# 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.

    """

    mygpg = newgpg(ui, **opts)

    sigver = "0"

    sigmessage = ""

    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()[: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')),

}