bundle2: client side support for a part to import external bundles

Bundle2 opens doors to advanced features allowing to reduce load on
mercurial servers, and improve clone experience for users on unstable or
slow networks.

For instance, it could be possible to pre-generate a bundle of a
repository, and give a pointer to it to clients cloning the repository,
followed by another changegroup with the remainder. For significantly
big repositories, this could come as several base bundles with e.g. 10k
changesets, which, combined with checkpoints (not part of this change),
would prevent users with flaky networks from starting over any time
their connection fails.

While the server-side support for those features doesn't exist yet, it
is preferable to have client-side support for this early-on, allowing
experiments on servers only requiring a vanilla client with bundle2
enabled.

tests/test-bundle2-remote-changegroup.t

@@ -0,0 +1,592 b''
+#require killdaemons
+
+Create an extension to test bundle2 remote-changegroup parts
+
+  $ cat > bundle2.py << EOF
+  > """A small extension to test bundle2 remote-changegroup parts.
+  > 
+  > Current bundle2 implementation doesn't provide a way to generate those
+  > parts, so they must be created by extensions.
+  > """
+  > from mercurial import bundle2, changegroup, exchange, util
+  > 
+  > def _getbundlechangegrouppart(bundler, repo, source, bundlecaps=None,
+  >                               b2caps=None, heads=None, common=None,
+  >                               **kwargs):
+  >     """this function replaces the changegroup part handler for getbundle.
+  >     It allows to create a set of arbitrary parts containing changegroups
+  >     and remote-changegroups, as described in a bundle2maker file in the
+  >     repository .hg/ directory.
+  > 
+  >     Each line of that bundle2maker file contain a description of the
+  >     part to add:
+  >       - changegroup common_revset heads_revset
+  >           Creates a changegroup part based, using common_revset and
+  >           heads_revset for changegroup.getchangegroup.
+  >       - remote-changegroup url file
+  >           Creates a remote-changegroup part for a bundle at the given
+  >           url. Size and digest, as required by the client, are computed
+  >           from the given file.
+  >       - raw-remote-changegroup <python expression>
+  >           Creates a remote-changegroup part with the data given in the
+  >           python expression as parameters. The python expression is
+  >           evaluated with eval, and is expected to be a dict.
+  >     """
+  >     def newpart(name, data=''):
+  >         """wrapper around bundler.newpart adding an extra part making the
+  >         client output information about each processed part"""
+  >         bundler.newpart('b2x:output', data=name)
+  >         part = bundler.newpart(name, data=data)
+  >         return part
+  > 
+  >     for line in open(repo.join('bundle2maker'), 'r'):
+  >         line = line.strip()
+  >         try:
+  >             verb, args = line.split(None, 1)
+  >         except ValueError:
+  >             verb, args = line, ''
+  >         if verb == 'remote-changegroup':
+  >            url, file = args.split()
+  >            bundledata = open(file, 'rb').read()
+  >            digest = util.digester.preferred(b2caps['digests'])
+  >            d = util.digester([digest], bundledata)
+  >            part = newpart('B2X:REMOTE-CHANGEGROUP')
+  >            part.addparam('url', url)
+  >            part.addparam('size', str(len(bundledata)))
+  >            part.addparam('digests', digest)
+  >            part.addparam('digest:%s' % digest, d[digest])
+  >         elif verb == 'raw-remote-changegroup':
+  >            part = newpart('B2X:REMOTE-CHANGEGROUP')
+  >            for k, v in eval(args).items():
+  >                part.addparam(k, str(v))
+  >         elif verb == 'changegroup':
+  >             _common, heads = args.split()
+  >             common.extend(repo.lookup(r) for r in repo.revs(_common))
+  >             heads = [repo.lookup(r) for r in repo.revs(heads)]
+  >             cg = changegroup.getchangegroup(repo, 'changegroup',
+  >                 heads=heads, common=common)
+  >             newpart('B2X:CHANGEGROUP', cg.getchunks())
+  >         else:
+  >             raise Exception('unknown verb')
+  > 
+  > exchange.getbundle2partsmapping['changegroup'] = _getbundlechangegrouppart
+  > EOF
+
+Start a simple HTTP server to serve bundles
+
+  $ python "$TESTDIR/dumbhttp.py" -p $HGPORT --pid dumb.pid
+  $ cat dumb.pid >> $DAEMON_PIDS
+
+  $ cat >> $HGRCPATH << EOF
+  > [experimental]
+  > bundle2-exp=True
+  > [ui]
+  > ssh=python "$TESTDIR/dummyssh"
+  > logtemplate={rev}:{node|short} {phase} {author} {bookmarks} {desc|firstline}
+  > EOF
+
+  $ hg init repo
+
+  $ hg -R repo unbundle $TESTDIR/bundles/rebase.hg
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+
+  $ hg -R repo log -G
+  o  7:02de42196ebe draft Nicolas Dumazet <[e-mail]>  H
+  |
+  | o  6:eea13746799a draft Nicolas Dumazet <[e-mail]>  G
+  |/|
+  o |  5:24b6387c8c8c draft Nicolas Dumazet <[e-mail]>  F
+  | |
+  | o  4:9520eea781bc draft Nicolas Dumazet <[e-mail]>  E
+  |/
+  | o  3:32af7686d403 draft Nicolas Dumazet <[e-mail]>  D
+  | |
+  | o  2:5fddd98957c8 draft Nicolas Dumazet <[e-mail]>  C
+  | |
+  | o  1:42ccdea3bb16 draft Nicolas Dumazet <[e-mail]>  B
+  |/
+  o  0:cd010b8cd998 draft Nicolas Dumazet <[e-mail]>  A
+  
+  $ hg clone repo orig
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+  $ cat > repo/.hg/hgrc << EOF
+  > [extensions]
+  > bundle2=$TESTTMP/bundle2.py
+  > EOF
+
+Test a pull with an remote-changegroup
+
+  $ hg bundle -R repo --base '0:4' -r '5:7' bundle.hg
+  3 changesets found
+  $ cat > repo/.hg/bundle2maker << EOF
+  > remote-changegroup http://localhost:$HGPORT/bundle.hg bundle.hg
+  > EOF
+  $ hg clone orig clone -r 3 -r 4
+  adding changesets
+  adding manifests
+  adding file changes
+  added 5 changesets with 5 changes to 5 files (+1 heads)
+  updating to branch default
+  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 2 changes to 2 files (+1 heads)
+  (run 'hg heads .' to see heads, 'hg merge' to merge)
+  $ hg -R clone log -G
+  o  7:02de42196ebe public Nicolas Dumazet <[e-mail]>  H
+  |
+  | o  6:eea13746799a public Nicolas Dumazet <[e-mail]>  G
+  |/|
+  o |  5:24b6387c8c8c public Nicolas Dumazet <[e-mail]>  F
+  | |
+  | o  4:9520eea781bc public Nicolas Dumazet <[e-mail]>  E
+  |/
+  | @  3:32af7686d403 public Nicolas Dumazet <[e-mail]>  D
+  | |
+  | o  2:5fddd98957c8 public Nicolas Dumazet <[e-mail]>  C
+  | |
+  | o  1:42ccdea3bb16 public Nicolas Dumazet <[e-mail]>  B
+  |/
+  o  0:cd010b8cd998 public Nicolas Dumazet <[e-mail]>  A
+  
+  $ rm -rf clone
+
+Test a pull with an remote-changegroup and a following changegroup
+
+  $ hg bundle -R repo --base 2 -r '3:4' bundle2.hg
+  2 changesets found
+  $ cat > repo/.hg/bundle2maker << EOF
+  > remote-changegroup http://localhost:$HGPORT/bundle2.hg bundle2.hg
+  > changegroup 0:4 5:7
+  > EOF
+  $ hg clone orig clone -r 2
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 3 changes to 3 files
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files (+1 heads)
+  remote: B2X:CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 2 changes to 2 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+  $ hg -R clone log -G
+  o  7:02de42196ebe public Nicolas Dumazet <[e-mail]>  H
+  |
+  | o  6:eea13746799a public Nicolas Dumazet <[e-mail]>  G
+  |/|
+  o |  5:24b6387c8c8c public Nicolas Dumazet <[e-mail]>  F
+  | |
+  | o  4:9520eea781bc public Nicolas Dumazet <[e-mail]>  E
+  |/
+  | o  3:32af7686d403 public Nicolas Dumazet <[e-mail]>  D
+  | |
+  | @  2:5fddd98957c8 public Nicolas Dumazet <[e-mail]>  C
+  | |
+  | o  1:42ccdea3bb16 public Nicolas Dumazet <[e-mail]>  B
+  |/
+  o  0:cd010b8cd998 public Nicolas Dumazet <[e-mail]>  A
+  
+  $ rm -rf clone
+
+Test a pull with a changegroup followed by an remote-changegroup
+
+  $ hg bundle -R repo --base '0:4' -r '5:7' bundle3.hg
+  3 changesets found
+  $ cat > repo/.hg/bundle2maker << EOF
+  > changegroup 000000000000 :4
+  > remote-changegroup http://localhost:$HGPORT/bundle3.hg bundle3.hg
+  > EOF
+  $ hg clone orig clone -r 2
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 3 changes to 3 files
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files (+1 heads)
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 2 changes to 2 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+  $ hg -R clone log -G
+  o  7:02de42196ebe public Nicolas Dumazet <[e-mail]>  H
+  |
+  | o  6:eea13746799a public Nicolas Dumazet <[e-mail]>  G
+  |/|
+  o |  5:24b6387c8c8c public Nicolas Dumazet <[e-mail]>  F
+  | |
+  | o  4:9520eea781bc public Nicolas Dumazet <[e-mail]>  E
+  |/
+  | o  3:32af7686d403 public Nicolas Dumazet <[e-mail]>  D
+  | |
+  | @  2:5fddd98957c8 public Nicolas Dumazet <[e-mail]>  C
+  | |
+  | o  1:42ccdea3bb16 public Nicolas Dumazet <[e-mail]>  B
+  |/
+  o  0:cd010b8cd998 public Nicolas Dumazet <[e-mail]>  A
+  
+  $ rm -rf clone
+
+Test a pull with two remote-changegroups and a changegroup
+
+  $ hg bundle -R repo --base 2 -r '3:4' bundle4.hg
+  2 changesets found
+  $ hg bundle -R repo --base '3:4' -r '5:6' bundle5.hg
+  2 changesets found
+  $ cat > repo/.hg/bundle2maker << EOF
+  > remote-changegroup http://localhost:$HGPORT/bundle4.hg bundle4.hg
+  > remote-changegroup http://localhost:$HGPORT/bundle5.hg bundle5.hg
+  > changegroup 0:6 7
+  > EOF
+  $ hg clone orig clone -r 2
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 3 changes to 3 files
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files (+1 heads)
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 1 changes to 1 files
+  remote: B2X:CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+  $ hg -R clone log -G
+  o  7:02de42196ebe public Nicolas Dumazet <[e-mail]>  H
+  |
+  | o  6:eea13746799a public Nicolas Dumazet <[e-mail]>  G
+  |/|
+  o |  5:24b6387c8c8c public Nicolas Dumazet <[e-mail]>  F
+  | |
+  | o  4:9520eea781bc public Nicolas Dumazet <[e-mail]>  E
+  |/
+  | o  3:32af7686d403 public Nicolas Dumazet <[e-mail]>  D
+  | |
+  | @  2:5fddd98957c8 public Nicolas Dumazet <[e-mail]>  C
+  | |
+  | o  1:42ccdea3bb16 public Nicolas Dumazet <[e-mail]>  B
+  |/
+  o  0:cd010b8cd998 public Nicolas Dumazet <[e-mail]>  A
+  
+  $ rm -rf clone
+
+Hash digest tests
+
+  $ hg bundle -R repo -a bundle6.hg
+  8 changesets found
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle6.hg', 'size': 1663, 'digests': 'sha1', 'digest:sha1': '2c880cfec23cff7d8f80c2f12958d1563cbdaba6'}
+  > EOF
+  $ hg clone ssh://user@dummy/repo clone
+  requesting all changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ rm -rf clone
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle6.hg', 'size': 1663, 'digests': 'md5', 'digest:md5': 'e22172c2907ef88794b7bea6642c2394'}
+  > EOF
+  $ hg clone ssh://user@dummy/repo clone
+  requesting all changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ rm -rf clone
+
+Hash digest mismatch throws an error
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle6.hg', 'size': 1663, 'digests': 'sha1', 'digest:sha1': '0' * 40}
+  > EOF
+  $ hg clone ssh://user@dummy/repo clone
+  requesting all changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  transaction abort!
+  rollback completed
+  abort: bundle at http://localhost:$HGPORT/bundle6.hg is corrupted:
+  sha1 mismatch: expected 0000000000000000000000000000000000000000, got 2c880cfec23cff7d8f80c2f12958d1563cbdaba6
+  [255]
+
+Multiple hash digests can be given
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle6.hg', 'size': 1663, 'digests': 'md5 sha1', 'digest:md5': 'e22172c2907ef88794b7bea6642c2394', 'digest:sha1': '2c880cfec23cff7d8f80c2f12958d1563cbdaba6'}
+  > EOF
+  $ hg clone ssh://user@dummy/repo clone
+  requesting all changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ rm -rf clone
+
+If either of the multiple hash digests mismatches, an error is thrown
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle6.hg', 'size': 1663, 'digests': 'md5 sha1', 'digest:md5': '0' * 32, 'digest:sha1': '2c880cfec23cff7d8f80c2f12958d1563cbdaba6'}
+  > EOF
+  $ hg clone ssh://user@dummy/repo clone
+  requesting all changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  transaction abort!
+  rollback completed
+  abort: bundle at http://localhost:$HGPORT/bundle6.hg is corrupted:
+  md5 mismatch: expected 00000000000000000000000000000000, got e22172c2907ef88794b7bea6642c2394
+  [255]
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle6.hg', 'size': 1663, 'digests': 'md5 sha1', 'digest:md5': 'e22172c2907ef88794b7bea6642c2394', 'digest:sha1': '0' * 40}
+  > EOF
+  $ hg clone ssh://user@dummy/repo clone
+  requesting all changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 8 changesets with 7 changes to 7 files (+2 heads)
+  transaction abort!
+  rollback completed
+  abort: bundle at http://localhost:$HGPORT/bundle6.hg is corrupted:
+  sha1 mismatch: expected 0000000000000000000000000000000000000000, got 2c880cfec23cff7d8f80c2f12958d1563cbdaba6
+  [255]
+
+Corruption tests
+
+  $ hg clone orig clone -r 2
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 3 changes to 3 files
+  updating to branch default
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > remote-changegroup http://localhost:$HGPORT/bundle4.hg bundle4.hg
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle5.hg', 'size': 578, 'digests': 'sha1', 'digest:sha1': '0' * 40}
+  > changegroup 0:6 7
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files (+1 heads)
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 1 changes to 1 files
+  transaction abort!
+  rollback completed
+  abort: bundle at http://localhost:$HGPORT/bundle5.hg is corrupted:
+  sha1 mismatch: expected 0000000000000000000000000000000000000000, got f29485d6bfd37db99983cfc95ecb52f8ca396106
+  [255]
+
+The entire transaction has been rolled back in the pull above
+
+  $ hg -R clone log -G
+  @  2:5fddd98957c8 public Nicolas Dumazet <[e-mail]>  C
+  |
+  o  1:42ccdea3bb16 public Nicolas Dumazet <[e-mail]>  B
+  |
+  o  0:cd010b8cd998 public Nicolas Dumazet <[e-mail]>  A
+  
+
+No params
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: remote-changegroup: missing "url" param
+  [255]
+
+Missing size
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle4.hg'}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: remote-changegroup: missing "size" param
+  [255]
+
+Invalid size
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle4.hg', 'size': 'foo'}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: remote-changegroup: invalid value for param "size"
+  [255]
+
+Size mismatch
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle4.hg', 'size': 42}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files (+1 heads)
+  transaction abort!
+  rollback completed
+  abort: bundle at http://localhost:$HGPORT/bundle4.hg is corrupted:
+  size mismatch: expected 42, got 581
+  [255]
+
+Unknown digest
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle4.hg', 'size': 581, 'digests': 'foo', 'digest:foo': 'bar'}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: missing support for b2x:remote-changegroup - digest:foo
+  [255]
+
+Missing digest
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'http://localhost:$HGPORT/bundle4.hg', 'size': 581, 'digests': 'sha1'}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: remote-changegroup: missing "digest:sha1" param
+  [255]
+
+Not an HTTP url
+
+  $ cat > repo/.hg/bundle2maker << EOF
+  > raw-remote-changegroup {'url': 'ssh://localhost:$HGPORT/bundle4.hg', 'size': 581}
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: remote-changegroup does not support ssh urls
+  [255]
+
+Not a bundle
+
+  $ cat > notbundle.hg << EOF
+  > foo
+  > EOF
+  $ cat > repo/.hg/bundle2maker << EOF
+  > remote-changegroup http://localhost:$HGPORT/notbundle.hg notbundle.hg
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: http://localhost:$HGPORT/notbundle.hg: not a Mercurial bundle
+  [255]
+
+Not a bundle 1.0
+
+  $ cat > notbundle10.hg << EOF
+  > HG2Y
+  > EOF
+  $ cat > repo/.hg/bundle2maker << EOF
+  > remote-changegroup http://localhost:$HGPORT/notbundle10.hg notbundle10.hg
+  > EOF
+  $ hg pull -R clone ssh://user@dummy/repo
+  pulling from ssh://user@dummy/repo
+  searching for changes
+  remote: B2X:REMOTE-CHANGEGROUP
+  abort: http://localhost:$HGPORT/notbundle10.hg: not a bundle version 1.0
+  [255]
+
+  $ hg -R clone log -G
+  @  2:5fddd98957c8 public Nicolas Dumazet <[e-mail]>  C
+  |
+  o  1:42ccdea3bb16 public Nicolas Dumazet <[e-mail]>  B
+  |
+  o  0:cd010b8cd998 public Nicolas Dumazet <[e-mail]>  A
+  
+  $ rm -rf clone
+
+  $ "$TESTDIR/killdaemons.py" $DAEMON_PIDS

mercurial/bundle2.py

@@ -151,6 +151,7 b' import urllib'
 import string
 import obsolete
 import pushkey
+import url
 
 import changegroup, error
 from i18n import _
@@ -797,6 +798,8 b" capabilities = {'HG2Y': (),"
                 'b2x:listkeys': (),
                 'b2x:pushkey': (),
                 'b2x:changegroup': (),
+                'digests': tuple(sorted(util.DIGESTS.keys())),
+                'b2x:remote-changegroup': ('http', 'https'),
                }
 
 def getrepocaps(repo):
@@ -850,6 +853,80 b' def handlechangegroup(op, inpart):'
         part.addparam('return', '%i' % ret, mandatory=False)
     assert not inpart.read()
 
+_remotechangegroupparams = tuple(['url', 'size', 'digests'] +
+    ['digest:%s' % k for k in util.DIGESTS.keys()])
+@parthandler('b2x:remote-changegroup', _remotechangegroupparams)
+def handleremotechangegroup(op, inpart):
+    """apply a bundle10 on the repo, given an url and validation information
+
+    All the information about the remote bundle to import are given as
+    parameters. The parameters include:
+      - url: the url to the bundle10.
+      - size: the bundle10 file size. It is used to validate what was
+        retrieved by the client matches the server knowledge about the bundle.
+      - digests: a space separated list of the digest types provided as
+        parameters.
+      - digest:<digest-type>: the hexadecimal representation of the digest with
+        that name. Like the size, it is used to validate what was retrieved by
+        the client matches what the server knows about the bundle.
+
+    When multiple digest types are given, all of them are checked.
+    """
+    try:
+        raw_url = inpart.params['url']
+    except KeyError:
+        raise util.Abort(_('remote-changegroup: missing "%s" param') % 'url')
+    parsed_url = util.url(raw_url)
+    if parsed_url.scheme not in capabilities['b2x:remote-changegroup']:
+        raise util.Abort(_('remote-changegroup does not support %s urls') %
+            parsed_url.scheme)
+
+    try:
+        size = int(inpart.params['size'])
+    except ValueError:
+        raise util.Abort(_('remote-changegroup: invalid value for param "%s"')
+            % 'size')
+    except KeyError:
+        raise util.Abort(_('remote-changegroup: missing "%s" param') % 'size')
+
+    digests = {}
+    for typ in inpart.params.get('digests', '').split():
+        param = 'digest:%s' % typ
+        try:
+            value = inpart.params[param]
+        except KeyError:
+            raise util.Abort(_('remote-changegroup: missing "%s" param') %
+                param)
+        digests[typ] = value
+
+    real_part = util.digestchecker(url.open(op.ui, raw_url), size, digests)
+
+    # Make sure we trigger a transaction creation
+    #
+    # The addchangegroup function will get a transaction object by itself, but
+    # we need to make sure we trigger the creation of a transaction object used
+    # for the whole processing scope.
+    op.gettransaction()
+    import exchange
+    cg = exchange.readbundle(op.repo.ui, real_part, raw_url)
+    if not isinstance(cg, changegroup.cg1unpacker):
+        raise util.Abort(_('%s: not a bundle version 1.0') %
+            util.hidepassword(raw_url))
+    ret = changegroup.addchangegroup(op.repo, cg, 'bundle2', 'bundle2')
+    op.records.add('changegroup', {'return': ret})
+    if op.reply is not None:
+        # This is definitly not the final form of this
+        # return. But one need to start somewhere.
+        part = op.reply.newpart('b2x:reply:changegroup')
+        part.addparam('in-reply-to', str(inpart.id), mandatory=False)
+        part.addparam('return', '%i' % ret, mandatory=False)
+    try:
+        real_part.validate()
+    except util.Abort, e:
+        raise util.Abort(_('bundle at %s is corrupted:\n%s') %
+            (util.hidepassword(raw_url), str(e)))
+    assert not inpart.read()
+
 @parthandler('b2x:reply:changegroup', ('return', 'in-reply-to'))
 def handlereplychangegroup(op, inpart):
     ret = int(inpart.params['return'])