mirror of
https://github.com/kovidgoyal/kitty
synced 2026-06-08 14:18:26 +02:00
fd4c7a4ed2
Now the kitten passes its script to /bin/sh and detects the login shell using various strategies based on the value of $USER on the remote machine. The strategies are tried one after another till one succeeds: 1) getent passwd $USER 2) id -P 3) python pwd module 4) parsing /etc/passwd The hope is that these strategies will fail on fewer systems than relying on the login shell being POSIX compliant.
278 lines
8.8 KiB
Python
278 lines
8.8 KiB
Python
#!/usr/bin/env python3
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# vim:fileencoding=utf-8
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# License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
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import os
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import re
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import shlex
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import subprocess
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import sys
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from contextlib import suppress
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from typing import List, NoReturn, Optional, Set, Tuple
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from kitty.utils import SSHConnectionData
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SHELL_SCRIPT = '''\
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#!/bin/sh
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# macOS ships with an ancient version of tic that cannot read from stdin, so we
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# create a temp file for it
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tmp=$(mktemp)
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cat >$tmp << 'TERMEOF'
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TERMINFO
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TERMEOF
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tic_out=$(tic -x -o $HOME/.terminfo $tmp 2>&1)
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rc=$?
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rm $tmp
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if [ "$rc" != "0" ]; then echo "$tic_out"; exit 1; fi
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if [ -z "$USER" ]; then export USER=$(whoami); fi
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export TERMINFO="$HOME/.terminfo"
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login_shell=""
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python=""
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login_shell_is_ok() {
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if [ -z "$login_shell" ] || [ ! -x "$login_shell" ]; then return 1; fi
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case "$login_shell" in
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*sh) return 0;
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esac
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return 1;
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}
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detect_python() {
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python=$(command -v python3)
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if [ -z "$python" ]; then python=$(command -v python2); fi
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if [ -z "$python" ]; then python=python; fi
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}
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using_getent() {
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cmd=$(command -v getent)
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if [ -z "$cmd" ]; then return; fi
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output=$($cmd passwd $USER 2>/dev/null)
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if [ $? = 0 ]; then login_shell=$(echo $output | cut -d: -f7); fi
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}
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using_id() {
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cmd=$(command -v id)
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if [ -z "$cmd" ]; then return; fi
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output=$($cmd -P $USER 2>/dev/null)
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if [ $? = 0 ]; then login_shell=$(echo $output | cut -d: -f7); fi
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}
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using_passwd() {
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cmd=$(command -v grep)
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if [ -z "$cmd" ]; then return; fi
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output=$($cmd "^$USER:" /etc/passwd 2>/dev/null)
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if [ $? = 0 ]; then login_shell=$(echo $output | cut -d: -f7); fi
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}
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using_python() {
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detect_python
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if [ ! -x "$python" ]; then return; fi
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output=$($python -c "import pwd, os; print(pwd.getpwuid(os.geteuid()).pw_shell)")
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if [ $? = 0 ]; then login_shell=$output; fi
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}
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execute_with_python() {
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detect_python
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exec $python -c "import os; os.execl('$login_shell', '-' '$shell_name')"
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}
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die() { echo "$*" 1>&2 ; exit 1; }
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using_getent
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if ! login_shell_is_ok; then using_id; fi
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if ! login_shell_is_ok; then using_python; fi
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if ! login_shell_is_ok; then using_passwd; fi
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if ! login_shell_is_ok; then die "Could not detect login shell"; fi
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# If a command was passed to SSH execute it here
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EXEC_CMD
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# We need to pass the first argument to the executed program with a leading -
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# to make sure the shell executes as a login shell. Note that not all shells
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# support exec -a so we use the below to try to detect such shells
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shell_name=$(basename $login_shell)
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if [ -z "$PIPESTATUS" ]; then
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# the dash shell does not support exec -a and also does not define PIPESTATUS
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execute_with_python
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fi
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exec -a "-$shell_name" $login_shell
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'''
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PYTHON_SCRIPT = '''\
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#!/usr/bin/env python
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from __future__ import print_function
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from tempfile import NamedTemporaryFile
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import subprocess, os, sys, pwd, binascii, json
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# macOS ships with an ancient version of tic that cannot read from stdin, so we
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# create a temp file for it
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with NamedTemporaryFile() as tmp:
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tmp.write(binascii.unhexlify('{terminfo}'))
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p = subprocess.Popen(['tic', '-x', '-o', os.path.expanduser('~/.terminfo'), tmp.name], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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stdout, stderr = p.communicate()
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if p.wait() != 0:
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getattr(sys.stderr, 'buffer', sys.stderr).write(stdout + stderr)
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raise SystemExit('Failed to compile terminfo using tic')
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command_to_execute = json.loads(binascii.unhexlify('{command_to_execute}'))
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try:
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shell_path = pwd.getpwuid(os.geteuid()).pw_shell or '/bin/sh'
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except KeyError:
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shell_path = '/bin/sh'
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shell_name = '-' + os.path.basename(shell_path)
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if command_to_execute:
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os.execlp(shell_path, shell_path, '-c', command_to_execute)
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os.execlp(shell_path, shell_name)
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'''
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def get_ssh_cli() -> Tuple[Set[str], Set[str]]:
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other_ssh_args: List[str] = []
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boolean_ssh_args: List[str] = []
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stderr = subprocess.Popen(['ssh'], stderr=subprocess.PIPE).stderr
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assert stderr is not None
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raw = stderr.read().decode('utf-8')
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for m in re.finditer(r'\[(.+?)\]', raw):
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q = m.group(1)
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if len(q) < 2 or q[0] != '-':
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continue
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if ' ' in q:
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other_ssh_args.append(q[1])
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else:
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boolean_ssh_args.extend(q[1:])
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return set('-' + x for x in boolean_ssh_args), set('-' + x for x in other_ssh_args)
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def get_connection_data(args: List[str]) -> Optional[SSHConnectionData]:
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boolean_ssh_args, other_ssh_args = get_ssh_cli()
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found_ssh = ''
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port: Optional[int] = None
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expecting_port = False
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expecting_option_val = False
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for i, arg in enumerate(args):
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if not found_ssh:
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if os.path.basename(arg).lower() in ('ssh', 'ssh.exe'):
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found_ssh = arg
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continue
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if arg.startswith('-') and not expecting_option_val:
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if arg in boolean_ssh_args:
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continue
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if arg.startswith('-p'):
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if arg[2:].isdigit():
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with suppress(Exception):
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port = int(arg[2:])
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elif arg == '-p':
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expecting_port = True
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expecting_option_val = True
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continue
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if expecting_option_val:
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if expecting_port:
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with suppress(Exception):
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port = int(arg)
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expecting_port = False
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expecting_option_val = False
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continue
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return SSHConnectionData(found_ssh, arg, port)
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def parse_ssh_args(args: List[str]) -> Tuple[List[str], List[str], bool]:
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boolean_ssh_args, other_ssh_args = get_ssh_cli()
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passthrough_args = {'-' + x for x in 'Nnf'}
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ssh_args = []
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server_args: List[str] = []
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expecting_option_val = False
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passthrough = False
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for arg in args:
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if len(server_args) > 1:
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server_args.append(arg)
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continue
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if arg.startswith('-') and not expecting_option_val:
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all_args = arg[1:]
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for i, arg in enumerate(all_args):
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arg = '-' + arg
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if arg in passthrough_args:
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passthrough = True
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if arg in boolean_ssh_args:
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ssh_args.append(arg)
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continue
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if arg in other_ssh_args:
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ssh_args.append(arg)
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rest = all_args[i+1:]
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if rest:
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ssh_args.append(rest)
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else:
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expecting_option_val = True
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break
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raise SystemExit('Unknown option: {}'.format(arg))
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continue
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if expecting_option_val:
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ssh_args.append(arg)
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expecting_option_val = False
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continue
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server_args.append(arg)
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if not server_args:
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raise SystemExit('Must specify server to connect to')
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return ssh_args, server_args, passthrough
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def quote(x: str) -> str:
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# we have to escape unbalanced quotes and other unparsable
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# args as they will break the shell script
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# But we do not want to quote things like * or 'echo hello'
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# See https://github.com/kovidgoyal/kitty/issues/1787
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try:
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shlex.split(x)
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except ValueError:
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x = shlex.quote(x)
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return x
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def get_posix_cmd(terminfo: str, remote_args: List[str]) -> List[str]:
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sh_script = SHELL_SCRIPT.replace('TERMINFO', terminfo, 1)
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command_to_execute = ''
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if remote_args:
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# ssh simply concatenates multiple commands using a space see
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# line 1129 of ssh.c and on the remote side sshd.c runs the
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# concatenated command as shell -c cmd
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args = [c.replace("'", """'"'"'""") for c in remote_args]
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command_to_execute = "exec $login_shell -c '{}'".format(' '.join(args))
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sh_script = sh_script.replace('EXEC_CMD', command_to_execute)
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return [f'/bin/sh -c {shlex.quote(sh_script)}']
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def get_python_cmd(terminfo: str, command_to_execute: List[str]) -> List[str]:
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import json
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script = PYTHON_SCRIPT.format(
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terminfo=terminfo.encode('utf-8').hex(),
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command_to_execute=json.dumps(' '.join(command_to_execute)).encode('utf-8').hex()
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)
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return [f'python -c "{script}"']
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def main(args: List[str]) -> NoReturn:
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args = args[1:]
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use_posix = True
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if args and args[0] == 'use-python':
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args = args[1:]
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use_posix = False
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ssh_args, server_args, passthrough = parse_ssh_args(args)
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cmd = ['ssh'] + ssh_args
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if passthrough:
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cmd += server_args
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else:
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hostname, remote_args = server_args[0], server_args[1:]
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cmd += ['-t', hostname]
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terminfo = subprocess.check_output(['infocmp', '-a']).decode('utf-8')
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f = get_posix_cmd if use_posix else get_python_cmd
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cmd += f(terminfo, remote_args)
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os.execvp('ssh', cmd)
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if __name__ == '__main__':
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main(sys.argv)
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