hgext/convert/git.py

git: skeleton of a new extension to _directly_ operate on git repos

This is based in part of work I did years ago in hgit, but it's mostly
new code since I'm using pygit2 instead of dulwich and the hg storage
interfaces have improved. Some cleanup of old hgit code by Pulkit,
which I greatly appreciate.

test-git-interop.t does not cover a whole lot of cases, but it
passes. It includes status, diff, making a new commit, and `hg annotate`
working on the git repository.

This is _not_ (yet) production quality code: this is an
experiment. Known technical debt lurking in this implementation:

 * Writing bookmarks just totally ignores transactions.
 * The way progress is threaded down into the gitstore is awful.
 * Ideally we'd find a way to incrementally reindex DAGs. I'm not sure
   how to do that efficiently, so we might need a "known only fast-forwards"
   mode on the DAG indexer for use on `hg commit` and friends.
 * We don't even _try_ to do anything reasonable for `hg pull` or `hg push`.
 * Mercurial need an interface for the changelog type.

Tests currently require git 2.24 as far as I'm aware: `git status` has
some changed output that I didn't try and handle in a compatible way.

This patch has produced some interesting cleanups, most recently on
the manifest type. I expect continuing down this road will produce
other meritorious cleanups throughout our code.

Differential Revision: https://phab.mercurial-scm.org/D6734

# git.py - git support for the convert extension
#
#  Copyright 2005-2009 Matt Mackall <[e-mail]> 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.
from __future__ import absolute_import

import os

from mercurial.i18n import _
from mercurial import (
    config,
    error,
    node as nodemod,
    pycompat,
)

from . import common


class submodule(object):
    def __init__(self, path, node, url):
        self.path = path
        self.node = node
        self.url = url

    def hgsub(self):
        return b"%s = [git]%s" % (self.path, self.url)

    def hgsubstate(self):
        return b"%s %s" % (self.node, self.path)


# Keys in extra fields that should not be copied if the user requests.
bannedextrakeys = {
    # Git commit object built-ins.
    b'tree',
    b'parent',
    b'author',
    b'committer',
    # Mercurial built-ins.
    b'branch',
    b'close',
}


class convert_git(common.converter_source, common.commandline):
    # Windows does not support GIT_DIR= construct while other systems
    # cannot remove environment variable. Just assume none have
    # both issues.

    def _gitcmd(self, cmd, *args, **kwargs):
        return cmd(b'--git-dir=%s' % self.path, *args, **kwargs)

    def gitrun0(self, *args, **kwargs):
        return self._gitcmd(self.run0, *args, **kwargs)

    def gitrun(self, *args, **kwargs):
        return self._gitcmd(self.run, *args, **kwargs)

    def gitrunlines0(self, *args, **kwargs):
        return self._gitcmd(self.runlines0, *args, **kwargs)

    def gitrunlines(self, *args, **kwargs):
        return self._gitcmd(self.runlines, *args, **kwargs)

    def gitpipe(self, *args, **kwargs):
        return self._gitcmd(self._run3, *args, **kwargs)

    def __init__(self, ui, repotype, path, revs=None):
        super(convert_git, self).__init__(ui, repotype, path, revs=revs)
        common.commandline.__init__(self, ui, b'git')

        # Pass an absolute path to git to prevent from ever being interpreted
        # as a URL
        path = os.path.abspath(path)

        if os.path.isdir(path + b"/.git"):
            path += b"/.git"
        if not os.path.exists(path + b"/objects"):
            raise common.NoRepo(
                _(b"%s does not look like a Git repository") % path
            )

        # The default value (50) is based on the default for 'git diff'.
        similarity = ui.configint(b'convert', b'git.similarity')
        if similarity < 0 or similarity > 100:
            raise error.Abort(_(b'similarity must be between 0 and 100'))
        if similarity > 0:
            self.simopt = [b'-C%d%%' % similarity]
            findcopiesharder = ui.configbool(
                b'convert', b'git.findcopiesharder'
            )
            if findcopiesharder:
                self.simopt.append(b'--find-copies-harder')

            renamelimit = ui.configint(b'convert', b'git.renamelimit')
            self.simopt.append(b'-l%d' % renamelimit)
        else:
            self.simopt = []

        common.checktool(b'git', b'git')

        self.path = path
        self.submodules = []

        self.catfilepipe = self.gitpipe(b'cat-file', b'--batch')

        self.copyextrakeys = self.ui.configlist(b'convert', b'git.extrakeys')
        banned = set(self.copyextrakeys) & bannedextrakeys
        if banned:
            raise error.Abort(
                _(b'copying of extra key is forbidden: %s')
                % _(b', ').join(sorted(banned))
            )

        committeractions = self.ui.configlist(
            b'convert', b'git.committeractions'
        )

        messagedifferent = None
        messagealways = None
        for a in committeractions:
            if a.startswith((b'messagedifferent', b'messagealways')):
                k = a
                v = None
                if b'=' in a:
                    k, v = a.split(b'=', 1)

                if k == b'messagedifferent':
                    messagedifferent = v or b'committer:'
                elif k == b'messagealways':
                    messagealways = v or b'committer:'

        if messagedifferent and messagealways:
            raise error.Abort(
                _(
                    b'committeractions cannot define both '
                    b'messagedifferent and messagealways'
                )
            )

        dropcommitter = b'dropcommitter' in committeractions
        replaceauthor = b'replaceauthor' in committeractions

        if dropcommitter and replaceauthor:
            raise error.Abort(
                _(
                    b'committeractions cannot define both '
                    b'dropcommitter and replaceauthor'
                )
            )

        if dropcommitter and messagealways:
            raise error.Abort(
                _(
                    b'committeractions cannot define both '
                    b'dropcommitter and messagealways'
                )
            )

        if not messagedifferent and not messagealways:
            messagedifferent = b'committer:'

        self.committeractions = {
            b'dropcommitter': dropcommitter,
            b'replaceauthor': replaceauthor,
            b'messagedifferent': messagedifferent,
            b'messagealways': messagealways,
        }

    def after(self):
        for f in self.catfilepipe:
            f.close()

    def getheads(self):
        if not self.revs:
            output, status = self.gitrun(
                b'rev-parse', b'--branches', b'--remotes'
            )
            heads = output.splitlines()
            if status:
                raise error.Abort(_(b'cannot retrieve git heads'))
        else:
            heads = []
            for rev in self.revs:
                rawhead, ret = self.gitrun(b'rev-parse', b'--verify', rev)
                heads.append(rawhead[:-1])
                if ret:
                    raise error.Abort(_(b'cannot retrieve git head "%s"') % rev)
        return heads

    def catfile(self, rev, ftype):
        if rev == nodemod.nullhex:
            raise IOError
        self.catfilepipe[0].write(rev + b'\n')
        self.catfilepipe[0].flush()
        info = self.catfilepipe[1].readline().split()
        if info[1] != ftype:
            raise error.Abort(
                _(b'cannot read %r object at %s')
                % (pycompat.bytestr(ftype), rev)
            )
        size = int(info[2])
        data = self.catfilepipe[1].read(size)
        if len(data) < size:
            raise error.Abort(
                _(b'cannot read %r object at %s: unexpected size')
                % (ftype, rev)
            )
        # read the trailing newline
        self.catfilepipe[1].read(1)
        return data

    def getfile(self, name, rev):
        if rev == nodemod.nullhex:
            return None, None
        if name == b'.hgsub':
            data = b'\n'.join([m.hgsub() for m in self.submoditer()])
            mode = b''
        elif name == b'.hgsubstate':
            data = b'\n'.join([m.hgsubstate() for m in self.submoditer()])
            mode = b''
        else:
            data = self.catfile(rev, b"blob")
            mode = self.modecache[(name, rev)]
        return data, mode

    def submoditer(self):
        null = nodemod.nullhex
        for m in sorted(self.submodules, key=lambda p: p.path):
            if m.node != null:
                yield m

    def parsegitmodules(self, content):
        """Parse the formatted .gitmodules file, example file format:
        [submodule "sub"]\n
        \tpath = sub\n
        \turl = git://giturl\n
        """
        self.submodules = []
        c = config.config()
        # Each item in .gitmodules starts with whitespace that cant be parsed
        c.parse(
            b'.gitmodules',
            b'\n'.join(line.strip() for line in content.split(b'\n')),
        )
        for sec in c.sections():
            s = c[sec]
            if b'url' in s and b'path' in s:
                self.submodules.append(submodule(s[b'path'], b'', s[b'url']))

    def retrievegitmodules(self, version):
        modules, ret = self.gitrun(
            b'show', b'%s:%s' % (version, b'.gitmodules')
        )
        if ret:
            # This can happen if a file is in the repo that has permissions
            # 160000, but there is no .gitmodules file.
            self.ui.warn(
                _(b"warning: cannot read submodules config file in %s\n")
                % version
            )
            return

        try:
            self.parsegitmodules(modules)
        except error.ParseError:
            self.ui.warn(
                _(b"warning: unable to parse .gitmodules in %s\n") % version
            )
            return

        for m in self.submodules:
            node, ret = self.gitrun(b'rev-parse', b'%s:%s' % (version, m.path))
            if ret:
                continue
            m.node = node.strip()

    def getchanges(self, version, full):
        if full:
            raise error.Abort(_(b"convert from git does not support --full"))
        self.modecache = {}
        cmd = (
            [b'diff-tree', b'-z', b'--root', b'-m', b'-r']
            + self.simopt
            + [version]
        )
        output, status = self.gitrun(*cmd)
        if status:
            raise error.Abort(_(b'cannot read changes in %s') % version)
        changes = []
        copies = {}
        seen = set()
        entry = None
        subexists = [False]
        subdeleted = [False]
        difftree = output.split(b'\x00')
        lcount = len(difftree)
        i = 0

        skipsubmodules = self.ui.configbool(b'convert', b'git.skipsubmodules')

        def add(entry, f, isdest):
            seen.add(f)
            h = entry[3]
            p = entry[1] == b"100755"
            s = entry[1] == b"120000"
            renamesource = not isdest and entry[4][0] == b'R'

            if f == b'.gitmodules':
                if skipsubmodules:
                    return

                subexists[0] = True
                if entry[4] == b'D' or renamesource:
                    subdeleted[0] = True
                    changes.append((b'.hgsub', nodemod.nullhex))
                else:
                    changes.append((b'.hgsub', b''))
            elif entry[1] == b'160000' or entry[0] == b':160000':
                if not skipsubmodules:
                    subexists[0] = True
            else:
                if renamesource:
                    h = nodemod.nullhex
                self.modecache[(f, h)] = (p and b"x") or (s and b"l") or b""
                changes.append((f, h))

        while i < lcount:
            l = difftree[i]
            i += 1
            if not entry:
                if not l.startswith(b':'):
                    continue
                entry = tuple(pycompat.bytestr(p) for p in l.split())
                continue
            f = l
            if entry[4][0] == b'C':
                copysrc = f
                copydest = difftree[i]
                i += 1
                f = copydest
                copies[copydest] = copysrc
            if f not in seen:
                add(entry, f, False)
            # A file can be copied multiple times, or modified and copied
            # simultaneously. So f can be repeated even if fdest isn't.
            if entry[4][0] == b'R':
                # rename: next line is the destination
                fdest = difftree[i]
                i += 1
                if fdest not in seen:
                    add(entry, fdest, True)
                    # .gitmodules isn't imported at all, so it being copied to
                    # and fro doesn't really make sense
                    if f != b'.gitmodules' and fdest != b'.gitmodules':
                        copies[fdest] = f
            entry = None

        if subexists[0]:
            if subdeleted[0]:
                changes.append((b'.hgsubstate', nodemod.nullhex))
            else:
                self.retrievegitmodules(version)
                changes.append((b'.hgsubstate', b''))
        return (changes, copies, set())

    def getcommit(self, version):
        c = self.catfile(version, b"commit")  # read the commit hash
        end = c.find(b"\n\n")
        message = c[end + 2 :]
        message = self.recode(message)
        l = c[:end].splitlines()
        parents = []
        author = committer = None
        extra = {}
        for e in l[1:]:
            n, v = e.split(b" ", 1)
            if n == b"author":
                p = v.split()
                tm, tz = p[-2:]
                author = b" ".join(p[:-2])
                if author[0] == b"<":
                    author = author[1:-1]
                author = self.recode(author)
            if n == b"committer":
                p = v.split()
                tm, tz = p[-2:]
                committer = b" ".join(p[:-2])
                if committer[0] == b"<":
                    committer = committer[1:-1]
                committer = self.recode(committer)
            if n == b"parent":
                parents.append(v)
            if n in self.copyextrakeys:
                extra[n] = v

        if self.committeractions[b'dropcommitter']:
            committer = None
        elif self.committeractions[b'replaceauthor']:
            author = committer

        if committer:
            messagealways = self.committeractions[b'messagealways']
            messagedifferent = self.committeractions[b'messagedifferent']
            if messagealways:
                message += b'\n%s %s\n' % (messagealways, committer)
            elif messagedifferent and author != committer:
                message += b'\n%s %s\n' % (messagedifferent, committer)

        tzs, tzh, tzm = tz[-5:-4] + b"1", tz[-4:-2], tz[-2:]
        tz = -int(tzs) * (int(tzh) * 3600 + int(tzm))
        date = tm + b" " + (b"%d" % tz)
        saverev = self.ui.configbool(b'convert', b'git.saverev')

        c = common.commit(
            parents=parents,
            date=date,
            author=author,
            desc=message,
            rev=version,
            extra=extra,
            saverev=saverev,
        )
        return c

    def numcommits(self):
        output, ret = self.gitrunlines(b'rev-list', b'--all')
        if ret:
            raise error.Abort(
                _(b'cannot retrieve number of commits in %s') % self.path
            )
        return len(output)

    def gettags(self):
        tags = {}
        alltags = {}
        output, status = self.gitrunlines(b'ls-remote', b'--tags', self.path)

        if status:
            raise error.Abort(_(b'cannot read tags from %s') % self.path)
        prefix = b'refs/tags/'

        # Build complete list of tags, both annotated and bare ones
        for line in output:
            line = line.strip()
            if line.startswith(b"error:") or line.startswith(b"fatal:"):
                raise error.Abort(_(b'cannot read tags from %s') % self.path)
            node, tag = line.split(None, 1)
            if not tag.startswith(prefix):
                continue
            alltags[tag[len(prefix) :]] = node

        # Filter out tag objects for annotated tag refs
        for tag in alltags:
            if tag.endswith(b'^{}'):
                tags[tag[:-3]] = alltags[tag]
            else:
                if tag + b'^{}' in alltags:
                    continue
                else:
                    tags[tag] = alltags[tag]

        return tags

    def getchangedfiles(self, version, i):
        changes = []
        if i is None:
            output, status = self.gitrunlines(
                b'diff-tree', b'--root', b'-m', b'-r', version
            )
            if status:
                raise error.Abort(_(b'cannot read changes in %s') % version)
            for l in output:
                if b"\t" not in l:
                    continue
                m, f = l[:-1].split(b"\t")
                changes.append(f)
        else:
            output, status = self.gitrunlines(
                b'diff-tree',
                b'--name-only',
                b'--root',
                b'-r',
                version,
                b'%s^%d' % (version, i + 1),
                b'--',
            )
            if status:
                raise error.Abort(_(b'cannot read changes in %s') % version)
            changes = [f.rstrip(b'\n') for f in output]

        return changes

    def getbookmarks(self):
        bookmarks = {}

        # Handle local and remote branches
        remoteprefix = self.ui.config(b'convert', b'git.remoteprefix')
        reftypes = [
            # (git prefix, hg prefix)
            (b'refs/remotes/origin/', remoteprefix + b'/'),
            (b'refs/heads/', b''),
        ]

        exclude = {
            b'refs/remotes/origin/HEAD',
        }

        try:
            output, status = self.gitrunlines(b'show-ref')
            for line in output:
                line = line.strip()
                rev, name = line.split(None, 1)
                # Process each type of branch
                for gitprefix, hgprefix in reftypes:
                    if not name.startswith(gitprefix) or name in exclude:
                        continue
                    name = b'%s%s' % (hgprefix, name[len(gitprefix) :])
                    bookmarks[name] = rev
        except Exception:
            pass

        return bookmarks

    def checkrevformat(self, revstr, mapname=b'splicemap'):
        """ git revision string is a 40 byte hex """
        self.checkhexformat(revstr, mapname)