openpgp: Refactor to use class for system environment as well

4 files changed, 122 insertions, 75 deletions

diff --git a/gemato/cli.py b/gemato/cli.py
index 6b3ab9e..7459841 100644
--- a/gemato/cli.py
+++ b/gemato/cli.py
@@ -43,11 +43,19 @@ def do_verify(args, argp):
             kwargs['fail_handler'] = verify_failure
         if not args.openpgp_verify:
             init_kwargs['verify_openpgp'] = False
-        with gemato.openpgp.OpenPGPEnvironment() as env:
+
+        # use isolated environment if key is specified;
+        # system environment otherwise
+        if args.openpgp_key is not None:
+            env_class = gemato.openpgp.OpenPGPEnvironment
+        else:
+            env_class = gemato.openpgp.OpenPGPSystemEnvironment
+
+        with env_class() as env:
             if args.openpgp_key is not None:
                 with io.open(args.openpgp_key, 'rb') as f:
                     env.import_key(f)
-                init_kwargs['openpgp_env'] = env
+            init_kwargs['openpgp_env'] = env
 
             start = timeit.default_timer()
             try:
@@ -113,11 +121,19 @@ def do_update(args, argp):
                     args.profile)
         if args.sign is not None:
             init_kwargs['sign_openpgp'] = args.sign
-        with gemato.openpgp.OpenPGPEnvironment() as env:
+
+        # use isolated environment if key is specified;
+        # system environment otherwise
+        if args.openpgp_key is not None:
+            env_class = gemato.openpgp.OpenPGPEnvironment
+        else:
+            env_class = gemato.openpgp.OpenPGPSystemEnvironment
+
+        with env_class() as env:
             if args.openpgp_key is not None:
                 with io.open(args.openpgp_key, 'rb') as f:
                     env.import_key(f)
-                init_kwargs['openpgp_env'] = env
+            init_kwargs['openpgp_env'] = env
 
             start = timeit.default_timer()
             try:
@@ -204,11 +220,19 @@ def do_create(args, argp):
                     args.profile)
         if args.sign is not None:
             init_kwargs['sign_openpgp'] = args.sign
-        with gemato.openpgp.OpenPGPEnvironment() as env:
+
+        # use isolated environment if key is specified;
+        # system environment otherwise
+        if args.openpgp_key is not None:
+            env_class = gemato.openpgp.OpenPGPEnvironment
+        else:
+            env_class = gemato.openpgp.OpenPGPSystemEnvironment
+
+        with env_class() as env:
             if args.openpgp_key is not None:
                 with io.open(args.openpgp_key, 'rb') as f:
                     env.import_key(f)
-                init_kwargs['openpgp_env'] = env
+            init_kwargs['openpgp_env'] = env
 
             start = timeit.default_timer()
             try:
diff --git a/gemato/manifest.py b/gemato/manifest.py
index 37d5288..39a8655 100644
--- a/gemato/manifest.py
+++ b/gemato/manifest.py
@@ -356,8 +356,8 @@ class ManifestFile(object):
         in text mode, and oriented at the beginning.
 
         If @verify_openpgp is True and the Manifest contains an OpenPGP
-        signature, the signature will be verified. Provide @openpgp_env
-        to perform the verification in specific environment.
+        signature, the signature will be verified. In that case,
+        @openpgp_env needs to be provided.
 
         If the verification succeeds, the openpgp_signed property will
         be set to True. If it fails or OpenPGP is not available,
@@ -434,8 +434,9 @@ class ManifestFile(object):
                     "Manifest terminated early, inside signature")
 
         if verify_openpgp and state == ManifestState.POST_SIGNED_DATA:
+            assert openpgp_env
             with io.StringIO(openpgp_data) as f:
-                gemato.openpgp.verify_file(f, env=openpgp_env)
+                openpgp_env.verify_file(f)
             self.openpgp_signed = True
 
     def dump(self, f, sign_openpgp=None, openpgp_keyid=None,
@@ -449,8 +450,9 @@ class ManifestFile(object):
         If it is None (the default), the file will be signed if it
         was originally signed with a valid signature.
 
-        @openpgp_keyid and @openpgp_env specify the key
-        and the environment to use for signing.
+        If @openpgp_keyid is not None, it specifies the key to use
+        for signing. If @sign_openpgp is not False, @openpgp_env must
+        provide an OpenPGP environment for signing.
 
         If @sort is True, the entries are sorted prior to dumping.
         """
@@ -462,12 +464,12 @@ class ManifestFile(object):
             self.entries = sorted(self.entries)
 
         if sign_openpgp:
+            assert openpgp_env
             with io.StringIO() as data:
                 # get the plain data into a stream
                 self.dump(data, sign_openpgp=False)
                 data.seek(0)
-                gemato.openpgp.clear_sign_file(data, f,
-                        keyid=openpgp_keyid, env=openpgp_env)
+                openpgp_env.clear_sign_file(data, f, keyid=openpgp_keyid)
         else:
             for e in self.entries:
                 f.write(u' '.join(e.to_list()) + '\n')
diff --git a/gemato/openpgp.py b/gemato/openpgp.py
index aadc9e5..2d6dd84 100644
--- a/gemato/openpgp.py
+++ b/gemato/openpgp.py
@@ -42,7 +42,76 @@ def _spawn_gpg(options, env_instance, stdin):
     return (p.wait(), out, err)
 
 
-class OpenPGPEnvironment(object):
+class OpenPGPEnvironmentBase(object):
+    """
+    Base class for OpenPGP environment.
+    """
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, exc_cb):
+        pass
+
+    def close(self):
+        pass
+
+    def import_key(self, keyfile):
+        """
+        Import a public key from open file @keyfile. The file should
+        be open for reading in binary mode, and oriented
+        at the beginning.
+        """
+
+        raise NotImplementedError('import_key() is not implemented by this OpenPGP provider')
+
+    def verify_file(self, f):
+        """
+        Perform an OpenPGP verification of Manifest data in open file @f.
+        The file should be open in text mode and set at the beginning
+        (or start of signed part). Raises an exception if the verification
+        fails.
+        """
+
+        raise NotImplementedError('verify_file() is not implemented by this OpenPGP provider')
+
+    def clear_sign_file(self, f, outf, keyid=None):
+        """
+        Create an OpenPGP cleartext signed message containing the data
+        from open file @f, and writing it into open file @outf.
+        Both files should be open in text mode and set at the appropriate
+        position. Raises an exception if signing fails.
+
+        Pass @keyid to specify the key to use. If not specified,
+        the implementation will use the default key.
+        """
+
+        raise NotImplementedError('clear_sign_file() is not implemented by this OpenPGP provider')
+
+
+class OpenPGPSystemEnvironment(OpenPGPEnvironmentBase):
+    """
+    The system environment for OpenPGP routines.
+    """
+
+    def verify_file(self, f):
+        exitst, out, err = _spawn_gpg(['--verify'], None, f.read().encode('utf8'))
+        if exitst != 0:
+            raise gemato.exceptions.OpenPGPVerificationFailure(err.decode('utf8'))
+
+    def clear_sign_file(self, f, outf, keyid=None):
+        args = []
+        if keyid is not None:
+            args += ['--local-user', keyid]
+        exitst, out, err = _spawn_gpg(['--clearsign'] + args, None,
+                                      f.read().encode('utf8'))
+        if exitst != 0:
+            raise gemato.exceptions.OpenPGPSigningFailure(err.decode('utf8'))
+
+        outf.write(out.decode('utf8'))
+
+
+class OpenPGPEnvironment(OpenPGPEnvironmentBase):
     """
     An isolated environment for OpenPGP routines. Used to get reliable
     verification results independently of user configuration.
@@ -64,9 +133,6 @@ class OpenPGPEnvironment(object):
 disable-scdaemon
 ''')
 
-    def __enter__(self):
-        return self
-
     def __exit__(self, exc_type, exc_value, exc_cb):
         if self._home is not None:
             self.close()
@@ -95,30 +161,25 @@ disable-scdaemon
             self._home = None
 
     def import_key(self, keyfile):
-        """
-        Import a public key from open file @keyfile. The file should
-        be open for reading in binary mode, and oriented
-        at the beginning.
-        """
-
         exitst, out, err = _spawn_gpg(['--import'], self, keyfile.read())
         if exitst != 0:
             raise RuntimeError('Unable to import key: {}'.format(err.decode('utf8')))
 
     def verify_file(self, f):
-        """
-        A convenience wrapper for verify_file(), using this environment.
-        """
-
-        verify_file(f, env=self)
+        exitst, out, err = _spawn_gpg(['--verify'], self, f.read().encode('utf8'))
+        if exitst != 0:
+            raise gemato.exceptions.OpenPGPVerificationFailure(err.decode('utf8'))
 
     def clear_sign_file(self, f, outf, keyid=None):
-        """
-        A convenience wrapper for clear_sign_file(), using this
-        environment.
-        """
+        args = []
+        if keyid is not None:
+            args += ['--local-user', keyid]
+        exitst, out, err = _spawn_gpg(['--clearsign'] + args, self,
+                                      f.read().encode('utf8'))
+        if exitst != 0:
+            raise gemato.exceptions.OpenPGPSigningFailure(err.decode('utf8'))
 
-        clear_sign_file(f, outf, keyid=keyid, env=self)
+        outf.write(out.decode('utf8'))
 
     @property
     def home(self):
@@ -126,43 +187,3 @@ disable-scdaemon
             raise RuntimeError(
                     'OpenPGPEnvironment has been closed')
         return self._home
-
-
-def verify_file(f, env=None):
-    """
-    Perform an OpenPGP verification of Manifest data in open file @f.
-    The file should be open in text mode and set at the beginning
-    (or start of signed part). Raises an exception if the verification
-    fails.
-
-    Note that this function does not distinguish whether the key
-    is trusted, and is subject to user configuration. To get reliable
-    results, prepare a dedicated OpenPGPEnvironment and pass it as @env.
-    """
-
-    exitst, out, err = _spawn_gpg(['--verify'], env, f.read().encode('utf8'))
-    if exitst != 0:
-        raise gemato.exceptions.OpenPGPVerificationFailure(err.decode('utf8'))
-
-
-def clear_sign_file(f, outf, keyid=None, env=None):
-    """
-    Create an OpenPGP cleartext signed message containing the data
-    from open file @f, and writing it into open file @outf.
-    Both files should be open in text mode and set at the appropriate
-    position. Raises an exception if signing fails.
-
-    Pass @keyid to specify the key to use. If not specified,
-    the implementation will use the default key. Pass @env to use
-    a dedicated OpenPGPEnvironment.
-    """
-
-    args = []
-    if keyid is not None:
-        args += ['--local-user', keyid]
-    exitst, out, err = _spawn_gpg(['--clearsign'] + args, env,
-                                  f.read().encode('utf8'))
-    if exitst != 0:
-        raise gemato.exceptions.OpenPGPSigningFailure(err.decode('utf8'))
-
-    outf.write(out.decode('utf8'))
diff --git a/gemato/recursiveloader.py b/gemato/recursiveloader.py
index befda32..35c304a 100644
--- a/gemato/recursiveloader.py
+++ b/gemato/recursiveloader.py
@@ -28,8 +28,8 @@ class ManifestLoader(object):
         @root_directory specifies top directory of Manifest tree.
 
         If @verify_openpgp is True and a Manifest contain an OpenPGP
-        signature, the signature will be verified. Provide @openpgp_env
-        to perform the verification in specific environment.
+        signature, the signature will be verified. @openpgp_env
+        is the OpenPGP environment to use.
         """
         self.root_directory = root_directory
         self.verify_openpgp = verify_openpgp