Add CachedRepo class with tests.

1 files changed, 147 insertions, 0 deletions

diff --git a/morphlib/cachedrepo.py b/morphlib/cachedrepo.py
new file mode 100644
index 00000000..998ba892
--- /dev/null
+++ b/morphlib/cachedrepo.py
@@ -0,0 +1,147 @@
+# Copyright (C) 2012  Codethink Limited
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+import binascii
+import cliapp
+import logging
+import os
+
+import morphlib.execute
+
+
+class InvalidReferenceError(cliapp.AppException):
+
+    def __init__(self, repo, ref):
+        Exception.__init__(self, '%s is an invalid reference for repo %s' %
+                           (ref, repo))
+
+
+class UnresolvedNamedReferenceError(cliapp.AppException):
+
+    def __init__(self, repo, ref):
+        Exception.__init__(self, '%s is not a SHA1 ref for repo %s' %
+                           (ref, repo))
+
+
+class CheckoutDirectoryExistsError(cliapp.AppException):
+
+    def __init__(self, repo, target_dir):
+        Exception.__init__(
+                self, 'Checkout directory %s for repo %s already exists' %
+                (target_dir, repo))
+
+
+class CheckoutError(cliapp.AppException):
+
+    def __init__(self, repo, ref, target_dir):
+        Exception.__init__(self, 'Failed to check out %s:%s into %s' %
+                           (repo, ref, target_dir))
+
+
+class UpdateError(cliapp.AppException):
+
+    def __init__(self, repo):
+        Exception.__init__(self, 'Failed to update cached version of repo %s' %
+                           repo)
+
+
+class CachedRepo(object):
+
+    def __init__(self, url, path):
+        self.url = url
+        self.path = path
+        self.ex = morphlib.execute.Execute(self.path, logging.debug)
+
+    def is_valid_sha1(self, ref):
+        valid_chars = 'abcdefABCDEF0123456789'
+        return len(ref) == 40 and all([x in valid_chars for x in ref])
+
+    def resolve_ref(self, ref):
+        try:
+            refs = self._show_ref(ref).split('\n')
+            # split each ref line into an array, drop non-origin branches
+            refs = [x.split() for x in refs if 'origin' in x]
+            binascii.unhexlify(refs[0][0])
+            return refs[0][0]
+        except morphlib.execute.CommandFailure:
+            if not self.is_valid_sha1(ref):
+                raise InvalidReferenceError(self, ref)
+            try:
+                binascii.unhexlify(ref)
+                return self._rev_list(ref)
+            except morphlib.execute.CommandFailure:
+                raise InvalidReferenceError(self, ref)
+
+    def cat(self, ref, filename):
+        if not self.is_valid_sha1(ref):
+            raise UnresolvedNamedReferenceError(self, ref)
+        try:
+            sha1 = self._rev_list(ref)
+            try:
+                return self._cat_file(sha1, filename)
+            except morphlib.execute.CommandFailure:
+                raise IOError('File %s does not exist in ref %s of repo %s' %
+                              (filename, ref, self))
+        except morphlib.execute.CommandFailure:
+            raise InvalidReferenceError(self, ref)
+
+    def checkout(self, ref, target_dir):
+        if not self.is_valid_sha1(ref):
+            raise UnresolvedNamedReferenceError(self, ref)
+
+        if os.path.exists(target_dir):
+            raise CheckoutDirectoryExistsError(self, target_dir)
+            
+        os.mkdir(target_dir)
+
+        try:
+            sha1 = self._rev_list(ref)
+            try:
+                self._copy_repository(self.path, target_dir)
+                self._checkout_ref(sha1, target_dir)
+            except morphlib.execute.CommandFailure:
+                raise CheckoutError(self, ref, target_dir)
+        except morphlib.execute.CommandFailure:
+            raise InvalidReferenceError(self, ref)
+
+    def update(self):
+        try:
+            self._update()
+        except morphlib.execute.CommandFailure:
+            raise UpdateError(self)
+
+    def _show_ref(self, ref): # pragma: no cover
+        return self.ex.runv(['git', 'show-ref', ref])
+
+    def _rev_list(self, ref): # pragma: no cover
+        return self.ex.runv(['git', 'rev-list', '--no-walk', ref])
+
+    def _cat_file(self, ref, filename): # pragma: no cover
+        return self.ex.runv(['git', 'cat-file', 'blob',
+                             '%s:%s' % (ref, filename)])
+
+    def _copy_repository(self, source_dir, target_dir): # pragma: no cover
+        self.ex.runv(['cp', '-a', os.path.join(source_dir, '.git'),
+                      target_dir])
+
+    def _checkout_ref(self, ref, target_dir): # pragma: no cover
+        self.ex.runv(['git', 'checkout', ref], pwd=target_dir)
+
+    def _update(self): # pragma: no cover
+        self.ex.runv(['git', 'remote', 'update', 'origin'])
+
+    def __str__(self): # pragma: no cover
+        return self.url