.inodes.length;
     this.PushInode(inode);

     for(var i = 0; i < children.length; i++) {
         this.LoadRecursive(children[i], p);
     }
 }

 // Loads the data from a url for a specific inode
 FS.prototype.LoadFile = function(idx) {
     var inode = this.inodes[idx];
     if (inode.status != STATUS_ON_SERVER) {
         return;
     }
     inode.status = STATUS_LOADING;
     this.filesinloadingqueue++;

     //if (inode.compressed) {
     //    inode.data = new Uint8Array(inode.size);
     //    LoadBinaryResource(inode.url + ".bz2",
     //    function(buffer){
     //        var buffer8 = new Uint8Array(buffer);
     //        var ofs = 0;
     //        bzip2.simple(buffer8, function(x){inode.data[ofs++] = x;}.bind(this) );
     //        inode.status = STATUS_OK;
     //        this.filesinloadingqueue--;
     //        this.HandleEvent(idx);
     //    }.bind(this),
     //    function(error){throw error;});
     //    return;
     //}

     if(this.baseurl)
     {
         LoadBinaryResource(this.baseurl + this.GetFullPath(inode.fid),
             function(buffer){
                 var data = this.inodedata[idx] = new Uint8Array(buffer);
                 inode.size = data.length; // correct size if the previous was wrong.
                 inode.status = STATUS_OK;

                 this.filesinloadingqueue--;
                 this.HandleEvent(idx);
             }.bind(this),
             function(error){throw error;});
     }
     else
     {
         // If baseurl is not set, we started with an empty filesystem. No files
         // can be loaded
     }
 }

 // -----------------------------------------------------

 FS.prototype.PushInode = function(inode) {
     if (inode.parentid != -1) {
         this.inodes.push(inode);
         inode.fid = this.inodes.length - 1;
         var parent_node = this.inodes[inode.parentid];
         parent_node.updatedir = true;
         inode.nextid = parent_node.firstid;
         parent_node.firstid = this.inodes.length-1;
         return;
     } else {
         if (this.inodes.length == 0) { // if root directory
             this.inodes.push(inode);
             return;
         }
     }

     message.Debug("Error in Filesystem: Pushed inode with name = "+ inode.name + " has no parent");
     message.Abort();

 }

 /** @constructor */
 function Inode(qidnumber)
 {
     this.updatedir = false; // did the directory listing changed?
     this.parentid = -1;
     this.firstid = -1; // first file id in directory
     this.nextid = -1; // next id in directory
     this.status = 0;
     this.name = "";
     this.size = 0x0;
     this.uid = 0x0;
     this.gid = 0x0;
     this.fid = 0;
     this.ctime = 0;
     this.atime = 0;
     this.mtime = 0;
     this.major = 0x0;
     this.minor = 0x0;
     //data = new Uint8Array(0);
     this.symlink = "";
     this.nlinks = 1;
     this.mode = 0x01ED;
     this.qid = {
         type: 0,
         version: 0,
         path: qidnumber,
     };
     this.caps = undefined;

     //this.qid_type = 0;
     //this.qid_version = 0;
     //this.qid_path = qidnumber;
 }

 FS.prototype.CreateInode = function() {
     //console.log("CreateInode", Error().stack);
     return new Inode(++this.qidnumber);
 };


 FS.prototype.CreateDirectory = function(name, parentid) {
     var x = this.CreateInode();
     x.name = name;
     x.parentid = parentid;
     x.mode = 0x01FF | S_IFDIR;
     x.updatedir = true;
     x.nlinks = 2; // . and ..
     if (parentid >= 0) {
         x.uid = this.inodes[parentid].uid;
         x.gid = this.inodes[parentid].gid;
         x.mode = (this.inodes[parentid].mode & 0x1FF) | S_IFDIR;
         this.inodes[parentid].nlinks++;
     }
     x.qid.type = S_IFDIR >> 8;
     this.PushInode(x);
     this.NotifyListeners(this.inodes.length-1, 'newdir');
     return this.inodes.length-1;
 }

 FS.prototype.CreateFile = function(filename, parentid) {
     var x = this.CreateInode();
     x.name = filename;
     x.parentid = parentid;
     x.uid = this.inodes[parentid].uid;
     x.gid = this.inodes[parentid].gid;
     this.inodes[parentid].nlinks++;
     x.qid.type = S_IFREG >> 8;
     x.mode = (this.inodes[parentid].mode & 0x1B6) | S_IFREG;
     this.PushInode(x);
     this.NotifyListeners(this.inodes.length-1, 'newfile');
     return this.inodes.length-1;
 }


 FS.prototype.CreateNode = function(filename, parentid, major, minor) {
     var x = this.CreateInode();
     x.name = filename;
     x.parentid = parentid;
     x.major = major;
     x.minor = minor;
     x.uid = this.inodes[parentid].uid;
     x.gid = this.inodes[parentid].gid;
     this.inodes[parentid].nlinks++;
     x.qid.type = S_IFSOCK >> 8;
     x.mode = (this.inodes[parentid].mode & 0x1B6);
     this.PushInode(x);
     return this.inodes.length-1;
 }

 FS.prototype.CreateSymlink = function(filename, parentid, symlink) {
     var x = this.CreateInode();
     x.name = filename;
     x.parentid = parentid;
     x.uid = this.inodes[parentid].uid;
     x.gid = this.inodes[parentid].gid;
     this.inodes[parentid].nlinks++;
     x.qid.type = S_IFLNK >> 8;
     x.symlink = symlink;
     x.mode = S_IFLNK;
     this.PushInode(x);
     return this.inodes.length-1;
 }

 FS.prototype.CreateTextFile = function(filename, parentid, str) {
     var id = this.CreateFile(filename, parentid);
     var x = this.inodes[id];
     var data = this.inodedata[id] = new Uint8Array(str.length);
     x.size = str.length;
     for (var j = 0; j < str.length; j++) {
         data[j] = str.charCodeAt(j);
     }
     return id;
 }

 /**
  * @param {Uint8Array} buffer
  */
 FS.prototype.CreateBinaryFile = function(filename, parentid, buffer) {
     var id = this.CreateFile(filename, parentid);
     var x = this.inodes[id];
     var data = this.inodedata[id] = new Uint8Array(buffer.length);
     data.set(buffer);
     x.size = buffer.length;
     return id;
 }


 FS.prototype.OpenInode = function(id, mode) {
     var inode = this.GetInode(id);
     if ((inode.mode&S_IFMT) == S_IFDIR) {
         this.FillDirectory(id);
     }
     /*
     var type = "";
     switch(inode.mode&S_IFMT) {
         case S_IFREG: type = "File"; break;
         case S_IFBLK: type = "Block Device"; break;
         case S_IFDIR: type = "Directory"; break;
         case S_IFCHR: type = "Character Device"; break;
     }
     */
     //message.Debug("open:" + this.GetFullPath(id) +  " type: " + inode.mode + " status:" + inode.status);
     if (inode.status == STATUS_ON_SERVER) {
         this.LoadFile(id);
         return false;
     }
     return true;
 }

 FS.prototype.CloseInode = function(id) {
     //message.Debug("close: " + this.GetFullPath(id));
     var inode = this.GetInode(id);
     if (inode.status == STATUS_UNLINKED) {
         //message.Debug("Filesystem: Delete unlinked file");
         inode.status = STATUS_INVALID;
         delete this.inodedata[id];
         inode.size = 0;
     }
 }

 FS.prototype.Rename = function(olddirid, oldname, newdirid, newname) {
     // message.Debug("Rename " + oldname + " to " + newname);
     if ((olddirid == newdirid) && (oldname == newname)) {
         return true;
     }
     var oldid = this.Search(olddirid, oldname);
     var oldpath = this.GetFullPath(oldid);
     if (oldid == -1) {
         return false;
     }
     var newid = this.Search(newdirid, newname);
     if (newid != -1) {
         this.Unlink(newid);
     }

     var idx = oldid; // idx contains the id which we want to rename
     var inode = this.inodes[idx];

     // remove inode ids
     if (this.inodes[inode.parentid].firstid == idx) {
         this.inodes[inode.parentid].firstid = inode.nextid;
     } else {
         var id = this.FindPreviousID(idx);
         if (id == -1) {
             message.Debug("Error in Filesystem: Cannot find previous id of inode");
             message.Abort();
         }
         this.inodes[id].nextid = inode.nextid;
     }

     inode.parentid = newdirid;
     inode.name = newname;
     inode.qid.version++;

     inode.nextid = this.inodes[inode.parentid].firstid;
     this.inodes[inode.parentid].firstid = idx;

     this.inodes[olddirid].updatedir = true;
     this.inodes[newdirid].updatedir = true;
     this.inodes[olddirid].nlinks--;
     this.inodes[newdirid].nlinks++;

     this.NotifyListeners(idx, "rename", {oldpath: oldpath});

     return true;
 }

 FS.prototype.Write = function(id, offset, count, GetByte) {
     this.NotifyListeners(id, 'write');
     var inode = this.inodes[id];
     var data = this.inodedata[id];

     if (!data || data.length < (offset+count)) {
         this.ChangeSize(id, Math.floor(((offset+count)*3)/2) );
         inode.size = offset + count;
         data = this.inodedata[id];
     } else
     if (inode.size < (offset+count)) {
         inode.size = offset + count;
     }
     for(var i=0; i<count; i++)
         data[offset+i] = GetByte();
 }

 FS.prototype.Search = function(parentid, name) {
     var id = this.inodes[parentid].firstid;
     while(id != -1) {
         if (this.inodes[id].parentid != parentid) { // consistency check
             message.Debug("Error in Filesystem: Found inode with wrong parent id");
         }
         if (this.inodes[id].name == name) return id;
         id = this.inodes[id].nextid;
     }
     return -1;
 }

 FS.prototype.GetTotalSize = function() {
     return this.used_size;
     //var size = 0;
     //for(var i=0; i<this.inodes.length; i++) {
     //    var d = this.inodes[i].data;
     //    size += d ? d.length : 0;
     //}
     //return size;
 }

 FS.prototype.GetSpace = function() {
     return this.total_size;
 };

 FS.prototype.GetFullPath = function(idx) {
     var path = "";

     while(idx != 0) {
         path = "/" + this.inodes[idx].name + path;
         idx = this.inodes[idx].parentid;
     }
     return path.substring(1);
 }

 // no double linked list. So, we need this
 FS.prototype.FindPreviousID = function(idx) {
     var inode = this.GetInode(idx);
     var id = this.inodes[inode.parentid].firstid;
     while(id != -1) {
         if (this.inodes[id].nextid == idx) return id;
         id = this.inodes[id].nextid;
     }
     return id;
 }

 FS.prototype.Unlink = function(idx) {
     this.NotifyListeners(idx, 'delete');
     if (idx == 0) return false; // root node cannot be deleted
     var inode = this.GetInode(idx);
     //message.Debug("Unlink " + inode.name);

     // check if directory is not empty
     if ((inode.mode&S_IFMT) == S_IFDIR) {
        if (inode.firstid != -1) return false;
     }

     // update ids
     if (this.inodes[inode.parentid].firstid == idx) {
         this.inodes[inode.parentid].firstid = inode.nextid;
     } else {
         var id = this.FindPreviousID(idx);
         if (id == -1) {
             message.Debug("Error in Filesystem: Cannot find previous id of inode");
             message.Abort();
         }
         this.inodes[id].nextid = inode.nextid;
     }
     // don't delete the content. The file is still accessible
     this.inodes[inode.parentid].updatedir = true;
     this.inodes[inode.parentid].nlinks--;
     inode.status = STATUS_UNLINKED;
     inode.nextid = -1;
     inode.firstid = -1;
     inode.parentid = -1;
     inode.nlinks--;
     return true;
 }

 FS.prototype.GetInode = function(idx)
 {
     if (isNaN(idx)) {
         message.Debug("Error in filesystem: id is not a number ");
         return 0;
     }

     if ((idx < 0) || (idx > this.inodes.length)) {
         message.Debug("Error in filesystem: Attempt to get inode with id " + idx);
         return 0;
     }
     return this.inodes[idx];
 }

 FS.prototype.ChangeSize = function(idx, newsize)
 {
     var inode = this.GetInode(idx);
     var temp = this.inodedata[idx];
     //message.Debug("change size to: " + newsize);
     if (newsize == inode.size) return;
     var data = this.inodedata[idx] = new Uint8Array(newsize);
     inode.size = newsize;
     if(!temp) return;
     var size = Math.min(temp.length, inode.size);
     for(var i=0; i<size; i++) {
         data[i] = temp[i];
     }
 }

 FS.prototype.SearchPath = function(path) {
     //path = path.replace(/\/\//g, "/");
     path = path.replace("//", "/");
     var walk = path.split("/");
     var n = walk.length;
     if (walk[n-1].length == 0) walk.pop();
     if (walk[0].length == 0) walk.shift();
     n = walk.length;

     var parentid = 0;
     var id = -1;
     for(var i=0; i<n; i++) {
         id = this.Search(parentid, walk[i]);
         if (id == -1) {
             if (i < n-1) return {id: -1, parentid: -1, name: walk[i]}; // one name of the path cannot be found
             return {id: -1, parentid: parentid, name: walk[i]}; // the last element in the path does not exist, but the parent
         }
         parentid = id;
     }
     return {id: id, parentid: parentid, name: walk[i]};
 }
 // -----------------------------------------------------

 FS.prototype.GetRecursiveList = function(dirid, list) {
     var id = this.inodes[dirid].firstid;
     while(id != -1) {
         list.push(id);
         if ((this.inodes[id].mode&S_IFMT) == S_IFDIR) {
             this.GetRecursiveList(id, list);
         }
         id = this.inodes[id].nextid;
     }
 }

 FS.prototype.MergeFile = function(file) {
     message.Debug("Merge path:" + file.name);
     var ids = this.SearchPath(file.name);
     if (ids.parentid == -1) return; // not even the path seems to exist
     if (ids.id == -1) {
         ids.id = this.CreateFile(ids.name, ids.parentid);
     }
     this.inodes[ids.id].data = file.data;
     this.inodes[ids.id].size = file.data.length;
     // Don't forget to update the timestamps !
     this.inodes[ids.id].mtime = Math.floor((new Date()).getTime()/1000);
     this.inodes[ids.id].atime = this.inodes[ids.id].mtime;
     this.inodes[ids.id].ctime = this.inodes[ids.id].mtime;
 }


 FS.prototype.RecursiveDelete = function(path) {
     var toDelete = []
     var ids = this.SearchPath(path);
     if (ids.parentid == -1 || ids.id == -1) return;

     this.GetRecursiveList(ids.id, toDelete);

     for(var i=toDelete.length-1; i>=0; i--)
         this.Unlink(toDelete[i]);

 }

 FS.prototype.DeleteNode = function(path) {
     var ids = this.SearchPath(path);
     if (ids.parentid == -1 || ids.id == -1) return;

     if ((this.inodes[ids.id].mode&S_IFMT) == S_IFREG){
         this.Unlink(ids.id);
         return;
     }
     if ((this.inodes[ids.id].mode&S_IFMT) == S_IFDIR){
         var toDelete = []
         this.GetRecursiveList(ids.id, toDelete);
         for(var i=toDelete.length-1; i>=0; i--)
             this.Unlink(toDelete[i]);
         this.Unlink(ids.id);
         return;
     }
 }

 /** @param {*=} info */
 FS.prototype.NotifyListeners = function(id, action, info) {
     //if(info==undefined)
     //    info = {};

     //var path = this.GetFullPath(id);
     //if (this.watchFiles[path] == true && action=='write') {
     //  message.Send("WatchFileEvent", path);
     //}
     //for (var directory in this.watchDirectories) {
     //    if (this.watchDirectories.hasOwnProperty(directory)) {
     //        var indexOf = path.indexOf(directory)
     //        if(indexOf == 0 || indexOf == 1)
     //            message.Send("WatchDirectoryEvent", {path: path, event: action, info: info});
     //    }
     //}
 }


 FS.prototype.Check = function() {
     for(var i=1; i<this.inodes.length; i++)
     {
         if (this.inodes[i].status == STATUS_INVALID) continue;
         if (this.inodes[i].nextid == i) {
             message.Debug("Error in filesystem: file points to itself");
             message.Abort();
         }

         var inode = this.GetInode(i);
         if (inode.parentid < 0) {
             message.Debug("Error in filesystem: negative parent id " + i);
         }
         var n = inode.name.length;
         if (n == 0) {
             message.Debug("Error in filesystem: inode with no name and id " + i);
         }

         for (var j in inode.name) {
             var c = inode.name.charCodeAt(j);
             if (c < 32) {
                 message.Debug("Error in filesystem: Unallowed char in filename");
             }
         }
     }
 }

 FS.prototype.FillDirectory = function(dirid) {
     var inode = this.GetInode(dirid);
     if (!inode.updatedir) return;
     var parentid = inode.parentid;
     if (parentid == -1) parentid = 0; // if root directory point to the root directory

     // first get size
     var size = 0;
     var id = this.inodes[dirid].firstid;
     while(id != -1) {
         size += 13 + 8 + 1 + 2 + UTF8.UTF8Length(this.inodes[id].name);
         id = this.inodes[id].nextid;
     }

     size += 13 + 8 + 1 + 2 + 1; // "." entry
     size += 13 + 8 + 1 + 2 + 2; // ".." entry
     //message.Debug("size of dir entry: " + size);
     var data = this.inodedata[dirid] = new Uint8Array(size);
     inode.size = size;

     var offset = 0x0;
     offset += marshall.Marshall(
         ["Q", "d", "b", "s"],
         [this.inodes[dirid].qid,
         offset+13+8+1+2+1,
         this.inodes[dirid].mode >> 12,
         "."],
         data, offset);

     offset += marshall.Marshall(
         ["Q", "d", "b", "s"],
         [this.inodes[parentid].qid,
         offset+13+8+1+2+2,
         this.inodes[parentid].mode >> 12,
         ".."],
         data, offset);

     id = this.inodes[dirid].firstid;
     while(id != -1) {
         offset += marshall.Marshall(
         ["Q", "d", "b", "s"],
         [
             this.inodes[id].qid,
             offset+13+8+1+2+UTF8.UTF8Length(this.inodes[id].name),
             this.inodes[id].mode >> 12,
             this.inodes[id].name
         ],
         data, offset);
         id = this.inodes[id].nextid;
     }
     inode.updatedir = false;
 }


 // -----------------------------------------------------

 // only support for security.capabilities
 // should return a  "struct vfs_cap_data" defined in
 // linux/capability for format
 // check also:
 //   sys/capability.h
 //   http://lxr.free-electrons.com/source/security/commoncap.c#L376
 //   http://man7.org/linux/man-pages/man7/capabilities.7.html
 //   http://man7.org/linux/man-pages/man8/getcap.8.html
 //   http://man7.org/linux/man-pages/man3/libcap.3.html
 FS.prototype.PrepareCAPs = function(id) {
     var inode = this.GetInode(id);
     if (inode.caps) return inode.caps.length;
     inode.caps = new Uint8Array(12);
     // format is little endian
     // magic_etc (revision=0x01: 12 bytes)
     inode.caps[0]  = 0x00;
     inode.caps[1]  = 0x00;
     inode.caps[2]  = 0x00;
     inode.caps[3]  = 0x01;
     // permitted (full capabilities)
     inode.caps[4]  = 0xFF;
     inode.caps[5]  = 0xFF;
     inode.caps[6]  = 0xFF;
     inode.caps[7]  = 0xFF;
     // inheritable (full capabilities
     inode.caps[8]  = 0xFF;
     inode.caps[9]  = 0xFF;
     inode.caps[10] = 0xFF;
     inode.caps[11] = 0xFF;

     return inode.caps.length;
 }
	// -------------------------------------------------
	// ----------------- FILESYSTEM---------------------
	// -------------------------------------------------
	// Implementation of a unix filesystem in memory.

	"use strict";

	var S_IRWXUGO = 0x1FF;
	var S_IFMT = 0xF000;
	var S_IFSOCK = 0xC000;
	var S_IFLNK = 0xA000;
	var S_IFREG = 0x8000;
	var S_IFBLK = 0x6000;
	var S_IFDIR = 0x4000;
	var S_IFCHR = 0x2000;

	//var S_IFIFO 0010000
	//var S_ISUID 0004000
	//var S_ISGID 0002000
	//var S_ISVTX 0001000

	var O_RDONLY = 0x0000; // open for reading only
	var O_WRONLY = 0x0001; // open for writing only
	var O_RDWR = 0x0002; // open for reading and writing
	var O_ACCMODE = 0x0003; // mask for above modes

	var STATUS_INVALID = -0x1;
	var STATUS_OK = 0x0;
	var STATUS_OPEN = 0x1;
	var STATUS_ON_SERVER = 0x2;
	var STATUS_LOADING = 0x3;
	var STATUS_UNLINKED = 0x4;


	/** @const */ var JSONFS_VERSION = 2;


	/** @const */ var JSONFS_IDX_NAME = 0
	/** @const */ var JSONFS_IDX_SIZE = 1
	/** @const */ var JSONFS_IDX_MTIME = 2
	/** @const */ var JSONFS_IDX_MODE = 3
	/** @const */ var JSONFS_IDX_UID = 4
	/** @const */ var JSONFS_IDX_GID = 5
	/** @const */ var JSONFS_IDX_TARGET = 6


	/** @constructor */
	function FS(baseurl) {
	/** @type {Array.<Inode>} */
	this.inodes = [];
	this.events = [];

	this.baseurl = baseurl;

	this.qidnumber = 0x0;
	this.filesinloadingqueue = 0;
	this.OnLoaded = function() {};

	//this.tar = new TAR(this);

	this.inodedata = {};

	this.total_size = 256 * 1024 * 1024 * 1024;
	this.used_size = 0;

	//RegisterMessage("LoadFilesystem", this.LoadFilesystem.bind(this) );
	//RegisterMessage("MergeFile", this.MergeFile.bind(this) );
	//RegisterMessage("tar",
	// function(data) {
	// SendToMaster("tar", this.tar.Pack(data));
	// }.bind(this)
	//);
	//RegisterMessage("sync",
	// function(data) {
	// SendToMaster("sync", this.tar.Pack(data));
	// }.bind(this)
	//);

	// root entry
	this.CreateDirectory("", -1);
	}


	// -----------------------------------------------------

	FS.prototype.AddEvent = function(id, OnEvent) {
	var inode = this.GetInode(id);
	if (inode.status == STATUS_OK) {
	OnEvent();
	return;
	}
	this.events.push({id: id, OnEvent: OnEvent});
	}

	FS.prototype.HandleEvent = function(id) {

	if (this.filesinloadingqueue == 0) {
	this.OnLoaded();
	this.OnLoaded = function() {}
	}
	//message.Debug("number of events: " + this.events.length);
	var newevents = [];
	for(var i=0; i<this.events.length; i++) {
	if (this.events[i].id == id) {
	this.events[i].OnEvent();
	} else {
	newevents.push(this.events[i]);
	}
	}
	this.events = newevents;
	}

	FS.prototype.OnJSONLoaded = function(fs)
	{
	if(DEBUG)
	{
	console.assert(fs, "Invalid fs passed to OnJSONLoaded");
	}

	//console.time("parse");
	var fsdata = JSON.parse(fs);
	//console.timeEnd("parse");

	if(fsdata["version"] !== JSONFS_VERSION)
	{
	throw "The filesystem JSON format has changed. " +
	"Please update your fs2json (https://github.com/copy/fs2json) and recreate the filesystem JSON.";
	}

	var fsroot = fsdata["fsroot"];
	this.used_size = fsdata["size"];

	var me = this;

	setTimeout(function()
	{
	//console.time("Load");
	//console.profile("Load");
	for(var i = 0; i < fsroot.length; i++) {
	me.LoadRecursive(fsroot[i], 0);
	}
	//console.profileEnd("Load");
	//console.timeEnd("Load");

	//if(DEBUG)
	//{
	// console.time("Check");
	// me.Check();
	// console.timeEnd("Check");
	//}

	me.OnLoaded();
	me.OnLoaded = function() {};
	}, 0);
	};

	FS.prototype.LoadRecursive = function(data, parentid)
	{
	var inode = this.CreateInode();

	inode.name = data[JSONFS_IDX_NAME]
	inode.size = data[JSONFS_IDX_SIZE];
	inode.mtime = data[JSONFS_IDX_MTIME];
	inode.ctime = inode.mtime;
	inode.atime = inode.mtime;
	inode.mode = data[JSONFS_IDX_MODE];
	inode.uid = data[JSONFS_IDX_UID];
	inode.gid = data[JSONFS_IDX_GID];

	inode.parentid = parentid;
	this.inodes[inode.parentid].nlinks++;

	var ifmt = inode.mode & S_IFMT;

	if(ifmt === S_IFDIR)
	{
	this.LoadDir(inode, data[JSONFS_IDX_TARGET]);
	}
	else if(ifmt === S_IFREG)
	{
	inode.status = STATUS_ON_SERVER;
	this.PushInode(inode);
	}
	else if(ifmt === S_IFLNK)
	{
	inode.symlink = data[JSONFS_IDX_TARGET];
	this.PushInode(inode);
	}
	else if(ifmt === S_IFSOCK)
	{
	// socket: ignore
	}
	else
	{
	dbg_log("Unexpected ifmt: " + h(ifmt) + " (" + inode.name + ")");
	}
	}

	FS.prototype.LoadDir = function(inode, children)
	{
	inode.updatedir = true;
	inode.nlinks = 2; // . and ..

	var p = this.inodes.length;
	this.PushInode(inode);

	for(var i = 0; i < children.length; i++) {
	this.LoadRecursive(children[i], p);
	}
	}

	// Loads the data from a url for a specific inode
	FS.prototype.LoadFile = function(idx) {
	var inode = this.inodes[idx];
	if (inode.status != STATUS_ON_SERVER) {
	return;
	}
	inode.status = STATUS_LOADING;
	this.filesinloadingqueue++;

	//if (inode.compressed) {
	// inode.data = new Uint8Array(inode.size);
	// LoadBinaryResource(inode.url + ".bz2",
	// function(buffer){
	// var buffer8 = new Uint8Array(buffer);
	// var ofs = 0;
	// bzip2.simple(buffer8, function(x){inode.data[ofs++] = x;}.bind(this) );
	// inode.status = STATUS_OK;
	// this.filesinloadingqueue--;
	// this.HandleEvent(idx);
	// }.bind(this),
	// function(error){throw error;});
	// return;
	//}

	if(this.baseurl)
	{
	LoadBinaryResource(this.baseurl + this.GetFullPath(inode.fid),
	function(buffer){
	var data = this.inodedata[idx] = new Uint8Array(buffer);
	inode.size = data.length; // correct size if the previous was wrong.
	inode.status = STATUS_OK;

	this.filesinloadingqueue--;
	this.HandleEvent(idx);
	}.bind(this),
	function(error){throw error;});
	}
	else
	{
	// If baseurl is not set, we started with an empty filesystem. No files
	// can be loaded
	}
	}

	// -----------------------------------------------------

	FS.prototype.PushInode = function(inode) {
	if (inode.parentid != -1) {
	this.inodes.push(inode);
	inode.fid = this.inodes.length - 1;
	var parent_node = this.inodes[inode.parentid];
	parent_node.updatedir = true;
	inode.nextid = parent_node.firstid;
	parent_node.firstid = this.inodes.length-1;
	return;
	} else {
	if (this.inodes.length == 0) { // if root directory
	this.inodes.push(inode);
	return;
	}
	}

	message.Debug("Error in Filesystem: Pushed inode with name = "+ inode.name + " has no parent");
	message.Abort();

	}

	/** @constructor */
	function Inode(qidnumber)
	{
	this.updatedir = false; // did the directory listing changed?
	this.parentid = -1;
	this.firstid = -1; // first file id in directory
	this.nextid = -1; // next id in directory
	this.status = 0;
	this.name = "";
	this.size = 0x0;
	this.uid = 0x0;
	this.gid = 0x0;
	this.fid = 0;
	this.ctime = 0;
	this.atime = 0;
	this.mtime = 0;
	this.major = 0x0;
	this.minor = 0x0;
	//data = new Uint8Array(0);
	this.symlink = "";
	this.nlinks = 1;
	this.mode = 0x01ED;
	this.qid = {
	type: 0,
	version: 0,
	path: qidnumber,
	};
	this.caps = undefined;

	//this.qid_type = 0;
	//this.qid_version = 0;
	//this.qid_path = qidnumber;
	}

	FS.prototype.CreateInode = function() {
	//console.log("CreateInode", Error().stack);
	return new Inode(++this.qidnumber);
	};


	FS.prototype.CreateDirectory = function(name, parentid) {
	var x = this.CreateInode();
	x.name = name;
	x.parentid = parentid;
	x.mode = 0x01FF \| S_IFDIR;
	x.updatedir = true;
	x.nlinks = 2; // . and ..
	if (parentid >= 0) {
	x.uid = this.inodes[parentid].uid;
	x.gid = this.inodes[parentid].gid;
	x.mode = (this.inodes[parentid].mode & 0x1FF) \| S_IFDIR;
	this.inodes[parentid].nlinks++;
	}
	x.qid.type = S_IFDIR >> 8;
	this.PushInode(x);
	this.NotifyListeners(this.inodes.length-1, 'newdir');
	return this.inodes.length-1;
	}

	FS.prototype.CreateFile = function(filename, parentid) {
	var x = this.CreateInode();
	x.name = filename;
	x.parentid = parentid;
	x.uid = this.inodes[parentid].uid;
	x.gid = this.inodes[parentid].gid;
	this.inodes[parentid].nlinks++;
	x.qid.type = S_IFREG >> 8;
	x.mode = (this.inodes[parentid].mode & 0x1B6) \| S_IFREG;
	this.PushInode(x);
	this.NotifyListeners(this.inodes.length-1, 'newfile');
	return this.inodes.length-1;
	}


	FS.prototype.CreateNode = function(filename, parentid, major, minor) {
	var x = this.CreateInode();
	x.name = filename;
	x.parentid = parentid;
	x.major = major;
	x.minor = minor;
	x.uid = this.inodes[parentid].uid;
	x.gid = this.inodes[parentid].gid;
	this.inodes[parentid].nlinks++;
	x.qid.type = S_IFSOCK >> 8;
	x.mode = (this.inodes[parentid].mode & 0x1B6);
	this.PushInode(x);
	return this.inodes.length-1;
	}

	FS.prototype.CreateSymlink = function(filename, parentid, symlink) {
	var x = this.CreateInode();
	x.name = filename;
	x.parentid = parentid;
	x.uid = this.inodes[parentid].uid;
	x.gid = this.inodes[parentid].gid;
	this.inodes[parentid].nlinks++;
	x.qid.type = S_IFLNK >> 8;
	x.symlink = symlink;
	x.mode = S_IFLNK;
	this.PushInode(x);
	return this.inodes.length-1;
	}

	FS.prototype.CreateTextFile = function(filename, parentid, str) {
	var id = this.CreateFile(filename, parentid);
	var x = this.inodes[id];
	var data = this.inodedata[id] = new Uint8Array(str.length);
	x.size = str.length;
	for (var j = 0; j < str.length; j++) {
	data[j] = str.charCodeAt(j);
	}
	return id;
	}

	/**
	* @param {Uint8Array} buffer
	*/
	FS.prototype.CreateBinaryFile = function(filename, parentid, buffer) {
	var id = this.CreateFile(filename, parentid);
	var x = this.inodes[id];
	var data = this.inodedata[id] = new Uint8Array(buffer.length);
	data.set(buffer);
	x.size = buffer.length;
	return id;
	}


	FS.prototype.OpenInode = function(id, mode) {
	var inode = this.GetInode(id);
	if ((inode.mode&S_IFMT) == S_IFDIR) {
	this.FillDirectory(id);
	}
	/*
	var type = "";
	switch(inode.mode&S_IFMT) {
	case S_IFREG: type = "File"; break;
	case S_IFBLK: type = "Block Device"; break;
	case S_IFDIR: type = "Directory"; break;
	case S_IFCHR: type = "Character Device"; break;
	}
	*/
	//message.Debug("open:" + this.GetFullPath(id) + " type: " + inode.mode + " status:" + inode.status);
	if (inode.status == STATUS_ON_SERVER) {
	this.LoadFile(id);
	return false;
	}
	return true;
	}

	FS.prototype.CloseInode = function(id) {
	//message.Debug("close: " + this.GetFullPath(id));
	var inode = this.GetInode(id);
	if (inode.status == STATUS_UNLINKED) {
	//message.Debug("Filesystem: Delete unlinked file");
	inode.status = STATUS_INVALID;
	delete this.inodedata[id];
	inode.size = 0;
	}
	}

	FS.prototype.Rename = function(olddirid, oldname, newdirid, newname) {
	// message.Debug("Rename " + oldname + " to " + newname);
	if ((olddirid == newdirid) && (oldname == newname)) {
	return true;
	}
	var oldid = this.Search(olddirid, oldname);
	var oldpath = this.GetFullPath(oldid);
	if (oldid == -1) {
	return false;
	}
	var newid = this.Search(newdirid, newname);
	if (newid != -1) {
	this.Unlink(newid);
	}

	var idx = oldid; // idx contains the id which we want to rename
	var inode = this.inodes[idx];

	// remove inode ids
	if (this.inodes[inode.parentid].firstid == idx) {
	this.inodes[inode.parentid].firstid = inode.nextid;
	} else {
	var id = this.FindPreviousID(idx);
	if (id == -1) {
	message.Debug("Error in Filesystem: Cannot find previous id of inode");
	message.Abort();
	}
	this.inodes[id].nextid = inode.nextid;
	}

	inode.parentid = newdirid;
	inode.name = newname;
	inode.qid.version++;

	inode.nextid = this.inodes[inode.parentid].firstid;
	this.inodes[inode.parentid].firstid = idx;

	this.inodes[olddirid].updatedir = true;
	this.inodes[newdirid].updatedir = true;
	this.inodes[olddirid].nlinks--;
	this.inodes[newdirid].nlinks++;

	this.NotifyListeners(idx, "rename", {oldpath: oldpath});

	return true;
	}

	FS.prototype.Write = function(id, offset, count, GetByte) {
	this.NotifyListeners(id, 'write');
	var inode = this.inodes[id];
	var data = this.inodedata[id];

	if (!data \|\| data.length < (offset+count)) {
	this.ChangeSize(id, Math.floor(((offset+count)*3)/2) );
	inode.size = offset + count;
	data = this.inodedata[id];
	} else
	if (inode.size < (offset+count)) {
	inode.size = offset + count;
	}
	for(var i=0; i<count; i++)
	data[offset+i] = GetByte();
	}

	FS.prototype.Search = function(parentid, name) {
	var id = this.inodes[parentid].firstid;
	while(id != -1) {
	if (this.inodes[id].parentid != parentid) { // consistency check
	message.Debug("Error in Filesystem: Found inode with wrong parent id");
	}
	if (this.inodes[id].name == name) return id;
	id = this.inodes[id].nextid;
	}
	return -1;
	}

	FS.prototype.GetTotalSize = function() {
	return this.used_size;
	//var size = 0;
	//for(var i=0; i<this.inodes.length; i++) {
	// var d = this.inodes[i].data;
	// size += d ? d.length : 0;
	//}
	//return size;
	}

	FS.prototype.GetSpace = function() {
	return this.total_size;
	};

	FS.prototype.GetFullPath = function(idx) {
	var path = "";

	while(idx != 0) {
	path = "/" + this.inodes[idx].name + path;
	idx = this.inodes[idx].parentid;
	}
	return path.substring(1);
	}

	// no double linked list. So, we need this
	FS.prototype.FindPreviousID = function(idx) {
	var inode = this.GetInode(idx);
	var id = this.inodes[inode.parentid].firstid;
	while(id != -1) {
	if (this.inodes[id].nextid == idx) return id;
	id = this.inodes[id].nextid;
	}
	return id;
	}

	FS.prototype.Unlink = function(idx) {
	this.NotifyListeners(idx, 'delete');
	if (idx == 0) return false; // root node cannot be deleted
	var inode = this.GetInode(idx);
	//message.Debug("Unlink " + inode.name);

	// check if directory is not empty
	if ((inode.mode&S_IFMT) == S_IFDIR) {
	if (inode.firstid != -1) return false;
	}

	// update ids
	if (this.inodes[inode.parentid].firstid == idx) {
	this.inodes[inode.parentid].firstid = inode.nextid;
	} else {
	var id = this.FindPreviousID(idx);
	if (id == -1) {
	message.Debug("Error in Filesystem: Cannot find previous id of inode");
	message.Abort();
	}
	this.inodes[id].nextid = inode.nextid;
	}
	// don't delete the content. The file is still accessible
	this.inodes[inode.parentid].updatedir = true;
	this.inodes[inode.parentid].nlinks--;
	inode.status = STATUS_UNLINKED;
	inode.nextid = -1;
	inode.firstid = -1;
	inode.parentid = -1;
	inode.nlinks--;
	return true;
	}

	FS.prototype.GetInode = function(idx)
	{
	if (isNaN(idx)) {
	message.Debug("Error in filesystem: id is not a number ");
	return 0;
	}

	if ((idx < 0) \|\| (idx > this.inodes.length)) {
	message.Debug("Error in filesystem: Attempt to get inode with id " + idx);
	return 0;
	}
	return this.inodes[idx];
	}

	FS.prototype.ChangeSize = function(idx, newsize)
	{
	var inode = this.GetInode(idx);
	var temp = this.inodedata[idx];
	//message.Debug("change size to: " + newsize);
	if (newsize == inode.size) return;
	var data = this.inodedata[idx] = new Uint8Array(newsize);
	inode.size = newsize;
	if(!temp) return;
	var size = Math.min(temp.length, inode.size);
	for(var i=0; i<size; i++) {
	data[i] = temp[i];
	}
	}

	FS.prototype.SearchPath = function(path) {
	//path = path.replace(/\/\//g, "/");
	path = path.replace("//", "/");
	var walk = path.split("/");
	var n = walk.length;
	if (walk[n-1].length == 0) walk.pop();
	if (walk[0].length == 0) walk.shift();
	n = walk.length;

	var parentid = 0;
	var id = -1;
	for(var i=0; i<n; i++) {
	id = this.Search(parentid, walk[i]);
	if (id == -1) {
	if (i < n-1) return {id: -1, parentid: -1, name: walk[i]}; // one name of the path cannot be found
	return {id: -1, parentid: parentid, name: walk[i]}; // the last element in the path does not exist, but the parent
	}
	parentid = id;
	}
	return {id: id, parentid: parentid, name: walk[i]};
	}
	// -----------------------------------------------------

	FS.prototype.GetRecursiveList = function(dirid, list) {
	var id = this.inodes[dirid].firstid;
	while(id != -1) {
	list.push(id);
	if ((this.inodes[id].mode&S_IFMT) == S_IFDIR) {
	this.GetRecursiveList(id, list);
	}
	id = this.inodes[id].nextid;
	}
	}

	FS.prototype.MergeFile = function(file) {
	message.Debug("Merge path:" + file.name);
	var ids = this.SearchPath(file.name);
	if (ids.parentid == -1) return; // not even the path seems to exist
	if (ids.id == -1) {
	ids.id = this.CreateFile(ids.name, ids.parentid);
	}
	this.inodes[ids.id].data = file.data;
	this.inodes[ids.id].size = file.data.length;
	// Don't forget to update the timestamps !
	this.inodes[ids.id].mtime = Math.floor((new Date()).getTime()/1000);
	this.inodes[ids.id].atime = this.inodes[ids.id].mtime;
	this.inodes[ids.id].ctime = this.inodes[ids.id].mtime;
	}


	FS.prototype.RecursiveDelete = function(path) {
	var toDelete = []
	var ids = this.SearchPath(path);
	if (ids.parentid == -1 \|\| ids.id == -1) return;

	this.GetRecursiveList(ids.id, toDelete);

	for(var i=toDelete.length-1; i>=0; i--)
	this.Unlink(toDelete[i]);

	}

	FS.prototype.DeleteNode = function(path) {
	var ids = this.SearchPath(path);
	if (ids.parentid == -1 \|\| ids.id == -1) return;

	if ((this.inodes[ids.id].mode&S_IFMT) == S_IFREG){
	this.Unlink(ids.id);
	return;
	}
	if ((this.inodes[ids.id].mode&S_IFMT) == S_IFDIR){
	var toDelete = []
	this.GetRecursiveList(ids.id, toDelete);
	for(var i=toDelete.length-1; i>=0; i--)
	this.Unlink(toDelete[i]);
	this.Unlink(ids.id);
	return;
	}
	}

	/** @param {=} info /
	FS.prototype.NotifyListeners = function(id, action, info) {
	//if(info==undefined)
	// info = {};

	//var path = this.GetFullPath(id);
	//if (this.watchFiles[path] == true && action=='write') {
	// message.Send("WatchFileEvent", path);
	//}
	//for (var directory in this.watchDirectories) {
	// if (this.watchDirectories.hasOwnProperty(directory)) {
	// var indexOf = path.indexOf(directory)
	// if(indexOf == 0 \|\| indexOf == 1)
	// message.Send("WatchDirectoryEvent", {path: path, event: action, info: info});
	// }
	//}
	}


	FS.prototype.Check = function() {
	for(var i=1; i<this.inodes.length; i++)
	{
	if (this.inodes[i].status == STATUS_INVALID) continue;
	if (this.inodes[i].nextid == i) {
	message.Debug("Error in filesystem: file points to itself");
	message.Abort();
	}

	var inode = this.GetInode(i);
	if (inode.parentid < 0) {
	message.Debug("Error in filesystem: negative parent id " + i);
	}
	var n = inode.name.length;
	if (n == 0) {
	message.Debug("Error in filesystem: inode with no name and id " + i);
	}

	for (var j in inode.name) {
	var c = inode.name.charCodeAt(j);
	if (c < 32) {
	message.Debug("Error in filesystem: Unallowed char in filename");
	}
	}
	}
	}

	FS.prototype.FillDirectory = function(dirid) {
	var inode = this.GetInode(dirid);
	if (!inode.updatedir) return;
	var parentid = inode.parentid;
	if (parentid == -1) parentid = 0; // if root directory point to the root directory

	// first get size
	var size = 0;
	var id = this.inodes[dirid].firstid;
	while(id != -1) {
	size += 13 + 8 + 1 + 2 + UTF8.UTF8Length(this.inodes[id].name);
	id = this.inodes[id].nextid;
	}

	size += 13 + 8 + 1 + 2 + 1; // "." entry
	size += 13 + 8 + 1 + 2 + 2; // ".." entry
	//message.Debug("size of dir entry: " + size);
	var data = this.inodedata[dirid] = new Uint8Array(size);
	inode.size = size;

	var offset = 0x0;
	offset += marshall.Marshall(
	["Q", "d", "b", "s"],
	[this.inodes[dirid].qid,
	offset+13+8+1+2+1,
	this.inodes[dirid].mode >> 12,
	"."],
	data, offset);

	offset += marshall.Marshall(
	["Q", "d", "b", "s"],
	[this.inodes[parentid].qid,
	offset+13+8+1+2+2,
	this.inodes[parentid].mode >> 12,
	".."],
	data, offset);

	id = this.inodes[dirid].firstid;
	while(id != -1) {
	offset += marshall.Marshall(
	["Q", "d", "b", "s"],
	[
	this.inodes[id].qid,
	offset+13+8+1+2+UTF8.UTF8Length(this.inodes[id].name),
	this.inodes[id].mode >> 12,
	this.inodes[id].name
	],
	data, offset);
	id = this.inodes[id].nextid;
	}
	inode.updatedir = false;
	}


	// -----------------------------------------------------

	// only support for security.capabilities
	// should return a "struct vfs_cap_data" defined in
	// linux/capability for format
	// check also:
	// sys/capability.h
	// http://lxr.free-electrons.com/source/security/commoncap.c#L376
	// http://man7.org/linux/man-pages/man7/capabilities.7.html
	// http://man7.org/linux/man-pages/man8/getcap.8.html
	// http://man7.org/linux/man-pages/man3/libcap.3.html
	FS.prototype.PrepareCAPs = function(id) {
	var inode = this.GetInode(id);
	if (inode.caps) return inode.caps.length;
	inode.caps = new Uint8Array(12);
	// format is little endian
	// magic_etc (revision=0x01: 12 bytes)
	inode.caps[0] = 0x00;
	inode.caps[1] = 0x00;
	inode.caps[2] = 0x00;
	inode.caps[3] = 0x01;
	// permitted (full capabilities)
	inode.caps[4] = 0xFF;
	inode.caps[5] = 0xFF;
	inode.caps[6] = 0xFF;
	inode.caps[7] = 0xFF;
	// inheritable (full capabilities
	inode.caps[8] = 0xFF;
	inode.caps[9] = 0xFF;
	inode.caps[10] = 0xFF;
	inode.caps[11] = 0xFF;

	return inode.caps.length;
	}