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;

 /** @constructor */
 function FS(baseurl) {
     this.inodes = [];
     this.events = [];

     this.baseurl = baseurl;

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

     //this.tar = new TAR(this);
     this.userinfo = [];

     this.inodedata = {};


     //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);

     this._state_skip = ["OnLoaded"];
 }


 // -----------------------------------------------------
 FS.prototype.LoadFilesystem = function(userinfo)
 {
     this.userinfo = userinfo;
     this.LoadFSXML(this.userinfo.basefsURL);
     this.OnLoaded = function() {
     }.bind(this);

 }


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

 FS.prototype.AddEvent = function(id, OnEvent) {
     var inode = this.inodes[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() {}
     }
     //DebugMessage("number of events: " + this.events.length);
     for(var i = this.events.length - 1; i >= 0; i--) {
         if (this.events[i].id != id) continue;
         this.events[i].OnEvent();
         this.events.splice(i, 1);
     }
 }


 // -----------------------------------------------------
 //FS.prototype.LoadImage = function(url)
 //{
 //    dbg_assert(false);
 //    if (!url) return;
 //    //DebugMessage("Load Image " + url);
 ///*
 //    if (typeof Worker !== 'undefined') {
 //        LoadBZIP2Resource(url,
 //            function(m){ for(var i=0; i<m.size; i++) this.tar.Unpack(m.data[i]); }.bind(this),
 //            function(e){DebugMessage("Error: Could not load " + url + ". Skipping.");});
 //        return;
 //    }
 //*/
 //    LoadBinaryResource(url,
 //    function(buffer){
 //        var buffer8 = new Uint8Array(buffer);
 //        bzip2.simple(buffer8, this.tar.Unpack.bind(this.tar));
 //    }.bind(this),
 //    function(error){DebugMessage("Error: Could not load " + url + ". Skipping.");});
 //}
 // -----------------------------------------------------


 function ReadVariable(buffer, offset) {
     var variable = [];
     variable.name = "";
     variable.value = "";

     // read blanks
     for(var i=offset; i<buffer.length; i++) {
         if (buffer[i] == '>') return variable;
         if (buffer[i] == '/') return variable;
         if (buffer[i] != ' ') break;
     }
     offset = i;
     if (buffer[i] == '>') return variable;

     // read variable name
     for(var i=offset; i<buffer.length; i++) {
         if (buffer[i] == '>') break;
         if (buffer[i] == '=') break;
         variable.name = variable.name + buffer[i];
     }
     offset = i+1;
     if (variable.name.length == 0) return variable;
     // read variable value
     for(var i=offset+1; i<buffer.length; i++) {
         if (buffer[i] == '>') break;
         if (buffer[i] == '\'') break;
         variable.value = variable.value + buffer[i];
     }
     offset = i+1;
     variable.offset = offset;
     DebugMessage("read " + variable.name + "=" + variable.value);
     return variable;
 }

 function ReadTag(buffer, offset) {
     var tag = [];
     tag.type = "";
     tag.name = "";
     tag.mode = 0x0;
     tag.uid = 0x0;
     tag.gid = 0x0;
     tag.path = "";
     tag.src = "";
     tag.compressed = false;
     tag.load = false;

     if (buffer[offset] != '<') return tag;
     for(var i=offset+1; i<buffer.length; i++) {
         if (buffer[i] ==  ' ') break;
         if (buffer[i] == '\n') break;
         if (buffer[i] == '>') break;
         tag.type = tag.type + buffer[i];
     }
     offset = i;
     // read variables
     do {
         var variable = ReadVariable(buffer, offset);
         if (variable.name == "name") tag.name = variable.value;
         if (variable.name == "mode") tag.mode = parseInt(variable.value, 8);
         if (variable.name == "uid") tag.uid = parseInt(variable.value, 10);
         if (variable.name == "gid") tag.gid = parseInt(variable.value, 10);
         if (variable.name == "path") tag.path = variable.value;
         if (variable.name == "size") tag.size = parseInt(variable.value, 10);
         if (variable.name == "src") tag.src = variable.value;
         if (variable.name == "compressed") tag.compressed = true;
         if (variable.name == "load") tag.load = true;
         offset = variable.offset;
     } while(variable.name.length != 0);
     return tag;
 };

 FS.prototype.CheckEarlyload = function(path)
 {
     for(var i=0; i<this.userinfo.earlyload.length; i++) {
         if (this.userinfo.earlyload[i] == path) {
             return true;
         }
     }
     return false;
 }

 FS.prototype.LoadFSXML = function(urls)
 {
     DebugMessage("Load filesystem information from " + urls);
     LoadXMLResource(urls, this.OnJSONLoaded.bind(this), function(error){throw error;});
 }

 FS.prototype.OnJSONLoaded = function(fs)
 {
     //console.time("JSON");
     var data = JSON.parse(fs);
     //console.timeEnd("JSON");

     var fsroot = data["fsroot"];
     var me = this;

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

         if(DEBUG)
         {
             //console.time("Check");
             //me.Check();
             //console.timeEnd("Check");
         }
     }, 100);

     function LoadRecursive(data, parentid)
     {
         var inode = me.CreateInode();

         inode.name = data.name;
         inode.uid = data.uid || 0;
         inode.gid = data.gid || 0;
         inode.atime = Math.floor(data.atime) || inode.atime;
         inode.ctime = Math.floor(data.ctime) || inode.ctime;
         inode.mtime = Math.floor(data.mtime) || inode.mtime;
         inode.parentid = parentid;
         inode.mode = data.mode & 511;
         inode.size = data.size || 0;

         switch(data.type)
         {
             case "dir":
                 inode.updatedir = true;
                 inode.mode |= S_IFDIR;
                 var p = me.inodes.length;
                 me.PushInode(inode);
                 var children = data.children;
                 for(var i = 0; i < children.length; i++) {
                     LoadRecursive(children[i], p);
                 }
                 break;

             case "file":
                 inode.mode |= S_IFREG;
                 var idx = me.inodes.length;
                 inode.status = STATUS_ON_SERVER;
                 me.PushInode(inode);
                 var url = me.baseurl + me.GetFullPath(idx);
                 inode.url = url;
                 break;

             case "link":
                 inode.mode |= S_IFLNK;
                 inode.symlink = data.target;
                 me.PushInode(inode);
                 break;

             default:
                 DebugMessage("Invalid message type: ", data.type);
                 abort();
         }
     }
 };

 // The filesystem is responsible to add the correct time. This is a hack
 // Have to find a better solution.
 FS.prototype.AppendDateHack = function(idx) {
     if (this.GetFullPath(idx) != "etc/init.d/rcS") return;
     var inode = this.inodes[idx];
     var date = new Date();
     var datestring =
         "\ndate -s \"" +
         date.getFullYear() +
         "-" +
         (date.getMonth()+1) +
         "-" +
         date.getDate() +
         " " +
         date.getHours() +
         ":" +
         date.getMinutes() +
         ":" +
         date.getSeconds() +
         "\"\n";
     var size = inode.size;
     this.ChangeSize(idx, size+datestring.length);
     var data = this.inodedata[idx];
     for(var i=0; i<datestring.length; i++) {
         data[i+size] = datestring.charCodeAt(i);
     }
 }


 // 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;
     //}

     LoadBinaryResource(inode.url,
         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;
             if (inode.name == "rcS") {
                 this.AppendDateHack(idx);
             }
             this.filesinloadingqueue--;
             this.HandleEvent(idx);
         }.bind(this),
         function(error){throw error;});

 }

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

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

     DebugMessage("Error in Filesystem: Pushed inode with name = "+ inode.name + " has no parent");
     abort();

 }


 FS.prototype.CreateInode = function() {
     //console.log("CreateInode", Error().stack);
     this.qidnumber++;
     var now = Math.floor(Date.now() / 1000);
     return {
         updatedir : false, // did the directory listing changed?
         parentid: -1,
         firstid : -1, // first file id in directory
         nextid : -1, // next id in directory
         status : 0,
         name : "",
         size : 0x0,
         uid : 0x0,
         gid : 0x0,
         ctime : now,
         atime : now,
         mtime : now,
         major : 0x0,
         minor : 0x0,
         //data : new Uint8Array(0),
         symlink : "",
         mode : 0x01ED,
         qid: {type: 0, version: 0, path: this.qidnumber},
         url: "", // url to download the file
         waswritten: false,
     };
 }


 FS.prototype.CreateDirectory = function(name, parentid) {
     var x = this.CreateInode();
     x.name = name;
     x.parentid = parentid;
     x.mode = 0x01FF | S_IFDIR;
     if (parentid >= 0) {
         x.uid = this.inodes[parentid].uid;
         x.gid = this.inodes[parentid].gid;
         x.mode = (this.inodes[parentid].mode & 0x1FF) | S_IFDIR;
     }
     x.qid.type = S_IFDIR >> 8;
     this.PushInode(x);
     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;
     x.qid.type = S_IFREG >> 8;
     x.mode = (this.inodes[parentid].mode & 0x1B6) | S_IFREG;
     this.PushInode(x);
     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;
     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;
     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.waswritten = true;
     x.size = str.length;
     for (var j in str) {
         data[j] = str.charCodeAt(j);
     }
     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;
     }
     */
     //DebugMessage("open:" + this.GetFullPath(id) + " status:" + inode.status);
     if (inode.status == STATUS_ON_SERVER) {
         this.LoadFile(id);
         return false;
     }
     return true;
 }

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

 FS.prototype.Rename = function(olddirid, oldname, newdirid, newname) {
     //DebugMessage("Rename " + oldname + " to " + newname);
     if ((olddirid == newdirid) && (oldname == newname)) {
         return true;
     }
     var oldid = this.Search(olddirid, oldname);
     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) {
             //DebugMessage("Error in Filesystem: Cannot find previous id of inode");
             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;
     return true;
 }

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

     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
             DebugMessage("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 1234567;
     //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.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) {
     if (idx == 0) return false; // root node cannot be deleted
     var inode = this.GetInode(idx);
     //DebugMessage("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) {
             DebugMessage("Error in Filesystem: Cannot find previous id of inode");
             abort();
         }
         this.inodes[id].nextid = inode.nextid;
     }
     // don't delete the content. The file is still accessible
     this.inodes[inode.parentid].updatedir = true;
     inode.status = STATUS_UNLINKED;
     inode.nextid = -1;
     inode.firstid = -1;
     inode.parentid = -1;
     return true;
 }

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

     if ((idx < 0) || (idx > this.inodes.length)) {
         DebugMessage("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];
     //DebugMessage("change size to: " + newsize);
     if (newsize == inode.size) return;
     var data = this.inodedata[idx] = new Uint8Array(newsize);
     inode.size = newsize;
     inode.waswritten = true;
     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) {
     throw "unimplemented";
     //DebugMessage("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;
 }


 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) {
             DebugMessage("Error in filesystem: file points to itself");
             abort();
         }

         var inode = this.GetInode(i);
         if (inode.parentid < 0) {
             DebugMessage("Error in filesystem: negative parent id " + i);
         }
         var n = inode.name.length;
         if (n == 0) {
             DebugMessage("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) {
                 DebugMessage("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 + UTF8Length(this.inodes[id].name);
         id = this.inodes[id].nextid;
     }

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

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

     offset += 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(
         ["Q", "d", "b", "s"],
         [this.inodes[id].qid,
         offset+13+8+1+2+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;
 }

 FS.prototype.ClearCache = function()
 {
     for(var id in this.inodedata)
     {
         if(!this.inodes[id].waswritten)
         {
             delete this.inodedata[id];
         }
     }
 };
	// -------------------------------------------------
	// ----------------- 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;

	/** @constructor */
	function FS(baseurl) {
	this.inodes = [];
	this.events = [];

	this.baseurl = baseurl;

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

	//this.tar = new TAR(this);
	this.userinfo = [];

	this.inodedata = {};


	//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);

	this._state_skip = ["OnLoaded"];
	}


	// -----------------------------------------------------
	FS.prototype.LoadFilesystem = function(userinfo)
	{
	this.userinfo = userinfo;
	this.LoadFSXML(this.userinfo.basefsURL);
	this.OnLoaded = function() {
	}.bind(this);

	}


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

	FS.prototype.AddEvent = function(id, OnEvent) {
	var inode = this.inodes[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() {}
	}
	//DebugMessage("number of events: " + this.events.length);
	for(var i = this.events.length - 1; i >= 0; i--) {
	if (this.events[i].id != id) continue;
	this.events[i].OnEvent();
	this.events.splice(i, 1);
	}
	}


	// -----------------------------------------------------
	//FS.prototype.LoadImage = function(url)
	//{
	// dbg_assert(false);
	// if (!url) return;
	// //DebugMessage("Load Image " + url);
	///*
	// if (typeof Worker !== 'undefined') {
	// LoadBZIP2Resource(url,
	// function(m){ for(var i=0; i<m.size; i++) this.tar.Unpack(m.data[i]); }.bind(this),
	// function(e){DebugMessage("Error: Could not load " + url + ". Skipping.");});
	// return;
	// }
	//*/
	// LoadBinaryResource(url,
	// function(buffer){
	// var buffer8 = new Uint8Array(buffer);
	// bzip2.simple(buffer8, this.tar.Unpack.bind(this.tar));
	// }.bind(this),
	// function(error){DebugMessage("Error: Could not load " + url + ". Skipping.");});
	//}
	// -----------------------------------------------------


	function ReadVariable(buffer, offset) {
	var variable = [];
	variable.name = "";
	variable.value = "";

	// read blanks
	for(var i=offset; i<buffer.length; i++) {
	if (buffer[i] == '>') return variable;
	if (buffer[i] == '/') return variable;
	if (buffer[i] != ' ') break;
	}
	offset = i;
	if (buffer[i] == '>') return variable;

	// read variable name
	for(var i=offset; i<buffer.length; i++) {
	if (buffer[i] == '>') break;
	if (buffer[i] == '=') break;
	variable.name = variable.name + buffer[i];
	}
	offset = i+1;
	if (variable.name.length == 0) return variable;
	// read variable value
	for(var i=offset+1; i<buffer.length; i++) {
	if (buffer[i] == '>') break;
	if (buffer[i] == '\'') break;
	variable.value = variable.value + buffer[i];
	}
	offset = i+1;
	variable.offset = offset;
	DebugMessage("read " + variable.name + "=" + variable.value);
	return variable;
	}

	function ReadTag(buffer, offset) {
	var tag = [];
	tag.type = "";
	tag.name = "";
	tag.mode = 0x0;
	tag.uid = 0x0;
	tag.gid = 0x0;
	tag.path = "";
	tag.src = "";
	tag.compressed = false;
	tag.load = false;

	if (buffer[offset] != '<') return tag;
	for(var i=offset+1; i<buffer.length; i++) {
	if (buffer[i] == ' ') break;
	if (buffer[i] == '\n') break;
	if (buffer[i] == '>') break;
	tag.type = tag.type + buffer[i];
	}
	offset = i;
	// read variables
	do {
	var variable = ReadVariable(buffer, offset);
	if (variable.name == "name") tag.name = variable.value;
	if (variable.name == "mode") tag.mode = parseInt(variable.value, 8);
	if (variable.name == "uid") tag.uid = parseInt(variable.value, 10);
	if (variable.name == "gid") tag.gid = parseInt(variable.value, 10);
	if (variable.name == "path") tag.path = variable.value;
	if (variable.name == "size") tag.size = parseInt(variable.value, 10);
	if (variable.name == "src") tag.src = variable.value;
	if (variable.name == "compressed") tag.compressed = true;
	if (variable.name == "load") tag.load = true;
	offset = variable.offset;
	} while(variable.name.length != 0);
	return tag;
	};

	FS.prototype.CheckEarlyload = function(path)
	{
	for(var i=0; i<this.userinfo.earlyload.length; i++) {
	if (this.userinfo.earlyload[i] == path) {
	return true;
	}
	}
	return false;
	}

	FS.prototype.LoadFSXML = function(urls)
	{
	DebugMessage("Load filesystem information from " + urls);
	LoadXMLResource(urls, this.OnJSONLoaded.bind(this), function(error){throw error;});
	}

	FS.prototype.OnJSONLoaded = function(fs)
	{
	//console.time("JSON");
	var data = JSON.parse(fs);
	//console.timeEnd("JSON");

	var fsroot = data["fsroot"];
	var me = this;

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

	if(DEBUG)
	{
	//console.time("Check");
	//me.Check();
	//console.timeEnd("Check");
	}
	}, 100);

	function LoadRecursive(data, parentid)
	{
	var inode = me.CreateInode();

	inode.name = data.name;
	inode.uid = data.uid \|\| 0;
	inode.gid = data.gid \|\| 0;
	inode.atime = Math.floor(data.atime) \|\| inode.atime;
	inode.ctime = Math.floor(data.ctime) \|\| inode.ctime;
	inode.mtime = Math.floor(data.mtime) \|\| inode.mtime;
	inode.parentid = parentid;
	inode.mode = data.mode & 511;
	inode.size = data.size \|\| 0;

	switch(data.type)
	{
	case "dir":
	inode.updatedir = true;
	inode.mode \|= S_IFDIR;
	var p = me.inodes.length;
	me.PushInode(inode);
	var children = data.children;
	for(var i = 0; i < children.length; i++) {
	LoadRecursive(children[i], p);
	}
	break;

	case "file":
	inode.mode \|= S_IFREG;
	var idx = me.inodes.length;
	inode.status = STATUS_ON_SERVER;
	me.PushInode(inode);
	var url = me.baseurl + me.GetFullPath(idx);
	inode.url = url;
	break;

	case "link":
	inode.mode \|= S_IFLNK;
	inode.symlink = data.target;
	me.PushInode(inode);
	break;

	default:
	DebugMessage("Invalid message type: ", data.type);
	abort();
	}
	}
	};

	// The filesystem is responsible to add the correct time. This is a hack
	// Have to find a better solution.
	FS.prototype.AppendDateHack = function(idx) {
	if (this.GetFullPath(idx) != "etc/init.d/rcS") return;
	var inode = this.inodes[idx];
	var date = new Date();
	var datestring =
	"\ndate -s \"" +
	date.getFullYear() +
	"-" +
	(date.getMonth()+1) +
	"-" +
	date.getDate() +
	" " +
	date.getHours() +
	":" +
	date.getMinutes() +
	":" +
	date.getSeconds() +
	"\"\n";
	var size = inode.size;
	this.ChangeSize(idx, size+datestring.length);
	var data = this.inodedata[idx];
	for(var i=0; i<datestring.length; i++) {
	data[i+size] = datestring.charCodeAt(i);
	}
	}


	// 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;
	//}

	LoadBinaryResource(inode.url,
	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;
	if (inode.name == "rcS") {
	this.AppendDateHack(idx);
	}
	this.filesinloadingqueue--;
	this.HandleEvent(idx);
	}.bind(this),
	function(error){throw error;});

	}

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

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

	DebugMessage("Error in Filesystem: Pushed inode with name = "+ inode.name + " has no parent");
	abort();

	}


	FS.prototype.CreateInode = function() {
	//console.log("CreateInode", Error().stack);
	this.qidnumber++;
	var now = Math.floor(Date.now() / 1000);
	return {
	updatedir : false, // did the directory listing changed?
	parentid: -1,
	firstid : -1, // first file id in directory
	nextid : -1, // next id in directory
	status : 0,
	name : "",
	size : 0x0,
	uid : 0x0,
	gid : 0x0,
	ctime : now,
	atime : now,
	mtime : now,
	major : 0x0,
	minor : 0x0,
	//data : new Uint8Array(0),
	symlink : "",
	mode : 0x01ED,
	qid: {type: 0, version: 0, path: this.qidnumber},
	url: "", // url to download the file
	waswritten: false,
	};
	}



	FS.prototype.CreateDirectory = function(name, parentid) {
	var x = this.CreateInode();
	x.name = name;
	x.parentid = parentid;
	x.mode = 0x01FF \| S_IFDIR;
	if (parentid >= 0) {
	x.uid = this.inodes[parentid].uid;
	x.gid = this.inodes[parentid].gid;
	x.mode = (this.inodes[parentid].mode & 0x1FF) \| S_IFDIR;
	}
	x.qid.type = S_IFDIR >> 8;
	this.PushInode(x);
	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;
	x.qid.type = S_IFREG >> 8;
	x.mode = (this.inodes[parentid].mode & 0x1B6) \| S_IFREG;
	this.PushInode(x);
	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;
	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;
	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.waswritten = true;
	x.size = str.length;
	for (var j in str) {
	data[j] = str.charCodeAt(j);
	}
	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;
	}
	*/
	//DebugMessage("open:" + this.GetFullPath(id) + " status:" + inode.status);
	if (inode.status == STATUS_ON_SERVER) {
	this.LoadFile(id);
	return false;
	}
	return true;
	}

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

	FS.prototype.Rename = function(olddirid, oldname, newdirid, newname) {
	//DebugMessage("Rename " + oldname + " to " + newname);
	if ((olddirid == newdirid) && (oldname == newname)) {
	return true;
	}
	var oldid = this.Search(olddirid, oldname);
	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) {
	//DebugMessage("Error in Filesystem: Cannot find previous id of inode");
	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;
	return true;
	}

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

	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
	DebugMessage("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 1234567;
	//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.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) {
	if (idx == 0) return false; // root node cannot be deleted
	var inode = this.GetInode(idx);
	//DebugMessage("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) {
	DebugMessage("Error in Filesystem: Cannot find previous id of inode");
	abort();
	}
	this.inodes[id].nextid = inode.nextid;
	}
	// don't delete the content. The file is still accessible
	this.inodes[inode.parentid].updatedir = true;
	inode.status = STATUS_UNLINKED;
	inode.nextid = -1;
	inode.firstid = -1;
	inode.parentid = -1;
	return true;
	}

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

	if ((idx < 0) \|\| (idx > this.inodes.length)) {
	DebugMessage("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];
	//DebugMessage("change size to: " + newsize);
	if (newsize == inode.size) return;
	var data = this.inodedata[idx] = new Uint8Array(newsize);
	inode.size = newsize;
	inode.waswritten = true;
	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) {
	throw "unimplemented";
	//DebugMessage("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;
	}


	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) {
	DebugMessage("Error in filesystem: file points to itself");
	abort();
	}

	var inode = this.GetInode(i);
	if (inode.parentid < 0) {
	DebugMessage("Error in filesystem: negative parent id " + i);
	}
	var n = inode.name.length;
	if (n == 0) {
	DebugMessage("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) {
	DebugMessage("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 + UTF8Length(this.inodes[id].name);
	id = this.inodes[id].nextid;
	}

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

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

	offset += 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(
	["Q", "d", "b", "s"],
	[this.inodes[id].qid,
	offset+13+8+1+2+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;
	}

	FS.prototype.ClearCache = function()
	{
	for(var id in this.inodedata)
	{
	if(!this.inodes[id].waswritten)
	{
	delete this.inodedata[id];
	}
	}
	};