sfwrap

#! /usr/bin/python

import os
import sys
import signal
from subprocess import Popen, PIPE

sf_command = 'sysfuck'
prog_argv = sys.argv[1:]
stdbuf_argv = [ 'stdbuf', '-o0' ]

# Check whether we're specifying the sysfuck command path explicitly.
if len(sys.argv) >= 2 and sys.argv[1][0:2] == '-c':
    if len(sys.argv[1]) == 2: # It's in a separate argument.
        sf_command = sys.argv[2]
        prog_argv = sys.argv[3:]
    else: # It's like '-c/path/to/sysfuck'.
        sf_command = sys.argv[1][2:]
        prog_argv = sys.argv[2:]

# We want the controlling program to be able to communicate with the user, but
# stdin and stdout go to sysfuck. So we open new file descriptors to use
# instead, so the program can read(3, ...) and write(4, ...).

# sysfuck needs file descriptors 3 and 4, and dup2() is the only way that I know
# of to make sure they're available. This also means programs can use fds 3 and
# 4 to talk to the terminal without going through sysfuck; asciisf uses this,
# for example.
os.dup2(0, 3)
os.dup2(1, 4)

prog_process = Popen(stdbuf_argv + prog_argv, stdin=PIPE, stdout=PIPE)

os.dup2(prog_process.stdout.fileno(), 3)
os.dup2(prog_process.stdin.fileno(), 4)
prog_process.stdout.close() # no need to have extra fds open in sysfuck
prog_process.stdin.close()

# Specifying the executable separately means it doesn't get included in the
# sysfuck process' argv, which is what we want.
sf_process = Popen(prog_argv, executable=sf_command)

# If one side of the pipeline exits but these are still open, then when the
# other side tries to do a read it will hang because it's listening on a pipe
# which has both ends open. By closing these, the read will fail immediately.
os.close(3)
os.close(4)

# By default, if the user presses ^C we get a python error message. The
# try/catch suppresses that.
try:
    status = sf_process.wait()

    if prog_process.returncode is None:
        os.kill(prog_process.pid, signal.SIGHUP)

    exit(status)
except KeyboardInterrupt:
    pass