mercurial/verify.py

merge: add a config to allow conflict-free merge of changes on adjacent lines

This change adds a config to make it no longer a conflict to merge changes
made on adjacent lines.

The reason these changes are considered a conflict is that there's no
region of text at the relevant position (sync region) that's kept unchanged
by both sides of the merge.

The problem can be solved by making the sync regions being a bit more
powerful: we can keep a 0-length sync region if we find that
a block unchanged by one side is ajacent to a block unchanged by the
other side.

Since these 0-length sync regions are emitted using the ~same algorithm
as the normal non-empty sync regions, this change involves no arbitrary
decisions and I expect it to work pretty well.

0-length sync regions do create an ambiguity in a special case where two
pairs of adjacent regions "meet" at the same point. This corresponds to
an insertion made at the same place by the two sides of the merge, and
this still results in a conflict.

# verify.py - repository integrity checking for Mercurial
#
# Copyright 2006, 2007 Olivia Mackall <[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.

from __future__ import annotations

import os

from .i18n import _
from .node import short
from .utils import stringutil

from . import (
    error,
    pycompat,
    requirements,
    revlog,
    transaction,
    util,
)

VERIFY_DEFAULT = 0
VERIFY_FULL = 1


def verify(repo, level=None):
    with repo.lock():
        v = verifier(repo, level)
        return v.verify()


def _normpath(f: bytes) -> bytes:
    # under hg < 2.4, convert didn't sanitize paths properly, so a
    # converted repo may contain repeated slashes
    while b'//' in f:
        f = f.replace(b'//', b'/')
    return f


HINT_FNCACHE = _(
    b'hint: run "hg debugrebuildfncache" to recover from corrupt fncache\n'
)

WARN_PARENT_DIR_UNKNOWN_REV = _(
    b"parent-directory manifest refers to unknown revision %s"
)

WARN_UNKNOWN_COPY_SOURCE = _(
    b"warning: copy source of '%s' not in parents of %s"
)

WARN_NULLID_COPY_SOURCE = _(
    b"warning: %s@%s: copy source revision is nullid %s:%s\n"
)


class verifier:
    def __init__(self, repo, level=None):
        self.repo = repo.unfiltered()
        self.ui = repo.ui
        self.match = repo.narrowmatch()
        if level is None:
            level = VERIFY_DEFAULT
        self._level = level
        self.badrevs = set()
        self.errors = 0
        self.warnings = 0
        self.havecl = len(repo.changelog) > 0
        self.havemf = len(repo.manifestlog.getstorage(b'')) > 0
        self.revlogv1 = repo.changelog._format_version != revlog.REVLOGV0
        self.lrugetctx = util.lrucachefunc(repo.unfiltered().__getitem__)
        self.refersmf = False
        self.fncachewarned = False
        # developer config: verify.skipflags
        self.skipflags = repo.ui.configint(b'verify', b'skipflags')
        self.warnorphanstorefiles = True

    def _warn(self, msg):
        """record a "warning" level issue"""
        self.ui.warn(msg + b"\n")
        self.warnings += 1

    def _err(self, linkrev, msg, filename=None):
        """record a "error" level issue"""
        if linkrev is not None:
            self.badrevs.add(linkrev)
            linkrev = b"%d" % linkrev
        else:
            linkrev = b'?'
        msg = b"%s: %s" % (linkrev, msg)
        if filename:
            msg = b"%s@%s" % (filename, msg)
        self.ui.warn(b" " + msg + b"\n")
        self.errors += 1

    def _exc(self, linkrev, msg, inst, filename=None):
        """record exception raised during the verify process"""
        fmsg = stringutil.forcebytestr(inst)
        if not fmsg:
            fmsg = pycompat.byterepr(inst)
        self._err(linkrev, b"%s: %s" % (msg, fmsg), filename)

    def _checkrevlog(self, obj, name, linkrev):
        """verify high level property of a revlog

        - revlog is present,
        - revlog is non-empty,
        - sizes (index and data) are correct,
        - revlog's format version is correct.
        """
        if not len(obj) and (self.havecl or self.havemf):
            self._err(linkrev, _(b"empty or missing %s") % name)
            return

        d = obj.checksize()
        if d[0]:
            self._err(None, _(b"data length off by %d bytes") % d[0], name)
        if d[1]:
            self._err(None, _(b"index contains %d extra bytes") % d[1], name)

        if obj._format_version != revlog.REVLOGV0:
            if not self.revlogv1:
                self._warn(_(b"warning: `%s' uses revlog format 1") % name)
        elif self.revlogv1:
            self._warn(_(b"warning: `%s' uses revlog format 0") % name)

    def _checkentry(self, obj, i, node, seen, linkrevs, f):
        """verify a single revlog entry

        arguments are:
        - obj:      the source revlog
        - i:        the revision number
        - node:     the revision node id
        - seen:     nodes previously seen for this revlog
        - linkrevs: [changelog-revisions] introducing "node"
        - f:        string label ("changelog", "manifest", or filename)

        Performs the following checks:
        - linkrev points to an existing changelog revision,
        - linkrev points to a changelog revision that introduces this revision,
        - linkrev points to the lowest of these changesets,
        - both parents exist in the revlog,
        - the revision is not duplicated.

        Return the linkrev of the revision (or None for changelog's revisions).
        """
        lr = obj.linkrev(obj.rev(node))
        if lr < 0 or (self.havecl and lr not in linkrevs):
            if lr < 0 or lr >= len(self.repo.changelog):
                msg = _(b"rev %d points to nonexistent changeset %d")
            else:
                msg = _(b"rev %d points to unexpected changeset %d")
            self._err(None, msg % (i, lr), f)
            if linkrevs:
                if f and len(linkrevs) > 1:
                    try:
                        # attempt to filter down to real linkrevs
                        linkrevs = []
                        for lr in linkrevs:
                            if self.lrugetctx(lr)[f].filenode() == node:
                                linkrevs.append(lr)
                    except Exception:
                        pass
                msg = _(b" (expected %s)")
                msg %= b" ".join(map(pycompat.bytestr, linkrevs))
                self._warn(msg)
            lr = None  # can't be trusted

        try:
            p1, p2 = obj.parents(node)
            if p1 not in seen and p1 != self.repo.nullid:
                msg = _(b"unknown parent 1 %s of %s") % (short(p1), short(node))
                self._err(lr, msg, f)
            if p2 not in seen and p2 != self.repo.nullid:
                msg = _(b"unknown parent 2 %s of %s") % (short(p2), short(node))
                self._err(lr, msg, f)
        except Exception as inst:
            self._exc(lr, _(b"checking parents of %s") % short(node), inst, f)

        if node in seen:
            self._err(lr, _(b"duplicate revision %d (%d)") % (i, seen[node]), f)
        seen[node] = i
        return lr

    def verify(self):
        """verify the content of the Mercurial repository

        This method run all verifications, displaying issues as they are found.

        return 1 if any error have been encountered, 0 otherwise."""
        # initial validation and generic report
        repo = self.repo
        ui = repo.ui
        if not repo.url().startswith(b'file:'):
            raise error.Abort(_(b"cannot verify bundle or remote repos"))

        if transaction.has_abandoned_transaction(repo):
            ui.warn(_(b"abandoned transaction found - run hg recover\n"))

        if ui.verbose or not self.revlogv1:
            ui.status(
                _(b"repository uses revlog format %d\n")
                % (self.revlogv1 and 1 or 0)
            )

        # data verification
        mflinkrevs, filelinkrevs = self._verifychangelog()
        filenodes = self._verifymanifest(mflinkrevs)
        del mflinkrevs
        self._crosscheckfiles(filelinkrevs, filenodes)
        totalfiles, filerevisions = self._verifyfiles(filenodes, filelinkrevs)

        if self.errors:
            ui.warn(_(b"not checking dirstate because of previous errors\n"))
            dirstate_errors = 0
        else:
            dirstate_errors = self._verify_dirstate()

        # final report
        ui.status(
            _(b"checked %d changesets with %d changes to %d files\n")
            % (len(repo.changelog), filerevisions, totalfiles)
        )
        if self.warnings:
            ui.warn(_(b"%d warnings encountered!\n") % self.warnings)
        if self.fncachewarned:
            ui.warn(HINT_FNCACHE)
        if self.errors:
            ui.warn(_(b"%d integrity errors encountered!\n") % self.errors)
            if self.badrevs:
                msg = _(b"(first damaged changeset appears to be %d)\n")
                msg %= min(self.badrevs)
                ui.warn(msg)
            if dirstate_errors:
                ui.warn(
                    _(b"dirstate inconsistent with current parent's manifest\n")
                )
                ui.warn(_(b"%d dirstate errors\n") % dirstate_errors)
            return 1
        return 0

    def _verifychangelog(self):
        """verify the changelog of a repository

        The following checks are performed:
        - all of `_checkrevlog` checks,
        - all of `_checkentry` checks (for each revisions),
        - each revision can be read.

        The function returns some of the data observed in the changesets as a
        (mflinkrevs, filelinkrevs) tuples:
        - mflinkrevs:   is a { manifest-node -> [changelog-rev] } mapping
        - filelinkrevs: is a { file-path -> [changelog-rev] } mapping

        If a matcher was specified, filelinkrevs will only contains matched
        files.
        """
        ui = self.ui
        repo = self.repo
        match = self.match
        cl = repo.changelog

        ui.status(_(b"checking changesets\n"))
        mflinkrevs = {}
        filelinkrevs = {}
        seen = {}
        self._checkrevlog(cl, b"changelog", 0)
        progress = ui.makeprogress(
            _(b'checking'), unit=_(b'changesets'), total=len(repo)
        )
        with cl.reading():
            for i in repo:
                progress.update(i)
                n = cl.node(i)
                self._checkentry(cl, i, n, seen, [i], b"changelog")

                try:
                    changes = cl.read(n)
                    if changes[0] != self.repo.nullid:
                        mflinkrevs.setdefault(changes[0], []).append(i)
                        self.refersmf = True
                    for f in changes[3]:
                        if match(f):
                            filelinkrevs.setdefault(_normpath(f), []).append(i)
                except Exception as inst:
                    self.refersmf = True
                    self._exc(i, _(b"unpacking changeset %s") % short(n), inst)
        progress.complete()
        return mflinkrevs, filelinkrevs

    def _verifymanifest(
        self, mflinkrevs, dir=b"", storefiles=None, subdirprogress=None
    ):
        """verify the manifestlog content

        Inputs:
        - mflinkrevs:     a {manifest-node -> [changelog-revisions]} mapping
        - dir:            a subdirectory to check (for tree manifest repo)
        - storefiles:     set of currently "orphan" files.
        - subdirprogress: a progress object

        This function checks:
        * all of `_checkrevlog` checks (for all manifest related revlogs)
        * all of `_checkentry` checks (for all manifest related revisions)
        * nodes for subdirectory exists in the sub-directory manifest
        * each manifest entries have a file path
        * each manifest node refered in mflinkrevs exist in the manifest log

        If tree manifest is in use and a matchers is specified, only the
        sub-directories matching it will be verified.

        return a two level mapping:
            {"path" -> { filenode -> changelog-revision}}

        This mapping primarily contains entries for every files in the
        repository. In addition, when tree-manifest is used, it also contains
        sub-directory entries.

        If a matcher is provided, only matching paths will be included.
        """
        repo = self.repo
        ui = self.ui
        match = self.match
        mfl = self.repo.manifestlog
        mf = mfl.getstorage(dir)

        if not dir:
            self.ui.status(_(b"checking manifests\n"))

        filenodes = {}
        subdirnodes = {}
        seen = {}
        label = b"manifest"
        if dir:
            label = dir
            revlogfiles = mf.files()
            storefiles.difference_update(revlogfiles)
            if subdirprogress:  # should be true since we're in a subdirectory
                subdirprogress.increment()
        if self.refersmf:
            # Do not check manifest if there are only changelog entries with
            # null manifests.
            self._checkrevlog(mf._revlog, label, 0)
        progress = ui.makeprogress(
            _(b'checking'), unit=_(b'manifests'), total=len(mf)
        )
        for i in mf:
            if not dir:
                progress.update(i)
            n = mf.node(i)
            lr = self._checkentry(mf, i, n, seen, mflinkrevs.get(n, []), label)
            if n in mflinkrevs:
                del mflinkrevs[n]
            elif dir:
                msg = _(b"%s not in parent-directory manifest") % short(n)
                self._err(lr, msg, label)
            else:
                self._err(lr, _(b"%s not in changesets") % short(n), label)

            try:
                mfdelta = mfl.get(dir, n).read_delta_new_entries(shallow=True)
                for f, fn, fl in mfdelta.iterentries():
                    if not f:
                        self._err(lr, _(b"entry without name in manifest"))
                    elif f == b"/dev/null":  # ignore this in very old repos
                        continue
                    fullpath = dir + _normpath(f)
                    if fl == b't':
                        if not match.visitdir(fullpath):
                            continue
                        sdn = subdirnodes.setdefault(fullpath + b'/', {})
                        sdn.setdefault(fn, []).append(lr)
                    else:
                        if not match(fullpath):
                            continue
                        filenodes.setdefault(fullpath, {}).setdefault(fn, lr)
            except Exception as inst:
                self._exc(lr, _(b"reading delta %s") % short(n), inst, label)
            if self._level >= VERIFY_FULL:
                try:
                    # Various issues can affect manifest. So we read each full
                    # text from storage. This triggers the checks from the core
                    # code (eg: hash verification, filename are ordered, etc.)
                    mfdelta = mfl.get(dir, n).read()
                except Exception as inst:
                    msg = _(b"reading full manifest %s") % short(n)
                    self._exc(lr, msg, inst, label)

        if not dir:
            progress.complete()

        if self.havemf:
            # since we delete entry in `mflinkrevs` during iteration, any
            # remaining entries are "missing". We need to issue errors for them.
            changesetpairs = [(c, m) for m in mflinkrevs for c in mflinkrevs[m]]
            for c, m in sorted(changesetpairs):
                if dir:
                    self._err(c, WARN_PARENT_DIR_UNKNOWN_REV % short(m), label)
                else:
                    msg = _(b"changeset refers to unknown revision %s")
                    msg %= short(m)
                    self._err(c, msg, label)

        if not dir and subdirnodes:
            self.ui.status(_(b"checking directory manifests\n"))
            storefiles = set()
            subdirs = set()
            revlogv1 = self.revlogv1
            undecodable = []
            for entry in repo.store.data_entries(undecodable=undecodable):
                for file_ in entry.files():
                    f = file_.unencoded_path
                    size = file_.file_size(repo.store.vfs)
                    if (size > 0 or not revlogv1) and f.startswith(b'meta/'):
                        storefiles.add(_normpath(f))
                        subdirs.add(os.path.dirname(f))
            for f in undecodable:
                self._err(None, _(b"cannot decode filename '%s'") % f)
            subdirprogress = ui.makeprogress(
                _(b'checking'), unit=_(b'manifests'), total=len(subdirs)
            )

        for subdir, linkrevs in subdirnodes.items():
            subdirfilenodes = self._verifymanifest(
                linkrevs, subdir, storefiles, subdirprogress
            )
            for f, onefilenodes in subdirfilenodes.items():
                filenodes.setdefault(f, {}).update(onefilenodes)

        if not dir and subdirnodes:
            assert subdirprogress is not None  # help pytype
            subdirprogress.complete()
            if self.warnorphanstorefiles:
                for f in sorted(storefiles):
                    self._warn(_(b"warning: orphan data file '%s'") % f)

        return filenodes

    def _crosscheckfiles(self, filelinkrevs, filenodes):
        repo = self.repo
        ui = self.ui
        ui.status(_(b"crosschecking files in changesets and manifests\n"))

        total = len(filelinkrevs) + len(filenodes)
        progress = ui.makeprogress(
            _(b'crosschecking'), unit=_(b'files'), total=total
        )
        if self.havemf:
            for f in sorted(filelinkrevs):
                progress.increment()
                if f not in filenodes:
                    lr = filelinkrevs[f][0]
                    self._err(lr, _(b"in changeset but not in manifest"), f)

        if self.havecl:
            for f in sorted(filenodes):
                progress.increment()
                if f not in filelinkrevs:
                    try:
                        fl = repo.file(f)
                        lr = min([fl.linkrev(fl.rev(n)) for n in filenodes[f]])
                    except Exception:
                        lr = None
                    self._err(lr, _(b"in manifest but not in changeset"), f)

        progress.complete()

    def _verifyfiles(self, filenodes, filelinkrevs):
        repo = self.repo
        ui = self.ui
        lrugetctx = self.lrugetctx
        revlogv1 = self.revlogv1
        havemf = self.havemf
        ui.status(_(b"checking files\n"))

        storefiles = set()
        undecodable = []
        for entry in repo.store.data_entries(undecodable=undecodable):
            for file_ in entry.files():
                size = file_.file_size(repo.store.vfs)
                f = file_.unencoded_path
                if (size > 0 or not revlogv1) and f.startswith(b'data/'):
                    storefiles.add(_normpath(f))
        for f in undecodable:
            self._err(None, _(b"cannot decode filename '%s'") % f)

        state = {
            # TODO this assumes revlog storage for changelog.
            b'expectedversion': self.repo.changelog._format_version,
            b'skipflags': self.skipflags,
            # experimental config: censor.policy
            b'erroroncensored': ui.config(b'censor', b'policy') == b'abort',
        }

        files = sorted(set(filenodes) | set(filelinkrevs))
        revisions = 0
        progress = ui.makeprogress(
            _(b'checking'), unit=_(b'files'), total=len(files)
        )
        for i, f in enumerate(files):
            progress.update(i, item=f)
            try:
                linkrevs = filelinkrevs[f]
            except KeyError:
                # in manifest but not in changelog
                linkrevs = []

            if linkrevs:
                lr = linkrevs[0]
            else:
                lr = None

            try:
                fl = repo.file(f)
            except error.StorageError as e:
                self._err(lr, _(b"broken revlog! (%s)") % e, f)
                continue

            for ff in fl.files():
                try:
                    storefiles.remove(ff)
                except KeyError:
                    if self.warnorphanstorefiles:
                        msg = _(b" warning: revlog '%s' not in fncache!")
                        self._warn(msg % ff)
                        self.fncachewarned = True

            if not len(fl) and (self.havecl or self.havemf):
                self._err(lr, _(b"empty or missing %s") % f)
            else:
                # Guard against implementations not setting this.
                state[b'skipread'] = set()
                state[b'safe_renamed'] = set()

                for problem in fl.verifyintegrity(state):
                    if problem.node is not None:
                        linkrev = fl.linkrev(fl.rev(problem.node))
                    else:
                        linkrev = None

                    if problem.warning:
                        self._warn(problem.warning)
                    elif problem.error:
                        linkrev_msg = linkrev if linkrev is not None else lr
                        self._err(linkrev_msg, problem.error, f)
                    else:
                        raise error.ProgrammingError(
                            b'problem instance does not set warning or error '
                            b'attribute: %s' % problem.msg
                        )

            seen = {}
            for i in fl:
                revisions += 1
                n = fl.node(i)
                lr = self._checkentry(fl, i, n, seen, linkrevs, f)
                if f in filenodes:
                    if havemf and n not in filenodes[f]:
                        self._err(lr, _(b"%s not in manifests") % (short(n)), f)
                    else:
                        del filenodes[f][n]

                if n in state[b'skipread'] and n not in state[b'safe_renamed']:
                    continue

                # check renames
                try:
                    # This requires resolving fulltext (at least on revlogs,
                    # though not with LFS revisions). We may want
                    # ``verifyintegrity()`` to pass a set of nodes with
                    # rename metadata as an optimization.
                    rp = fl.renamed(n)
                    if rp:
                        if lr is not None and ui.verbose:
                            ctx = lrugetctx(lr)
                            if not any(rp[0] in pctx for pctx in ctx.parents()):
                                self._warn(WARN_UNKNOWN_COPY_SOURCE % (f, ctx))
                        fl2 = repo.file(rp[0])
                        if not len(fl2):
                            m = _(b"empty or missing copy source revlog %s:%s")
                            self._err(lr, m % (rp[0], short(rp[1])), f)
                        elif rp[1] == self.repo.nullid:
                            msg = WARN_NULLID_COPY_SOURCE
                            msg %= (f, lr, rp[0], short(rp[1]))
                            ui.note(msg)
                        else:
                            fl2.rev(rp[1])
                except Exception as inst:
                    self._exc(
                        lr, _(b"checking rename of %s") % short(n), inst, f
                    )

            # cross-check
            if f in filenodes:
                fns = [(v, k) for k, v in filenodes[f].items()]
                for lr, node in sorted(fns):
                    msg = _(b"manifest refers to unknown revision %s")
                    self._err(lr, msg % short(node), f)
        progress.complete()

        if self.warnorphanstorefiles:
            for f in sorted(storefiles):
                self._warn(_(b"warning: orphan data file '%s'") % f)

        return len(files), revisions

    def _verify_dirstate(self):
        """Check that the dirstate is consistent with the parent's manifest"""
        repo = self.repo
        ui = self.ui
        ui.status(_(b"checking dirstate\n"))

        parent1, parent2 = repo.dirstate.parents()
        m1 = repo[parent1].manifest()
        m2 = repo[parent2].manifest()
        dirstate_errors = 0

        is_narrow = requirements.NARROW_REQUIREMENT in repo.requirements
        narrow_matcher = repo.narrowmatch() if is_narrow else None

        for err in repo.dirstate.verify(m1, m2, parent1, narrow_matcher):
            ui.error(err)
            dirstate_errors += 1

        if dirstate_errors:
            self.errors += dirstate_errors
        return dirstate_errors