When the function calls the read function, it returns after receiving only one character

**Describe the bug**
When the function calls the read function, it returns after receiving only one character

**To Reproduce**
Steps to reproduce the behavior:

**Expected behavior**
When the function calls the read function, i can entry a string.

**Screenshots**

**Please complete the following information:**
* OS: Ubuntu18.04
* gdbgui version (`gdbgui -v`): 0.15.0.1
* gdb version (`gdb -v`): 8.1.0.20180409-git
* browser [e.g. chrome, safari]: firefox
* python packages (`pip freeze`):

**Additional context**