# HG changeset patch
# User FUJIWARA Katsunori <fo...@lares.dti.ne.jp>
# Date 1474548717 -32400
# Thu Sep 22 21:51:57 2016 +0900
# Node ID 012c44bc655e19121818ab0c3e34bf610a6dc1cf
# Parent 6b0eb9c2264b6fe8d4d70dfe15c600058d9f0f41
vfs: use checkambigatclosing in checkambig=True but atomictemp=False case
In Mercurial source tree, opening a file in "a"/"a+" mode like below
doesn't specify atomictemp=True for vfs, and this avoids file stat
ambiguity check by atomictempfile.
- writing changes out in revlog layer uses "a+" mode
- truncation in repair.strip() uses "a" mode
- truncation in transaction._playback() uses "a" mode
If steps below occurs at "the same time in sec", all of mtime, ctime
and size are same between (1) and (3).
1. append data to revlog-style file (and close transaction)
2. discard appended data by truncation (strip or rollback)
3. append same size but different data to revlog-style file again
Therefore, cache validation doesn't work after (3) as expected.
This patch uses checkambigatclosing in checkambig=True but
atomictemp=False case, to check (and get rid of) file stat ambiguity
at closing.
This is a part of ExactCacheValidationPlan.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -587,6 +587,12 @@ class vfs(abstractvfs):
if nlink == 0:
self._fixfilemode(f)
+ if checkambig:
+ if mode in ('r', 'rb'):
+ raise error.Abort(_('implementation error: mode %s is not'
+ ' valid for checkambig=True') % mode)
+ fp = checkambigatclosing(fp)
+
if backgroundclose:
if not self._backgroundfilecloser:
raise error.Abort(_('backgroundclose can only be used when a '
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