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Differential D6474

tests: show how the dirstate can end up containing wrong information
ClosedPublic

Authored by valentin.gatienbaron on Jun 3 2019, 9:00 AM.

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rHG0eb8c61c306b: tests: show how the dirstate can end up containing wrong information
rHGd9a50456ea3d: tests: show how the dirstate can end up containing wrong information
Summary

which can result in bad status output.

Concretely, this seems to be easily triggered by having a build system
watching the filesystem for changes, and rebuilding files that are
both tracked and generated while an update is happening.

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AMtests/test-dirstate-race2.t (39 lines)

Diff 15488

tests/test-dirstate-race2.t

  • This file was added.
Checking the size/permissions/file-type of files stored in the
dirstate after an update where the files are changed concurrently
outside of hg's control.
$ hg init repo
$ cd repo
$ echo a > a
$ hg commit -qAm _
$ echo aa > a
$ hg commit -m _
$ hg debugdirstate --no-dates
n 644 3 (set |unset) a (re)
$ cat >> $TESTTMP/dirstaterace.py << EOF
> from mercurial import (
> extensions,
> merge,
> )
> def extsetup(ui):
> extensions.wrapfunction(merge, 'applyupdates', wrap)
> def wrap(orig, *args, **kwargs):
> res = orig(*args, **kwargs)
> with open("a", "w"):
> pass # just truncate the file
> return res
> EOF
Do an update where file 'a' is changed between hg writing it to disk
and hg writing the dirstate. It results in a corrupted dirstate, which
stores the wrong size, and thus hg status shows spuriously modified
files.
$ hg up -r 0 --config extensions.race=$TESTTMP/dirstaterace.py
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg debugdirstate --no-dates
n 644 0 (set |unset) a (re)
$ echo a > a; hg status; hg diff
M a