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
# posix.py - Posix utility function implementations for Mercurial
#
# Copyright 2005-2009 Olivia Mackall <olivia@selenic.com> and others
#
# 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 fcntl
import getpass
import grp
import os
import pwd
import re
import select
import stat
import sys
import tempfile
import unicodedata
from .i18n import _
from .pycompat import (
getattr,
open,
)
from . import (
encoding,
error,
policy,
pycompat,
)
osutil = policy.importmod('osutil')
normpath = os.path.normpath
samestat = os.path.samestat
abspath = os.path.abspath # re-exports
try:
oslink = os.link
except AttributeError:
# Some platforms build Python without os.link on systems that are
# vaguely unix-like but don't have hardlink support. For those
# poor souls, just say we tried and that it failed so we fall back
# to copies.
def oslink(src, dst):
raise OSError(
errno.EINVAL, b'hardlinks not supported: %s to %s' % (src, dst)
)
readlink = os.readlink
unlink = os.unlink
rename = os.rename
removedirs = os.removedirs
expandglobs = False
umask = os.umask(0)
os.umask(umask)
posixfile = open
def split(p):
"""Same as posixpath.split, but faster
>>> import posixpath
>>> for f in [b'/absolute/path/to/file',
... b'relative/path/to/file',
... b'file_alone',
... b'path/to/directory/',
... b'/multiple/path//separators',
... b'/file_at_root',
... b'///multiple_leading_separators_at_root',
... b'']:
... assert split(f) == posixpath.split(f), f
"""
ht = p.rsplit(b'/', 1)
if len(ht) == 1:
return b'', p
nh = ht[0].rstrip(b'/')
if nh:
return nh, ht[1]
return ht[0] + b'/', ht[1]
def openhardlinks():
'''return true if it is safe to hold open file handles to hardlinks'''
return True
def nlinks(name):
'''return number of hardlinks for the given file'''
return os.lstat(name).st_nlink
def parsepatchoutput(output_line):
"""parses the output produced by patch and returns the filename"""
pf = output_line[14:]
if pycompat.sysplatform == b'OpenVMS':
if pf[0] == b'`':
pf = pf[1:-1] # Remove the quotes
else:
if pf.startswith(b"'") and pf.endswith(b"'") and b" " in pf:
pf = pf[1:-1] # Remove the quotes
return pf
def sshargs(sshcmd, host, user, port):
'''Build argument list for ssh'''
args = user and (b"%s@%s" % (user, host)) or host
if b'-' in args[:1]:
raise error.Abort(
_(b'illegal ssh hostname or username starting with -: %s') % args
)
args = shellquote(args)
if port:
args = b'-p %s %s' % (shellquote(port), args)
return args
def isexec(f):
"""check whether a file is executable"""
return os.lstat(f).st_mode & 0o100 != 0
def setflags(f, l, x):
st = os.lstat(f)
s = st.st_mode
if l:
if not stat.S_ISLNK(s):
# switch file to link
with open(f, b'rb') as fp:
data = fp.read()
unlink(f)
try:
os.symlink(data, f)
except OSError:
# failed to make a link, rewrite file
with open(f, b"wb") as fp:
fp.write(data)
# no chmod needed at this point
return
if stat.S_ISLNK(s):
# switch link to file
data = os.readlink(f)
unlink(f)
with open(f, b"wb") as fp:
fp.write(data)
s = 0o666 & ~umask # avoid restatting for chmod
sx = s & 0o100
if st.st_nlink > 1 and bool(x) != bool(sx):
# the file is a hardlink, break it
with open(f, b"rb") as fp:
data = fp.read()
unlink(f)
with open(f, b"wb") as fp:
fp.write(data)
if x and not sx:
# Turn on +x for every +r bit when making a file executable
# and obey umask.
os.chmod(f, s | (s & 0o444) >> 2 & ~umask)
elif not x and sx:
# Turn off all +x bits
os.chmod(f, s & 0o666)
def copymode(src, dst, mode=None, enforcewritable=False):
"""Copy the file mode from the file at path src to dst.
If src doesn't exist, we're using mode instead. If mode is None, we're
using umask."""
try:
st_mode = os.lstat(src).st_mode & 0o777
except OSError as inst:
if inst.errno != errno.ENOENT:
raise
st_mode = mode
if st_mode is None:
st_mode = ~umask
st_mode &= 0o666
new_mode = st_mode
if enforcewritable:
new_mode |= stat.S_IWUSR
os.chmod(dst, new_mode)
def checkexec(path):
"""
Check whether the given path is on a filesystem with UNIX-like exec flags
Requires a directory (like /foo/.hg)
"""
# VFAT on some Linux versions can flip mode but it doesn't persist
# a FS remount. Frequently we can detect it if files are created
# with exec bit on.
try:
EXECFLAGS = stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH
basedir = os.path.join(path, b'.hg')
cachedir = os.path.join(basedir, b'wcache')
storedir = os.path.join(basedir, b'store')
if not os.path.exists(cachedir):
try:
# we want to create the 'cache' directory, not the '.hg' one.
# Automatically creating '.hg' directory could silently spawn
# invalid Mercurial repositories. That seems like a bad idea.
os.mkdir(cachedir)
if os.path.exists(storedir):
copymode(storedir, cachedir)
else:
copymode(basedir, cachedir)
except (IOError, OSError):
# we other fallback logic triggers
pass
if os.path.isdir(cachedir):
checkisexec = os.path.join(cachedir, b'checkisexec')
checknoexec = os.path.join(cachedir, b'checknoexec')
try:
m = os.stat(checkisexec).st_mode
except OSError as e:
if e.errno != errno.ENOENT:
raise
# checkisexec does not exist - fall through ...
else:
# checkisexec exists, check if it actually is exec
if m & EXECFLAGS != 0:
# ensure checkisexec exists, check it isn't exec
try:
m = os.stat(checknoexec).st_mode
except OSError as e:
if e.errno != errno.ENOENT:
raise
open(checknoexec, b'w').close() # might fail
m = os.stat(checknoexec).st_mode
if m & EXECFLAGS == 0:
# check-exec is exec and check-no-exec is not exec
return True
# checknoexec exists but is exec - delete it
unlink(checknoexec)
# checkisexec exists but is not exec - delete it
unlink(checkisexec)
# check using one file, leave it as checkisexec
checkdir = cachedir
else:
# check directly in path and don't leave checkisexec behind
checkdir = path
checkisexec = None
fh, fn = pycompat.mkstemp(dir=checkdir, prefix=b'hg-checkexec-')
try:
os.close(fh)
m = os.stat(fn).st_mode
if m & EXECFLAGS == 0:
os.chmod(fn, m & 0o777 | EXECFLAGS)
if os.stat(fn).st_mode & EXECFLAGS != 0:
if checkisexec is not None:
os.rename(fn, checkisexec)
fn = None
return True
finally:
if fn is not None:
unlink(fn)
except (IOError, OSError):
# we don't care, the user probably won't be able to commit anyway
return False
def checklink(path):
"""check whether the given path is on a symlink-capable filesystem"""
# mktemp is not racy because symlink creation will fail if the
# file already exists
while True:
cachedir = os.path.join(path, b'.hg', b'wcache')
checklink = os.path.join(cachedir, b'checklink')
# try fast path, read only
if os.path.islink(checklink):
return True
if os.path.isdir(cachedir):
checkdir = cachedir
else:
checkdir = path
cachedir = None
name = tempfile.mktemp(
dir=pycompat.fsdecode(checkdir), prefix=r'checklink-'
)
name = pycompat.fsencode(name)
try:
fd = None
if cachedir is None:
fd = pycompat.namedtempfile(
dir=checkdir, prefix=b'hg-checklink-'
)
target = os.path.basename(fd.name)
else:
# create a fixed file to link to; doesn't matter if it
# already exists.
target = b'checklink-target'
try:
fullpath = os.path.join(cachedir, target)
open(fullpath, b'w').close()
except IOError as inst:
# pytype: disable=unsupported-operands
if inst[0] == errno.EACCES:
# pytype: enable=unsupported-operands
# If we can't write to cachedir, just pretend
# that the fs is readonly and by association
# that the fs won't support symlinks. This
# seems like the least dangerous way to avoid
# data loss.
return False
raise
try:
os.symlink(target, name)
if cachedir is None:
unlink(name)
else:
try:
os.rename(name, checklink)
except OSError:
unlink(name)
return True
except OSError as inst:
# link creation might race, try again
if inst.errno == errno.EEXIST:
continue
raise
finally:
if fd is not None:
fd.close()
except AttributeError:
return False
except OSError as inst:
# sshfs might report failure while successfully creating the link
if inst.errno == errno.EIO and os.path.exists(name):
unlink(name)
return False
def checkosfilename(path):
"""Check that the base-relative path is a valid filename on this platform.
Returns None if the path is ok, or a UI string describing the problem."""
return None # on posix platforms, every path is ok
def getfsmountpoint(dirpath):
"""Get the filesystem mount point from a directory (best-effort)
Returns None if we are unsure. Raises OSError on ENOENT, EPERM, etc.
"""
return getattr(osutil, 'getfsmountpoint', lambda x: None)(dirpath)
def getfstype(dirpath):
"""Get the filesystem type name from a directory (best-effort)
Returns None if we are unsure. Raises OSError on ENOENT, EPERM, etc.
"""
return getattr(osutil, 'getfstype', lambda x: None)(dirpath)
def get_password():
return encoding.strtolocal(getpass.getpass(''))
def setbinary(fd):
pass
def pconvert(path):
return path
def localpath(path):
return path
def samefile(fpath1, fpath2):
"""Returns whether path1 and path2 refer to the same file. This is only
guaranteed to work for files, not directories."""
return os.path.samefile(fpath1, fpath2)
def samedevice(fpath1, fpath2):
"""Returns whether fpath1 and fpath2 are on the same device. This is only
guaranteed to work for files, not directories."""
st1 = os.lstat(fpath1)
st2 = os.lstat(fpath2)
return st1.st_dev == st2.st_dev
# os.path.normcase is a no-op, which doesn't help us on non-native filesystems
def normcase(path):
return path.lower()
# what normcase does to ASCII strings
normcasespec = encoding.normcasespecs.lower
# fallback normcase function for non-ASCII strings
normcasefallback = normcase
if pycompat.isdarwin:
def normcase(path):
"""
Normalize a filename for OS X-compatible comparison:
- escape-encode invalid characters
- decompose to NFD
- lowercase
- omit ignored characters [200c-200f, 202a-202e, 206a-206f,feff]
>>> normcase(b'UPPER')
'upper'
>>> normcase(b'Caf\\xc3\\xa9')
'cafe\\xcc\\x81'
>>> normcase(b'\\xc3\\x89')
'e\\xcc\\x81'
>>> normcase(b'\\xb8\\xca\\xc3\\xca\\xbe\\xc8.JPG') # issue3918
'%b8%ca%c3\\xca\\xbe%c8.jpg'
"""
try:
return encoding.asciilower(path) # exception for non-ASCII
except UnicodeDecodeError:
return normcasefallback(path)
normcasespec = encoding.normcasespecs.lower
def normcasefallback(path):
try:
u = path.decode('utf-8')
except UnicodeDecodeError:
# OS X percent-encodes any bytes that aren't valid utf-8
s = b''
pos = 0
l = len(path)
while pos < l:
try:
c = encoding.getutf8char(path, pos)
pos += len(c)
except ValueError:
c = b'%%%02X' % ord(path[pos : pos + 1])
pos += 1
s += c
u = s.decode('utf-8')
# Decompose then lowercase (HFS+ technote specifies lower)
enc = unicodedata.normalize('NFD', u).lower().encode('utf-8')
# drop HFS+ ignored characters
return encoding.hfsignoreclean(enc)
if pycompat.sysplatform == b'cygwin':
# workaround for cygwin, in which mount point part of path is
# treated as case sensitive, even though underlying NTFS is case
# insensitive.
# default mount points
cygwinmountpoints = sorted(
[
b"/usr/bin",
b"/usr/lib",
b"/cygdrive",
],
reverse=True,
)
# use upper-ing as normcase as same as NTFS workaround
def normcase(path):
pathlen = len(path)
if (pathlen == 0) or (path[0] != pycompat.ossep):
# treat as relative
return encoding.upper(path)
# to preserve case of mountpoint part
for mp in cygwinmountpoints:
if not path.startswith(mp):
continue
mplen = len(mp)
if mplen == pathlen: # mount point itself
return mp
if path[mplen] == pycompat.ossep:
return mp + encoding.upper(path[mplen:])
return encoding.upper(path)
normcasespec = encoding.normcasespecs.other
normcasefallback = normcase
# Cygwin translates native ACLs to POSIX permissions,
# but these translations are not supported by native
# tools, so the exec bit tends to be set erroneously.
# Therefore, disable executable bit access on Cygwin.
def checkexec(path):
return False
# Similarly, Cygwin's symlink emulation is likely to create
# problems when Mercurial is used from both Cygwin and native
# Windows, with other native tools, or on shared volumes
def checklink(path):
return False
_needsshellquote = None
def shellquote(s):
if pycompat.sysplatform == b'OpenVMS':
return b'"%s"' % s
global _needsshellquote
if _needsshellquote is None:
_needsshellquote = re.compile(br'[^a-zA-Z0-9._/+-]').search
if s and not _needsshellquote(s):
# "s" shouldn't have to be quoted
return s
else:
return b"'%s'" % s.replace(b"'", b"'\\''")
def shellsplit(s):
"""Parse a command string in POSIX shell way (best-effort)"""
return pycompat.shlexsplit(s, posix=True)
def testpid(pid):
'''return False if pid dead, True if running or not sure'''
if pycompat.sysplatform == b'OpenVMS':
return True
try:
os.kill(pid, 0)
return True
except OSError as inst:
return inst.errno != errno.ESRCH
def isowner(st):
"""Return True if the stat object st is from the current user."""
return st.st_uid == os.getuid()
def findexe(command):
"""Find executable for command searching like which does.
If command is a basename then PATH is searched for command.
PATH isn't searched if command is an absolute or relative path.
If command isn't found None is returned."""
if pycompat.sysplatform == b'OpenVMS':
return command
def findexisting(executable):
b'Will return executable if existing file'
if os.path.isfile(executable) and os.access(executable, os.X_OK):
return executable
return None
if pycompat.ossep in command:
return findexisting(command)
if pycompat.sysplatform == b'plan9':
return findexisting(os.path.join(b'/bin', command))
for path in encoding.environ.get(b'PATH', b'').split(pycompat.ospathsep):
executable = findexisting(os.path.join(path, command))
if executable is not None:
return executable
return None
def setsignalhandler():
pass
_wantedkinds = {stat.S_IFREG, stat.S_IFLNK}
def statfiles(files):
"""Stat each file in files. Yield each stat, or None if a file does not
exist or has a type we don't care about."""
lstat = os.lstat
getkind = stat.S_IFMT
for nf in files:
try:
st = lstat(nf)
if getkind(st.st_mode) not in _wantedkinds:
st = None
except OSError as err:
if err.errno not in (errno.ENOENT, errno.ENOTDIR):
raise
st = None
yield st
def getuser():
'''return name of current user'''
return pycompat.fsencode(getpass.getuser())
def username(uid=None):
"""Return the name of the user with the given uid.
If uid is None, return the name of the current user."""
if uid is None:
uid = os.getuid()
try:
return pycompat.fsencode(pwd.getpwuid(uid)[0])
except KeyError:
return b'%d' % uid
def groupname(gid=None):
"""Return the name of the group with the given gid.
If gid is None, return the name of the current group."""
if gid is None:
gid = os.getgid()
try:
return pycompat.fsencode(grp.getgrgid(gid)[0])
except KeyError:
return pycompat.bytestr(gid)
def groupmembers(name):
"""Return the list of members of the group with the given
name, KeyError if the group does not exist.
"""
name = pycompat.fsdecode(name)
return pycompat.rapply(pycompat.fsencode, list(grp.getgrnam(name).gr_mem))
def spawndetached(args):
return os.spawnvp(os.P_NOWAIT | getattr(os, 'P_DETACH', 0), args[0], args)
def gethgcmd():
return sys.argv[:1]
def makedir(path, notindexed):
os.mkdir(path)
def lookupreg(key, name=None, scope=None):
return None
def hidewindow():
"""Hide current shell window.
Used to hide the window opened when starting asynchronous
child process under Windows, unneeded on other systems.
"""
pass
class cachestat:
def __init__(self, path):
self.stat = os.stat(path)
def cacheable(self):
return bool(self.stat.st_ino)
__hash__ = object.__hash__
def __eq__(self, other):
try:
# Only dev, ino, size, mtime and atime are likely to change. Out
# of these, we shouldn't compare atime but should compare the
# rest. However, one of the other fields changing indicates
# something fishy going on, so return False if anything but atime
# changes.
return (
self.stat.st_mode == other.stat.st_mode
and self.stat.st_ino == other.stat.st_ino
and self.stat.st_dev == other.stat.st_dev
and self.stat.st_nlink == other.stat.st_nlink
and self.stat.st_uid == other.stat.st_uid
and self.stat.st_gid == other.stat.st_gid
and self.stat.st_size == other.stat.st_size
and self.stat[stat.ST_MTIME] == other.stat[stat.ST_MTIME]
and self.stat[stat.ST_CTIME] == other.stat[stat.ST_CTIME]
)
except AttributeError:
return False
def __ne__(self, other):
return not self == other
def statislink(st):
'''check whether a stat result is a symlink'''
return st and stat.S_ISLNK(st.st_mode)
def statisexec(st):
'''check whether a stat result is an executable file'''
return st and (st.st_mode & 0o100 != 0)
def poll(fds):
"""block until something happens on any file descriptor
This is a generic helper that will check for any activity
(read, write. exception) and return the list of touched files.
In unsupported cases, it will raise a NotImplementedError"""
try:
while True:
try:
res = select.select(fds, fds, fds)
break
except select.error as inst:
if inst.args[0] == errno.EINTR:
continue
raise
except ValueError: # out of range file descriptor
raise NotImplementedError()
return sorted(list(set(sum(res, []))))
def readpipe(pipe):
"""Read all available data from a pipe."""
# We can't fstat() a pipe because Linux will always report 0.
# So, we set the pipe to non-blocking mode and read everything
# that's available.
flags = fcntl.fcntl(pipe, fcntl.F_GETFL)
flags |= os.O_NONBLOCK
oldflags = fcntl.fcntl(pipe, fcntl.F_SETFL, flags)
try:
chunks = []
while True:
try:
s = pipe.read()
if not s:
break
chunks.append(s)
except IOError:
break
return b''.join(chunks)
finally:
fcntl.fcntl(pipe, fcntl.F_SETFL, oldflags)
def bindunixsocket(sock, path):
"""Bind the UNIX domain socket to the specified path"""
# use relative path instead of full path at bind() if possible, since
# AF_UNIX path has very small length limit (107 chars) on common
# platforms (see sys/un.h)
dirname, basename = os.path.split(path)
bakwdfd = None
try:
if dirname:
bakwdfd = os.open(b'.', os.O_DIRECTORY)
os.chdir(dirname)
sock.bind(basename)
if bakwdfd:
os.fchdir(bakwdfd)
finally:
if bakwdfd:
os.close(bakwdfd)