comparison mercurial/dirstate.py @ 42456:87a34c767384

merge: fix race that could cause wrong size in dirstate

The problem is that hg merge/update/etc work the following way:
1. figure out what files to update
2. apply the update to disk
3. apply the update to in-memory dirstate
4. write dirstate

where step3 looks at the filesystem and assumes it sees the result of
step2. If a file is changed between step2 and step3, step3 will record
incorrect information in the dirstate.

I avoid this by passing the size step3 needs directly from step2, for
the common path (not implemented for change/delete conflicts for
instance).

I didn't fix the same race for the exec bit for now, because it's less
likely to be problematic and I had trouble due to the fact that the
dirstate stores the permissions differently from the manifest (st_mode
vs '' 'l' 'x'), in combination with tests that pretend that symlinks
are not supported.

However, I moved the lstat from step3 to step2, which should tighten
the race window markedly, both for the exec bit and for the mtime.

Differential Revision: https://phab.mercurial-scm.org/D6475

42455:5ca136bbd3f6

                        (pycompat.bytestr(d), pycompat.bytestr(f)))
        self._dirty = True
        self._updatedfiles.add(f)
        self._map.addfile(f, oldstate, state, mode, size, mtime)

    def normal(self, f):
        '''Mark a file normal and clean.'''
        s = os.lstat(self._join(f))
        mtime = s[stat.ST_MTIME]
        self._addpath(f, 'n', s.st_mode,
                      s.st_size & _rangemask, mtime & _rangemask)
        self._map.copymap.pop(f, None)
        if f in self._map.nonnormalset:
            self._map.nonnormalset.remove(f)
        if mtime > self._lastnormaltime:
            # Remember the most recent modification timeslot for status(),

42456:87a34c767384

                        (pycompat.bytestr(d), pycompat.bytestr(f)))
        self._dirty = True
        self._updatedfiles.add(f)
        self._map.addfile(f, oldstate, state, mode, size, mtime)

    def normal(self, f, parentfiledata=None):
        '''Mark a file normal and clean.

        parentfiledata: (mode, size, mtime) of the clean file

        parentfiledata should be computed from memory (for mode,
        size), as or close as possible from the point where we
        determined the file was clean, to limit the risk of the
        file having been changed by an external process between the
        moment where the file was determined to be clean and now.'''
        if parentfiledata:
            (mode, size, mtime) = parentfiledata
        else:
            s = os.lstat(self._join(f))
            mode = s.st_mode
            size = s.st_size
            mtime = s[stat.ST_MTIME]
        self._addpath(f, 'n', mode, size & _rangemask, mtime & _rangemask)
        self._map.copymap.pop(f, None)
        if f in self._map.nonnormalset:
            self._map.nonnormalset.remove(f)
        if mtime > self._lastnormaltime:
            # Remember the most recent modification timeslot for status(),