util: enable hardlink for copyfile

util: enable hardlink for copyfile

This patch removes the global variable "allowhardlinks" that disables
hardlink in all cases, so hardlink gets enabled if the filesystem type is
whitelisted.

Third party extensions wanting to enable hardlink support unconditionally
can replace "_hardlinkfswhitelist.__contains__".

--- a/mercurial/util.py	Sun Mar 12 00:26:20 2017 -0800
+++ b/mercurial/util.py	Sun Mar 12 01:03:23 2017 -0800
@@ -1055,11 +1055,6 @@
 
     return check
 
-# Hardlinks are problematic on CIFS, do not allow hardlinks
-# until we find a way to work around it cleanly (issue4546).
-# This is a variable so extensions can opt-in to using them.
-allowhardlinks = False
-
 # a whilelist of known filesystems where hardlink works reliably
 _hardlinkfswhitelist = set([
     'btrfs',
@@ -1095,7 +1090,7 @@
         fstype = getattr(osutil, 'getfstype', lambda x: None)(destdir)
         if fstype not in _hardlinkfswhitelist:
             hardlink = False
-    if allowhardlinks and hardlink:
+    if hardlink:
         try:
             oslink(src, dest)
             return

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-hardlinks-whitelisted.t	Sun Mar 12 01:03:23 2017 -0800
@@ -0,0 +1,389 @@
+#require hardlink
+#require hardlink-whitelisted
+
+This test is similar to test-hardlinks.t, but will only run on some filesystems
+that we are sure to have known good hardlink supports (see issue4546 for an
+example where the filesystem claims hardlink support but is actually
+problematic).
+
+  $ cat > nlinks.py <<EOF
+  > import sys
+  > from mercurial import util
+  > for f in sorted(sys.stdin.readlines()):
+  >     f = f[:-1]
+  >     print util.nlinks(f), f
+  > EOF
+
+  $ nlinksdir()
+  > {
+  >     find $1 -type f | python $TESTTMP/nlinks.py
+  > }
+
+Some implementations of cp can't create hardlinks (replaces 'cp -al' on Linux):
+
+  $ cat > linkcp.py <<EOF
+  > from mercurial import util
+  > import sys
+  > util.copyfiles(sys.argv[1], sys.argv[2], hardlink=True)
+  > EOF
+
+  $ linkcp()
+  > {
+  >     python $TESTTMP/linkcp.py $1 $2
+  > }
+
+Prepare repo r1:
+
+  $ hg init r1
+  $ cd r1
+
+  $ echo c1 > f1
+  $ hg add f1
+  $ hg ci -m0
+
+  $ mkdir d1
+  $ cd d1
+  $ echo c2 > f2
+  $ hg add f2
+  $ hg ci -m1
+  $ cd ../..
+
+  $ nlinksdir r1/.hg/store
+  1 r1/.hg/store/00changelog.i
+  1 r1/.hg/store/00manifest.i
+  1 r1/.hg/store/data/d1/f2.i
+  1 r1/.hg/store/data/f1.i
+  1 r1/.hg/store/fncache
+  1 r1/.hg/store/phaseroots
+  1 r1/.hg/store/undo
+  1 r1/.hg/store/undo.backup.fncache
+  1 r1/.hg/store/undo.backupfiles
+  1 r1/.hg/store/undo.phaseroots
+
+
+Create hardlinked clone r2:
+
+  $ hg clone -U --debug r1 r2 --config progress.debug=true
+  linking: 1
+  linking: 2
+  linking: 3
+  linking: 4
+  linking: 5
+  linking: 6
+  linking: 7
+  linked 7 files
+
+Create non-hardlinked clone r3:
+
+  $ hg clone --pull r1 r3
+  requesting all changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files
+  updating to branch default
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+
+Repos r1 and r2 should now contain hardlinked files:
+
+  $ nlinksdir r1/.hg/store
+  2 r1/.hg/store/00changelog.i
+  2 r1/.hg/store/00manifest.i
+  2 r1/.hg/store/data/d1/f2.i
+  2 r1/.hg/store/data/f1.i
+  2 r1/.hg/store/fncache
+  1 r1/.hg/store/phaseroots
+  1 r1/.hg/store/undo
+  1 r1/.hg/store/undo.backup.fncache
+  1 r1/.hg/store/undo.backupfiles
+  1 r1/.hg/store/undo.phaseroots
+
+  $ nlinksdir r2/.hg/store
+  2 r2/.hg/store/00changelog.i
+  2 r2/.hg/store/00manifest.i
+  2 r2/.hg/store/data/d1/f2.i
+  2 r2/.hg/store/data/f1.i
+  2 r2/.hg/store/fncache
+
+Repo r3 should not be hardlinked:
+
+  $ nlinksdir r3/.hg/store
+  1 r3/.hg/store/00changelog.i
+  1 r3/.hg/store/00manifest.i
+  1 r3/.hg/store/data/d1/f2.i
+  1 r3/.hg/store/data/f1.i
+  1 r3/.hg/store/fncache
+  1 r3/.hg/store/phaseroots
+  1 r3/.hg/store/undo
+  1 r3/.hg/store/undo.backupfiles
+  1 r3/.hg/store/undo.phaseroots
+
+
+Create a non-inlined filelog in r3:
+
+  $ cd r3/d1
+  >>> f = open('data1', 'wb')
+  >>> for x in range(10000):
+  ...     f.write("%s\n" % str(x))
+  >>> f.close()
+  $ for j in 0 1 2 3 4 5 6 7 8 9; do
+  >   cat data1 >> f2
+  >   hg commit -m$j
+  > done
+  $ cd ../..
+
+  $ nlinksdir r3/.hg/store
+  1 r3/.hg/store/00changelog.i
+  1 r3/.hg/store/00manifest.i
+  1 r3/.hg/store/data/d1/f2.d
+  1 r3/.hg/store/data/d1/f2.i
+  1 r3/.hg/store/data/f1.i
+  1 r3/.hg/store/fncache
+  1 r3/.hg/store/phaseroots
+  1 r3/.hg/store/undo
+  1 r3/.hg/store/undo.backup.fncache
+  1 r3/.hg/store/undo.backup.phaseroots
+  1 r3/.hg/store/undo.backupfiles
+  1 r3/.hg/store/undo.phaseroots
+
+Push to repo r1 should break up most hardlinks in r2:
+
+  $ hg -R r2 verify
+  checking changesets
+  checking manifests
+  crosschecking files in changesets and manifests
+  checking files
+  2 files, 2 changesets, 2 total revisions
+
+  $ cd r3
+  $ hg push
+  pushing to $TESTTMP/r1 (glob)
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 10 changesets with 10 changes to 1 files
+
+  $ cd ..
+
+  $ nlinksdir r2/.hg/store
+  1 r2/.hg/store/00changelog.i
+  1 r2/.hg/store/00manifest.i
+  1 r2/.hg/store/data/d1/f2.i
+  2 r2/.hg/store/data/f1.i
+  2 r2/.hg/store/fncache
+
+  $ hg -R r2 verify
+  checking changesets
+  checking manifests
+  crosschecking files in changesets and manifests
+  checking files
+  2 files, 2 changesets, 2 total revisions
+
+
+  $ cd r1
+  $ hg up
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+Committing a change to f1 in r1 must break up hardlink f1.i in r2:
+
+  $ echo c1c1 >> f1
+  $ hg ci -m00
+  $ cd ..
+
+  $ nlinksdir r2/.hg/store
+  1 r2/.hg/store/00changelog.i
+  1 r2/.hg/store/00manifest.i
+  1 r2/.hg/store/data/d1/f2.i
+  1 r2/.hg/store/data/f1.i
+  2 r2/.hg/store/fncache
+
+
+  $ cd r3
+  $ hg tip --template '{rev}:{node|short}\n'
+  11:a6451b6bc41f
+  $ echo bla > f1
+  $ hg ci -m1
+  $ cd ..
+
+Create hardlinked copy r4 of r3 (on Linux, we would call 'cp -al'):
+
+  $ linkcp r3 r4
+
+r4 has hardlinks in the working dir (not just inside .hg):
+
+  $ nlinksdir r4
+  2 r4/.hg/00changelog.i
+  2 r4/.hg/branch
+  2 r4/.hg/cache/branch2-served
+  2 r4/.hg/cache/checkisexec
+  3 r4/.hg/cache/checklink (?)
+  ? r4/.hg/cache/checklink-target (glob)
+  2 r4/.hg/cache/checknoexec
+  2 r4/.hg/cache/rbc-names-v1
+  2 r4/.hg/cache/rbc-revs-v1
+  2 r4/.hg/dirstate
+  2 r4/.hg/hgrc
+  2 r4/.hg/last-message.txt
+  2 r4/.hg/requires
+  2 r4/.hg/store/00changelog.i
+  2 r4/.hg/store/00manifest.i
+  2 r4/.hg/store/data/d1/f2.d
+  2 r4/.hg/store/data/d1/f2.i
+  2 r4/.hg/store/data/f1.i
+  2 r4/.hg/store/fncache
+  2 r4/.hg/store/phaseroots
+  2 r4/.hg/store/undo
+  2 r4/.hg/store/undo.backup.fncache
+  2 r4/.hg/store/undo.backup.phaseroots
+  2 r4/.hg/store/undo.backupfiles
+  2 r4/.hg/store/undo.phaseroots
+  4 r4/.hg/undo.backup.dirstate
+  2 r4/.hg/undo.bookmarks
+  2 r4/.hg/undo.branch
+  2 r4/.hg/undo.desc
+  4 r4/.hg/undo.dirstate
+  2 r4/d1/data1
+  2 r4/d1/f2
+  2 r4/f1
+
+Update back to revision 11 in r4 should break hardlink of file f1:
+
+  $ hg -R r4 up 11
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+  $ nlinksdir r4
+  2 r4/.hg/00changelog.i
+  1 r4/.hg/branch
+  2 r4/.hg/cache/branch2-served
+  2 r4/.hg/cache/checkisexec
+  2 r4/.hg/cache/checklink-target
+  2 r4/.hg/cache/checknoexec
+  2 r4/.hg/cache/rbc-names-v1
+  2 r4/.hg/cache/rbc-revs-v1
+  1 r4/.hg/dirstate
+  2 r4/.hg/hgrc
+  2 r4/.hg/last-message.txt
+  2 r4/.hg/requires
+  2 r4/.hg/store/00changelog.i
+  2 r4/.hg/store/00manifest.i
+  2 r4/.hg/store/data/d1/f2.d
+  2 r4/.hg/store/data/d1/f2.i
+  2 r4/.hg/store/data/f1.i
+  2 r4/.hg/store/fncache
+  2 r4/.hg/store/phaseroots
+  2 r4/.hg/store/undo
+  2 r4/.hg/store/undo.backup.fncache
+  2 r4/.hg/store/undo.backup.phaseroots
+  2 r4/.hg/store/undo.backupfiles
+  2 r4/.hg/store/undo.phaseroots
+  4 r4/.hg/undo.backup.dirstate
+  2 r4/.hg/undo.bookmarks
+  2 r4/.hg/undo.branch
+  2 r4/.hg/undo.desc
+  4 r4/.hg/undo.dirstate
+  2 r4/d1/data1
+  2 r4/d1/f2
+  1 r4/f1
+
+
+Test hardlinking outside hg:
+
+  $ mkdir x
+  $ echo foo > x/a
+
+  $ linkcp x y
+  $ echo bar >> y/a
+
+No diff if hardlink:
+
+  $ diff x/a y/a
+
+Test mq hardlinking:
+
+  $ echo "[extensions]" >> $HGRCPATH
+  $ echo "mq=" >> $HGRCPATH
+
+  $ hg init a
+  $ cd a
+
+  $ hg qimport -n foo - << EOF
+  > # HG changeset patch
+  > # Date 1 0
+  > diff -r 2588a8b53d66 a
+  > --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  > +++ b/a	Wed Jul 23 15:54:29 2008 +0200
+  > @@ -0,0 +1,1 @@
+  > +a
+  > EOF
+  adding foo to series file
+
+  $ hg qpush
+  applying foo
+  now at: foo
+
+  $ cd ..
+  $ linkcp a b
+  $ cd b
+
+  $ hg qimport -n bar - << EOF
+  > # HG changeset patch
+  > # Date 2 0
+  > diff -r 2588a8b53d66 a
+  > --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  > +++ b/b	Wed Jul 23 15:54:29 2008 +0200
+  > @@ -0,0 +1,1 @@
+  > +b
+  > EOF
+  adding bar to series file
+
+  $ hg qpush
+  applying bar
+  now at: bar
+
+  $ cat .hg/patches/status
+  430ed4828a74fa4047bc816a25500f7472ab4bfe:foo
+  4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c:bar
+
+  $ cat .hg/patches/series
+  foo
+  bar
+
+  $ cat ../a/.hg/patches/status
+  430ed4828a74fa4047bc816a25500f7472ab4bfe:foo
+
+  $ cat ../a/.hg/patches/series
+  foo
+
+Test tags hardlinking:
+
+  $ hg qdel -r qbase:qtip
+  patch foo finalized without changeset message
+  patch bar finalized without changeset message
+
+  $ hg tag -l lfoo
+  $ hg tag foo
+
+  $ cd ..
+  $ linkcp b c
+  $ cd c
+
+  $ hg tag -l -r 0 lbar
+  $ hg tag -r 0 bar
+
+  $ cat .hgtags
+  4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo
+  430ed4828a74fa4047bc816a25500f7472ab4bfe bar
+
+  $ cat .hg/localtags
+  4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo
+  430ed4828a74fa4047bc816a25500f7472ab4bfe lbar
+
+  $ cat ../b/.hgtags
+  4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo
+
+  $ cat ../b/.hg/localtags
+  4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo
+
+  $ cd ..

--- a/tests/test-hardlinks.t	Sun Mar 12 00:26:20 2017 -0800
+++ b/tests/test-hardlinks.t	Sun Mar 12 01:03:23 2017 -0800
@@ -166,7 +166,7 @@
   1 r2/.hg/store/00manifest.i
   1 r2/.hg/store/data/d1/f2.i
   2 r2/.hg/store/data/f1.i
-  1 r2/.hg/store/fncache
+  [12] r2/\.hg/store/fncache (re)
 
   $ hg -R r2 verify
   checking changesets
@@ -191,7 +191,7 @@
   1 r2/.hg/store/00manifest.i
   1 r2/.hg/store/data/d1/f2.i
   1 r2/.hg/store/data/f1.i
-  1 r2/.hg/store/fncache
+  [12] r2/\.hg/store/fncache (re)
 
 
   $ cd r3
@@ -233,11 +233,11 @@
   2 r4/.hg/store/undo.backup.phaseroots
   2 r4/.hg/store/undo.backupfiles
   2 r4/.hg/store/undo.phaseroots
-  2 r4/.hg/undo.backup.dirstate
+  [24] r4/\.hg/undo\.backup\.dirstate (re)
   2 r4/.hg/undo.bookmarks
   2 r4/.hg/undo.branch
   2 r4/.hg/undo.desc
-  2 r4/.hg/undo.dirstate
+  [24] r4/\.hg/undo\.dirstate (re)
   2 r4/d1/data1
   2 r4/d1/f2
   2 r4/f1
@@ -272,11 +272,11 @@
   2 r4/.hg/store/undo.backup.phaseroots
   2 r4/.hg/store/undo.backupfiles
   2 r4/.hg/store/undo.phaseroots
-  2 r4/.hg/undo.backup.dirstate
+  [24] r4/\.hg/undo\.backup\.dirstate (re)
   2 r4/.hg/undo.bookmarks
   2 r4/.hg/undo.branch
   2 r4/.hg/undo.desc
-  2 r4/.hg/undo.dirstate
+  [24] r4/\.hg/undo\.dirstate (re)
   2 r4/d1/data1
   2 r4/d1/f2
   1 r4/f1