scmutil: add file object wrapper class to check ambiguity at closing
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 adds file object wrapper class checkambigatclosing to check
(and get rid of) ambiguity at closing. It is used by vfs in subsequent
patch.
This is a part of ExactCacheValidationPlan.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
BTW, checkambigatclosing is tested in test-filecache.py, even though
it doesn't use filecache itself, because filecache assumes that file
stat ambiguity never occurs (and there is no another test-*.py related
to filecache).
https://bz.mercurial-scm.org/660 and:
https://bz.mercurial-scm.org/322
$ hg init
$ echo a > a
$ mkdir b
$ echo b > b/b
$ hg commit -A -m "a is file, b is dir"
adding a
adding b/b
File replaced with directory:
$ rm a
$ mkdir a
$ echo a > a/a
Should fail - would corrupt dirstate:
$ hg add a/a
abort: file 'a' in dirstate clashes with 'a/a'
[255]
Removing shadow:
$ hg rm --after a
Should succeed - shadow removed:
$ hg add a/a
Directory replaced with file:
$ rm -r b
$ echo b > b
Should fail - would corrupt dirstate:
$ hg add b
abort: directory 'b' already in dirstate
[255]
Removing shadow:
$ hg rm --after b/b
Should succeed - shadow removed:
$ hg add b
Look what we got:
$ hg st
A a/a
A b
R a
R b/b
Revert reintroducing shadow - should fail:
$ rm -r a b
$ hg revert b/b
abort: file 'b' in dirstate clashes with 'b/b'
[255]
Revert all - should succeed:
$ hg revert --all
undeleting a
forgetting a/a (glob)
forgetting b
undeleting b/b (glob)
$ hg st
Issue3423:
$ hg forget a
$ echo zed > a
$ hg revert a
$ hg st
? a.orig
$ rm a.orig
addremove:
$ rm -r a b
$ mkdir a
$ echo a > a/a
$ echo b > b
$ hg addremove -s 0
removing a
adding a/a
adding b
removing b/b
$ hg st
A a/a
A b
R a
R b/b
commit:
$ hg ci -A -m "a is dir, b is file"
$ hg st --all
C a/a
C b
Long directory replaced with file:
$ mkdir d
$ mkdir d/d
$ echo d > d/d/d
$ hg commit -A -m "d is long directory"
adding d/d/d
$ rm -r d
$ echo d > d
Should fail - would corrupt dirstate:
$ hg add d
abort: directory 'd' already in dirstate
[255]
Removing shadow:
$ hg rm --after d/d/d
Should succeed - shadow removed:
$ hg add d
$ hg ci -md
Update should work at least with clean working directory:
$ rm -r a b d
$ hg up -r 0
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg st --all
C a
C b/b
$ rm -r a b
$ hg up -r 1
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg st --all
C a/a
C b