# GnuPG signing extension for Mercurial

#

# Copyright 2005, 2006 Benoit Boissinot <benoit.boissinot@ens-lyon.org>

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

import os, tempfile, binascii

from mercurial import util, commands

from mercurial import node as hgnode

from mercurial.i18n import _

class gpg:

    def __init__(self, path, key=None):

        self.path = path

        self.key = (key and " --local-user \"%s\"" % key) or ""

    def sign(self, data):

        gpgcmd = "%s --sign --detach-sign%s" % (self.path, self.key)

        return util.filter(data, gpgcmd)

    def verify(self, data, sig):

        """ returns of the good and bad signatures"""

        sigfile = datafile = None

        try:

            # create temporary files

            fd, sigfile = tempfile.mkstemp(prefix="hg-gpg-", suffix=".sig")

            fp = os.fdopen(fd, 'wb')

            fp.write(sig)

            fp.close()

            fd, datafile = tempfile.mkstemp(prefix="hg-gpg-", suffix=".txt")

            fp = os.fdopen(fd, 'wb')

            fp.write(data)

            fp.close()

            gpgcmd = ("%s --logger-fd 1 --status-fd 1 --verify "

                      "\"%s\" \"%s\"" % (self.path, sigfile, datafile))

            ret = util.filter("", gpgcmd)

        finally:

            for f in (sigfile, datafile):

                try:

                    if f: os.unlink(f)

                except: pass

        keys = []

        key, fingerprint = None, None

        err = ""

        for l in ret.splitlines():

            # see DETAILS in the gnupg documentation

            # filter the logger output

            if not l.startswith("[GNUPG:]"):

                continue

            l = l[9:]

            if l.startswith("ERRSIG"):

                err = _("error while verifying signature")

                break

            elif l.startswith("VALIDSIG"):

                # fingerprint of the primary key

                fingerprint = l.split()[10]

            elif (l.startswith("GOODSIG") or

                  l.startswith("EXPSIG") or

                  l.startswith("EXPKEYSIG") or

                  l.startswith("BADSIG")):

                if key is not None:

                    keys.append(key + [fingerprint])

                key = l.split(" ", 2)

                fingerprint = None

        if err:

            return err, []

        if key is not None:

            keys.append(key + [fingerprint])

        return err, keys

def newgpg(ui, **opts):

    """create a new gpg instance"""

    gpgpath = ui.config("gpg", "cmd", "gpg")

    gpgkey = opts.get('key')

    if not gpgkey:

        gpgkey = ui.config("gpg", "key", None)

    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(" ", 2), (context, ln))

            ln +=1

    fl = repo.file(".hgsigs")

    h = fl.heads()

    h.reverse()

    # read the heads

    for r in h:

        fn = ".hgsigs|%s" % hgnode.short(r)

        for item in parsefile(fl.read(r).splitlines(), fn):

            yield item

    try:

        # read local signatures

        fn = "localsigs"

        for item in parsefile(repo.opener(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 = "%s:%d" % (fn, ln)

    node = hgnode.bin(node)

    data = node2txt(repo, node, version)

    sig = binascii.a2b_base64(sig)

    err, keys = mygpg.verify(data, sig)

    if err:

        ui.warn("%s:%d %s\n" % (fn, ln , err))

        return None

    validkeys = []

    # warn for expired key and/or sigs

    for key in keys:

        if key[0] == "BADSIG":

            ui.write(_("%s Bad signature from \"%s\"\n") % (prefix, key[2]))

            continue

        if key[0] == "EXPSIG":

            ui.write(_("%s Note: Signature has expired"

                       " (signed by: \"%s\")\n") % (prefix, key[2]))

        elif key[0] == "EXPKEYSIG":

            ui.write(_("%s Note: This key has expired"

                       " (signed by: \"%s\")\n") % (prefix, key[2]))

        validkeys.append((key[1], key[2], key[3]))

    return validkeys

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(_("%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)

    nodes = list(revs)

    nodes.reverse()

    for rev in nodes:

        for k in revs[rev]:

            r = "%5d:%s" % (rev, hgnode.hex(repo.changelog.node(rev)))

            ui.write("%-30s %s\n" % (keystr(ui, k), r))

def check(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(_("No valid signature for %s\n") % hgnode.short(rev))

        return

    # print summary

    ui.write("%s is signed by:\n" % hgnode.short(rev))

    for key in keys:

        ui.write(" %s\n" % keystr(ui, key))

def keystr(ui, key):

    """associate a string to a key (username, comment)"""

    keyid, user, fingerprint = key

    comment = ui.config("gpg", fingerprint, None)

    if comment:

        return "%s (%s)" % (user, comment)

    else:

        return user

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.

    See 'hg help dates' for a list of formats valid for -d/--date.

    """

    mygpg = newgpg(ui, **opts)

    sigver = "0"

    sigmessage = ""

    date = opts.get('date')

    if date:

        opts['date'] = util.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 util.Abort(_('uncommitted merge - please provide a '

                               'specific revision'))

        if not nodes:

            nodes = [repo.changelog.tip()]

    for n in nodes:

        hexnode = hgnode.hex(n)

        ui.write("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 util.Abort(_("Error while signing"))

        sig = binascii.b2a_base64(sig)

        sig = sig.replace("\n", "")

        sigmessage += "%s %s %s\n" % (hexnode, sigver, sig)

    # write it

    if opts['local']:

        repo.opener("localsigs", "ab").write(sigmessage)

        return

    for x in repo.status(unknown=True)[:5]:

        if ".hgsigs" in x and not opts["force"]:

            raise util.Abort(_("working copy of .hgsigs is changed "

                               "(please commit .hgsigs manually "

                               "or use --force)"))

    repo.wfile(".hgsigs", "ab").write(sigmessage)

    if '.hgsigs' not in repo.dirstate:

        repo.add([".hgsigs"])

    if opts["no_commit"]:

        return

    message = opts['message']

    if not message:

        message = "\n".join([_("Added signature for changeset %s")

                             % hgnode.short(n)

                             for n in nodes])

    try:

        repo.commit([".hgsigs"], message, opts['user'], opts['date'])

    except ValueError, inst:

        raise util.Abort(str(inst))

def node2txt(repo, node, ver):

    """map a manifest into some text"""

    if ver == "0":

        return "%s\n" % hgnode.hex(node)

    else:

        raise util.Abort(_("unknown signature version"))

cmdtable = {

    "sign":

        (sign,

         [('l', 'local', None, _('make the signature local')),

          ('f', 'force', None, _('sign even if the sigfile is modified')),

          ('', 'no-commit', None, _('do not commit the sigfile after signing')),

          ('k', 'key', '', _('the key id to sign with')),

          ('m', 'message', '', _('commit message')),

         ] + commands.commitopts2,

         _('hg sign [OPTION]... [REVISION]...')),

    "sigcheck": (check, [], _('hg sigcheck REVISION')),

    "sigs": (sigs, [], _('hg sigs')),

}