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
import contextlib
import errno
import os
import posixpath
import stat
from .i18n import _
from . import (
encoding,
error,
policy,
pycompat,
util,
)
if pycompat.TYPE_CHECKING:
from typing import (
Any,
Callable,
Iterator,
Optional,
)
rustdirs = policy.importrust('dirstate', 'Dirs')
parsers = policy.importmod('parsers')
def _lowerclean(s):
# type: (bytes) -> bytes
return encoding.hfsignoreclean(s.lower())
class pathauditor:
"""ensure that a filesystem path contains no banned components.
the following properties of a path are checked:
- ends with a directory separator
- under top-level .hg
- starts at the root of a windows drive
- contains ".."
More check are also done about the file system states:
- traverses a symlink (e.g. a/symlink_here/b)
- inside a nested repository (a callback can be used to approve
some nested repositories, e.g., subrepositories)
The file system checks are only done when 'realfs' is set to True (the
default). They should be disable then we are auditing path for operation on
stored history.
If 'cached' is set to True, audited paths and sub-directories are cached.
Be careful to not keep the cache of unmanaged directories for long because
audited paths may be replaced with symlinks.
"""
def __init__(self, root, callback=None, realfs=True, cached=False):
self.audited = set()
self.auditeddir = set()
self.root = root
self._realfs = realfs
self._cached = cached
self.callback = callback
if os.path.lexists(root) and not util.fscasesensitive(root):
self.normcase = util.normcase
else:
self.normcase = lambda x: x
def __call__(self, path, mode=None):
# type: (bytes, Optional[Any]) -> None
"""Check the relative path.
path may contain a pattern (e.g. foodir/**.txt)"""
path = util.localpath(path)
normpath = self.normcase(path)
if normpath in self.audited:
return
# AIX ignores "/" at end of path, others raise EISDIR.
if util.endswithsep(path):
raise error.InputError(
_(b"path ends in directory separator: %s") % path
)
parts = util.splitpath(path)
if (
os.path.splitdrive(path)[0]
or _lowerclean(parts[0]) in (b'.hg', b'.hg.', b'')
or pycompat.ospardir in parts
):
raise error.InputError(
_(b"path contains illegal component: %s") % path
)
# Windows shortname aliases
for p in parts:
if b"~" in p:
first, last = p.split(b"~", 1)
if last.isdigit() and first.upper() in [b"HG", b"HG8B6C"]:
raise error.InputError(
_(b"path contains illegal component: %s") % path
)
if b'.hg' in _lowerclean(path):
lparts = [_lowerclean(p) for p in parts]
for p in b'.hg', b'.hg.':
if p in lparts[1:]:
pos = lparts.index(p)
base = os.path.join(*parts[:pos])
raise error.InputError(
_(b"path '%s' is inside nested repo %r")
% (path, pycompat.bytestr(base))
)
normparts = util.splitpath(normpath)
assert len(parts) == len(normparts)
parts.pop()
normparts.pop()
# It's important that we check the path parts starting from the root.
# We don't want to add "foo/bar/baz" to auditeddir before checking if
# there's a "foo/.hg" directory. This also means we won't accidentally
# traverse a symlink into some other filesystem (which is potentially
# expensive to access).
for i in range(len(parts)):
prefix = pycompat.ossep.join(parts[: i + 1])
normprefix = pycompat.ossep.join(normparts[: i + 1])
if normprefix in self.auditeddir:
continue
if self._realfs:
self._checkfs(prefix, path)
if self._cached:
self.auditeddir.add(normprefix)
if self._cached:
self.audited.add(normpath)
def _checkfs(self, prefix, path):
# type: (bytes, bytes) -> None
"""raise exception if a file system backed check fails"""
curpath = os.path.join(self.root, prefix)
try:
st = os.lstat(curpath)
except OSError as err:
# EINVAL can be raised as invalid path syntax under win32.
# They must be ignored for patterns can be checked too.
if err.errno not in (errno.ENOENT, errno.ENOTDIR, errno.EINVAL):
raise
else:
if stat.S_ISLNK(st.st_mode):
msg = _(b'path %r traverses symbolic link %r') % (
pycompat.bytestr(path),
pycompat.bytestr(prefix),
)
raise error.Abort(msg)
elif stat.S_ISDIR(st.st_mode) and os.path.isdir(
os.path.join(curpath, b'.hg')
):
if not self.callback or not self.callback(curpath):
msg = _(b"path '%s' is inside nested repo %r")
raise error.Abort(msg % (path, pycompat.bytestr(prefix)))
def check(self, path):
# type: (bytes) -> bool
try:
self(path)
return True
except (OSError, error.Abort):
return False
@contextlib.contextmanager
def cached(self):
if self._cached:
yield
else:
try:
self._cached = True
yield
finally:
self.audited.clear()
self.auditeddir.clear()
self._cached = False
def canonpath(root, cwd, myname, auditor=None):
# type: (bytes, bytes, bytes, Optional[pathauditor]) -> bytes
"""return the canonical path of myname, given cwd and root
>>> def check(root, cwd, myname):
... a = pathauditor(root, realfs=False)
... try:
... return canonpath(root, cwd, myname, a)
... except error.Abort:
... return 'aborted'
>>> def unixonly(root, cwd, myname, expected='aborted'):
... if pycompat.iswindows:
... return expected
... return check(root, cwd, myname)
>>> def winonly(root, cwd, myname, expected='aborted'):
... if not pycompat.iswindows:
... return expected
... return check(root, cwd, myname)
>>> winonly(b'd:\\\\repo', b'c:\\\\dir', b'filename')
'aborted'
>>> winonly(b'c:\\\\repo', b'c:\\\\dir', b'filename')
'aborted'
>>> winonly(b'c:\\\\repo', b'c:\\\\', b'filename')
'aborted'
>>> winonly(b'c:\\\\repo', b'c:\\\\', b'repo\\\\filename',
... b'filename')
'filename'
>>> winonly(b'c:\\\\repo', b'c:\\\\repo', b'filename', b'filename')
'filename'
>>> winonly(b'c:\\\\repo', b'c:\\\\repo\\\\subdir', b'filename',
... b'subdir/filename')
'subdir/filename'
>>> unixonly(b'/repo', b'/dir', b'filename')
'aborted'
>>> unixonly(b'/repo', b'/', b'filename')
'aborted'
>>> unixonly(b'/repo', b'/', b'repo/filename', b'filename')
'filename'
>>> unixonly(b'/repo', b'/repo', b'filename', b'filename')
'filename'
>>> unixonly(b'/repo', b'/repo/subdir', b'filename', b'subdir/filename')
'subdir/filename'
"""
if util.endswithsep(root):
rootsep = root
else:
rootsep = root + pycompat.ossep
name = myname
if not os.path.isabs(name):
name = os.path.join(root, cwd, name)
name = os.path.normpath(name)
if auditor is None:
auditor = pathauditor(root)
if name != rootsep and name.startswith(rootsep):
name = name[len(rootsep) :]
auditor(name)
return util.pconvert(name)
elif name == root:
return b''
else:
# Determine whether `name' is in the hierarchy at or beneath `root',
# by iterating name=dirname(name) until that causes no change (can't
# check name == '/', because that doesn't work on windows). The list
# `rel' holds the reversed list of components making up the relative
# file name we want.
rel = []
while True:
try:
s = util.samefile(name, root)
except OSError:
s = False
if s:
if not rel:
# name was actually the same as root (maybe a symlink)
return b''
rel.reverse()
name = os.path.join(*rel)
auditor(name)
return util.pconvert(name)
dirname, basename = util.split(name)
rel.append(basename)
if dirname == name:
break
name = dirname
# A common mistake is to use -R, but specify a file relative to the repo
# instead of cwd. Detect that case, and provide a hint to the user.
hint = None
try:
if cwd != root:
canonpath(root, root, myname, auditor)
relpath = util.pathto(root, cwd, b'')
if relpath.endswith(pycompat.ossep):
relpath = relpath[:-1]
hint = _(b"consider using '--cwd %s'") % relpath
except error.Abort:
pass
raise error.Abort(
_(b"%s not under root '%s'") % (myname, root), hint=hint
)
def normasprefix(path):
# type: (bytes) -> bytes
"""normalize the specified path as path prefix
Returned value can be used safely for "p.startswith(prefix)",
"p[len(prefix):]", and so on.
For efficiency, this expects "path" argument to be already
normalized by "os.path.normpath", "os.path.realpath", and so on.
See also issue3033 for detail about need of this function.
>>> normasprefix(b'/foo/bar').replace(pycompat.ossep, b'/')
'/foo/bar/'
>>> normasprefix(b'/').replace(pycompat.ossep, b'/')
'/'
"""
d, p = os.path.splitdrive(path)
if len(p) != len(pycompat.ossep):
return path + pycompat.ossep
else:
return path
def finddirs(path):
# type: (bytes) -> Iterator[bytes]
pos = path.rfind(b'/')
while pos != -1:
yield path[:pos]
pos = path.rfind(b'/', 0, pos)
yield b''
class dirs:
'''a multiset of directory names from a set of file paths'''
def __init__(self, map, only_tracked=False):
"""
a dict map indicates a dirstate while a list indicates a manifest
"""
self._dirs = {}
addpath = self.addpath
if isinstance(map, dict) and only_tracked:
for f, s in map.items():
if s.state != b'r':
addpath(f)
elif only_tracked:
msg = b"`only_tracked` is only supported with a dict source"
raise error.ProgrammingError(msg)
else:
for f in map:
addpath(f)
def addpath(self, path):
# type: (bytes) -> None
dirs = self._dirs
for base in finddirs(path):
if base.endswith(b'/'):
raise ValueError(
"found invalid consecutive slashes in path: %r" % base
)
if base in dirs:
dirs[base] += 1
return
dirs[base] = 1
def delpath(self, path):
# type: (bytes) -> None
dirs = self._dirs
for base in finddirs(path):
if dirs[base] > 1:
dirs[base] -= 1
return
del dirs[base]
def __iter__(self):
return iter(self._dirs)
def __contains__(self, d):
# type: (bytes) -> bool
return d in self._dirs
if util.safehasattr(parsers, 'dirs'):
dirs = parsers.dirs
if rustdirs is not None:
dirs = rustdirs
# forward two methods from posixpath that do what we need, but we'd
# rather not let our internals know that we're thinking in posix terms
# - instead we'll let them be oblivious.
join = posixpath.join
dirname = posixpath.dirname # type: Callable[[bytes], bytes]