filemerge: add support for partial conflict resolution by external tool
A common class of merge conflicts is in imports/#includes/etc. It's
relatively easy to write a tool that can resolve these conflicts,
perhaps by naively just unioning the statements and leaving any
cleanup to other tools to do later [1]. Such specialized tools cannot
generally resolve all conflicts in a file, of course. Let's therefore
call them "partial merge tools". Note that the internal simplemerge
algorithm is such a partial merge tool - one that only resolves
trivial "conflicts" where one side is unchanged or both sides change
in the same way.
One can also imagine having smarter language-aware partial tools that
merge the AST. It may be useful for such tools to interactively let
the user resolve any conflicts it can't resolve itself. However,
having the option of implementing it as a partial merge tool means
that the developer doesn't *need* to create a UI for it. Instead, the
user can resolve any remaining conflicts with their regular merge tool
(e.g. `:merge3` or `meld).
We don't currently have a way to let the user define such partial
merge tools. That's what this patch addresses. It lets the user
configure partial merge tools to run. Each tool can be configured to
run only on files matching certain patterns (e.g. "*.py"). The tool
takes three inputs (local, base, other) and resolves conflicts by
updating these in place. For example, let's say the inputs are these:
base:
```
import sys
def main():
print('Hello')
```
local:
```
import os
import sys
def main():
print('Hi')
```
other:
```
import re
import sys
def main():
print('Howdy')
```
A partial merge tool could now resolve the conflicting imports by
replacing the import statements in *all* files by the following
snippet, while leaving the remainder of the files unchanged.
```
import os
import re
import sys
```
As a result, simplemerge and any regular merge tool that runs after
the partial merge tool(s) will consider the imports to be
non-conflicting and will only present the conflict in `main()` to the
user.
Differential Revision: https://phab.mercurial-scm.org/D12356
# sshpeer.py - ssh repository proxy class for mercurial
#
# Copyright 2005, 2006 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 re
import uuid
from .i18n import _
from .pycompat import getattr
from . import (
error,
pycompat,
util,
wireprototypes,
wireprotov1peer,
wireprotov1server,
)
from .utils import (
procutil,
stringutil,
urlutil,
)
def _serverquote(s):
"""quote a string for the remote shell ... which we assume is sh"""
if not s:
return s
if re.match(b'[a-zA-Z0-9@%_+=:,./-]*$', s):
return s
return b"'%s'" % s.replace(b"'", b"'\\''")
def _forwardoutput(ui, pipe, warn=False):
"""display all data currently available on pipe as remote output.
This is non blocking."""
if pipe and not pipe.closed:
s = procutil.readpipe(pipe)
if s:
display = ui.warn if warn else ui.status
for l in s.splitlines():
display(_(b"remote: "), l, b'\n')
class doublepipe:
"""Operate a side-channel pipe in addition of a main one
The side-channel pipe contains server output to be forwarded to the user
input. The double pipe will behave as the "main" pipe, but will ensure the
content of the "side" pipe is properly processed while we wait for blocking
call on the "main" pipe.
If large amounts of data are read from "main", the forward will cease after
the first bytes start to appear. This simplifies the implementation
without affecting actual output of sshpeer too much as we rarely issue
large read for data not yet emitted by the server.
The main pipe is expected to be a 'bufferedinputpipe' from the util module
that handle all the os specific bits. This class lives in this module
because it focus on behavior specific to the ssh protocol."""
def __init__(self, ui, main, side):
self._ui = ui
self._main = main
self._side = side
def _wait(self):
"""wait until some data are available on main or side
return a pair of boolean (ismainready, issideready)
(This will only wait for data if the setup is supported by `util.poll`)
"""
if (
isinstance(self._main, util.bufferedinputpipe)
and self._main.hasbuffer
):
# Main has data. Assume side is worth poking at.
return True, True
fds = [self._main.fileno(), self._side.fileno()]
try:
act = util.poll(fds)
except NotImplementedError:
# non supported yet case, assume all have data.
act = fds
return (self._main.fileno() in act, self._side.fileno() in act)
def write(self, data):
return self._call(b'write', data)
def read(self, size):
r = self._call(b'read', size)
if size != 0 and not r:
# We've observed a condition that indicates the
# stdout closed unexpectedly. Check stderr one
# more time and snag anything that's there before
# letting anyone know the main part of the pipe
# closed prematurely.
_forwardoutput(self._ui, self._side)
return r
def unbufferedread(self, size):
r = self._call(b'unbufferedread', size)
if size != 0 and not r:
# We've observed a condition that indicates the
# stdout closed unexpectedly. Check stderr one
# more time and snag anything that's there before
# letting anyone know the main part of the pipe
# closed prematurely.
_forwardoutput(self._ui, self._side)
return r
def readline(self):
return self._call(b'readline')
def _call(self, methname, data=None):
"""call <methname> on "main", forward output of "side" while blocking"""
# data can be '' or 0
if (data is not None and not data) or self._main.closed:
_forwardoutput(self._ui, self._side)
return b''
while True:
mainready, sideready = self._wait()
if sideready:
_forwardoutput(self._ui, self._side)
if mainready:
meth = getattr(self._main, methname)
if data is None:
return meth()
else:
return meth(data)
def close(self):
return self._main.close()
@property
def closed(self):
return self._main.closed
def flush(self):
return self._main.flush()
def _cleanuppipes(ui, pipei, pipeo, pipee, warn):
"""Clean up pipes used by an SSH connection."""
didsomething = False
if pipeo and not pipeo.closed:
didsomething = True
pipeo.close()
if pipei and not pipei.closed:
didsomething = True
pipei.close()
if pipee and not pipee.closed:
didsomething = True
# Try to read from the err descriptor until EOF.
try:
for l in pipee:
ui.status(_(b'remote: '), l)
except (IOError, ValueError):
pass
pipee.close()
if didsomething and warn is not None:
# Encourage explicit close of sshpeers. Closing via __del__ is
# not very predictable when exceptions are thrown, which has led
# to deadlocks due to a peer get gc'ed in a fork
# We add our own stack trace, because the stacktrace when called
# from __del__ is useless.
ui.develwarn(b'missing close on SSH connection created at:\n%s' % warn)
def _makeconnection(ui, sshcmd, args, remotecmd, path, sshenv=None):
"""Create an SSH connection to a server.
Returns a tuple of (process, stdin, stdout, stderr) for the
spawned process.
"""
cmd = b'%s %s %s' % (
sshcmd,
args,
procutil.shellquote(
b'%s -R %s serve --stdio'
% (_serverquote(remotecmd), _serverquote(path))
),
)
ui.debug(b'running %s\n' % cmd)
# no buffer allow the use of 'select'
# feel free to remove buffering and select usage when we ultimately
# move to threading.
stdin, stdout, stderr, proc = procutil.popen4(cmd, bufsize=0, env=sshenv)
return proc, stdin, stdout, stderr
def _clientcapabilities():
"""Return list of capabilities of this client.
Returns a list of capabilities that are supported by this client.
"""
protoparams = {b'partial-pull'}
comps = [
e.wireprotosupport().name
for e in util.compengines.supportedwireengines(util.CLIENTROLE)
]
protoparams.add(b'comp=%s' % b','.join(comps))
return protoparams
def _performhandshake(ui, stdin, stdout, stderr):
def badresponse():
# Flush any output on stderr. In general, the stderr contains errors
# from the remote (ssh errors, some hg errors), and status indications
# (like "adding changes"), with no current way to tell them apart.
# Here we failed so early that it's almost certainly only errors, so
# use warn=True so -q doesn't hide them.
_forwardoutput(ui, stderr, warn=True)
msg = _(b'no suitable response from remote hg')
hint = ui.config(b'ui', b'ssherrorhint')
raise error.RepoError(msg, hint=hint)
# The handshake consists of sending wire protocol commands in reverse
# order of protocol implementation and then sniffing for a response
# to one of them.
#
# Those commands (from oldest to newest) are:
#
# ``between``
# Asks for the set of revisions between a pair of revisions. Command
# present in all Mercurial server implementations.
#
# ``hello``
# Instructs the server to advertise its capabilities. Introduced in
# Mercurial 0.9.1.
#
# ``upgrade``
# Requests upgrade from default transport protocol version 1 to
# a newer version. Introduced in Mercurial 4.6 as an experimental
# feature.
#
# The ``between`` command is issued with a request for the null
# range. If the remote is a Mercurial server, this request will
# generate a specific response: ``1\n\n``. This represents the
# wire protocol encoded value for ``\n``. We look for ``1\n\n``
# in the output stream and know this is the response to ``between``
# and we're at the end of our handshake reply.
#
# The response to the ``hello`` command will be a line with the
# length of the value returned by that command followed by that
# value. If the server doesn't support ``hello`` (which should be
# rare), that line will be ``0\n``. Otherwise, the value will contain
# RFC 822 like lines. Of these, the ``capabilities:`` line contains
# the capabilities of the server.
#
# The ``upgrade`` command isn't really a command in the traditional
# sense of version 1 of the transport because it isn't using the
# proper mechanism for formatting insteads: instead, it just encodes
# arguments on the line, delimited by spaces.
#
# The ``upgrade`` line looks like ``upgrade <token> <capabilities>``.
# If the server doesn't support protocol upgrades, it will reply to
# this line with ``0\n``. Otherwise, it emits an
# ``upgraded <token> <protocol>`` line to both stdout and stderr.
# Content immediately following this line describes additional
# protocol and server state.
#
# In addition to the responses to our command requests, the server
# may emit "banner" output on stdout. SSH servers are allowed to
# print messages to stdout on login. Issuing commands on connection
# allows us to flush this banner output from the server by scanning
# for output to our well-known ``between`` command. Of course, if
# the banner contains ``1\n\n``, this will throw off our detection.
requestlog = ui.configbool(b'devel', b'debug.peer-request')
# Generate a random token to help identify responses to version 2
# upgrade request.
token = pycompat.sysbytes(str(uuid.uuid4()))
try:
pairsarg = b'%s-%s' % (b'0' * 40, b'0' * 40)
handshake = [
b'hello\n',
b'between\n',
b'pairs %d\n' % len(pairsarg),
pairsarg,
]
if requestlog:
ui.debug(b'devel-peer-request: hello+between\n')
ui.debug(b'devel-peer-request: pairs: %d bytes\n' % len(pairsarg))
ui.debug(b'sending hello command\n')
ui.debug(b'sending between command\n')
stdin.write(b''.join(handshake))
stdin.flush()
except IOError:
badresponse()
# Assume version 1 of wire protocol by default.
protoname = wireprototypes.SSHV1
reupgraded = re.compile(b'^upgraded %s (.*)$' % stringutil.reescape(token))
lines = [b'', b'dummy']
max_noise = 500
while lines[-1] and max_noise:
try:
l = stdout.readline()
_forwardoutput(ui, stderr, warn=True)
# Look for reply to protocol upgrade request. It has a token
# in it, so there should be no false positives.
m = reupgraded.match(l)
if m:
protoname = m.group(1)
ui.debug(b'protocol upgraded to %s\n' % protoname)
# If an upgrade was handled, the ``hello`` and ``between``
# requests are ignored. The next output belongs to the
# protocol, so stop scanning lines.
break
# Otherwise it could be a banner, ``0\n`` response if server
# doesn't support upgrade.
if lines[-1] == b'1\n' and l == b'\n':
break
if l:
ui.debug(b'remote: ', l)
lines.append(l)
max_noise -= 1
except IOError:
badresponse()
else:
badresponse()
caps = set()
# For version 1, we should see a ``capabilities`` line in response to the
# ``hello`` command.
if protoname == wireprototypes.SSHV1:
for l in reversed(lines):
# Look for response to ``hello`` command. Scan from the back so
# we don't misinterpret banner output as the command reply.
if l.startswith(b'capabilities:'):
caps.update(l[:-1].split(b':')[1].split())
break
# Error if we couldn't find capabilities, this means:
#
# 1. Remote isn't a Mercurial server
# 2. Remote is a <0.9.1 Mercurial server
# 3. Remote is a future Mercurial server that dropped ``hello``
# and other attempted handshake mechanisms.
if not caps:
badresponse()
# Flush any output on stderr before proceeding.
_forwardoutput(ui, stderr, warn=True)
return protoname, caps
class sshv1peer(wireprotov1peer.wirepeer):
def __init__(
self, ui, url, proc, stdin, stdout, stderr, caps, autoreadstderr=True
):
"""Create a peer from an existing SSH connection.
``proc`` is a handle on the underlying SSH process.
``stdin``, ``stdout``, and ``stderr`` are handles on the stdio
pipes for that process.
``caps`` is a set of capabilities supported by the remote.
``autoreadstderr`` denotes whether to automatically read from
stderr and to forward its output.
"""
self._url = url
self.ui = ui
# self._subprocess is unused. Keeping a handle on the process
# holds a reference and prevents it from being garbage collected.
self._subprocess = proc
# And we hook up our "doublepipe" wrapper to allow querying
# stderr any time we perform I/O.
if autoreadstderr:
stdout = doublepipe(ui, util.bufferedinputpipe(stdout), stderr)
stdin = doublepipe(ui, stdin, stderr)
self._pipeo = stdin
self._pipei = stdout
self._pipee = stderr
self._caps = caps
self._autoreadstderr = autoreadstderr
self._initstack = b''.join(util.getstackframes(1))
# Commands that have a "framed" response where the first line of the
# response contains the length of that response.
_FRAMED_COMMANDS = {
b'batch',
}
# Begin of ipeerconnection interface.
def url(self):
return self._url
def local(self):
return None
def peer(self):
return self
def canpush(self):
return True
def close(self):
self._cleanup()
# End of ipeerconnection interface.
# Begin of ipeercommands interface.
def capabilities(self):
return self._caps
# End of ipeercommands interface.
def _readerr(self):
_forwardoutput(self.ui, self._pipee)
def _abort(self, exception):
self._cleanup()
raise exception
def _cleanup(self, warn=None):
_cleanuppipes(self.ui, self._pipei, self._pipeo, self._pipee, warn=warn)
def __del__(self):
self._cleanup(warn=self._initstack)
def _sendrequest(self, cmd, args, framed=False):
if self.ui.debugflag and self.ui.configbool(
b'devel', b'debug.peer-request'
):
dbg = self.ui.debug
line = b'devel-peer-request: %s\n'
dbg(line % cmd)
for key, value in sorted(args.items()):
if not isinstance(value, dict):
dbg(line % b' %s: %d bytes' % (key, len(value)))
else:
for dk, dv in sorted(value.items()):
dbg(line % b' %s-%s: %d' % (key, dk, len(dv)))
self.ui.debug(b"sending %s command\n" % cmd)
self._pipeo.write(b"%s\n" % cmd)
_func, names = wireprotov1server.commands[cmd]
keys = names.split()
wireargs = {}
for k in keys:
if k == b'*':
wireargs[b'*'] = args
break
else:
wireargs[k] = args[k]
del args[k]
for k, v in sorted(wireargs.items()):
self._pipeo.write(b"%s %d\n" % (k, len(v)))
if isinstance(v, dict):
for dk, dv in v.items():
self._pipeo.write(b"%s %d\n" % (dk, len(dv)))
self._pipeo.write(dv)
else:
self._pipeo.write(v)
self._pipeo.flush()
# We know exactly how many bytes are in the response. So return a proxy
# around the raw output stream that allows reading exactly this many
# bytes. Callers then can read() without fear of overrunning the
# response.
if framed:
amount = self._getamount()
return util.cappedreader(self._pipei, amount)
return self._pipei
def _callstream(self, cmd, **args):
args = pycompat.byteskwargs(args)
return self._sendrequest(cmd, args, framed=cmd in self._FRAMED_COMMANDS)
def _callcompressable(self, cmd, **args):
args = pycompat.byteskwargs(args)
return self._sendrequest(cmd, args, framed=cmd in self._FRAMED_COMMANDS)
def _call(self, cmd, **args):
args = pycompat.byteskwargs(args)
return self._sendrequest(cmd, args, framed=True).read()
def _callpush(self, cmd, fp, **args):
# The server responds with an empty frame if the client should
# continue submitting the payload.
r = self._call(cmd, **args)
if r:
return b'', r
# The payload consists of frames with content followed by an empty
# frame.
for d in iter(lambda: fp.read(4096), b''):
self._writeframed(d)
self._writeframed(b"", flush=True)
# In case of success, there is an empty frame and a frame containing
# the integer result (as a string).
# In case of error, there is a non-empty frame containing the error.
r = self._readframed()
if r:
return b'', r
return self._readframed(), b''
def _calltwowaystream(self, cmd, fp, **args):
# The server responds with an empty frame if the client should
# continue submitting the payload.
r = self._call(cmd, **args)
if r:
# XXX needs to be made better
raise error.Abort(_(b'unexpected remote reply: %s') % r)
# The payload consists of frames with content followed by an empty
# frame.
for d in iter(lambda: fp.read(4096), b''):
self._writeframed(d)
self._writeframed(b"", flush=True)
return self._pipei
def _getamount(self):
l = self._pipei.readline()
if l == b'\n':
if self._autoreadstderr:
self._readerr()
msg = _(b'check previous remote output')
self._abort(error.OutOfBandError(hint=msg))
if self._autoreadstderr:
self._readerr()
try:
return int(l)
except ValueError:
self._abort(error.ResponseError(_(b"unexpected response:"), l))
def _readframed(self):
size = self._getamount()
if not size:
return b''
return self._pipei.read(size)
def _writeframed(self, data, flush=False):
self._pipeo.write(b"%d\n" % len(data))
if data:
self._pipeo.write(data)
if flush:
self._pipeo.flush()
if self._autoreadstderr:
self._readerr()
def makepeer(ui, path, proc, stdin, stdout, stderr, autoreadstderr=True):
"""Make a peer instance from existing pipes.
``path`` and ``proc`` are stored on the eventual peer instance and may
not be used for anything meaningful.
``stdin``, ``stdout``, and ``stderr`` are the pipes connected to the
SSH server's stdio handles.
This function is factored out to allow creating peers that don't
actually spawn a new process. It is useful for starting SSH protocol
servers and clients via non-standard means, which can be useful for
testing.
"""
try:
protoname, caps = _performhandshake(ui, stdin, stdout, stderr)
except Exception:
_cleanuppipes(ui, stdout, stdin, stderr, warn=None)
raise
if protoname == wireprototypes.SSHV1:
return sshv1peer(
ui,
path,
proc,
stdin,
stdout,
stderr,
caps,
autoreadstderr=autoreadstderr,
)
else:
_cleanuppipes(ui, stdout, stdin, stderr, warn=None)
raise error.RepoError(
_(b'unknown version of SSH protocol: %s') % protoname
)
def instance(ui, path, create, intents=None, createopts=None):
"""Create an SSH peer.
The returned object conforms to the ``wireprotov1peer.wirepeer`` interface.
"""
u = urlutil.url(path, parsequery=False, parsefragment=False)
if u.scheme != b'ssh' or not u.host or u.path is None:
raise error.RepoError(_(b"couldn't parse location %s") % path)
urlutil.checksafessh(path)
if u.passwd is not None:
raise error.RepoError(_(b'password in URL not supported'))
sshcmd = ui.config(b'ui', b'ssh')
remotecmd = ui.config(b'ui', b'remotecmd')
sshaddenv = dict(ui.configitems(b'sshenv'))
sshenv = procutil.shellenviron(sshaddenv)
remotepath = u.path or b'.'
args = procutil.sshargs(sshcmd, u.host, u.user, u.port)
if create:
# We /could/ do this, but only if the remote init command knows how to
# handle them. We don't yet make any assumptions about that. And without
# querying the remote, there's no way of knowing if the remote even
# supports said requested feature.
if createopts:
raise error.RepoError(
_(
b'cannot create remote SSH repositories '
b'with extra options'
)
)
cmd = b'%s %s %s' % (
sshcmd,
args,
procutil.shellquote(
b'%s init %s'
% (_serverquote(remotecmd), _serverquote(remotepath))
),
)
ui.debug(b'running %s\n' % cmd)
res = ui.system(cmd, blockedtag=b'sshpeer', environ=sshenv)
if res != 0:
raise error.RepoError(_(b'could not create remote repo'))
proc, stdin, stdout, stderr = _makeconnection(
ui, sshcmd, args, remotecmd, remotepath, sshenv
)
peer = makepeer(ui, path, proc, stdin, stdout, stderr)
# Finally, if supported by the server, notify it about our own
# capabilities.
if b'protocaps' in peer.capabilities():
try:
peer._call(
b"protocaps", caps=b' '.join(sorted(_clientcapabilities()))
)
except IOError:
peer._cleanup()
raise error.RepoError(_(b'capability exchange failed'))
return peer