Isolate filesystem qid counting to each v86 instance

lib/filesystem.js

@@ -44,14 +44,19 @@ var STATUS_FORWARDING = 0x5;
 /** @const */ var JSONFS_IDX_TARGET = 6;
 
 
-/** @constructor */
-function FS(baseurl) {
+/**
+ * @constructor
+ * @param {string=} baseurl
+ * @param {{ last_qidnumber: number }=} qidcounter Another fs's qidcounter to synchronise with.
+ */
+function FS(baseurl, qidcounter) {
     /** @type {Array.<!Inode>} */
     this.inodes = [];
     this.events = [];
 
     this.baseurl = baseurl;
 
+    this.qidcounter = qidcounter || { last_qidnumber: 0 };
     this.filesinloadingqueue = 0;
     this.OnLoaded = function() {};
 
@@ -82,14 +87,12 @@ function FS(baseurl) {
     this.CreateDirectory("", -1);
 }
 
-FS.last_qidnumber = 0;
-
 FS.prototype.get_state = function()
 {
     const state = [];
 
     state[0] = this.inodes;
-    state[1] = FS.last_qidnumber;
+    state[1] = this.qidcounter.last_qidnumber;
     state[2] = [];
     for(let entry of Object.entries(this.inodedata))
     {
@@ -106,7 +109,7 @@ FS.prototype.get_state = function()
 FS.prototype.set_state = function(state)
 {
     this.inodes = state[0].map(state => { const inode = new Inode(0); inode.set_state(state); return inode; });
-    FS.last_qidnumber = state[1];
+    this.qidcounter.last_qidnumber = state[1];
     this.inodedata = {};
     for(let [key, value] of state[2])
     {
@@ -126,6 +129,7 @@ FS.prototype.set_state = function(state)
     {
         const mount = new FSMountInfo(null);
         mount.set_state(mount_state);
+        mount.fs.qidcounter = this.qidcounter;
         this.mounts.push(mount);
     }
 };
@@ -543,7 +547,7 @@ FS.prototype.divert = function(old_idx)
 FS.prototype.CreateInode = function() {
     //console.log("CreateInode", Error().stack);
     const now = Math.round(Date.now() / 1000);
-    const inode = new Inode(++FS.last_qidnumber);
+    const inode = new Inode(++this.qidcounter.last_qidnumber);
     inode.atime = inode.ctime = inode.mtime = now;
     return inode;
 };
@@ -1571,6 +1575,9 @@ FS.prototype.follow_fs = function(inode)
  */
 FS.prototype.Mount = function(path, fs)
 {
+    dbg_assert(fs.qidcounter === this.qidcounter,
+        "Cannot mount filesystem whose qid numbers aren't synchronised with current filesystem.");
+
     const path_infos = this.SearchPath(path);
 
     if(path_infos.id === -1)

src/browser/starter.js

@@ -1081,7 +1081,7 @@ V86Starter.prototype.serial0_send = function(data)
  */
 V86Starter.prototype.mount_fs = function(path, baseurl, basefs, callback)
 {
-    const newfs = new FS(baseurl);
+    const newfs = new FS(baseurl, this.fs9p.qidcounter);
     const mount = () =>
     {
         const idx = this.fs9p.Mount(path, newfs);