view tests/test-symlink-placeholder.t @ 22196:23fe278bde43

largefiles: keep largefiles from colliding with normal one during linear merge

Before this patch, linear merging of modified or newly added largefile
causes unexpected result, if (1) largefile collides with same name
normal one in the target revision and (2) "local" largefile is chosen,
even though branch merging between such revisions doesn't.

Expected result of such linear merging is:

  (1) (not yet recorded) largefile is kept in the working directory
  (2) largefile is marked as (re-)"added"
  (3) colliding normal file is marked as "removed"

But actual result is:

  (1) largefile in the working directory is unlinked
  (2) largefile is marked as "normal" (so treated as "missing")
  (3) the dirstate entry for colliding normal file is just dropped

(1) is very serious, because there is no way to restore temporarily
modified largefiles.

(3) prevents the next commit from adding the manifest with correct
"removal of (normal) file" information for newly created changeset.

The root cause of this problem is putting "lfile" into "actions['r']"
in linear-merging case. At liner merging, "actions['r']" causes:

  - unlinking "target file" in the working directory, but "lfile" as
    "target file" is also largefile itself in this case

  - dropping the dirstate entry for target file

"actions['f']" (= "forget") does only the latter, and this is reason
why this patch doesn't choose putting "lfile" into it instead of
"actions['r']".

This patch newly introduces action "lfmr" (LargeFiles: Mark as
Removed) to mark colliding normal file as "removed" without unlinking
it.

This patch uses "hg debugdirstate" instead of "hg status" in test,
because:

  - choosing "local largefile" hides "removed" status of "remote
    normal file" in "hg status" output, and

  - "hg status" for "large2" in this case has another problem fixed in
    the subsequent patch

#require symlink

Create extension that can disable symlink support:

  $ cat > nolink.py <<EOF
  > from mercurial import extensions, util
  > def setflags(orig, f, l, x):
  >     pass
  > def checklink(orig, path):
  >     return False
  > def extsetup(ui):
  >     extensions.wrapfunction(util, 'setflags', setflags)
  >     extensions.wrapfunction(util, 'checklink', checklink)
  > EOF

  $ hg init unix-repo
  $ cd unix-repo
  $ echo foo > a
  $ ln -s a b
  $ hg ci -Am0
  adding a
  adding b
  $ cd ..

Simulate a checkout shared on NFS/Samba:

  $ hg clone -q unix-repo shared
  $ cd shared
  $ rm b
  $ echo foo > b
  $ hg --config extensions.n=$TESTTMP/nolink.py status --debug
  ignoring suspect symlink placeholder "b"

Make a clone using placeholders:

  $ hg --config extensions.n=$TESTTMP/nolink.py clone . ../win-repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ../win-repo
  $ cat b
  a (no-eol)
  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug

Empty placeholder:

  $ rm b
  $ touch b
  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug
  ignoring suspect symlink placeholder "b"

Write binary data to the placeholder:

  >>> open('b', 'w').write('this is a binary\0')
  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug
  ignoring suspect symlink placeholder "b"

Write a long string to the placeholder:

  >>> open('b', 'w').write('this' * 1000)
  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug
  ignoring suspect symlink placeholder "b"

Commit shouldn't succeed:

  $ hg --config extensions.n=$TESTTMP/nolink.py ci -m1
  nothing changed
  [1]

Write a valid string to the placeholder:

  >>> open('b', 'w').write('this')
  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug
  M b
  $ hg --config extensions.n=$TESTTMP/nolink.py ci -m1
  $ hg manifest tip --verbose
  644   a
  644 @ b

  $ cd ..