lib/bb/siggen.py

#
# SPDX-License-Identifier: GPL-2.0-only
#

import hashlib
import logging
import os
import re
import tempfile
import pickle
import bb.data
import difflib
import simplediff
import json
import bb.compress.zstd
from bb.checksum import FileChecksumCache
from bb import runqueue
import hashserv
import hashserv.client

logger = logging.getLogger('BitBake.SigGen')
hashequiv_logger = logging.getLogger('BitBake.SigGen.HashEquiv')

class SetEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, set):
            return dict(_set_object=list(sorted(obj)))
        return json.JSONEncoder.default(self, obj)

def SetDecoder(dct):
    if '_set_object' in dct:
        return set(dct['_set_object'])
    return dct

def init(d):
    siggens = [obj for obj in globals().values()
                      if type(obj) is type and issubclass(obj, SignatureGenerator)]

    desired = d.getVar("BB_SIGNATURE_HANDLER") or "noop"
    for sg in siggens:
        if desired == sg.name:
            return sg(d)
            break
    else:
        logger.error("Invalid signature generator '%s', using default 'noop'\n"
                     "Available generators: %s", desired,
                     ', '.join(obj.name for obj in siggens))
        return SignatureGenerator(d)

class SignatureGenerator(object):
    """
    """
    name = "noop"

    # If the derived class supports multiconfig datacaches, set this to True
    # The default is False for backward compatibility with derived signature
    # generators that do not understand multiconfig caches
    supports_multiconfig_datacaches = False

    def __init__(self, data):
        self.basehash = {}
        self.taskhash = {}
        self.unihash = {}
        self.runtaskdeps = {}
        self.file_checksum_values = {}
        self.taints = {}
        self.unitaskhashes = {}
        self.tidtopn = {}
        self.setscenetasks = set()

    def finalise(self, fn, d, varient):
        return

    def postparsing_clean_cache(self):
        return

    def get_unihash(self, tid):
        return self.taskhash[tid]

    def prep_taskhash(self, tid, deps, dataCaches):
        return

    def get_taskhash(self, tid, deps, dataCaches):
        self.taskhash[tid] = hashlib.sha256(tid.encode("utf-8")).hexdigest()
        return self.taskhash[tid]

    def writeout_file_checksum_cache(self):
        """Write/update the file checksum cache onto disk"""
        return

    def stampfile(self, stampbase, file_name, taskname, extrainfo):
        return ("%s.%s.%s" % (stampbase, taskname, extrainfo)).rstrip('.')

    def stampcleanmask(self, stampbase, file_name, taskname, extrainfo):
        return ("%s.%s.%s" % (stampbase, taskname, extrainfo)).rstrip('.')

    def dump_sigtask(self, fn, task, stampbase, runtime):
        return

    def invalidate_task(self, task, d, fn):
        bb.build.del_stamp(task, d, fn)

    def dump_sigs(self, dataCache, options):
        return

    def get_taskdata(self):
        return (self.runtaskdeps, self.taskhash, self.unihash, self.file_checksum_values, self.taints, self.basehash, self.unitaskhashes, self.tidtopn, self.setscenetasks)

    def set_taskdata(self, data):
        self.runtaskdeps, self.taskhash, self.unihash, self.file_checksum_values, self.taints, self.basehash, self.unitaskhashes, self.tidtopn, self.setscenetasks = data

    def reset(self, data):
        self.__init__(data)

    def get_taskhashes(self):
        return self.taskhash, self.unihash, self.unitaskhashes, self.tidtopn

    def set_taskhashes(self, hashes):
        self.taskhash, self.unihash, self.unitaskhashes, self.tidtopn = hashes

    def save_unitaskhashes(self):
        return

    def set_setscene_tasks(self, setscene_tasks):
        return

    @classmethod
    def get_data_caches(cls, dataCaches, mc):
        """
        This function returns the datacaches that should be passed to signature
        generator functions. If the signature generator supports multiconfig
        caches, the entire dictionary of data caches is sent, otherwise a
        special proxy is sent that support both index access to all
        multiconfigs, and also direct access for the default multiconfig.

        The proxy class allows code in this class itself to always use
        multiconfig aware code (to ease maintenance), but derived classes that
        are unaware of multiconfig data caches can still access the default
        multiconfig as expected.

        Do not override this function in derived classes; it will be removed in
        the future when support for multiconfig data caches is mandatory
        """
        class DataCacheProxy(object):
            def __init__(self):
                pass

            def __getitem__(self, key):
                return dataCaches[key]

            def __getattr__(self, name):
                return getattr(dataCaches[mc], name)

        if cls.supports_multiconfig_datacaches:
            return dataCaches

        return DataCacheProxy()

    def exit(self):
        return

class SignatureGeneratorBasic(SignatureGenerator):
    """
    """
    name = "basic"

    def __init__(self, data):
        self.basehash = {}
        self.taskhash = {}
        self.unihash = {}
        self.taskdeps = {}
        self.runtaskdeps = {}
        self.file_checksum_values = {}
        self.taints = {}
        self.gendeps = {}
        self.lookupcache = {}
        self.setscenetasks = set()
        self.basehash_ignore_vars = set((data.getVar("BB_BASEHASH_IGNORE_VARS") or "").split())
        self.taskhash_ignore_tasks = None
        self.init_rundepcheck(data)
        checksum_cache_file = data.getVar("BB_HASH_CHECKSUM_CACHE_FILE")
        if checksum_cache_file:
            self.checksum_cache = FileChecksumCache()
            self.checksum_cache.init_cache(data, checksum_cache_file)
        else:
            self.checksum_cache = None

        self.unihash_cache = bb.cache.SimpleCache("3")
        self.unitaskhashes = self.unihash_cache.init_cache(data, "bb_unihashes.dat", {})
        self.localdirsexclude = (data.getVar("BB_SIGNATURE_LOCAL_DIRS_EXCLUDE") or "CVS .bzr .git .hg .osc .p4 .repo .svn").split()
        self.tidtopn = {}

    def init_rundepcheck(self, data):
        self.taskhash_ignore_tasks = data.getVar("BB_TASKHASH_IGNORE_TASKS") or None
        if self.taskhash_ignore_tasks:
            self.twl = re.compile(self.taskhash_ignore_tasks)
        else:
            self.twl = None

    def _build_data(self, fn, d):

        ignore_mismatch = ((d.getVar("BB_HASH_IGNORE_MISMATCH") or '') == '1')
        tasklist, gendeps, lookupcache = bb.data.generate_dependencies(d, self.basehash_ignore_vars)

        taskdeps, basehash = bb.data.generate_dependency_hash(tasklist, gendeps, lookupcache, self.basehash_ignore_vars, fn)

        for task in tasklist:
            tid = fn + ":" + task
            if not ignore_mismatch and tid in self.basehash and self.basehash[tid] != basehash[tid]:
                bb.error("When reparsing %s, the basehash value changed from %s to %s. The metadata is not deterministic and this needs to be fixed." % (tid, self.basehash[tid], basehash[tid]))
                bb.error("The following commands may help:")
                cmd = "$ bitbake %s -c%s" % (d.getVar('PN'), task)
                # Make sure sigdata is dumped before run printdiff
                bb.error("%s -Snone" % cmd)
                bb.error("Then:")
                bb.error("%s -Sprintdiff\n" % cmd)
            self.basehash[tid] = basehash[tid]

        self.taskdeps[fn] = taskdeps
        self.gendeps[fn] = gendeps
        self.lookupcache[fn] = lookupcache

        return taskdeps

    def set_setscene_tasks(self, setscene_tasks):
        self.setscenetasks = set(setscene_tasks)

    def finalise(self, fn, d, variant):

        mc = d.getVar("__BBMULTICONFIG", False) or ""
        if variant or mc:
            fn = bb.cache.realfn2virtual(fn, variant, mc)

        try:
            taskdeps = self._build_data(fn, d)
        except bb.parse.SkipRecipe:
            raise
        except:
            bb.warn("Error during finalise of %s" % fn)
            raise

        #Slow but can be useful for debugging mismatched basehashes
        #for task in self.taskdeps[fn]:
        #    self.dump_sigtask(fn, task, d.getVar("STAMP"), False)

        for task in taskdeps:
            d.setVar("BB_BASEHASH:task-%s" % task, self.basehash[fn + ":" + task])

    def postparsing_clean_cache(self):
        #
        # After parsing we can remove some things from memory to reduce our memory footprint
        #
        self.gendeps = {}
        self.lookupcache = {}
        self.taskdeps = {}

    def rundep_check(self, fn, recipename, task, dep, depname, dataCaches):
        # Return True if we should keep the dependency, False to drop it
        # We only manipulate the dependencies for packages not in the ignore
        # list
        if self.twl and not self.twl.search(recipename):
            # then process the actual dependencies
            if self.twl.search(depname):
                return False
        return True

    def read_taint(self, fn, task, stampbase):
        taint = None
        try:
            with open(stampbase + '.' + task + '.taint', 'r') as taintf:
                taint = taintf.read()
        except IOError:
            pass
        return taint

    def prep_taskhash(self, tid, deps, dataCaches):

        (mc, _, task, fn) = bb.runqueue.split_tid_mcfn(tid)

        self.basehash[tid] = dataCaches[mc].basetaskhash[tid]
        self.runtaskdeps[tid] = []
        self.file_checksum_values[tid] = []
        recipename = dataCaches[mc].pkg_fn[fn]

        self.tidtopn[tid] = recipename

        for dep in sorted(deps, key=clean_basepath):
            (depmc, _, _, depmcfn) = bb.runqueue.split_tid_mcfn(dep)
            depname = dataCaches[depmc].pkg_fn[depmcfn]
            if not self.supports_multiconfig_datacaches and mc != depmc:
                # If the signature generator doesn't understand multiconfig
                # data caches, any dependency not in the same multiconfig must
                # be skipped for backward compatibility
                continue
            if not self.rundep_check(fn, recipename, task, dep, depname, dataCaches):
                continue
            if dep not in self.taskhash:
                bb.fatal("%s is not in taskhash, caller isn't calling in dependency order?" % dep)
            self.runtaskdeps[tid].append(dep)

        if task in dataCaches[mc].file_checksums[fn]:
            if self.checksum_cache:
                checksums = self.checksum_cache.get_checksums(dataCaches[mc].file_checksums[fn][task], recipename, self.localdirsexclude)
            else:
                checksums = bb.fetch2.get_file_checksums(dataCaches[mc].file_checksums[fn][task], recipename, self.localdirsexclude)
            for (f,cs) in checksums:
                self.file_checksum_values[tid].append((f,cs))

        taskdep = dataCaches[mc].task_deps[fn]
        if 'nostamp' in taskdep and task in taskdep['nostamp']:
            # Nostamp tasks need an implicit taint so that they force any dependent tasks to run
            if tid in self.taints and self.taints[tid].startswith("nostamp:"):
                # Don't reset taint value upon every call
                pass
            else:
                import uuid
                taint = str(uuid.uuid4())
                self.taints[tid] = "nostamp:" + taint

        taint = self.read_taint(fn, task, dataCaches[mc].stamp[fn])
        if taint:
            self.taints[tid] = taint
            logger.warning("%s is tainted from a forced run" % tid)

        return

    def get_taskhash(self, tid, deps, dataCaches):

        data = self.basehash[tid]
        for dep in self.runtaskdeps[tid]:
            data = data + self.get_unihash(dep)

        for (f, cs) in self.file_checksum_values[tid]:
            if cs:
                if "/./" in f:
                    data = data + "./" + f.split("/./")[1]
                data = data + cs

        if tid in self.taints:
            if self.taints[tid].startswith("nostamp:"):
                data = data + self.taints[tid][8:]
            else:
                data = data + self.taints[tid]

        h = hashlib.sha256(data.encode("utf-8")).hexdigest()
        self.taskhash[tid] = h
        #d.setVar("BB_TASKHASH:task-%s" % task, taskhash[task])
        return h

    def writeout_file_checksum_cache(self):
        """Write/update the file checksum cache onto disk"""
        if self.checksum_cache:
            self.checksum_cache.save_extras()
            self.checksum_cache.save_merge()
        else:
            bb.fetch2.fetcher_parse_save()
            bb.fetch2.fetcher_parse_done()

    def save_unitaskhashes(self):
        self.unihash_cache.save(self.unitaskhashes)

    def dump_sigtask(self, fn, task, stampbase, runtime):

        tid = fn + ":" + task
        referencestamp = stampbase
        if isinstance(runtime, str) and runtime.startswith("customfile"):
            sigfile = stampbase
            referencestamp = runtime[11:]
        elif runtime and tid in self.taskhash:
            sigfile = stampbase + "." + task + ".sigdata" + "." + self.get_unihash(tid)
        else:
            sigfile = stampbase + "." + task + ".sigbasedata" + "." + self.basehash[tid]

        with bb.utils.umask(0o002):
            bb.utils.mkdirhier(os.path.dirname(sigfile))

        data = {}
        data['task'] = task
        data['basehash_ignore_vars'] = self.basehash_ignore_vars
        data['taskhash_ignore_tasks'] = self.taskhash_ignore_tasks
        data['taskdeps'] = self.taskdeps[fn][task]
        data['basehash'] = self.basehash[tid]
        data['gendeps'] = {}
        data['varvals'] = {}
        data['varvals'][task] = self.lookupcache[fn][task]
        for dep in self.taskdeps[fn][task]:
            if dep in self.basehash_ignore_vars:
                continue
            data['gendeps'][dep] = self.gendeps[fn][dep]
            data['varvals'][dep] = self.lookupcache[fn][dep]

        if runtime and tid in self.taskhash:
            data['runtaskdeps'] = self.runtaskdeps[tid]
            data['file_checksum_values'] = []
            for f,cs in self.file_checksum_values[tid]:
                if "/./" in f:
                    data['file_checksum_values'].append(("./" + f.split("/./")[1], cs))
                else:
                    data['file_checksum_values'].append((os.path.basename(f), cs))
            data['runtaskhashes'] = {}
            for dep in data['runtaskdeps']:
                data['runtaskhashes'][dep] = self.get_unihash(dep)
            data['taskhash'] = self.taskhash[tid]
            data['unihash'] = self.get_unihash(tid)

        taint = self.read_taint(fn, task, referencestamp)
        if taint:
            data['taint'] = taint

        if runtime and tid in self.taints:
            if 'nostamp:' in self.taints[tid]:
                data['taint'] = self.taints[tid]

        computed_basehash = calc_basehash(data)
        if computed_basehash != self.basehash[tid]:
            bb.error("Basehash mismatch %s versus %s for %s" % (computed_basehash, self.basehash[tid], tid))
        if runtime and tid in self.taskhash:
            computed_taskhash = calc_taskhash(data)
            if computed_taskhash != self.taskhash[tid]:
                bb.error("Taskhash mismatch %s versus %s for %s" % (computed_taskhash, self.taskhash[tid], tid))
                sigfile = sigfile.replace(self.taskhash[tid], computed_taskhash)

        fd, tmpfile = tempfile.mkstemp(dir=os.path.dirname(sigfile), prefix="sigtask.")
        try:
            with bb.compress.zstd.open(fd, "wt", encoding="utf-8", num_threads=1) as f:
                json.dump(data, f, sort_keys=True, separators=(",", ":"), cls=SetEncoder)
                f.flush()
            os.chmod(tmpfile, 0o664)
            bb.utils.rename(tmpfile, sigfile)
        except (OSError, IOError) as err:
            try:
                os.unlink(tmpfile)
            except OSError:
                pass
            raise err

    def dump_sigfn(self, fn, dataCaches, options):
        if fn in self.taskdeps:
            for task in self.taskdeps[fn]:
                tid = fn + ":" + task
                mc = bb.runqueue.mc_from_tid(tid)
                if tid not in self.taskhash:
                    continue
                if dataCaches[mc].basetaskhash[tid] != self.basehash[tid]:
                    bb.error("Bitbake's cached basehash does not match the one we just generated (%s)!" % tid)
                    bb.error("The mismatched hashes were %s and %s" % (dataCaches[mc].basetaskhash[tid], self.basehash[tid]))
                self.dump_sigtask(fn, task, dataCaches[mc].stamp[fn], True)

class SignatureGeneratorBasicHash(SignatureGeneratorBasic):
    name = "basichash"

    def get_stampfile_hash(self, tid):
        if tid in self.taskhash:
            return self.taskhash[tid]

        # If task is not in basehash, then error
        return self.basehash[tid]

    def stampfile(self, stampbase, fn, taskname, extrainfo, clean=False):
        if taskname != "do_setscene" and taskname.endswith("_setscene"):
            tid = fn + ":" + taskname[:-9]
        else:
            tid = fn + ":" + taskname
        if clean:
            h = "*"
        else:
            h = self.get_stampfile_hash(tid)

        return ("%s.%s.%s.%s" % (stampbase, taskname, h, extrainfo)).rstrip('.')

    def stampcleanmask(self, stampbase, fn, taskname, extrainfo):
        return self.stampfile(stampbase, fn, taskname, extrainfo, clean=True)

    def invalidate_task(self, task, d, fn):
        bb.note("Tainting hash to force rebuild of task %s, %s" % (fn, task))
        bb.build.write_taint(task, d, fn)

class SignatureGeneratorUniHashMixIn(object):
    def __init__(self, data):
        self.extramethod = {}
        super().__init__(data)

    def get_taskdata(self):
        return (self.server, self.method, self.extramethod) + super().get_taskdata()

    def set_taskdata(self, data):
        self.server, self.method, self.extramethod = data[:3]
        super().set_taskdata(data[3:])

    def client(self):
        if getattr(self, '_client', None) is None:
            self._client = hashserv.create_client(self.server)
        return self._client

    def reset(self, data):
        if getattr(self, '_client', None) is not None:
            self._client.close()
            self._client = None
        return super().reset(data)

    def exit(self):
        if getattr(self, '_client', None) is not None:
            self._client.close()
            self._client = None
        return super().exit()

    def get_stampfile_hash(self, tid):
        if tid in self.taskhash:
            # If a unique hash is reported, use it as the stampfile hash. This
            # ensures that if a task won't be re-run if the taskhash changes,
            # but it would result in the same output hash
            unihash = self._get_unihash(tid)
            if unihash is not None:
                return unihash

        return super().get_stampfile_hash(tid)

    def set_unihash(self, tid, unihash):
        (mc, fn, taskname, taskfn) = bb.runqueue.split_tid_mcfn(tid)
        key = mc + ":" + self.tidtopn[tid] + ":" + taskname
        self.unitaskhashes[key] = (self.taskhash[tid], unihash)
        self.unihash[tid] = unihash

    def _get_unihash(self, tid, checkkey=None):
        if tid not in self.tidtopn:
            return None
        (mc, fn, taskname, taskfn) = bb.runqueue.split_tid_mcfn(tid)
        key = mc + ":" + self.tidtopn[tid] + ":" + taskname
        if key not in self.unitaskhashes:
            return None
        if not checkkey:
            checkkey = self.taskhash[tid]
        (key, unihash) = self.unitaskhashes[key]
        if key != checkkey:
            return None
        return unihash

    def get_unihash(self, tid):
        taskhash = self.taskhash[tid]

        # If its not a setscene task we can return
        if self.setscenetasks and tid not in self.setscenetasks:
            self.unihash[tid] = None
            return taskhash

        # TODO: This cache can grow unbounded. It probably only needs to keep
        # for each task
        unihash =  self._get_unihash(tid)
        if unihash is not None:
            self.unihash[tid] = unihash
            return unihash

        # In the absence of being able to discover a unique hash from the
        # server, make it be equivalent to the taskhash. The unique "hash" only
        # really needs to be a unique string (not even necessarily a hash), but
        # making it match the taskhash has a few advantages:
        #
        # 1) All of the sstate code that assumes hashes can be the same
        # 2) It provides maximal compatibility with builders that don't use
        #    an equivalency server
        # 3) The value is easy for multiple independent builders to derive the
        #    same unique hash from the same input. This means that if the
        #    independent builders find the same taskhash, but it isn't reported
        #    to the server, there is a better chance that they will agree on
        #    the unique hash.
        unihash = taskhash

        try:
            method = self.method
            if tid in self.extramethod:
                method = method + self.extramethod[tid]
            data = self.client().get_unihash(method, self.taskhash[tid])
            if data:
                unihash = data
                # A unique hash equal to the taskhash is not very interesting,
                # so it is reported it at debug level 2. If they differ, that
                # is much more interesting, so it is reported at debug level 1
                hashequiv_logger.debug((1, 2)[unihash == taskhash], 'Found unihash %s in place of %s for %s from %s' % (unihash, taskhash, tid, self.server))
            else:
                hashequiv_logger.debug2('No reported unihash for %s:%s from %s' % (tid, taskhash, self.server))
        except ConnectionError as e:
            bb.warn('Error contacting Hash Equivalence Server %s: %s' % (self.server, str(e)))

        self.set_unihash(tid, unihash)
        self.unihash[tid] = unihash
        return unihash

    def report_unihash(self, path, task, d):
        import importlib

        taskhash = d.getVar('BB_TASKHASH')
        unihash = d.getVar('BB_UNIHASH')
        report_taskdata = d.getVar('SSTATE_HASHEQUIV_REPORT_TASKDATA') == '1'
        tempdir = d.getVar('T')
        fn = d.getVar('BB_FILENAME')
        tid = fn + ':do_' + task
        key = tid + ':' + taskhash

        if self.setscenetasks and tid not in self.setscenetasks:
            return

        # This can happen if locked sigs are in action. Detect and just exit
        if taskhash != self.taskhash[tid]:
            return

        # Sanity checks
        cache_unihash = self._get_unihash(tid, checkkey=taskhash)
        if cache_unihash is None:
            bb.fatal('%s not in unihash cache. Please report this error' % key)

        if cache_unihash != unihash:
            bb.fatal("Cache unihash %s doesn't match BB_UNIHASH %s" % (cache_unihash, unihash))

        sigfile = None
        sigfile_name = "depsig.do_%s.%d" % (task, os.getpid())
        sigfile_link = "depsig.do_%s" % task

        try:
            sigfile = open(os.path.join(tempdir, sigfile_name), 'w+b')

            locs = {'path': path, 'sigfile': sigfile, 'task': task, 'd': d}

            if "." in self.method:
                (module, method) = self.method.rsplit('.', 1)
                locs['method'] = getattr(importlib.import_module(module), method)
                outhash = bb.utils.better_eval('method(path, sigfile, task, d)', locs)
            else:
                outhash = bb.utils.better_eval(self.method + '(path, sigfile, task, d)', locs)

            try:
                extra_data = {}

                owner = d.getVar('SSTATE_HASHEQUIV_OWNER')
                if owner:
                    extra_data['owner'] = owner

                if report_taskdata:
                    sigfile.seek(0)

                    extra_data['PN'] = d.getVar('PN')
                    extra_data['PV'] = d.getVar('PV')
                    extra_data['PR'] = d.getVar('PR')
                    extra_data['task'] = task
                    extra_data['outhash_siginfo'] = sigfile.read().decode('utf-8')

                method = self.method
                if tid in self.extramethod:
                    method = method + self.extramethod[tid]

                data = self.client().report_unihash(taskhash, method, outhash, unihash, extra_data)
                new_unihash = data['unihash']

                if new_unihash != unihash:
                    hashequiv_logger.debug('Task %s unihash changed %s -> %s by server %s' % (taskhash, unihash, new_unihash, self.server))
                    bb.event.fire(bb.runqueue.taskUniHashUpdate(fn + ':do_' + task, new_unihash), d)
                    self.set_unihash(tid, new_unihash)
                    d.setVar('BB_UNIHASH', new_unihash)
                else:
                    hashequiv_logger.debug('Reported task %s as unihash %s to %s' % (taskhash, unihash, self.server))
            except ConnectionError as e:
                bb.warn('Error contacting Hash Equivalence Server %s: %s' % (self.server, str(e)))
        finally:
            if sigfile:
                sigfile.close()

                sigfile_link_path = os.path.join(tempdir, sigfile_link)
                bb.utils.remove(sigfile_link_path)

                try:
                    os.symlink(sigfile_name, sigfile_link_path)
                except OSError:
                    pass

    def report_unihash_equiv(self, tid, taskhash, wanted_unihash, current_unihash, datacaches):
        try:
            extra_data = {}
            method = self.method
            if tid in self.extramethod:
                method = method + self.extramethod[tid]

            data = self.client().report_unihash_equiv(taskhash, method, wanted_unihash, extra_data)
            hashequiv_logger.verbose('Reported task %s as unihash %s to %s (%s)' % (tid, wanted_unihash, self.server, str(data)))

            if data is None:
                bb.warn("Server unable to handle unihash report")
                return False

            finalunihash = data['unihash']

            if finalunihash == current_unihash:
                hashequiv_logger.verbose('Task %s unihash %s unchanged by server' % (tid, finalunihash))
            elif finalunihash == wanted_unihash:
                hashequiv_logger.verbose('Task %s unihash changed %s -> %s as wanted' % (tid, current_unihash, finalunihash))
                self.set_unihash(tid, finalunihash)
                return True
            else:
                # TODO: What to do here?
                hashequiv_logger.verbose('Task %s unihash reported as unwanted hash %s' % (tid, finalunihash))

        except ConnectionError as e:
            bb.warn('Error contacting Hash Equivalence Server %s: %s' % (self.server, str(e)))

        return False

#
# Dummy class used for bitbake-selftest
#
class SignatureGeneratorTestEquivHash(SignatureGeneratorUniHashMixIn, SignatureGeneratorBasicHash):
    name = "TestEquivHash"
    def init_rundepcheck(self, data):
        super().init_rundepcheck(data)
        self.server = data.getVar('BB_HASHSERVE')
        self.method = "sstate_output_hash"

#
# Dummy class used for bitbake-selftest
#
class SignatureGeneratorTestMulticonfigDepends(SignatureGeneratorBasicHash):
    name = "TestMulticonfigDepends"
    supports_multiconfig_datacaches = True

def dump_this_task(outfile, d):
    import bb.parse
    fn = d.getVar("BB_FILENAME")
    task = "do_" + d.getVar("BB_CURRENTTASK")
    referencestamp = bb.build.stamp_internal(task, d, None, True)
    bb.parse.siggen.dump_sigtask(fn, task, outfile, "customfile:" + referencestamp)

def init_colors(enable_color):
    """Initialise colour dict for passing to compare_sigfiles()"""
    # First set up the colours
    colors = {'color_title':   '\033[1m',
              'color_default': '\033[0m',
              'color_add':     '\033[0;32m',
              'color_remove':  '\033[0;31m',
             }
    # Leave all keys present but clear the values
    if not enable_color:
        for k in colors.keys():
            colors[k] = ''
    return colors

def worddiff_str(oldstr, newstr, colors=None):
    if not colors:
        colors = init_colors(False)
    diff = simplediff.diff(oldstr.split(' '), newstr.split(' '))
    ret = []
    for change, value in diff:
        value = ' '.join(value)
        if change == '=':
            ret.append(value)
        elif change == '+':
            item = '{color_add}{{+{value}+}}{color_default}'.format(value=value, **colors)
            ret.append(item)
        elif change == '-':
            item = '{color_remove}[-{value}-]{color_default}'.format(value=value, **colors)
            ret.append(item)
    whitespace_note = ''
    if oldstr != newstr and ' '.join(oldstr.split()) == ' '.join(newstr.split()):
        whitespace_note = ' (whitespace changed)'
    return '"%s"%s' % (' '.join(ret), whitespace_note)

def list_inline_diff(oldlist, newlist, colors=None):
    if not colors:
        colors = init_colors(False)
    diff = simplediff.diff(oldlist, newlist)
    ret = []
    for change, value in diff:
        value = ' '.join(value)
        if change == '=':
            ret.append("'%s'" % value)
        elif change == '+':
            item = '{color_add}+{value}{color_default}'.format(value=value, **colors)
            ret.append(item)
        elif change == '-':
            item = '{color_remove}-{value}{color_default}'.format(value=value, **colors)
            ret.append(item)
    return '[%s]' % (', '.join(ret))

def clean_basepath(basepath):
    basepath, dir, recipe_task = basepath.rsplit("/", 2)
    cleaned = dir + '/' + recipe_task

    if basepath[0] == '/':
        return cleaned

    if basepath.startswith("mc:") and basepath.count(':') >= 2:
        mc, mc_name, basepath = basepath.split(":", 2)
        mc_suffix = ':mc:' + mc_name
    else:
        mc_suffix = ''

    # mc stuff now removed from basepath. Whatever was next, if present will be the first
    # suffix. ':/', recipe path start, marks the end of this. Something like
    # 'virtual:a[:b[:c]]:/path...' (b and c being optional)
    if basepath[0] != '/':
        cleaned += ':' + basepath.split(':/', 1)[0]

    return cleaned + mc_suffix

def clean_basepaths(a):
    b = {}
    for x in a:
        b[clean_basepath(x)] = a[x]
    return b

def clean_basepaths_list(a):
    b = []
    for x in a:
        b.append(clean_basepath(x))
    return b

# Handled renamed fields
def handle_renames(data):
    if 'basewhitelist' in data:
        data['basehash_ignore_vars'] = data['basewhitelist']
        del data['basewhitelist']
    if 'taskwhitelist' in data:
        data['taskhash_ignore_tasks'] = data['taskwhitelist']
        del data['taskwhitelist']


def compare_sigfiles(a, b, recursecb=None, color=False, collapsed=False):
    output = []

    colors = init_colors(color)
    def color_format(formatstr, **values):
        """
        Return colour formatted string.
        NOTE: call with the format string, not an already formatted string
        containing values (otherwise you could have trouble with { and }
        characters)
        """
        if not formatstr.endswith('{color_default}'):
            formatstr += '{color_default}'
        # In newer python 3 versions you can pass both of these directly,
        # but we only require 3.4 at the moment
        formatparams = {}
        formatparams.update(colors)
        formatparams.update(values)
        return formatstr.format(**formatparams)

    with bb.compress.zstd.open(a, "rt", encoding="utf-8", num_threads=1) as f:
        a_data = json.load(f, object_hook=SetDecoder)
    with bb.compress.zstd.open(b, "rt", encoding="utf-8", num_threads=1) as f:
        b_data = json.load(f, object_hook=SetDecoder)

    for data in [a_data, b_data]:
        handle_renames(data)

    def dict_diff(a, b, ignored_vars=set()):
        sa = set(a.keys())
        sb = set(b.keys())
        common = sa & sb
        changed = set()
        for i in common:
            if a[i] != b[i] and i not in ignored_vars:
                changed.add(i)
        added = sb - sa
        removed = sa - sb
        return changed, added, removed

    def file_checksums_diff(a, b):
        from collections import Counter

        # Convert lists back to tuples
        a = [(f[0], f[1]) for f in a]
        b = [(f[0], f[1]) for f in b]

        # Compare lists, ensuring we can handle duplicate filenames if they exist
        removedcount = Counter(a)
        removedcount.subtract(b)
        addedcount = Counter(b)
        addedcount.subtract(a)
        added = []
        for x in b:
            if addedcount[x] > 0:
                addedcount[x] -= 1
                added.append(x)
        removed = []
        changed = []
        for x in a:
            if removedcount[x] > 0:
                removedcount[x] -= 1
                for y in added:
                    if y[0] == x[0]:
                        changed.append((x[0], x[1], y[1]))
                        added.remove(y)
                        break
                else:
                    removed.append(x)
        added = [x[0] for x in added]
        removed = [x[0] for x in removed]
        return changed, added, removed

    if 'basehash_ignore_vars' in a_data and a_data['basehash_ignore_vars'] != b_data['basehash_ignore_vars']:
        output.append(color_format("{color_title}basehash_ignore_vars changed{color_default} from '%s' to '%s'") % (a_data['basehash_ignore_vars'], b_data['basehash_ignore_vars']))
        if a_data['basehash_ignore_vars'] and b_data['basehash_ignore_vars']:
            output.append("changed items: %s" % a_data['basehash_ignore_vars'].symmetric_difference(b_data['basehash_ignore_vars']))

    if 'taskhash_ignore_tasks' in a_data and a_data['taskhash_ignore_tasks'] != b_data['taskhash_ignore_tasks']:
        output.append(color_format("{color_title}taskhash_ignore_tasks changed{color_default} from '%s' to '%s'") % (a_data['taskhash_ignore_tasks'], b_data['taskhash_ignore_tasks']))
        if a_data['taskhash_ignore_tasks'] and b_data['taskhash_ignore_tasks']:
            output.append("changed items: %s" % a_data['taskhash_ignore_tasks'].symmetric_difference(b_data['taskhash_ignore_tasks']))

    if a_data['taskdeps'] != b_data['taskdeps']:
        output.append(color_format("{color_title}Task dependencies changed{color_default} from:\n%s\nto:\n%s") % (sorted(a_data['taskdeps']), sorted(b_data['taskdeps'])))

    if a_data['basehash'] != b_data['basehash'] and not collapsed:
        output.append(color_format("{color_title}basehash changed{color_default} from %s to %s") % (a_data['basehash'], b_data['basehash']))

    changed, added, removed = dict_diff(a_data['gendeps'], b_data['gendeps'], a_data['basehash_ignore_vars'] & b_data['basehash_ignore_vars'])
    if changed:
        for dep in sorted(changed):
            output.append(color_format("{color_title}List of dependencies for variable %s changed from '{color_default}%s{color_title}' to '{color_default}%s{color_title}'") % (dep, a_data['gendeps'][dep], b_data['gendeps'][dep]))
            if a_data['gendeps'][dep] and b_data['gendeps'][dep]:
                output.append("changed items: %s" % a_data['gendeps'][dep].symmetric_difference(b_data['gendeps'][dep]))
    if added:
        for dep in sorted(added):
            output.append(color_format("{color_title}Dependency on variable %s was added") % (dep))
    if removed:
        for dep in sorted(removed):
            output.append(color_format("{color_title}Dependency on Variable %s was removed") % (dep))


    changed, added, removed = dict_diff(a_data['varvals'], b_data['varvals'])
    if changed:
        for dep in sorted(changed):
            oldval = a_data['varvals'][dep]
            newval = b_data['varvals'][dep]
            if newval and oldval and ('\n' in oldval or '\n' in newval):
                diff = difflib.unified_diff(oldval.splitlines(), newval.splitlines(), lineterm='')
                # Cut off the first two lines, since we aren't interested in
                # the old/new filename (they are blank anyway in this case)
                difflines = list(diff)[2:]
                if color:
                    # Add colour to diff output
                    for i, line in enumerate(difflines):
                        if line.startswith('+'):
                            line = color_format('{color_add}{line}', line=line)
                            difflines[i] = line
                        elif line.startswith('-'):
                            line = color_format('{color_remove}{line}', line=line)
                            difflines[i] = line
                output.append(color_format("{color_title}Variable {var} value changed:{color_default}\n{diff}", var=dep, diff='\n'.join(difflines)))
            elif newval and oldval and (' ' in oldval or ' ' in newval):
                output.append(color_format("{color_title}Variable {var} value changed:{color_default}\n{diff}", var=dep, diff=worddiff_str(oldval, newval, colors)))
            else:
                output.append(color_format("{color_title}Variable {var} value changed from '{color_default}{oldval}{color_title}' to '{color_default}{newval}{color_title}'{color_default}", var=dep, oldval=oldval, newval=newval))

    if not 'file_checksum_values' in a_data:
         a_data['file_checksum_values'] = []
    if not 'file_checksum_values' in b_data:
         b_data['file_checksum_values'] = []

    changed, added, removed = file_checksums_diff(a_data['file_checksum_values'], b_data['file_checksum_values'])
    if changed:
        for f, old, new in changed:
            output.append(color_format("{color_title}Checksum for file %s changed{color_default} from %s to %s") % (f, old, new))
    if added:
        for f in added:
            output.append(color_format("{color_title}Dependency on checksum of file %s was added") % (f))
    if removed:
        for f in removed:
            output.append(color_format("{color_title}Dependency on checksum of file %s was removed") % (f))

    if not 'runtaskdeps' in a_data:
         a_data['runtaskdeps'] = {}
    if not 'runtaskdeps' in b_data:
         b_data['runtaskdeps'] = {}

    if not collapsed:
        if len(a_data['runtaskdeps']) != len(b_data['runtaskdeps']):
            changed = ["Number of task dependencies changed"]
        else:
            changed = []
            for idx, task in enumerate(a_data['runtaskdeps']):
                a = a_data['runtaskdeps'][idx]
                b = b_data['runtaskdeps'][idx]
                if a_data['runtaskhashes'][a] != b_data['runtaskhashes'][b] and not collapsed:
                    changed.append("%s with hash %s\n changed to\n%s with hash %s" % (clean_basepath(a), a_data['runtaskhashes'][a], clean_basepath(b), b_data['runtaskhashes'][b]))

        if changed:
            clean_a = clean_basepaths_list(a_data['runtaskdeps'])
            clean_b = clean_basepaths_list(b_data['runtaskdeps'])
            if clean_a != clean_b:
                output.append(color_format("{color_title}runtaskdeps changed:{color_default}\n%s") % list_inline_diff(clean_a, clean_b, colors))
            else:
                output.append(color_format("{color_title}runtaskdeps changed:"))
            output.append("\n".join(changed))


    if 'runtaskhashes' in a_data and 'runtaskhashes' in b_data:
        a = a_data['runtaskhashes']
        b = b_data['runtaskhashes']
        changed, added, removed = dict_diff(a, b)
        if added:
            for dep in sorted(added):
                bdep_found = False
                if removed:
                    for bdep in removed:
                        if b[dep] == a[bdep]:
                            #output.append("Dependency on task %s was replaced by %s with same hash" % (dep, bdep))
                            bdep_found = True
                if not bdep_found:
                    output.append(color_format("{color_title}Dependency on task %s was added{color_default} with hash %s") % (clean_basepath(dep), b[dep]))
        if removed:
            for dep in sorted(removed):
                adep_found = False
                if added:
                    for adep in added:
                        if b[adep] == a[dep]:
                            #output.append("Dependency on task %s was replaced by %s with same hash" % (adep, dep))
                            adep_found = True
                if not adep_found:
                    output.append(color_format("{color_title}Dependency on task %s was removed{color_default} with hash %s") % (clean_basepath(dep), a[dep]))
        if changed:
            for dep in sorted(changed):
                if not collapsed:
                    output.append(color_format("{color_title}Hash for task dependency %s changed{color_default} from %s to %s") % (clean_basepath(dep), a[dep], b[dep]))
                if callable(recursecb):
                    recout = recursecb(dep, a[dep], b[dep])
                    if recout:
                        if collapsed:
                            output.extend(recout)
                        else:
                            # If a dependent hash changed, might as well print the line above and then defer to the changes in
                            # that hash since in all likelyhood, they're the same changes this task also saw.
                            output = [output[-1]] + recout

    a_taint = a_data.get('taint', None)
    b_taint = b_data.get('taint', None)
    if a_taint != b_taint:
        if a_taint and a_taint.startswith('nostamp:'):
            a_taint = a_taint.replace('nostamp:', 'nostamp(uuid4):')
        if b_taint and b_taint.startswith('nostamp:'):
            b_taint = b_taint.replace('nostamp:', 'nostamp(uuid4):')
        output.append(color_format("{color_title}Taint (by forced/invalidated task) changed{color_default} from %s to %s") % (a_taint, b_taint))

    return output


def calc_basehash(sigdata):
    task = sigdata['task']
    basedata = sigdata['varvals'][task]

    if basedata is None:
        basedata = ''

    alldeps = sigdata['taskdeps']
    for dep in alldeps:
        basedata = basedata + dep
        val = sigdata['varvals'][dep]
        if val is not None:
            basedata = basedata + str(val)

    return hashlib.sha256(basedata.encode("utf-8")).hexdigest()

def calc_taskhash(sigdata):
    data = sigdata['basehash']

    for dep in sigdata['runtaskdeps']:
        data = data + sigdata['runtaskhashes'][dep]

    for c in sigdata['file_checksum_values']:
        if c[1]:
            if "./" in c[0]:
                data = data + c[0]
            data = data + c[1]

    if 'taint' in sigdata:
        if 'nostamp:' in sigdata['taint']:
            data = data + sigdata['taint'][8:]
        else:
            data = data + sigdata['taint']

    return hashlib.sha256(data.encode("utf-8")).hexdigest()


def dump_sigfile(a):
    output = []

    with bb.compress.zstd.open(a, "rt", encoding="utf-8", num_threads=1) as f:
        a_data = json.load(f, object_hook=SetDecoder)

    handle_renames(a_data)

    output.append("basehash_ignore_vars: %s" % (sorted(a_data['basehash_ignore_vars'])))

    output.append("taskhash_ignore_tasks: %s" % (sorted(a_data['taskhash_ignore_tasks'] or [])))

    output.append("Task dependencies: %s" % (sorted(a_data['taskdeps'])))

    output.append("basehash: %s" % (a_data['basehash']))

    for dep in sorted(a_data['gendeps']):
        output.append("List of dependencies for variable %s is %s" % (dep, sorted(a_data['gendeps'][dep])))

    for dep in sorted(a_data['varvals']):
        output.append("Variable %s value is %s" % (dep, a_data['varvals'][dep]))

    if 'runtaskdeps' in a_data:
        output.append("Tasks this task depends on: %s" % (sorted(a_data['runtaskdeps'])))

    if 'file_checksum_values' in a_data:
        output.append("This task depends on the checksums of files: %s" % (sorted(a_data['file_checksum_values'])))

    if 'runtaskhashes' in a_data:
        for dep in sorted(a_data['runtaskhashes']):
            output.append("Hash for dependent task %s is %s" % (dep, a_data['runtaskhashes'][dep]))

    if 'taint' in a_data:
        if a_data['taint'].startswith('nostamp:'):
            msg = a_data['taint'].replace('nostamp:', 'nostamp(uuid4):')
        else:
            msg = a_data['taint']
        output.append("Tainted (by forced/invalidated task): %s" % msg)

    if 'task' in a_data:
        computed_basehash = calc_basehash(a_data)
        output.append("Computed base hash is %s and from file %s" % (computed_basehash, a_data['basehash']))
    else:
        output.append("Unable to compute base hash")

    computed_taskhash = calc_taskhash(a_data)
    output.append("Computed task hash is %s" % computed_taskhash)

    return output