view tests/test-subrepo-relative-path.t @ 12938:bf826c0b9537 stable

opener: check hardlink count reporting (issue1866)

The Linux CIFS kernel driver (even in 2.6.36) suffers from a hardlink
count blindness bug (lstat() returning 1 in st_nlink when it is expected
to return >1), which causes repository corruption if Mercurial running
on Linux pushes or commits to a hardlinked repository stored on a Windows
share, if that share is mounted using the CIFS driver.

This patch works around issue1866 and improves the workaround done in
50523b4407f6 to fix issue761, by teaching the opener to lazily execute a
runtime check (new function checknlink) to see if the hardlink count
reported by nlinks() can be trusted.

Since nlinks() is also known to return varying count values (1 or >1)
depending on whether the file is open or not and depending on what client
and server software combination is being used for accessing and serving
the Windows share, we deliberately open the file before calling nlinks() in
order to have a stable precondition. Trying to depend on the precondition
"file closed" would be fragile, as the file could have been opened very
easily somewhere else in the program.

Preparing the subrepository 'sub'

  $ hg init sub
  $ echo sub > sub/sub
  $ hg add -R sub
  adding sub/sub
  $ hg commit -R sub -m "sub import"

Preparing the 'main' repo which depends on the subrepo 'sub'

  $ hg init main
  $ echo main > main/main
  $ echo "sub = ../sub" > main/.hgsub
  $ hg clone sub main/sub
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg add -R main
  adding main/.hgsub
  adding main/main
  $ hg commit -R main -m "main import"
  committing subrepository sub

Cleaning both repositories, just as a clone -U

  $ hg up -C -R sub null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg up -C -R main null
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ rm -rf main/sub

Serving them both using hgweb

  $ printf '[paths]\n/main = main\nsub = sub\n' > webdir.conf
  $ hg serve --webdir-conf webdir.conf -a localhost -p $HGPORT \
  >    -A /dev/null -E /dev/null --pid-file hg.pid -d
  $ cat hg.pid >> $DAEMON_PIDS

Clone main from hgweb

  $ hg clone "http://localhost:$HGPORT/main" cloned
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  updating to branch default
  pulling subrepo sub from http://localhost:$HGPORT/sub
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

Checking cloned repo ids

  $ hg id -R cloned
  fdfeeb3e979e tip
  $ hg id -R cloned/sub
  863c1745b441 tip

subrepo debug for 'main' clone

  $ hg debugsub -R cloned
  path sub
   source   ../sub
   revision 863c1745b441bd97a8c4a096e87793073f4fb215

  $ "$TESTDIR/killdaemons.py"