censor: make censor acquire locks before processing
Before this patch, "hg censor" executes below:
- without acquisition of wlock, examine whether the working
directory refers the revision of the file to be censored or not
- without acquisition of store lock (slock), replace existing
filelog of file to be censored with censored one,
Replacement consists of steps below, and it is assumed that the
destination filelog at (1) isn't changed before renaming at (3).
1. read existing filelog in
2. write filelog entries (both censored and not) into temporary file
3. rename from temporary file to existing filelog to be censored
It may cause unintentional result, if another command runs parallelly
(see also issue4368).
This patch makes "hg censor" acquire wlock and slock before
processing.
Corrupt an hg repo with two pulls.
create one repo with a long history
$ hg init source1
$ cd source1
$ touch foo
$ hg add foo
$ for i in 1 2 3 4 5 6 7 8 9 10; do
> echo $i >> foo
> hg ci -m $i
> done
$ cd ..
create one repo with a shorter history
$ hg clone -r 0 source1 source2
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd source2
$ echo a >> foo
$ hg ci -m a
$ cd ..
create a third repo to pull both other repos into it
$ hg init corrupted
$ cd corrupted
use a hook to make the second pull start while the first one is still running
$ echo '[hooks]' >> .hg/hgrc
$ echo 'prechangegroup = sleep 5' >> .hg/hgrc
start a pull...
$ hg pull ../source1 > pull.out 2>&1 &
... and start another pull before the first one has finished
$ sleep 1
$ hg pull ../source2 2>/dev/null
pulling from ../source2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
$ cat pull.out
pulling from ../source1
requesting all changes
adding changesets
adding manifests
adding file changes
added 10 changesets with 10 changes to 1 files
(run 'hg update' to get a working copy)
see the result
$ wait
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 11 changesets, 11 total revisions
$ cd ..