Add some missing Truffle Boundaries

Author: steve-s

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/EmulatedPosixSupport.java

@@ -2023,14 +2023,15 @@ final MMapHandle mmap(long length, int prot, int flags, int fd, long offset,
         // we create a new channel, the file may be closed but the mmap object should still work
         SeekableByteChannel fileChannel;
         try {
-            fileChannel = file.newByteChannel(options);
+            fileChannel = newByteChannel(file, options);
             position(fileChannel, offset);
             return new MMapHandle(fileChannel, offset);
         } catch (IOException e) {
             throw posixException(OSErrorEnum.fromException(e));
         }
     }
 
+    @TruffleBoundary
     private static Set<StandardOpenOption> mmapProtToOptions(int prot) {
         HashSet<StandardOpenOption> options = new HashSet<>();
         if ((prot & PROT_READ) != 0) {
@@ -2045,6 +2046,11 @@ private static Set<StandardOpenOption> mmapProtToOptions(int prot) {
         return options;
     }
 
+    @TruffleBoundary
+    private static SeekableByteChannel newByteChannel(TruffleFile file, Set<StandardOpenOption> options) throws IOException {
+        return file.newByteChannel(options);
+    }
+
     @ExportMessage
     @SuppressWarnings("static-method")
     public byte mmapReadByte(Object mmap, long index,
@@ -2137,14 +2143,19 @@ public void mmapUnmap(Object mmap, @SuppressWarnings("unused") long length) thro
         MMapHandle handle = (MMapHandle) mmap;
         if (handle.channel != null) {
             try {
-                handle.channel.close();
+                closeChannel(handle.channel);
             } catch (IOException e) {
                 throw posixException(OSErrorEnum.fromException(e));
             }
             handle.channel = null;
         }
     }
 
+    @TruffleBoundary
+    private static void closeChannel(Channel ch) throws IOException {
+        ch.close();
+    }
+
     @TruffleBoundary
     private static void position(SeekableByteChannel ch, long offset) throws IOException {
         ch.position(offset);