wireproto: correctly escape batched args and responses (issue4739) This issue appears to be as old as wireproto batching itself: I can reproduce the failure as far back as 08ef6b5f3715 trivially by rebasing the test changes in this patch, which was back in the 1.9 era. I didn't test before that change, because prior to that the testfile has a different name and I'm lazy. Note that the test thought it was checking this case, but it actually wasn't: it put a literal ; in the arg and response for its greet command, but the mangle/unmangle step defined in the test meant that instead of "Fo, =;o" going over the wire, "Gp-!><p" went instead, which doesn't contain any special characters (those being [.=;]) and thus not exercising the escaping. The test has been updated to use pre-unmangled special characters, so the request is now "Fo+<:o", which mangles to "Gp,=;p". I have confirmed that the test fails without the adjustment to the escaping rules in wireproto.py. No existing clients of RPC batching were depending on the old behavior in any way. The only *actual* users of batchable RPCs in core were: 1) largefiles, wherein it batches up many statlfile calls. It sends hexlified hashes over the wire and gets a 0, 1, or 2 back as a response. No risk of special characters. 2) setdiscovery, which was using heads() and known(), both of which communicate via hexlified nodes. Again, no risk of special characters. Since the escaping functionality has been completely broken since it was introduced, we know that it has no users. As such, we can change the escaping mechanism without having to worry about backwards compatibility issues. For the curious, this was detected by chance: it happens that the lz4-compressed text of a test file for remotefilelog compressed to something containing a ;, which then caused the failure when I moved remotefilelog to using batching for file content fetching.

Create a repository:

  $ hg config
  defaults.backout=-d "0 0"
  defaults.commit=-d "0 0"
  defaults.shelve=--date "0 0"
  defaults.tag=-d "0 0"
  devel.all-warnings=true
  largefiles.usercache=$TESTTMP/.cache/largefiles (glob)
  ui.slash=True
  ui.interactive=False
  ui.mergemarkers=detailed
  ui.promptecho=True
  $ hg init t
  $ cd t

Make a changeset:

  $ echo a > a
  $ hg add a
  $ hg commit -m test

This command is ancient:

  $ hg history
  changeset:   0:acb14030fe0a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     test
  

Verify that updating to revision 0 via commands.update() works properly

  $ cat <<EOF > update_to_rev0.py
  > from mercurial import ui, hg, commands
  > myui = ui.ui()
  > repo = hg.repository(myui, path='.')
  > commands.update(myui, repo, rev=0)
  > EOF
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ python ./update_to_rev0.py
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg identify -n
  0


Poke around at hashes:

  $ hg manifest --debug
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a

  $ hg cat a
  a

Verify should succeed:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

At the end...

  $ cd ..