# commandserver.py - communicate with Mercurial's API over a pipe
#
# Copyright Olivia Mackall <olivia@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import errno
import gc
import os
import random
import signal
import socket
import struct
import traceback
try:
import selectors
selectors.BaseSelector
except ImportError:
from .thirdparty import selectors2 as selectors
from .i18n import _
from .pycompat import getattr
from . import (
encoding,
error,
loggingutil,
pycompat,
repocache,
util,
vfs as vfsmod,
)
from .utils import (
cborutil,
procutil,
)
class channeledoutput:
"""
Write data to out in the following format:
data length (unsigned int),
data
"""
def __init__(self, out, channel):
self.out = out
self.channel = channel
@property
def name(self):
return b'<%c-channel>' % self.channel
def write(self, data):
if not data:
return
# single write() to guarantee the same atomicity as the underlying file
self.out.write(struct.pack(b'>cI', self.channel, len(data)) + data)
self.out.flush()
def __getattr__(self, attr):
if attr in ('isatty', 'fileno', 'tell', 'seek'):
raise AttributeError(attr)
return getattr(self.out, attr)
class channeledmessage:
"""
Write encoded message and metadata to out in the following format:
data length (unsigned int),
encoded message and metadata, as a flat key-value dict.
Each message should have 'type' attribute. Messages of unknown type
should be ignored.
"""
# teach ui that write() can take **opts
structured = True
def __init__(self, out, channel, encodename, encodefn):
self._cout = channeledoutput(out, channel)
self.encoding = encodename
self._encodefn = encodefn
def write(self, data, **opts):
opts = pycompat.byteskwargs(opts)
if data is not None:
opts[b'data'] = data
self._cout.write(self._encodefn(opts))
def __getattr__(self, attr):
return getattr(self._cout, attr)
class channeledinput:
"""
Read data from in_.
Requests for input are written to out in the following format:
channel identifier - 'I' for plain input, 'L' line based (1 byte)
how many bytes to send at most (unsigned int),
The client replies with:
data length (unsigned int), 0 meaning EOF
data
"""
maxchunksize = 4 * 1024
def __init__(self, in_, out, channel):
self.in_ = in_
self.out = out
self.channel = channel
@property
def name(self):
return b'<%c-channel>' % self.channel
def read(self, size=-1):
if size < 0:
# if we need to consume all the clients input, ask for 4k chunks
# so the pipe doesn't fill up risking a deadlock
size = self.maxchunksize
s = self._read(size, self.channel)
buf = s
while s:
s = self._read(size, self.channel)
buf += s
return buf
else:
return self._read(size, self.channel)
def _read(self, size, channel):
if not size:
return b''
assert size > 0
# tell the client we need at most size bytes
self.out.write(struct.pack(b'>cI', channel, size))
self.out.flush()
length = self.in_.read(4)
length = struct.unpack(b'>I', length)[0]
if not length:
return b''
else:
return self.in_.read(length)
def readline(self, size=-1):
if size < 0:
size = self.maxchunksize
s = self._read(size, b'L')
buf = s
# keep asking for more until there's either no more or
# we got a full line
while s and not s.endswith(b'\n'):
s = self._read(size, b'L')
buf += s
return buf
else:
return self._read(size, b'L')
def __iter__(self):
return self
def next(self):
l = self.readline()
if not l:
raise StopIteration
return l
__next__ = next
def __getattr__(self, attr):
if attr in ('isatty', 'fileno', 'tell', 'seek'):
raise AttributeError(attr)
return getattr(self.in_, attr)
_messageencoders = {
b'cbor': lambda v: b''.join(cborutil.streamencode(v)),
}
def _selectmessageencoder(ui):
encnames = ui.configlist(b'cmdserver', b'message-encodings')
for n in encnames:
f = _messageencoders.get(n)
if f:
return n, f
raise error.Abort(
b'no supported message encodings: %s' % b' '.join(encnames)
)
class server:
"""
Listens for commands on fin, runs them and writes the output on a channel
based stream to fout.
"""
def __init__(self, ui, repo, fin, fout, prereposetups=None):
self.cwd = encoding.getcwd()
if repo:
# the ui here is really the repo ui so take its baseui so we don't
# end up with its local configuration
self.ui = repo.baseui
self.repo = repo
self.repoui = repo.ui
else:
self.ui = ui
self.repo = self.repoui = None
self._prereposetups = prereposetups
self.cdebug = channeledoutput(fout, b'd')
self.cerr = channeledoutput(fout, b'e')
self.cout = channeledoutput(fout, b'o')
self.cin = channeledinput(fin, fout, b'I')
self.cresult = channeledoutput(fout, b'r')
if self.ui.config(b'cmdserver', b'log') == b'-':
# switch log stream of server's ui to the 'd' (debug) channel
# (don't touch repo.ui as its lifetime is longer than the server)
self.ui = self.ui.copy()
setuplogging(self.ui, repo=None, fp=self.cdebug)
self.cmsg = None
if ui.config(b'ui', b'message-output') == b'channel':
encname, encfn = _selectmessageencoder(ui)
self.cmsg = channeledmessage(fout, b'm', encname, encfn)
self.client = fin
# If shutdown-on-interrupt is off, the default SIGINT handler is
# removed so that client-server communication wouldn't be interrupted.
# For example, 'runcommand' handler will issue three short read()s.
# If one of the first two read()s were interrupted, the communication
# channel would be left at dirty state and the subsequent request
# wouldn't be parsed. So catching KeyboardInterrupt isn't enough.
self._shutdown_on_interrupt = ui.configbool(
b'cmdserver', b'shutdown-on-interrupt'
)
self._old_inthandler = None
if not self._shutdown_on_interrupt:
self._old_inthandler = signal.signal(signal.SIGINT, signal.SIG_IGN)
def cleanup(self):
"""release and restore resources taken during server session"""
if not self._shutdown_on_interrupt:
signal.signal(signal.SIGINT, self._old_inthandler)
def _read(self, size):
if not size:
return b''
data = self.client.read(size)
# is the other end closed?
if not data:
raise EOFError
return data
def _readstr(self):
"""read a string from the channel
format:
data length (uint32), data
"""
length = struct.unpack(b'>I', self._read(4))[0]
if not length:
return b''
return self._read(length)
def _readlist(self):
"""read a list of NULL separated strings from the channel"""
s = self._readstr()
if s:
return s.split(b'\0')
else:
return []
def _dispatchcommand(self, req):
from . import dispatch # avoid cycle
if self._shutdown_on_interrupt:
# no need to restore SIGINT handler as it is unmodified.
return dispatch.dispatch(req)
try:
signal.signal(signal.SIGINT, self._old_inthandler)
return dispatch.dispatch(req)
except error.SignalInterrupt:
# propagate SIGBREAK, SIGHUP, or SIGTERM.
raise
except KeyboardInterrupt:
# SIGINT may be received out of the try-except block of dispatch(),
# so catch it as last ditch. Another KeyboardInterrupt may be
# raised while handling exceptions here, but there's no way to
# avoid that except for doing everything in C.
pass
finally:
signal.signal(signal.SIGINT, signal.SIG_IGN)
# On KeyboardInterrupt, print error message and exit *after* SIGINT
# handler removed.
req.ui.error(_(b'interrupted!\n'))
return -1
def runcommand(self):
"""reads a list of \0 terminated arguments, executes
and writes the return code to the result channel"""
from . import dispatch # avoid cycle
args = self._readlist()
# copy the uis so changes (e.g. --config or --verbose) don't
# persist between requests
copiedui = self.ui.copy()
uis = [copiedui]
if self.repo:
self.repo.baseui = copiedui
# clone ui without using ui.copy because this is protected
repoui = self.repoui.__class__(self.repoui)
repoui.copy = copiedui.copy # redo copy protection
uis.append(repoui)
self.repo.ui = self.repo.dirstate._ui = repoui
self.repo.invalidateall()
for ui in uis:
ui.resetstate()
# any kind of interaction must use server channels, but chg may
# replace channels by fully functional tty files. so nontty is
# enforced only if cin is a channel.
if not util.safehasattr(self.cin, b'fileno'):
ui.setconfig(b'ui', b'nontty', b'true', b'commandserver')
req = dispatch.request(
args[:],
copiedui,
self.repo,
self.cin,
self.cout,
self.cerr,
self.cmsg,
prereposetups=self._prereposetups,
)
try:
ret = self._dispatchcommand(req) & 255
# If shutdown-on-interrupt is off, it's important to write the
# result code *after* SIGINT handler removed. If the result code
# were lost, the client wouldn't be able to continue processing.
self.cresult.write(struct.pack(b'>i', int(ret)))
finally:
# restore old cwd
if b'--cwd' in args:
os.chdir(self.cwd)
def getencoding(self):
"""writes the current encoding to the result channel"""
self.cresult.write(encoding.encoding)
def serveone(self):
cmd = self.client.readline()[:-1]
if cmd:
handler = self.capabilities.get(cmd)
if handler:
handler(self)
else:
# clients are expected to check what commands are supported by
# looking at the servers capabilities
raise error.Abort(_(b'unknown command %s') % cmd)
return cmd != b''
capabilities = {b'runcommand': runcommand, b'getencoding': getencoding}
def serve(self):
hellomsg = b'capabilities: ' + b' '.join(sorted(self.capabilities))
hellomsg += b'\n'
hellomsg += b'encoding: ' + encoding.encoding
hellomsg += b'\n'
if self.cmsg:
hellomsg += b'message-encoding: %s\n' % self.cmsg.encoding
hellomsg += b'pid: %d' % procutil.getpid()
if util.safehasattr(os, b'getpgid'):
hellomsg += b'\n'
hellomsg += b'pgid: %d' % os.getpgid(0)
# write the hello msg in -one- chunk
self.cout.write(hellomsg)
try:
while self.serveone():
pass
except EOFError:
# we'll get here if the client disconnected while we were reading
# its request
return 1
return 0
def setuplogging(ui, repo=None, fp=None):
"""Set up server logging facility
If cmdserver.log is '-', log messages will be sent to the given fp.
It should be the 'd' channel while a client is connected, and otherwise
is the stderr of the server process.
"""
# developer config: cmdserver.log
logpath = ui.config(b'cmdserver', b'log')
if not logpath:
return
# developer config: cmdserver.track-log
tracked = set(ui.configlist(b'cmdserver', b'track-log'))
if logpath == b'-' and fp:
logger = loggingutil.fileobjectlogger(fp, tracked)
elif logpath == b'-':
logger = loggingutil.fileobjectlogger(ui.ferr, tracked)
else:
logpath = util.abspath(util.expandpath(logpath))
# developer config: cmdserver.max-log-files
maxfiles = ui.configint(b'cmdserver', b'max-log-files')
# developer config: cmdserver.max-log-size
maxsize = ui.configbytes(b'cmdserver', b'max-log-size')
vfs = vfsmod.vfs(os.path.dirname(logpath))
logger = loggingutil.filelogger(
vfs,
os.path.basename(logpath),
tracked,
maxfiles=maxfiles,
maxsize=maxsize,
)
targetuis = {ui}
if repo:
targetuis.add(repo.baseui)
targetuis.add(repo.ui)
for u in targetuis:
u.setlogger(b'cmdserver', logger)
class pipeservice:
def __init__(self, ui, repo, opts):
self.ui = ui
self.repo = repo
def init(self):
pass
def run(self):
ui = self.ui
# redirect stdio to null device so that broken extensions or in-process
# hooks will never cause corruption of channel protocol.
with ui.protectedfinout() as (fin, fout):
sv = server(ui, self.repo, fin, fout)
try:
return sv.serve()
finally:
sv.cleanup()
def _initworkerprocess():
# use a different process group from the master process, in order to:
# 1. make the current process group no longer "orphaned" (because the
# parent of this process is in a different process group while
# remains in a same session)
# according to POSIX 2.2.2.52, orphaned process group will ignore
# terminal-generated stop signals like SIGTSTP (Ctrl+Z), which will
# cause trouble for things like ncurses.
# 2. the client can use kill(-pgid, sig) to simulate terminal-generated
# SIGINT (Ctrl+C) and process-exit-generated SIGHUP. our child
# processes like ssh will be killed properly, without affecting
# unrelated processes.
os.setpgid(0, 0)
# change random state otherwise forked request handlers would have a
# same state inherited from parent.
random.seed()
def _serverequest(ui, repo, conn, createcmdserver, prereposetups):
fin = conn.makefile('rb')
fout = conn.makefile('wb')
sv = None
try:
sv = createcmdserver(repo, conn, fin, fout, prereposetups)
try:
sv.serve()
# handle exceptions that may be raised by command server. most of
# known exceptions are caught by dispatch.
except error.Abort as inst:
ui.error(_(b'abort: %s\n') % inst.message)
except IOError as inst:
if inst.errno != errno.EPIPE:
raise
except KeyboardInterrupt:
pass
finally:
sv.cleanup()
except: # re-raises
# also write traceback to error channel. otherwise client cannot
# see it because it is written to server's stderr by default.
if sv:
cerr = sv.cerr
else:
cerr = channeledoutput(fout, b'e')
cerr.write(encoding.strtolocal(traceback.format_exc()))
raise
finally:
fin.close()
try:
fout.close() # implicit flush() may cause another EPIPE
except IOError as inst:
if inst.errno != errno.EPIPE:
raise
class unixservicehandler:
"""Set of pluggable operations for unix-mode services
Almost all methods except for createcmdserver() are called in the main
process. You can't pass mutable resource back from createcmdserver().
"""
pollinterval = None
def __init__(self, ui):
self.ui = ui
def bindsocket(self, sock, address):
util.bindunixsocket(sock, address)
sock.listen(socket.SOMAXCONN)
self.ui.status(_(b'listening at %s\n') % address)
self.ui.flush() # avoid buffering of status message
def unlinksocket(self, address):
os.unlink(address)
def shouldexit(self):
"""True if server should shut down; checked per pollinterval"""
return False
def newconnection(self):
"""Called when main process notices new connection"""
def createcmdserver(self, repo, conn, fin, fout, prereposetups):
"""Create new command server instance; called in the process that
serves for the current connection"""
return server(self.ui, repo, fin, fout, prereposetups)
class unixforkingservice:
"""
Listens on unix domain socket and forks server per connection
"""
def __init__(self, ui, repo, opts, handler=None):
self.ui = ui
self.repo = repo
self.address = opts[b'address']
if not util.safehasattr(socket, b'AF_UNIX'):
raise error.Abort(_(b'unsupported platform'))
if not self.address:
raise error.Abort(_(b'no socket path specified with --address'))
self._servicehandler = handler or unixservicehandler(ui)
self._sock = None
self._mainipc = None
self._workeripc = None
self._oldsigchldhandler = None
self._workerpids = set() # updated by signal handler; do not iterate
self._socketunlinked = None
# experimental config: cmdserver.max-repo-cache
maxlen = ui.configint(b'cmdserver', b'max-repo-cache')
if maxlen < 0:
raise error.Abort(_(b'negative max-repo-cache size not allowed'))
self._repoloader = repocache.repoloader(ui, maxlen)
# attempt to avoid crash in CoreFoundation when using chg after fix in
# a89381e04c58
if pycompat.isdarwin:
procutil.gui()
def init(self):
self._sock = socket.socket(socket.AF_UNIX)
# IPC channel from many workers to one main process; this is actually
# a uni-directional pipe, but is backed by a DGRAM socket so each
# message can be easily separated.
o = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM)
self._mainipc, self._workeripc = o
self._servicehandler.bindsocket(self._sock, self.address)
if util.safehasattr(procutil, b'unblocksignal'):
procutil.unblocksignal(signal.SIGCHLD)
o = signal.signal(signal.SIGCHLD, self._sigchldhandler)
self._oldsigchldhandler = o
self._socketunlinked = False
self._repoloader.start()
def _unlinksocket(self):
if not self._socketunlinked:
self._servicehandler.unlinksocket(self.address)
self._socketunlinked = True
def _cleanup(self):
signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
self._sock.close()
self._mainipc.close()
self._workeripc.close()
self._unlinksocket()
self._repoloader.stop()
# don't kill child processes as they have active clients, just wait
self._reapworkers(0)
def run(self):
try:
self._mainloop()
finally:
self._cleanup()
def _mainloop(self):
exiting = False
h = self._servicehandler
selector = selectors.DefaultSelector()
selector.register(
self._sock, selectors.EVENT_READ, self._acceptnewconnection
)
selector.register(
self._mainipc, selectors.EVENT_READ, self._handlemainipc
)
while True:
if not exiting and h.shouldexit():
# clients can no longer connect() to the domain socket, so
# we stop queuing new requests.
# for requests that are queued (connect()-ed, but haven't been
# accept()-ed), handle them before exit. otherwise, clients
# waiting for recv() will receive ECONNRESET.
self._unlinksocket()
exiting = True
try:
events = selector.select(timeout=h.pollinterval)
except OSError as inst:
# selectors2 raises ETIMEDOUT if timeout exceeded while
# handling signal interrupt. That's probably wrong, but
# we can easily get around it.
if inst.errno != errno.ETIMEDOUT:
raise
events = []
if not events:
# only exit if we completed all queued requests
if exiting:
break
continue
for key, _mask in events:
key.data(key.fileobj, selector)
selector.close()
def _acceptnewconnection(self, sock, selector):
h = self._servicehandler
try:
conn, _addr = sock.accept()
except socket.error as inst:
if inst.args[0] == errno.EINTR:
return
raise
# Future improvement: On Python 3.7, maybe gc.freeze() can be used
# to prevent COW memory from being touched by GC.
# https://instagram-engineering.com/
# copy-on-write-friendly-python-garbage-collection-ad6ed5233ddf
pid = os.fork()
if pid:
try:
self.ui.log(
b'cmdserver', b'forked worker process (pid=%d)\n', pid
)
self._workerpids.add(pid)
h.newconnection()
finally:
conn.close() # release handle in parent process
else:
try:
selector.close()
sock.close()
self._mainipc.close()
self._runworker(conn)
conn.close()
self._workeripc.close()
os._exit(0)
except: # never return, hence no re-raises
try:
self.ui.traceback(force=True)
finally:
os._exit(255)
def _handlemainipc(self, sock, selector):
"""Process messages sent from a worker"""
try:
path = sock.recv(32768) # large enough to receive path
except socket.error as inst:
if inst.args[0] == errno.EINTR:
return
raise
self._repoloader.load(path)
def _sigchldhandler(self, signal, frame):
self._reapworkers(os.WNOHANG)
def _reapworkers(self, options):
while self._workerpids:
try:
pid, _status = os.waitpid(-1, options)
except OSError as inst:
if inst.errno == errno.EINTR:
continue
if inst.errno != errno.ECHILD:
raise
# no child processes at all (reaped by other waitpid()?)
self._workerpids.clear()
return
if pid == 0:
# no waitable child processes
return
self.ui.log(b'cmdserver', b'worker process exited (pid=%d)\n', pid)
self._workerpids.discard(pid)
def _runworker(self, conn):
signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
_initworkerprocess()
h = self._servicehandler
try:
_serverequest(
self.ui,
self.repo,
conn,
h.createcmdserver,
prereposetups=[self._reposetup],
)
finally:
gc.collect() # trigger __del__ since worker process uses os._exit
def _reposetup(self, ui, repo):
if not repo.local():
return
class unixcmdserverrepo(repo.__class__):
def close(self):
super(unixcmdserverrepo, self).close()
try:
self._cmdserveripc.send(self.root)
except socket.error:
self.ui.log(
b'cmdserver', b'failed to send repo root to master\n'
)
repo.__class__ = unixcmdserverrepo
repo._cmdserveripc = self._workeripc
cachedrepo = self._repoloader.get(repo.root)
if cachedrepo is None:
return
repo.ui.log(b'repocache', b'repo from cache: %s\n', repo.root)
repocache.copycache(cachedrepo, repo)