Mercurial > public > mercurial-scm > hg-stable
diff mercurial/dirstate.py @ 42472:87a34c767384
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
| author | Valentin Gatien-Baron <valentin.gatienbaron@gmail.com> |
|---|---|
| date | Mon, 27 May 2019 16:55:46 -0400 |
| parents | a3a8887e4426 |
| children | 760a7851e9ba |
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--- a/mercurial/dirstate.py Wed Jun 12 13:10:52 2019 -0400 +++ b/mercurial/dirstate.py Mon May 27 16:55:46 2019 -0400 @@ -391,12 +391,24 @@ 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) + 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)