#!/usr/bin/python3
+# This file is part of chiark-utils, a collection of useful programs
+# used on chiark.greenend.org.uk.
+#
+# This file is:
+# Copyright 2018 Citrix Systems Ltd
+#
+# This is free software; you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 3, or (at your option) any later version.
+#
+# This is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+# details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, consult the Free Software Foundation's
+# website at www.fsf.org, or the GNU Project website at www.gnu.org.
+
import sys
import fishdescriptor.fish
+import optparse
+import re
+import subprocess
+import socket
+import os
+
+donor = None
+
+usage = '''fishdescriptor [-p|--pid] <pid> <action>... [-p|--pid <pid> <action>...]
+
+<action>s
+ [<here-fd>=]<there-fd>
+ fish the openfile referenced by descriptor <there-fd> in
+ (the most recent) <pid> and keep a descriptor onto it;
+ and, optionally, give it the number <here-fd> for exec
+ exec <program> [<arg>...]
+ execute a process with each specified <here>
+ as an actual fd
+ sockinfo
+ calls getsockname/getpeername on the most recent
+ <there-fd>
+
+ -p|-pid <pid>
+ now attach to <pid>, detaching from previous pid
+'''
+
+pending = []
+# list of (nominal, there) where nominal might be None
+
+fdmap = { }
+# fdmap[nominal] = (actual, Donor, there)
+
+def implement_pending():
+ try: actuals = donor.fish([pend[1] for pend in pending])
+ except fishdescriptor.fish.Error as e:
+ print('fishdescriptor error: %s' % e, file=sys.stderr)
+ sys.exit(127)
+ assert(len(actuals) == len(pending))
+ for (nominal, there), actual in zip(pending, actuals):
+ overwriting_info = fdmap.get(nominal)
+ if overwriting_info is not None: os.close(overwriting_info[0])
+ fdmap[nominal] = [actual, donor, there]
+
+def implement_sockinfo(nominal):
+ (actual, tdonor, there) = fdmap[nominal]
+ # socket.fromfd requires the AF. But of course we don't know the AF.
+ # There isn't a sane way to get it in Python:
+ # https://utcc.utoronto.ca/~cks/space/blog/python/SocketFromFdMistake
+ # Rejected options:
+ # https://github.com/tiran/socketfromfd
+ # adds a dependency, not portable due to reliance on SO_DOMAIN
+ # call getsockname using ctypes
+ # no sane way to discover how to unpack sa_family_t
+ perl_script = '''
+ use strict;
+ use Socket;
+ use POSIX;
+ my $sa = getsockname STDIN;
+ exit 0 if !defined $sa and $!==ENOTSOCK;
+ my $family = sockaddr_family $sa;
+ print $family, "\n" or die $!;
+ '''
+ famp = subprocess.Popen(
+ stdin = actual,
+ stdout = subprocess.PIPE,
+ args = ['perl','-we',perl_script]
+ )
+ (output, dummy) = famp.communicate()
+ family = int(output)
+
+ sock = socket.fromfd(actual, family, 0)
+
+ print("[%s] %d sockinfo" % (tdonor.pid, there), end='')
+ for f in (lambda: socket.AddressFamily(family).name,
+ lambda: repr(sock.getsockname()),
+ lambda: repr(sock.getpeername())):
+ try: info = f()
+ except Exception as e: info = repr(e)
+ print("\t", info, sep='', end='')
+ print("")
+
+ sock.close()
+
+def permute_fds_for_exec():
+ actual2intended = { info[0]: nominal for nominal, info in fdmap.items() }
+ # invariant at the start of each loop iteration:
+ # for each intended (aka `nominal') we have processed:
+ # relevant open-file is only held in fd intended
+ # (unless `nominal' is None in which case it is closed)
+ # for each intended (aka `nominal') we have NOT processed:
+ # relevant open-file is only held in actual
+ # where actual = fdmap[nominal][0]
+ # and where actual2intended[actual] = nominal
+ # we can rely on processing each intended only once,
+ # since they're hash keys
+ # the post-condition is not really a valid state (fdmap
+ # is nonsense) but we call this function just before exec
+ for intended, (actual, tdonor, there) in fdmap.items():
+ if intended == actual:
+ continue
+ if intended is not None:
+ inway_intended = actual2intended.get(intended)
+ if inway_intended is not None:
+ inway_moved = os.dup(intended)
+ actual2intended[inway_moved] = inway_intended
+ fdmap[inway_intended][0] = inway_moved
+ os.dup2(actual, intended)
+ os.close(actual)
+
+def implement_exec(argl):
+ if donor is not None: donor.detach()
+ sys.stdout.flush()
+ permute_fds_for_exec()
+ os.execvp(argl[0], argl)
+
+def set_donor(pid):
+ global donor
+ if donor is not None: donor.detach()
+ donor = fishdescriptor.fish.Donor(pid, debug=ov.debug)
+
+def ocb_set_donor(option, opt, value, parser):
+ set_donor(value)
+
+ov = optparse.Values()
+
+def process_args():
+ global ov
+
+ m = None
+
+ def arg_matches(regexp):
+ nonlocal m
+ m = re.search(regexp, arg)
+ return m
+
+ op = optparse.OptionParser(usage=usage)
+
+ op.disable_interspersed_args()
+ op.add_option('-p','--pid', type='int', action='callback',
+ callback=ocb_set_donor)
+ op.add_option('-D','--debug', action='store_const',
+ dest='debug', const=sys.stderr)
+ ov.debug = None
+
+ args = sys.argv[1:]
+ last_nominal = None # None or (nominal,) ie None or (None,) or (int,)
+
+ while True:
+ (ov, args) = op.parse_args(args=args, values=ov)
+ if not len(args): break
+
+ arg = args.pop(0)
-pid = int(sys.argv[1])
-fds = [int(x) for x in sys.argv[2:]]
+ if donor is None:
+ set_donor(int(arg))
+ elif arg_matches(r'^(?:(\d+)=)?(\d+)?$'):
+ (nominal, there) = m.groups()
+ nominal = None if nominal is None else int(nominal)
+ there = int(there)
+ pending.append((nominal,there))
+ last_nominal = (nominal,)
+ elif arg == 'exec':
+ if not len(args):
+ op.error("exec needs command to run")
+ implement_pending()
+ implement_exec(args)
+ elif arg == 'sockinfo':
+ if last_nominal is None:
+ op.error('sockinfo needs a prior fd spec')
+ implement_pending()
+ implement_sockinfo(last_nominal[0])
+ else:
+ op.error("unknown argument/option `%s'" % arg)
-d = fishdescriptor.fish.Donor(pid)
-r = d.fish(fds)
-print(repr(r))
+process_args()
~ian / chiark-utils.git / blobdiff