feat: new truncate method (#43)

README.md

@@ -217,6 +217,23 @@ smb2Client.writeFile('path\\to\\my\\file.txt', 'Hello Node', function(err) {
 });
 ```
 
+> `smb2Client.truncate ( filename, length, callback )`
+
+-   `filename` String
+-   `length` Number
+-   `callback` Function
+
+Asynchronously truncate a file to a size of precisely length bytes.
+
+Example:
+
+```javascript
+smb2Client.truncate('path\\to\\my\\file.txt', 10, function(err) {
+    if (err) throw err;
+    console.log("It's truncated!");
+});
+```
+
 ### Streams
 
 > `smb2Client.createReadStream ( fileName, [options], callback )`

RELEASE.md

 # Releases
 
+## 0.14.0
+- smb2.truncate
+
 ## 0.4.0
 - smb2.ensureDir
 

lib/api/truncate.js

+var SMB2Forge = require('../tools/smb2-forge');
+var SMB2Request = SMB2Forge.request;
+var BigInt = require('../tools/bigint');
+var FILE_WRITE_DATA = require('../structures/constants').FILE_WRITE_DATA;
+
+function setFileSize(file, fileLength, connection, cb) {
+  SMB2Request(
+    'set_info',
+    {
+      FileId: file.FileId,
+      FileInfoClass: 'FileEndOfFileInformation',
+      Buffer: fileLength.toBuffer(),
+    },
+    connection,
+    cb
+  );
+}
+
+module.exports = function truncate(path, length, cb) {
+  var connection = this;
+
+  SMB2Request(
+    'open',
+    { path: path, desiredAccess: FILE_WRITE_DATA },
+    connection,
+    function(err, file) {
+      if (err != null) {
+        return cb(err);
+      }
+
+      setFileSize(file, new BigInt(8, length), connection, function(err) {
+        SMB2Request('close', file, connection, function() {
+          cb(err);
+        });
+      });
+    }
+  );
+};

lib/messages/open.js

@@ -4,7 +4,6 @@ var message = require('../tools/message');
 module.exports = message({
   generate: function(connection, params) {
     var buffer = Buffer.from(params.path, 'ucs2');
-
     return new SMB2Message({
       headers: {
         Command: 'CREATE',
@@ -16,6 +15,7 @@ module.exports = message({
         Buffer: buffer,
         NameOffset: 0x0078,
         CreateContextsOffset: 0x007a + buffer.length,
+        DesiredAccess: params.desiredAccess,
       },
     });
   },

lib/smb2.js

@@ -136,3 +136,6 @@ proto.write = autoPromise(require('./api/write'), function(
   };
 });
 proto.close = autoPromise(require('./api/close'));
+proto.truncate = autoPromise(
+  SMB2Connection.requireConnect(require('./api/truncate'))
+);

lib/structures/constants.js

@@ -13,4 +13,10 @@ module.exports = {
   // Where do they come from?!
   MAX_READ_LENGTH: 0x00010000,
   MAX_WRITE_LENGTH: 0x00010000 - 0x71,
+
+  /**
+   * 2.2.13.1.1 SMB2 File_Pipe_Printer_Access_Mask
+   * https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/77b36d0f-6016-458a-a7a0-0f4a72ae1534
+   */
+  FILE_WRITE_DATA: 0x00000002,
 };