hgext/gpg.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

# Copyright 2005, 2006 Benoit Boissinot <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''commands to sign and verify changesets'''

from __future__ import absolute_import

import binascii
import os

from mercurial.i18n import _
from mercurial import (
    cmdutil,
    error,
    help,
    match,
    node as hgnode,
    pycompat,
    registrar,
)
from mercurial.utils import (
    dateutil,
    procutil,
)

cmdtable = {}
command = registrar.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'

configtable = {}
configitem = registrar.configitem(configtable)

configitem(
    b'gpg', b'cmd', default=b'gpg',
)
configitem(
    b'gpg', b'key', default=None,
)
configitem(
    b'gpg', b'.*', default=None, generic=True,
)

# Custom help category
_HELP_CATEGORY = b'gpg'
help.CATEGORY_ORDER.insert(
    help.CATEGORY_ORDER.index(registrar.command.CATEGORY_HELP), _HELP_CATEGORY
)
help.CATEGORY_NAMES[_HELP_CATEGORY] = b'Signing changes (GPG)'


class gpg(object):
    def __init__(self, path, key=None):
        self.path = path
        self.key = (key and b" --local-user \"%s\"" % key) or b""

    def sign(self, data):
        gpgcmd = b"%s --sign --detach-sign%s" % (self.path, self.key)
        return procutil.filter(data, gpgcmd)

    def verify(self, data, sig):
        """ returns of the good and bad signatures"""
        sigfile = datafile = None
        try:
            # create temporary files
            fd, sigfile = pycompat.mkstemp(prefix=b"hg-gpg-", suffix=b".sig")
            fp = os.fdopen(fd, 'wb')
            fp.write(sig)
            fp.close()
            fd, datafile = pycompat.mkstemp(prefix=b"hg-gpg-", suffix=b".txt")
            fp = os.fdopen(fd, 'wb')
            fp.write(data)
            fp.close()
            gpgcmd = (
                b"%s --logger-fd 1 --status-fd 1 --verify \"%s\" \"%s\""
                % (self.path, sigfile, datafile,)
            )
            ret = procutil.filter(b"", gpgcmd)
        finally:
            for f in (sigfile, datafile):
                try:
                    if f:
                        os.unlink(f)
                except OSError:
                    pass
        keys = []
        key, fingerprint = None, None
        for l in ret.splitlines():
            # see DETAILS in the gnupg documentation
            # filter the logger output
            if not l.startswith(b"[GNUPG:]"):
                continue
            l = l[9:]
            if l.startswith(b"VALIDSIG"):
                # fingerprint of the primary key
                fingerprint = l.split()[10]
            elif l.startswith(b"ERRSIG"):
                key = l.split(b" ", 3)[:2]
                key.append(b"")
                fingerprint = None
            elif (
                l.startswith(b"GOODSIG")
                or l.startswith(b"EXPSIG")
                or l.startswith(b"EXPKEYSIG")
                or l.startswith(b"BADSIG")
            ):
                if key is not None:
                    keys.append(key + [fingerprint])
                key = l.split(b" ", 2)
                fingerprint = None
        if key is not None:
            keys.append(key + [fingerprint])
        return keys


def newgpg(ui, **opts):
    """create a new gpg instance"""
    gpgpath = ui.config(b"gpg", b"cmd")
    gpgkey = opts.get('key')
    if not gpgkey:
        gpgkey = ui.config(b"gpg", b"key")
    return gpg(gpgpath, gpgkey)


def sigwalk(repo):
    """
    walk over every sigs, yields a couple
    ((node, version, sig), (filename, linenumber))
    """

    def parsefile(fileiter, context):
        ln = 1
        for l in fileiter:
            if not l:
                continue
            yield (l.split(b" ", 2), (context, ln))
            ln += 1

    # read the heads
    fl = repo.file(b".hgsigs")
    for r in reversed(fl.heads()):
        fn = b".hgsigs|%s" % hgnode.short(r)
        for item in parsefile(fl.read(r).splitlines(), fn):
            yield item
    try:
        # read local signatures
        fn = b"localsigs"
        for item in parsefile(repo.vfs(fn), fn):
            yield item
    except IOError:
        pass


def getkeys(ui, repo, mygpg, sigdata, context):
    """get the keys who signed a data"""
    fn, ln = context
    node, version, sig = sigdata
    prefix = b"%s:%d" % (fn, ln)
    node = hgnode.bin(node)

    data = node2txt(repo, node, version)
    sig = binascii.a2b_base64(sig)
    keys = mygpg.verify(data, sig)

    validkeys = []
    # warn for expired key and/or sigs
    for key in keys:
        if key[0] == b"ERRSIG":
            ui.write(_(b"%s Unknown key ID \"%s\"\n") % (prefix, key[1]))
            continue
        if key[0] == b"BADSIG":
            ui.write(_(b"%s Bad signature from \"%s\"\n") % (prefix, key[2]))
            continue
        if key[0] == b"EXPSIG":
            ui.write(
                _(b"%s Note: Signature has expired (signed by: \"%s\")\n")
                % (prefix, key[2])
            )
        elif key[0] == b"EXPKEYSIG":
            ui.write(
                _(b"%s Note: This key has expired (signed by: \"%s\")\n")
                % (prefix, key[2])
            )
        validkeys.append((key[1], key[2], key[3]))
    return validkeys


@command(b"sigs", [], _(b'hg sigs'), helpcategory=_HELP_CATEGORY)
def sigs(ui, repo):
    """list signed changesets"""
    mygpg = newgpg(ui)
    revs = {}

    for data, context in sigwalk(repo):
        node, version, sig = data
        fn, ln = context
        try:
            n = repo.lookup(node)
        except KeyError:
            ui.warn(_(b"%s:%d node does not exist\n") % (fn, ln))
            continue
        r = repo.changelog.rev(n)
        keys = getkeys(ui, repo, mygpg, data, context)
        if not keys:
            continue
        revs.setdefault(r, [])
        revs[r].extend(keys)
    for rev in sorted(revs, reverse=True):
        for k in revs[rev]:
            r = b"%5d:%s" % (rev, hgnode.hex(repo.changelog.node(rev)))
            ui.write(b"%-30s %s\n" % (keystr(ui, k), r))


@command(b"sigcheck", [], _(b'hg sigcheck REV'), helpcategory=_HELP_CATEGORY)
def sigcheck(ui, repo, rev):
    """verify all the signatures there may be for a particular revision"""
    mygpg = newgpg(ui)
    rev = repo.lookup(rev)
    hexrev = hgnode.hex(rev)
    keys = []

    for data, context in sigwalk(repo):
        node, version, sig = data
        if node == hexrev:
            k = getkeys(ui, repo, mygpg, data, context)
            if k:
                keys.extend(k)

    if not keys:
        ui.write(_(b"no valid signature for %s\n") % hgnode.short(rev))
        return

    # print summary
    ui.write(_(b"%s is signed by:\n") % hgnode.short(rev))
    for key in keys:
        ui.write(b" %s\n" % keystr(ui, key))


def keystr(ui, key):
    """associate a string to a key (username, comment)"""
    keyid, user, fingerprint = key
    comment = ui.config(b"gpg", fingerprint)
    if comment:
        return b"%s (%s)" % (user, comment)
    else:
        return user


@command(
    b"sign",
    [
        (b'l', b'local', None, _(b'make the signature local')),
        (b'f', b'force', None, _(b'sign even if the sigfile is modified')),
        (
            b'',
            b'no-commit',
            None,
            _(b'do not commit the sigfile after signing'),
        ),
        (b'k', b'key', b'', _(b'the key id to sign with'), _(b'ID')),
        (b'm', b'message', b'', _(b'use text as commit message'), _(b'TEXT')),
        (b'e', b'edit', False, _(b'invoke editor on commit messages')),
    ]
    + cmdutil.commitopts2,
    _(b'hg sign [OPTION]... [REV]...'),
    helpcategory=_HELP_CATEGORY,
)
def sign(ui, repo, *revs, **opts):
    """add a signature for the current or given revision

    If no revision is given, the parent of the working directory is used,
    or tip if no revision is checked out.

    The ``gpg.cmd`` config setting can be used to specify the command
    to run. A default key can be specified with ``gpg.key``.

    See :hg:`help dates` for a list of formats valid for -d/--date.
    """
    with repo.wlock():
        return _dosign(ui, repo, *revs, **opts)


def _dosign(ui, repo, *revs, **opts):
    mygpg = newgpg(ui, **opts)
    opts = pycompat.byteskwargs(opts)
    sigver = b"0"
    sigmessage = b""

    date = opts.get(b'date')
    if date:
        opts[b'date'] = dateutil.parsedate(date)

    if revs:
        nodes = [repo.lookup(n) for n in revs]
    else:
        nodes = [
            node for node in repo.dirstate.parents() if node != hgnode.nullid
        ]
        if len(nodes) > 1:
            raise error.Abort(
                _(b'uncommitted merge - please provide a specific revision')
            )
        if not nodes:
            nodes = [repo.changelog.tip()]

    for n in nodes:
        hexnode = hgnode.hex(n)
        ui.write(
            _(b"signing %d:%s\n") % (repo.changelog.rev(n), hgnode.short(n))
        )
        # build data
        data = node2txt(repo, n, sigver)
        sig = mygpg.sign(data)
        if not sig:
            raise error.Abort(_(b"error while signing"))
        sig = binascii.b2a_base64(sig)
        sig = sig.replace(b"\n", b"")
        sigmessage += b"%s %s %s\n" % (hexnode, sigver, sig)

    # write it
    if opts[b'local']:
        repo.vfs.append(b"localsigs", sigmessage)
        return

    if not opts[b"force"]:
        msigs = match.exact([b'.hgsigs'])
        if any(repo.status(match=msigs, unknown=True, ignored=True)):
            raise error.Abort(
                _(b"working copy of .hgsigs is changed "),
                hint=_(b"please commit .hgsigs manually"),
            )

    sigsfile = repo.wvfs(b".hgsigs", b"ab")
    sigsfile.write(sigmessage)
    sigsfile.close()

    if b'.hgsigs' not in repo.dirstate:
        repo[None].add([b".hgsigs"])

    if opts[b"no_commit"]:
        return

    message = opts[b'message']
    if not message:
        # we don't translate commit messages
        message = b"\n".join(
            [
                b"Added signature for changeset %s" % hgnode.short(n)
                for n in nodes
            ]
        )
    try:
        editor = cmdutil.getcommiteditor(
            editform=b'gpg.sign', **pycompat.strkwargs(opts)
        )
        repo.commit(
            message, opts[b'user'], opts[b'date'], match=msigs, editor=editor
        )
    except ValueError as inst:
        raise error.Abort(pycompat.bytestr(inst))


def node2txt(repo, node, ver):
    """map a manifest into some text"""
    if ver == b"0":
        return b"%s\n" % hgnode.hex(node)
    else:
        raise error.Abort(_(b"unknown signature version"))


def extsetup(ui):
    # Add our category before "Repository maintenance".
    help.CATEGORY_ORDER.insert(
        help.CATEGORY_ORDER.index(command.CATEGORY_MAINTENANCE), _HELP_CATEGORY
    )
    help.CATEGORY_NAMES[_HELP_CATEGORY] = b'GPG signing'