# HG changeset patch
# User Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>
# Date 1581652277 18000
# Node ID 8407031f195f77f8cacd0a6bd180a4a0045da423
# Parent  0275000564c453a85e89eddfab1a357e6aeae327
bookmarks: prevent pushes of divergent bookmarks (foo@remote)

Before this change, such bookmarks are write-only: a client can push
them but not pull/read them. And because these bookmark can't be read,
even pushes are limited (for instance trying to delete such a bookmark
fails with a vanilla client because the client thinks the bookmark is
neither on the local nor the remote).

This change makes the server refuses such bookmarks, and for earlier
errors, makes the client refuse to send them.

I think the change of behavior is acceptable because I think this is a
bug in push/pull, and I don't think we change the behavior of `hg
unbundle`, because it doesn't seem that `hg bundle` ever store
bookmarks (and even if it did, it would seem weird anyway to try to
send divergent bookmarks).

Differential Revision: https://phab.mercurial-scm.org/D8117

diff -r 0275000564c4 -r 8407031f195f mercurial/bookmarks.py
--- a/mercurial/bookmarks.py	Thu Feb 13 22:06:57 2020 -0500
+++ b/mercurial/bookmarks.py	Thu Feb 13 22:51:17 2020 -0500
@@ -487,6 +487,8 @@
 
 
 def pushbookmark(repo, key, old, new):
+    if isdivergent(key):
+        return False
     if bookmarksinstore(repo):
         wlock = util.nullcontextmanager()
     else:
diff -r 0275000564c4 -r 8407031f195f mercurial/bundle2.py
--- a/mercurial/bundle2.py	Thu Feb 13 22:06:57 2020 -0500
+++ b/mercurial/bundle2.py	Thu Feb 13 22:51:17 2020 -0500
@@ -2368,6 +2368,11 @@
                     b'prepushkey', throw=True, **pycompat.strkwargs(hookargs)
                 )
 
+        for book, node in changes:
+            if bookmarks.isdivergent(book):
+                msg = _(b'cannot accept divergent bookmark %s!') % book
+                raise error.Abort(msg)
+
         bookstore.applychanges(op.repo, op.gettransaction(), changes)
 
         if pushkeycompat:
diff -r 0275000564c4 -r 8407031f195f mercurial/exchange.py
--- a/mercurial/exchange.py	Thu Feb 13 22:06:57 2020 -0500
+++ b/mercurial/exchange.py	Thu Feb 13 22:51:17 2020 -0500
@@ -856,7 +856,11 @@
     for b, scid, dcid in addsrc:
         if b in explicit:
             explicit.remove(b)
-            pushop.outbookmarks.append((b, b'', scid))
+            if bookmod.isdivergent(b):
+                pushop.ui.warn(_(b'cannot push divergent bookmark %s!\n') % b)
+                pushop.bkresult = 2
+            else:
+                pushop.outbookmarks.append((b, b'', scid))
     # search for overwritten bookmark
     for b, scid, dcid in list(advdst) + list(diverge) + list(differ):
         if b in explicit:
diff -r 0275000564c4 -r 8407031f195f relnotes/next
--- a/relnotes/next	Thu Feb 13 22:06:57 2020 -0500
+++ b/relnotes/next	Thu Feb 13 22:51:17 2020 -0500
@@ -24,6 +24,7 @@
  * Use `hg copy --forget --at-rev REV` to unmark already committed
    copies.
 
+ * prevent pushes of divergent bookmarks (foo@remote)
 
 == Bug Fixes  ==
 
diff -r 0275000564c4 -r 8407031f195f tests/test-bookmarks-pushpull.t
--- a/tests/test-bookmarks-pushpull.t	Thu Feb 13 22:06:57 2020 -0500
+++ b/tests/test-bookmarks-pushpull.t	Thu Feb 13 22:51:17 2020 -0500
@@ -328,6 +328,17 @@
 
 #endif
 
+Divergent bookmark cannot be exported
+
+  $ hg book W@default
+  $ hg push -B W@default ../a
+  pushing to ../a
+  searching for changes
+  cannot push divergent bookmark W@default!
+  no changes found
+  [2]
+  $ hg book -d W@default
+
 export the active bookmark
 
   $ hg bookmark V