vcs: Minimal change to expose the shadow repository

Based on my original research, this was the "minimal" starting point. It shows
that three concepts are needed for the "repo_name":

* From the security standpoint we think of the shadow repository having the same
  ACL as the target repository of the pull request. This is because the pull
  request itself is considered to be a part of the target repository.

  Out of this thought, the variable "acl_repo_name" is used whenever we want to
  check permissions or when we need the database configuration of the
  repository. An alternative name would have been "db_repo_name", but the usage
  for ACL checking is the most important one.

* From the web interaction perspective, we need the URL which was originally
  used to get to the repository. This is because based on this base URL commands
  can be identified. Especially for Git this is important, so that the commands
  are correctly recognized.

  Since the URL is in the focus, this is called "url_repo_name".

* Finally we have to deal with the repository on the file system. This is what
  the VCS layer deal with normally, so this name is called "vcs_repo_name".


The original repository interaction is a special case where all three names are
the same.

When interacting with a pull request, these three names are typically all
different.

This change is minimal in a sense that it just makes the interaction with a
shadow repository barely work, without checking any special constraints yet.
This was the starting point for further work on this topic.

rhodecode/lib/middleware/simplevcs.py

@@ -83,12 +83,15 b' class SimpleVCS(object):'
 
     SCM = 'unknown'
 
+    acl_repo_name = None
+    url_repo_name = None
+    vcs_repo_name = None
+
     def __init__(self, application, config, registry):
         self.registry = registry
         self.application = application
         self.config = config
         # re-populated by specialized middleware
-        self.repo_name = None
         self.repo_vcs_config = base.Config()
 
         # base path of repo locations
@@ -102,6 +105,11 b' class SimpleVCS(object):'
         self.ip_addr = '0.0.0.0'
 
     @property
+    def repo_name(self):
+        # TODO: johbo: Remove, switch to correct repo name attribute
+        return self.acl_repo_name
+
+    @property
     def scm_app(self):
         custom_implementation = self.config.get('vcs.scm_app_implementation')
         if custom_implementation and custom_implementation != 'pyro4':
@@ -340,7 +348,8 b' class SimpleVCS(object):'
         # REQUEST HANDLING
         # ======================================================================
         str_repo_name = safe_str(self.repo_name)
-        repo_path = os.path.join(safe_str(self.basepath), str_repo_name)
+        repo_path = os.path.join(
+            safe_str(self.basepath), safe_str(self.vcs_repo_name))
         log.debug('Repository path is %s', repo_path)
 
         fix_PATH()
@@ -350,7 +359,7 b' class SimpleVCS(object):'
             action, self.SCM, str_repo_name, safe_str(username), ip_addr)
 
         return self._generate_vcs_response(
-            environ, start_response, repo_path, self.repo_name, extras, action)
+            environ, start_response, repo_path, self.url_repo_name, extras, action)
 
     @initialize_generator
     def _generate_vcs_response(
@@ -365,7 +374,7 b' class SimpleVCS(object):'
         the first chunk is produced by the underlying WSGI application.
         """
         callback_daemon, extras = self._prepare_callback_daemon(extras)
-        config = self._create_config(extras, repo_name)
+        config = self._create_config(extras, self.acl_repo_name)
         log.debug('HOOKS extras is %s', extras)
         app = self._create_wsgi_app(repo_path, repo_name, config)
 

rhodecode/lib/middleware/vcs.py

@@ -176,18 +176,44 b' class VCSMiddleware(object):'
             environ['PATH_INFO'] = vcs_handler._get_by_id(environ['PATH_INFO'])
             repo_name = vcs_handler._get_repository_name(environ)
 
+            acl_repo_name = repo_name
+            vcs_repo_name = repo_name
+            url_repo_name = repo_name
+            pr_id = None
+
+            # TODO: johbo: recognize a pull request based on pattern matching
+            if '/pull-request/' in repo_name:
+                acl_repo_name, other = repo_name.split('/pull-request/')
+                # TODO: johbo: Set shadow repo path
+                basename, repo_segment = acl_repo_name.rsplit('/', 1)
+                pr_id = int(other[0:-len('/repository')])
+                vcs_repo_name = '{basename}/.__shadow_{repo_segment}_pr-{pr_id}'.format(
+                    basename=basename,
+                    repo_segment=repo_segment,
+                    pr_id=pr_id)
+
+            log.debug('repo_names %s', {
+                'acl_repo_name': acl_repo_name,
+                'vcs_repo_name': vcs_repo_name,
+                'url_repo_name': url_repo_name,
+            })
+            log.debug('pull_request %s', pr_id)
+
             # check for type, presence in database and on filesystem
             if not vcs_handler.is_valid_and_existing_repo(
-                    repo_name, vcs_handler.basepath, vcs_handler.SCM):
+                    acl_repo_name, vcs_handler.basepath, vcs_handler.SCM):
                 return HTTPNotFound()(environ, start_response)
 
             # TODO: johbo: Needed for the Pyro4 backend and Mercurial only.
             # Remove once we fully switched to the HTTP backend.
-            environ['REPO_NAME'] = repo_name
+            environ['REPO_NAME'] = url_repo_name
 
             # register repo_name and it's config back to the handler
-            vcs_handler.repo_name = repo_name
-            vcs_handler.repo_vcs_config = self.vcs_config(repo_name)
+            vcs_handler.acl_repo_name = acl_repo_name
+            vcs_handler.url_repo_name = url_repo_name
+            vcs_handler.vcs_repo_name = vcs_repo_name
+            vcs_handler.pr_id = pr_id
+            vcs_handler.repo_vcs_config = self.vcs_config(acl_repo_name)
 
             vcs_handler = self.wrap_in_gzip_if_enabled(
                 vcs_handler, self.config)

rhodecode/tests/lib/middleware/test_simplevcs.py

@@ -44,7 +44,9 b' class StubVCSController(simplevcs.Simple'
 
     def __init__(self, *args, **kwargs):
         super(StubVCSController, self).__init__(*args, **kwargs)
-        self.repo_name = HG_REPO
+        self.acl_repo_name = HG_REPO
+        self.url_repo_name = HG_REPO
+        self.vcs_repo_name = HG_REPO
 
     def _get_repository_name(self, environ):
         return HG_REPO