vfs: copy if EPERM to avoid file stat ambiguity forcibly at closing
authorFUJIWARA Katsunori <foozy@lares.dti.ne.jp>
Tue, 04 Jul 2017 23:13:47 +0900
changeset 33280 646352291f5b
parent 33279 7912404b70f2
child 33281 6af0f023d014
vfs: copy if EPERM to avoid file stat ambiguity forcibly at closing Now, files (to be truncated) are opened with checkambig=True, only if localrepository caches it. Therefore, straightforward "copy if EPERM" is always reasonable to avoid file stat ambiguity at closing. This patch makes checkambigatclosing close wrapper copy the target file, and advance mtime on it after renaming, if EPERM. This can avoid file stat ambiguity, even if the target file is owned by another (see issue5418 and issue5584 for detail). This patch factors main logic out instead of changing checkambigatclosing._checkambig() directly, in order to reuse it.
mercurial/vfs.py
--- a/mercurial/vfs.py	Tue Jul 04 23:13:47 2017 +0900
+++ b/mercurial/vfs.py	Tue Jul 04 23:13:47 2017 +0900
@@ -22,6 +22,23 @@
     util,
 )
 
+def _avoidambig(path, oldstat):
+    """Avoid file stat ambiguity forcibly
+
+    This function causes copying ``path`` file, if it is owned by
+    another (see issue5418 and issue5584 for detail).
+    """
+    def checkandavoid():
+        newstat = util.filestat.frompath(path)
+        # return whether file stat ambiguity is (already) avoided
+        return (not newstat.isambig(oldstat) or
+                newstat.avoidambig(path, oldstat))
+    if not checkandavoid():
+        # simply copy to change owner of path to get privilege to
+        # advance mtime (see issue5418)
+        util.rename(util.mktempcopy(path), path)
+        checkandavoid()
+
 class abstractvfs(object):
     """Abstract base class; cannot be instantiated"""
 
@@ -613,10 +630,7 @@
     def _checkambig(self):
         oldstat = self._oldstat
         if oldstat.stat:
-            newstat = util.filestat.frompath(self._origfh.name)
-            if newstat.isambig(oldstat):
-                # stat of changed file is ambiguous to original one
-                newstat.avoidambig(self._origfh.name, oldstat)
+            _avoidambig(self._origfh.name, oldstat)
 
     def __exit__(self, exc_type, exc_value, exc_tb):
         self._origfh.__exit__(exc_type, exc_value, exc_tb)