Source code for

"""Job control for the xonsh shell."""
import collections
import contextlib
import ctypes
import os
import signal
import subprocess
import sys
import threading
import time
import typing as tp

from xonsh.built_ins import XSH
from xonsh.cli_utils import Annotated, Arg, ArgParserAlias
from import RichCompletion
from xonsh.lazyasd import LazyObject
from import on_main_thread, unthreadable

# Track time stamp of last exit command, so that two consecutive attempts to
# exit can kill all jobs and exit.
_last_exit_time: tp.Optional[float] = None

# Thread-local data for job control. Allows threadable callable aliases
# (ProcProxyThread) to maintain job control information separate from the main
# thread.
# _jobs_thread_local.tasks is a queue used to keep track of the tasks. On
# the main thread, it is set to _tasks_main.
# is a dictionary used to keep track of the jobs.
# On the main thread, it is set to XSH.all_jobs.
_jobs_thread_local = threading.local()

# Task queue for the main thread
# The use_main_jobs context manager uses this variable to access the tasks on
# the main thread.
_tasks_main: tp.Deque[int] = collections.deque()

[docs]@contextlib.contextmanager def use_main_jobs(): """Context manager that replaces a thread's task queue and job dictionary with those of the main thread This allows another thread (e.g. the commands jobs, disown, and bg) to handle the main thread's job control. """ old_tasks = get_tasks() old_jobs = get_jobs() try: _jobs_thread_local.tasks = _tasks_main = XSH.all_jobs yield finally: _jobs_thread_local.tasks = old_tasks = old_jobs
[docs]def get_tasks() -> tp.Deque[int]: try: return _jobs_thread_local.tasks except AttributeError: if on_main_thread(): _jobs_thread_local.tasks = _tasks_main else: _jobs_thread_local.tasks = collections.deque() return _jobs_thread_local.tasks
[docs]def get_jobs() -> tp.Dict[int, tp.Dict]: try: return except AttributeError: if on_main_thread(): = XSH.all_jobs else: = {} return
if ON_DARWIN: def _send_signal(job, signal): # On OS X, os.killpg() may cause PermissionError when there are # any zombie processes in the process group. # See github issue #1012 for details for pid in job["pids"]: if pid is None: # the pid of an aliased proc is None continue try: os.kill(pid, signal) except ProcessLookupError: pass elif ON_WINDOWS: pass elif ON_CYGWIN or ON_MSYS: # Similar to what happened on OSX, more issues on Cygwin # (see Github issue #514). def _send_signal(job, signal): try: os.killpg(job["pgrp"], signal) except Exception: for pid in job["pids"]: try: os.kill(pid, signal) except Exception: pass else: def _send_signal(job, signal): pgrp = job["pgrp"] if pgrp is None: for pid in job["pids"]: try: os.kill(pid, signal) except Exception: pass else: os.killpg(job["pgrp"], signal) if ON_WINDOWS: def _continue(job): job["status"] = "running" def _kill(job): subprocess.check_output( ["taskkill", "/F", "/T", "/PID", str(job["obj"].pid)], stderr=subprocess.STDOUT, ) _hup = _kill # there is no equivalent of SIGHUP on Windows def ignore_sigtstp(): pass def give_terminal_to(pgid): pass def wait_for_active_job(last_task=None, backgrounded=False, return_error=False): """ Wait for the active job to finish, to be killed by SIGINT, or to be suspended by ctrl-z. """ active_task = get_next_task() # Return when there are no foreground active task if active_task is None: return last_task obj = active_task["obj"] _continue(active_task) while obj.returncode is None: try: obj.wait(0.01) except subprocess.TimeoutExpired: pass except KeyboardInterrupt: try: _kill(active_task) except subprocess.CalledProcessError: pass # ignore error if process closed before we got here return wait_for_active_job(last_task=active_task) else: def _continue(job): _send_signal(job, signal.SIGCONT) job["status"] = "running" def _kill(job): _send_signal(job, signal.SIGKILL) def _hup(job): _send_signal(job, signal.SIGHUP)
[docs] def ignore_sigtstp(): signal.signal(signal.SIGTSTP, signal.SIG_IGN)
_shell_pgrp = os.getpgrp() # type:ignore _block_when_giving = LazyObject( lambda: ( signal.SIGTTOU, # type:ignore signal.SIGTTIN, # type:ignore signal.SIGTSTP, # type:ignore signal.SIGCHLD, # type:ignore ), globals(), "_block_when_giving", ) if ON_CYGWIN or ON_MSYS: # on cygwin, signal.pthread_sigmask does not exist in Python, even # though pthread_sigmask is defined in the kernel. thus, we use # ctypes to mimic the calls in the "normal" version below. LIBC.pthread_sigmask.restype = ctypes.c_int LIBC.pthread_sigmask.argtypes = [ ctypes.c_int, ctypes.POINTER(ctypes.c_ulong), ctypes.POINTER(ctypes.c_ulong), ] def _pthread_sigmask(how, signals): mask = 0 for sig in signals: mask |= 1 << sig oldmask = ctypes.c_ulong() mask = ctypes.c_ulong(mask) result = LIBC.pthread_sigmask( how, ctypes.byref(mask), ctypes.byref(oldmask) ) if result: raise OSError(result, "Sigmask error.") return { sig for sig in getattr(signal, "Signals", range(0, 65)) if (oldmask.value >> sig) & 1 } else: _pthread_sigmask = signal.pthread_sigmask # type:ignore # give_terminal_to is a simplified version of: # give_terminal_to from bash 4.3 source, jobs.c, line 4030 # this will give the terminal to the process group pgid
[docs] def give_terminal_to(pgid): if pgid is None: return False oldmask = _pthread_sigmask(signal.SIG_BLOCK, _block_when_giving) try: os.tcsetpgrp(FD_STDERR, pgid) return True except ProcessLookupError: # when the process finished before giving terminal to it, # see issue #2288 return False except OSError as e: if e.errno == 22: # [Errno 22] Invalid argument # there are cases that all the processes of pgid have # finished, then we don't need to do anything here, see # issue #2220 return False elif e.errno == 25: # [Errno 25] Inappropriate ioctl for device # There are also cases where we are not connected to a # real TTY, even though we may be run in interactive # mode. See issue #2267 for an example with emacs return False else: raise finally: _pthread_sigmask(signal.SIG_SETMASK, oldmask)
[docs] def wait_for_active_job(last_task=None, backgrounded=False, return_error=False): """ Wait for the active job to finish, to be killed by SIGINT, or to be suspended by ctrl-z. """ active_task = get_next_task() # Return when there are no foreground active task if active_task is None: return last_task obj = active_task["obj"] backgrounded = False try: _, wcode = os.waitpid(, os.WUNTRACED) except ChildProcessError as e: # No child processes if return_error: return e else: return _safe_wait_for_active_job( last_task=active_task, backgrounded=backgrounded ) if os.WIFSTOPPED(wcode): active_task["status"] = "stopped" backgrounded = True elif os.WIFSIGNALED(wcode): print() # get a newline because ^C will have been printed obj.signal = (os.WTERMSIG(wcode), os.WCOREDUMP(wcode)) obj.returncode = None else: obj.returncode = os.WEXITSTATUS(wcode) obj.signal = None return wait_for_active_job(last_task=active_task, backgrounded=backgrounded)
def _safe_wait_for_active_job(last_task=None, backgrounded=False): """Safely call wait_for_active_job()""" have_error = True while have_error: try: rtn = wait_for_active_job( last_task=last_task, backgrounded=backgrounded, return_error=True ) except ChildProcessError as e: rtn = e have_error = isinstance(rtn, ChildProcessError) return rtn
[docs]def get_next_task(): """Get the next active task and put it on top of the queue""" tasks = get_tasks() _clear_dead_jobs() selected_task = None for tid in tasks: task = get_task(tid) if not task["bg"] and task["status"] == "running": selected_task = tid break if selected_task is None: return tasks.remove(selected_task) tasks.appendleft(selected_task) return get_task(selected_task)
[docs]def get_task(tid): return get_jobs()[tid]
def _clear_dead_jobs(): to_remove = set() tasks = get_tasks() for tid in tasks: obj = get_task(tid)["obj"] if obj is None or obj.poll() is not None: to_remove.add(tid) for job in to_remove: tasks.remove(job) del get_jobs()[job]
[docs]def format_job_string(num: int) -> str: try: job = get_jobs()[num] except KeyError: return "" tasks = get_tasks() pos = "+" if tasks[0] == num else "-" if tasks[1] == num else " " status = job["status"] cmd = " ".join([" ".join(i) if isinstance(i, list) else i for i in job["cmds"]]) pid = job["pids"][-1] bg = " &" if job["bg"] else "" return f"[{num}]{pos} {status}: {cmd}{bg} ({pid})"
[docs]def get_next_job_number(): """Get the lowest available unique job number (for the next job created).""" _clear_dead_jobs() i = 1 while i in get_jobs(): i += 1 return i
[docs]def add_job(info): """Add a new job to the jobs dictionary.""" num = get_next_job_number() info["started"] = time.time() info["status"] = "running" get_tasks().appendleft(num) get_jobs()[num] = info if info["bg"] and XSH.env.get("XONSH_INTERACTIVE"): print_one_job(num)
[docs]def clean_jobs(): """Clean up jobs for exiting shell In non-interactive mode, send SIGHUP to all jobs. In interactive mode, check for suspended or background jobs, print a warning if any exist, and return False. Otherwise, return True. """ jobs_clean = True if XSH.env["XONSH_INTERACTIVE"]: _clear_dead_jobs() if get_jobs(): global _last_exit_time hist = XSH.history if hist is not None and len(hist.tss) > 0: last_cmd_start = hist.tss[-1][0] else: last_cmd_start = None if _last_exit_time and last_cmd_start and _last_exit_time > last_cmd_start: # Exit occurred after last command started, so it was called as # part of the last command and is now being called again # immediately. Kill jobs and exit without reminder about # unfinished jobs in this case. hup_all_jobs() else: if len(get_jobs()) > 1: msg = "there are unfinished jobs" else: msg = "there is an unfinished job" if XSH.env["SHELL_TYPE"] != "prompt_toolkit": # The Ctrl+D binding for prompt_toolkit already inserts a # newline print() print(f"xonsh: {msg}", file=sys.stderr) print("-" * 5, file=sys.stderr) jobs([], stdout=sys.stderr) print("-" * 5, file=sys.stderr) print( 'Type "exit" or press "ctrl-d" again to force quit.', file=sys.stderr, ) jobs_clean = False _last_exit_time = time.time() else: hup_all_jobs() return jobs_clean
[docs]def hup_all_jobs(): """ Send SIGHUP to all child processes (called when exiting xonsh). """ _clear_dead_jobs() for job in get_jobs().values(): _hup(job)
[docs]@use_main_jobs() def jobs(args, stdin=None, stdout=sys.stdout, stderr=None): """ xonsh command: jobs Display a list of all current jobs. """ _clear_dead_jobs() for j in get_tasks(): print_one_job(j, outfile=stdout) return None, None
[docs]def resume_job(args, wording: tp.Literal["fg", "bg"]): """ used by fg and bg to resume a job either in the foreground or in the background. """ _clear_dead_jobs() tasks = get_tasks() if len(tasks) == 0: return "", "There are currently no suspended jobs" if len(args) == 0: tid = tasks[0] # take the last manipulated task by default elif len(args) == 1: try: if args[0] == "+": # take the last manipulated task tid = tasks[0] elif args[0] == "-": # take the second to last manipulated task tid = tasks[1] else: tid = int(args[0]) except (ValueError, IndexError): return "", f"Invalid job: {args[0]}\n" if tid not in get_jobs(): return "", f"Invalid job: {args[0]}\n" else: return "", f"{wording} expects 0 or 1 arguments, not {len(args)}\n" # Put this one on top of the queue tasks.remove(tid) tasks.appendleft(tid) job = get_task(tid) job["bg"] = False job["status"] = "running" if XSH.env.get("XONSH_INTERACTIVE"): print_one_job(tid) pipeline = job["pipeline"] pipeline.resume( job, tee_output=(wording == "fg") ) # do not tee output for background jobs
[docs]@unthreadable def fg(args, stdin=None): """ xonsh command: fg Bring the currently active job to the foreground, or, if a single number is given as an argument, bring that job to the foreground. Additionally, specify "+" for the most recent job and "-" for the second most recent job. """ return resume_job(args, wording="fg")
[docs]@use_main_jobs() def bg(args, stdin=None): """xonsh command: bg Resume execution of the currently active job in the background, or, if a single number is given as an argument, resume that job in the background. """ res = resume_job(args, wording="bg") if res is None: curtask = get_task(get_tasks()[0]) curtask["bg"] = True _continue(curtask) else: return res
[docs]def job_id_completer(xsh, **_): """Return currently running jobs ids""" for job_id in get_jobs(): yield RichCompletion(str(job_id), description=format_job_string(job_id))
[docs]@use_main_jobs() def disown_fn( job_ids: Annotated[ tp.Sequence[int], Arg(type=int, nargs="*", completer=job_id_completer) ], force_auto_continue=False, ): """Remove the specified jobs from the job table; the shell will no longer report their status, and will not complain if you try to exit an interactive shell with them running or stopped. If the jobs are currently stopped and the $AUTO_CONTINUE option is not set ($AUTO_CONTINUE = False), a warning is printed containing information about how to make them continue after they have been disowned. Parameters ---------- job_ids Jobs to act on or none to disown the current job force_auto_continue : -c, --continue Automatically continue stopped jobs when they are disowned, equivalent to setting $AUTO_CONTINUE=True """ tasks = get_tasks() if len(tasks) == 0: return "", "There are no active jobs" messages = [] # if args.job_ids is empty, use the active task for tid in job_ids or [tasks[0]]: try: current_task = get_task(tid) except KeyError: return "", f"'{tid}' is not a valid job ID" auto_cont = XSH.env.get("AUTO_CONTINUE", False) if auto_cont or force_auto_continue: _continue(current_task) elif current_task["status"] == "stopped": messages.append( f"warning: job is suspended, use " f"'kill -CONT -{current_task['pids'][-1]}' " f"to resume\n" ) # Stop tracking this task tasks.remove(tid) del get_jobs()[tid] messages.append(f"Removed job {tid} ({current_task['status']})") if messages: return "".join(messages)
disown = ArgParserAlias(prog="disown", func=disown_fn, has_args=True)