Introduce forwarding inodes. Implement fs.Mount
Add forward_path info to fs.SearchPath. Handle forwarding for fs.Search.
This commit is contained in:
Ernest Wong
Fabian
parent
070c38c6a1
commit
e6ef68b334
1 changed files with 216 additions and 7 deletions
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@ -29,6 +29,7 @@ var STATUS_OK = 0x0;
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var STATUS_ON_SERVER = 0x2;
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var STATUS_LOADING = 0x3;
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var STATUS_UNLINKED = 0x4;
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var STATUS_FORWARDING = 0x5;
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/** @const */ var JSONFS_VERSION = 2;
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@ -62,6 +63,9 @@ function FS(baseurl) {
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this.total_size = 256 * 1024 * 1024 * 1024;
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this.used_size = 0;
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/** @type {!Array<!FSMountInfo>} */
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this.mounts = [];
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//RegisterMessage("LoadFilesystem", this.LoadFilesystem.bind(this) );
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//RegisterMessage("MergeFile", this.MergeFile.bind(this) );
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//RegisterMessage("tar",
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@ -92,6 +96,8 @@ FS.prototype.get_state = function()
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}
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state[3] = this.total_size;
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state[4] = this.used_size;
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state[5] = this.baseurl;
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state[6] = this.mounts.map(mnt => mnt.fs);
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return state;
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};
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@ -113,6 +119,14 @@ FS.prototype.set_state = function(state)
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}
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this.total_size = state[3];
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this.used_size = state[4];
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this.baseurl = state[5];
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this.mounts = [];
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for(const mount_state of state[6])
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{
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const mount = new FSMountInfo(null);
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mount.set_state(mount_state);
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this.mounts.push(mount);
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}
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};
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@ -341,6 +355,10 @@ function Inode(qidnumber)
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this.nlinks = 1;
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this.dirty = false; // has this file changed?
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// For forwarders:
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this.mount_id = -1; // which fs in this.mounts does this inode forward to?
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this.foreign_id = -1; // which foreign inode id does it represent?
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//this.qid_type = 0;
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//this.qid_version = 0;
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//this.qid_path = qidnumber;
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@ -372,6 +390,8 @@ Inode.prototype.get_state = function()
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state[20] = this.caps;
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state[21] = this.nlinks;
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state[22] = this.dirty;
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state[23] = this.mount_id;
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state[24] = this.foreign_id;
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return state;
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};
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@ -400,6 +420,8 @@ Inode.prototype.set_state = function(state)
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this.caps = state[20];
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this.nlinks = state[21];
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this.dirty = state[22];
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this.mount_id = state[23];
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this.foreign_id = state[24];
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};
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FS.prototype.CreateInode = function() {
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@ -611,11 +633,21 @@ FS.prototype.Read = function(inodeid, offset, count)
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};
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FS.prototype.Search = function(parentid, name) {
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var id = this.inodes[parentid].firstid;
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const parent_inode = this.inodes[parentid];
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if(this.is_forwarder(parent_inode))
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{
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const foreign_parentid = parent_inode.foreign_id;
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const foreign_id = this.follow_fs(parent_inode).Search(foreign_parentid, name);
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if(foreign_id === -1) return -1;
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return this.get_forwarder(parent_inode.mount_id, foreign_id);
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}
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var id = parent_inode.firstid;
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while(id != -1) {
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if (this.inodes[id].parentid != parentid) { // consistency check
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message.Debug("Error in Filesystem: Found inode with wrong parent id");
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}
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dbg_assert(this.GetParent(id) === parentid,
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"Error in Filesystem: Found inode (" + this.inodes[id].name + ") with wrong parent id. " +
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"Expected: " + parentid + ", Actual: " + this.GetParent(id));
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if (this.inodes[id].name == name) return id;
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id = this.inodes[id].nextid;
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}
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@ -763,15 +795,20 @@ FS.prototype.SearchPath = function(path) {
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var parentid = 0;
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var id = -1;
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let forward_path = null;
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for(var i=0; i<n; i++) {
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id = this.Search(parentid, walk[i]);
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if(!forward_path && this.is_forwarder(this.inodes[parentid]))
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{
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forward_path = "/" + walk.slice(i).join("/");
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}
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if (id == -1) {
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if (i < n-1) return {id: -1, parentid: -1, name: walk[i]}; // one name of the path cannot be found
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return {id: -1, parentid: parentid, name: walk[i]}; // the last element in the path does not exist, but the parent
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if (i < n-1) return {id: -1, parentid: -1, name: walk[i], forward_path }; // one name of the path cannot be found
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return {id: -1, parentid: parentid, name: walk[i], forward_path}; // the last element in the path does not exist, but the parent
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}
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parentid = id;
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}
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return {id: id, parentid: parentid, name: walk[i]};
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return {id: id, parentid: parentid, name: walk[i], forward_path};
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};
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// -----------------------------------------------------
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@ -988,3 +1025,175 @@ FS.prototype.PrepareCAPs = function(id) {
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return inode.caps.length;
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};
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// -----------------------------------------------------
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/**
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* @constructor
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* @param {FS} filesystem
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*/
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function FSMountInfo(filesystem)
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{
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/** @type {FS}*/
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this.fs = filesystem;
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/** @type {!Map<number,number>} */
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this.backtrack = new Map();
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}
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FSMountInfo.prototype.get_state = function()
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{
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const state = [];
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state[0] = this.fs;
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state[1] = [];
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for(const entry of this.backtrack.entries())
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{
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state[1].push(entry);
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}
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return state;
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};
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FSMountInfo.prototype.set_state = function(state)
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{
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this.fs = new FS(undefined);
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fs.set_state(state[0]);
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this.backtrack = new Map(state[1]);
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};
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/**
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* @private
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* @param {number} idx Local idx of inode.
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* @param {number} mount_id Mount number of the destination fs.
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* @param {number} foreign_id Foreign idx of destination inode.
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*/
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FS.prototype.set_forwarder = function(idx, mount_id, foreign_id)
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{
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const inode = this.inodes[idx];
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if(this.is_forwarder(inode))
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{
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this.mounts[inode.mount_id].backtrack.delete(inode.foreign_id);
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}
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inode.status = STATUS_FORWARDING;
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inode.mount_id = mount_id;
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inode.foreign_id = foreign_id;
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this.mounts[mount_id].backtrack.set(foreign_id, idx);
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};
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/**
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* @private
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* @param {number} mount_id Mount number of the destination fs.
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* @param {number} foreign_id Foreign idx of destination inode.
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* @return {number} Local idx of newly created forwarder.
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*/
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FS.prototype.create_forwarder = function(mount_id, foreign_id)
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{
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dbg_assert(foreign_id !== 0, "Filesystem: root forwarder should not be created.");
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const inode = this.CreateInode();
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const idx = this.inodes.length;
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this.inodes.push(inode);
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inode.fid = idx;
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this.set_forwarder(idx, mount_id, foreign_id);
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return idx;
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};
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/**
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* @private
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* @param {Inode} inode
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* @return {boolean}
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*/
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FS.prototype.is_forwarder = function(inode)
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{
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return inode.status === STATUS_FORWARDING;
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};
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/**
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* Ensures forwarder exists, and returns such forwarder, for the described foreign inode.
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* @private
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* @param {number} mount_id
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* @param {number} foreign_id
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* @return {number} Local idx of a forwarder to described inode.
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*/
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FS.prototype.get_forwarder = function(mount_id, foreign_id)
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{
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const mount = this.mounts[mount_id];
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dbg_assert(foreign_id >= 0, "Filesystem get_forwarder: invalid foreign_id: " + foreign_id);
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dbg_assert(mount, "Filesystem get_forwarder: invalid mount number: " + mount_id);
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const result = mount.backtrack.get(foreign_id);
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if(result === undefined)
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{
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// Create if not already exists.
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return this.create_forwarder(mount_id, foreign_id);
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}
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return result;
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};
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/**
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* @private
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* @param {Inode} inode
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*/
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FS.prototype.delete_forwarder = function(inode)
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{
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dbg_assert(this.is_forwarder(inode), "Filesystem delete_forwarder: expected forwarder");
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inode.status = STATUS_INVALID;
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this.mounts[inode.mount_id].backtrack.delete(inode.foreign_id);
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};
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/**
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* @private
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* @param {Inode} inode
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* @return {FS}
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*/
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FS.prototype.follow_fs = function(inode)
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{
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const mount = this.mounts[inode.mount_id];
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dbg_assert(this.is_forwarder(inode),
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"Filesystem follow_fs: inode should be a forwarding inode");
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dbg_assert(mount, "Filesystem follow_fs: inode<id=" + inode.fid + ", name=" +
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inode.name + "> should point to valid mounted FS");
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return mount.fs;
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};
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/**
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* Mount another filesystem onto an existing directory.
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* @param {string} path Path to existing directrory relative to this filesystem.
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* @param {FS} fs
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*/
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FS.prototype.Mount = function(path, fs)
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{
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const path_infos = this.SearchPath(path);
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if(path_infos.id === -1)
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{
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dbg_log("Mount failed: path not found: " + path, LOG_9P);
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return -1;
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}
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if(path_infos.forward_path)
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{
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const parent = this.inodes[path_infos.parentid];
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this.follow_fs(parent).Mount(path_infos.forward_path, fs);
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return;
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}
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const mount_id = this.mounts.length;
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this.mounts.push(new FSMountInfo(fs));
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// Existing inode is already linked. Just set forwarding information.
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this.set_forwarder(path_infos.id, mount_id, 0);
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return path_infos.id;
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};
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