In order to fix issue5418, 0d920bcb0fd1 made vfs.rename(checkambig=True)
omit advancing mtime of renamed file, if renamed file is owned by
another (EPERM is raised in this case).
But this omission causes rewinding mtime at restoration in such
situation, and makes avoiding file stat ambiguity difficult, because
ExactCacheValidationPlan assumes that mtime should be advanced, if a
file is changed in same ctime.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
Ambiguity of file stat also requires issue5584 to be fixed with other
than file stat, but "hash of file", "generation ID" and so on were
already rejected ideas (please see original RFC linked from "Outline
of issue" in ExactCacheValidationPlan page).
This omission occurs:
- only for non append-only files (dirstate, bookmarks, and phaseroots), and
- only if previous transaction is rollbacked by another user
The latter means "sharing a repository clone via group permission".
This is reasonable usecase, but not ordinary for many users, IMHO.
"hg rollback" itself has been deprecated since Mercurial 2.7, too.
Therefore, increasing the cost at rollbacking previous transaction
executed by another a little seems reasonable, for avoidance of file
stat ambiguity.
This patch does:
- create copy of (already renamed) source file, if advancing mtime
fails for EPERM
- rename from copied file to destination file, and
- advance mtime of renamed file, which is now owned by current user
This patch also factors "self.join(src)" out to reduce redundancy.
See the previous commit for why. Marked as API change since osutil.listdir()
seems widely used in third-party extensions.
The win32mbcs extension is updated to wrap both util. and windows. aliases.
Thoughout hg code, we see a pattern of attempting to remove a file and then
catching and ignoring any errors due to a missing file in the calling code.
Let's unify this pattern in a single implementation in the vfs layer.
The 'scmutil' is growing large (1500+ lines) and 2/5 of it is related to vfs.
We extract the 'vfs' related code in its own module get both module back to a
better scale and clearer contents.
We keep all the references available in 'scmutil' for now as many reference
needs to be updated.
