start/end options are supported by writable/readable streams.

lib/api/src/createReadStream.js

@@ -8,12 +8,19 @@ const requestAsync = Bluebird.promisify(request)
 const maxPacketSize = 0x00010000
 
 class SmbReadableStream extends Readable {
-  constructor (connection, file, options) {
+  constructor (connection, file, options = {}) {
     super(options)
+
+    const {
+      start = 0,
+      end,
+      encoding
+    } = options
+
     this.connection = connection
-    this.encoding = options && options.encoding
+    this.encoding = encoding
     this.file = file
-    this.offset = new Bigint(8)
+    this.offset = new Bigint(8, start)
 
     let fileLength = 0
     for (let i = 0; i < file.EndofFile.length; i++) {
@@ -21,6 +28,10 @@ class SmbReadableStream extends Readable {
     }
     this.fileLength = fileLength
     this.wait = false
+
+    if (end >= 0 && end < fileLength) {
+      this.fileLength = end + 1
+    }
   }
 
   async _read (size) {

lib/api/src/createWriteStream.js

@@ -8,12 +8,18 @@ const requestAsync = Bluebird.promisify(request)
 const maxPacketSize = new Bigint(8, 0x00010000 - 0x71)
 
 class SmbWritableStream extends Writable {
-  constructor (connection, file, options) {
+  constructor (connection, file, options = {}) {
     super(options)
+
+    const {
+      encoding = 'utf8',
+      start = 0
+    } = options
+
     this.connection = connection
-    this.encoding = options.encoding || 'utf8'
+    this.encoding = encoding
     this.file = file
-    this.offset = new Bigint(8)
+    this.offset = new Bigint(8, start)
   }
 
   async _write (chunk, encoding, next) {