mercurial/grep.py

revlog: avoid possible collision between directory and temporary index

Since 6.4, we create a temporary index file to write the split data without
overwriting the inline version too early. However, the store encoding does not
prevent these new `.i.s` file to collide with a directory with the same name.
While the odds for such a collision to happens are fairly low, the collision
would prevent Mercurial from working.

The store encoding have a mitigation solution in place to prevent such
collisions from happening for `.i` and `.d` files, but not for other extensions.
We cannot update this encoding scheme to solve the issue since it would diverge
from older version of Mercurial.

Instead, we create an alternative directory tree dedicated to such files.
The use of the `.i` extension combined with store encoding will prevent
collisions there.

# grep.py - logic for history walk and grep
#
# Copyright 2005-2007 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.


import difflib

from .i18n import _

from . import (
    error,
    match as matchmod,
    pycompat,
    scmutil,
    util,
)


def matchlines(body, regexp):
    begin = 0
    linenum = 0
    while begin < len(body):
        match = regexp.search(body, begin)
        if not match:
            break
        mstart, mend = match.span()
        linenum += body.count(b'\n', begin, mstart) + 1
        lstart = body.rfind(b'\n', begin, mstart) + 1 or begin
        begin = body.find(b'\n', mend) + 1 or len(body) + 1
        lend = begin - 1
        yield linenum, mstart - lstart, mend - lstart, body[lstart:lend]


class linestate:
    def __init__(self, line, linenum, colstart, colend):
        self.line = line
        self.linenum = linenum
        self.colstart = colstart
        self.colend = colend

    def __hash__(self):
        return hash(self.line)

    def __eq__(self, other):
        return self.line == other.line

    def findpos(self, regexp):
        """Iterate all (start, end) indices of matches"""
        yield self.colstart, self.colend
        p = self.colend
        while p < len(self.line):
            m = regexp.search(self.line, p)
            if not m:
                break
            if m.end() == p:
                p += 1
            else:
                yield m.span()
                p = m.end()


def difflinestates(a, b):
    sm = difflib.SequenceMatcher(None, a, b)
    for tag, alo, ahi, blo, bhi in sm.get_opcodes():
        if tag == 'insert':
            for i in range(blo, bhi):
                yield (b'+', b[i])
        elif tag == 'delete':
            for i in range(alo, ahi):
                yield (b'-', a[i])
        elif tag == 'replace':
            for i in range(alo, ahi):
                yield (b'-', a[i])
            for i in range(blo, bhi):
                yield (b'+', b[i])


class grepsearcher:
    """Search files and revisions for lines matching the given pattern

    Options:
    - all_files to search unchanged files at that revision.
    - diff to search files in the parent revision so diffs can be generated.
    - follow to skip files across copies and renames.
    """

    def __init__(
        self, ui, repo, regexp, all_files=False, diff=False, follow=False
    ):
        self._ui = ui
        self._repo = repo
        self._regexp = regexp
        self._all_files = all_files
        self._diff = diff
        self._follow = follow

        self._getfile = util.lrucachefunc(repo.file)
        self._getrenamed = scmutil.getrenamedfn(repo)

        self._matches = {}
        self._copies = {}
        self._skip = set()
        self._revfiles = {}

    def skipfile(self, fn, rev):
        """Exclude the given file (and the copy at the specified revision)
        from future search"""
        copy = self._copies.get(rev, {}).get(fn)
        self._skip.add(fn)
        if copy:
            self._skip.add(copy)

    def searchfiles(self, revs, makefilematcher):
        """Walk files and revisions to yield (fn, ctx, pstates, states)
        matches

        states is a list of linestate objects. pstates may be empty unless
        diff is True.
        """
        for ctx in scmutil.walkchangerevs(
            self._repo, revs, makefilematcher, self._prep
        ):
            rev = ctx.rev()
            parent = ctx.p1().rev()
            for fn in sorted(self._revfiles.get(rev, [])):
                states = self._matches[rev][fn]
                copy = self._copies.get(rev, {}).get(fn)
                if fn in self._skip:
                    if copy:
                        self._skip.add(copy)
                    continue
                pstates = self._matches.get(parent, {}).get(copy or fn, [])
                if pstates or states:
                    yield fn, ctx, pstates, states
            del self._revfiles[rev]
            # We will keep the matches dict for the duration of the window
            # clear the matches dict once the window is over
            if not self._revfiles:
                self._matches.clear()

    def _grepbody(self, fn, rev, body):
        self._matches[rev].setdefault(fn, [])
        m = self._matches[rev][fn]
        if body is None:
            return

        for lnum, cstart, cend, line in matchlines(body, self._regexp):
            s = linestate(line, lnum, cstart, cend)
            m.append(s)

    def _readfile(self, ctx, fn):
        rev = ctx.rev()
        if rev is None:
            fctx = ctx[fn]
            try:
                return fctx.data()
            except FileNotFoundError:
                pass
        else:
            flog = self._getfile(fn)
            fnode = ctx.filenode(fn)
            try:
                return flog.read(fnode)
            except error.CensoredNodeError:
                self._ui.warn(
                    _(
                        b'cannot search in censored file: '
                        b'%(filename)s:%(revnum)s\n'
                    )
                    % {b'filename': fn, b'revnum': pycompat.bytestr(rev)}
                )

    def _prep(self, ctx, fmatch):
        rev = ctx.rev()
        pctx = ctx.p1()
        self._matches.setdefault(rev, {})
        if self._diff:
            parent = pctx.rev()
            self._matches.setdefault(parent, {})
        files = self._revfiles.setdefault(rev, [])
        if rev is None:
            # in `hg grep pattern`, 2/3 of the time is spent is spent in
            # pathauditor checks without this in mozilla-central
            contextmanager = self._repo.wvfs.audit.cached
        else:
            contextmanager = util.nullcontextmanager
        with contextmanager():
            # TODO: maybe better to warn missing files?
            if self._all_files:
                fmatch = matchmod.badmatch(fmatch, lambda f, msg: None)
                filenames = ctx.matches(fmatch)
            else:
                filenames = (f for f in ctx.files() if fmatch(f))
            for fn in filenames:
                # fn might not exist in the revision (could be a file removed by
                # the revision). We could check `fn not in ctx` even when rev is
                # None, but it's less racy to protect againt that in readfile.
                if rev is not None and fn not in ctx:
                    continue

                copy = None
                if self._follow:
                    copy = self._getrenamed(fn, rev)
                    if copy:
                        self._copies.setdefault(rev, {})[fn] = copy
                        if fn in self._skip:
                            self._skip.add(copy)
                if fn in self._skip:
                    continue
                files.append(fn)

                if fn not in self._matches[rev]:
                    self._grepbody(fn, rev, self._readfile(ctx, fn))

                if self._diff:
                    pfn = copy or fn
                    if pfn not in self._matches[parent] and pfn in pctx:
                        self._grepbody(pfn, parent, self._readfile(pctx, pfn))