implementing lchown()

README.md

@@ -372,6 +372,7 @@ const fs = new Filer.FileSystem(options, callback);
 * [fs.utimes(path, atime, mtime, callback)](#utimes)
 * [fs.chown(path, uid, gid, callback)](#chown)
 * [fs.fchown(fd, uid, gid, callback)](#fchown)
+* [fs.lchown(path, uid, gid, callback)](#lchown)
 * [fs.chmod(path, mode, callback)](#chmod)
 * [fs.fchmod(fd, mode, callback)](#fchmod)
 * [fs.futimes(fd, atime, mtime, callback)](#fsutimes)
@@ -923,6 +924,19 @@ fs.open('/myfile.txt', function(err, fd) {
 });
 ```
 
+#### fs.lchown(path, uid, gid, callback)<a name="lchown"></a>
+
+lchown() is like chown(), but does not dereference symbolic links. Asynchronous [lchown(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/chown.html). Callback gets no additional arguments. Both `uid` (user id) and `gid` (group id) arguments should be a JavaScript Number.  By default, `0x0` is used (i.e., `root:root` ownership).
+
+Example:
+
+```javascript
+fs.lchown('/myfile.txt', 500, 500, function(err) {
+  if(err) throw err;
+  // /myfile.txt is now owned by user with id 500, group 500
+});
+```  
+
 #### fs.chmod(path, mode, callback)<a name="chmod"></a>
 
 Changes the mode of a file. Asynchronous [chmod(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/chmod.html). Callback gets no additional arguments. The `mode` argument should be a JavaScript Number, which combines file type and permission information.  Here are a list of common values useful for setting the `mode`:

src/filesystem/implementation.js

@@ -278,6 +278,14 @@ function find_node(context, path, callback) {
   }
 }
 
+/**
+ * find_lnode
+ */
+// in: file or directory path
+// out: node structure, or error
+function find_symbolic_node(context, path, callback) {
+  lstat_file(context, path, callback);
+} 
 
 /**
  * set extended attribute (refactor)
@@ -2060,6 +2068,19 @@ function fchown_file(context, ofd, uid, gid, callback) {
   ofd.getNode(context, update_owner);
 }
 
+function lchown_file(context, path, uid, gid, callback) { 
+  function update_owner(error, node) {
+    if (error) {
+      callback(error);
+    } else {
+      node.uid = uid;
+      node.gid = gid;
+      update_node_times(context, path, node, { mtime: Date.now() }, callback);
+    }
+  }
+  find_symbolic_node(context, path, update_owner);
+} 
+
 function getxattr(context, path, name, callback) {
   getxattr_file(context, path, name, callback);
 }
@@ -2244,6 +2265,17 @@ function fchown(context, fd, uid, gid, callback) {
   }
 }
 
+function lchown(context, path, uid, gid, callback) {
+  if(!isUint32(uid)) {
+    return callback(new Errors.EINVAL('uid must be a valid integer', uid));
+  }
+  if(!isUint32(gid)) {
+    return callback(new Errors.EINVAL('gid must be a valid integer', gid));
+  }
+
+  lchown_file(context, path, uid, gid, callback);
+}
+
 function rename(context, oldpath, newpath, callback) {
   oldpath = normalize(oldpath);
   newpath = normalize(newpath);
@@ -2425,7 +2457,7 @@ module.exports = {
   ftruncate,
   futimes,
   getxattr,
-  // lchown - https://github.com/filerjs/filer/issues/620
+  lchown,
   // lchmod - https://github.com/filerjs/filer/issues/619
   link,
   lseek,

src/filesystem/interface.js

@@ -340,7 +340,7 @@ function FileSystem(options, callback) {
     { name: 'ftruncate' },
     { name: 'futimes' },
     { name: 'getxattr', promises: true, absPathArgs: [0] },
-    // lchown - https://github.com/filerjs/filer/issues/620
+    { name: 'lchown' },
     // lchmod - https://github.com/filerjs/filer/issues/619
     { name: 'link', promises: true, absPathArgs: [0, 1] },
     { name: 'lseek' },

tests/spec/fs.chown.spec.js

@@ -1,7 +1,7 @@
 var util = require('../lib/test-utils.js');
 var expect = require('chai').expect;
 
-describe('fs.chown, fs.fchown', function() {
+describe('fs.chown, fs.fchown, fs.lchown', function() {
   beforeEach(util.setup);
   afterEach(util.cleanup);
 
@@ -27,6 +27,20 @@ describe('fs.chown, fs.fchown', function() {
     });
   });
 
+  it('lchown should expect an interger value for uid', function(done) {
+    var fs = util.fs();
+
+    fs.open('/file', 'w', function(err, fd) {
+      if(err) throw err;
+
+      fs.lchown(fd, '1001', 1001, function(err) {
+        expect(err).to.exist;
+        expect(err.code).to.equal('EINVAL');
+        fs.close(fd, done);
+      });
+    });
+  }); 
+
   it('fchown should expect an interger value for uid', function(done) {
     var fs = util.fs();
 
@@ -55,6 +69,20 @@ describe('fs.chown, fs.fchown', function() {
     });
   });
 
+  it('lchown should expect an interger value for gid', function(done) {
+    var fs = util.fs();
+
+    fs.open('/file', 'w', function(err, fd) {
+      if(err) throw err;
+
+      fs.lchown(fd, 1001, '1001', function(err) {
+        expect(err).to.exist;
+        expect(err.code).to.equal('EINVAL');
+        fs.close(fd, done);
+      });
+    });
+  }); 
+
   it('fchown should expect an interger value for gid', function(done) {
     var fs = util.fs();
 
@@ -107,6 +135,18 @@ describe('fs.chown, fs.fchown', function() {
               fs.stat('/file', function(err, stats) {
                 if(err) throw err;
 
+                expect(stats.uid).to.equal(500);
+                expect(stats.gid).to.equal(500);
+                //done();
+              });
+            });
+
+            fs.lchown('/file', 500, 500, function(err) {
+              if(err) throw err;
+        
+              fs.lstat('/file', function(err, stats) {
+                if(err) throw err;
+        
                 expect(stats.uid).to.equal(500);
                 expect(stats.gid).to.equal(500);
                 done();