sys.stdin.read never returns when terminal set to raw mode

[sgorestodd]

Environment data

• PTVSD version: 4.2.9
• OS and version: Kubuntu Linux kernel 5.0
• Python version (& distribution if applicable, e.g. Anaconda): 3.7.3
• Using VS Code or Visual Studio: VS Code

Actual behavior

sys.stdin.read never returns, even if Enter key is pressed. This is only if the terminal is set to raw mode. Otherwise it works normally.

Expected behavior

sys.stdin.read should return characters that have been entered into stdin while in raw mode. This is a popular method of reading single characters without newlines in Linux as can be seen in these stackoverflow posts.

Python read a single character from the user
Reading a single character (getch style) in Python is not working in Unix

Steps to reproduce:

1. Toggle character reading via the short program below.

import sys
import termios
import tty

fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
tty.setraw(fd)
# ch = os.read(fd, 1)           # Works
# ch = sys.stdin.buffer.read(1) # Works
ch = sys.stdin.read(1)          # Never returns!
print(ch)
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)

2. Run the program in the integrated terminal with launch.json settings as below.

  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Python: Current File",
      "type": "python",
      "request": "launch",
      "program": "${file}",
      "console": "integratedTerminal"
    }
  ]
}

[fabioz]

I'll investigate.