showchars.py

#!/usr/bin/env python
"""Author: Manlio Perillo
"""

from sys import stdin
from codecs import getincrementaldecoder
from termios import (
    tcgetattr, tcsetattr, TCSAFLUSH,
    BRKINT, ICRNL, INPCK, ISTRIP, IXON,
    OPOST,
    ECHO, ICANON, IEXTEN, ISIG,
    CSIZE, PARENB, CS8,
    VMIN, VTIME)

iflag, oflag, cflag, lflag, ispeed, ospeed, cc = range(7)


def setraw():
    """Set terminal to raw mode.

    Code adapted from
        Advanced Programming in the UNIX Environment
        W. Richard Stevens
        Stephen A. Rago
    """

    def restore():
        tcsetattr(fd, TCSAFLUSH, old)

    fd = stdin.fileno()
    old = tcgetattr(fd)
    new = tcgetattr(fd)

    # Echo off, canonical mode off, extended input processing off,
    # signal chars off
    new[lflag] &= ~(ECHO | ICANON | IEXTEN | ISIG)

    # No SIGINT on BREAK, CR-to-NL off, input parity check off, don't
    # strip 8th bit on input, output control flow off
    #new[iflag] &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON)
    # NOTE: output control flow off disable SIGSTOP/SIGCONT
    new[iflag] &= ~(BRKINT | IXON)

    # Clear size bits, parity checking off
    #new[cflag] &= ~(CSIZE | PARENB)

    # Set 8 bits/char
    #new[cflag] |= CS8

    # Output processing off
    #new[oflag] &= ~(OPOST)

    # 1 byte at a time, with 3 seconds timeout
    new[cc][VMIN] = 0
    new[cc][VTIME] = 30

    tcsetattr(fd, TCSAFLUSH, new)

    return restore


def showchars():
    fd = stdin.fileno()
    # BUG: assume UTF-8 only
    codec = getincrementaldecoder("UTF-8")("strict")

    while True:
        # ALT: use select
        byte = stdin.read(1)
        if byte:
            # Assemble Unicode character
            ch = codec.decode(byte)
            if ch:
                print "%s %X" % (ch, ord(ch))
            else:
                print "%X " % ord(byte),
        else:
            # Timeout
            break


def main():
    # BUG: do not call restore when a signal is received
    # BUG: bell is not disabled
    restore = setraw()

    try:
        showchars()
    finally:
        restore()


if __name__ == "__main__":
    main()