Add support for querying attributes

Expose a method in the repository which allows querying an attribute for
a file and converts the result to the python equivalent.

Author: carlosmn

pygit2/__init__.py

@@ -65,6 +65,12 @@
 GIT_REPOSITORY_INIT_SHARED_GROUP = C.GIT_REPOSITORY_INIT_SHARED_GROUP
 GIT_REPOSITORY_INIT_SHARED_ALL = C.GIT_REPOSITORY_INIT_SHARED_ALL
 
+# GIT_ATTR_CHECK_*
+GIT_ATTR_CHECK_FILE_THEN_INDEX = C.GIT_ATTR_CHECK_FILE_THEN_INDEX
+GIT_ATTR_CHECK_INDEX_THEN_FILE = C.GIT_ATTR_CHECK_INDEX_THEN_FILE
+GIT_ATTR_CHECK_INDEX_ONLY      = C.GIT_ATTR_CHECK_INDEX_ONLY
+GIT_ATTR_CHECK_NO_SYSTEM       = C.GIT_ATTR_CHECK_NO_SYSTEM
+
 
 def init_repository(path, bare=False,
                     flags=GIT_REPOSITORY_INIT_MKPATH,

pygit2/decl.h

@@ -702,3 +702,18 @@ int git_merge_commits(git_index **out, git_repository *repo, const git_commit *o
 int git_merge_trees(git_index **out, git_repository *repo, const git_tree *ancestor_tree, const git_tree *our_tree, const git_tree *their_tree, const git_merge_options *opts);
 int git_merge_file_from_index(git_merge_file_result *out, git_repository *repo, const git_index_entry *ancestor, const git_index_entry *ours, const git_index_entry *theirs, const git_merge_file_options *opts);
 void git_merge_file_result_free(git_merge_file_result *result);
+
+#define GIT_ATTR_CHECK_FILE_THEN_INDEX ...
+#define GIT_ATTR_CHECK_INDEX_THEN_FILE ...
+#define GIT_ATTR_CHECK_INDEX_ONLY      ...
+#define GIT_ATTR_CHECK_NO_SYSTEM       ...
+
+typedef enum {
+	GIT_ATTR_UNSPECIFIED_T = 0,
+	GIT_ATTR_TRUE_T,
+	GIT_ATTR_FALSE_T,
+	GIT_ATTR_VALUE_T,
+} git_attr_t;
+
+int git_attr_get(const char **value_out, git_repository *repo, uint32_t flags, const char *path, const char *name);
+git_attr_t git_attr_value(const char *attr);

pygit2/repository.py

@@ -764,3 +764,41 @@ def ahead_behind(self, local, upstream):
         check_error(err)
 
         return int(ahead[0]), int(behind[0])
+
+    #
+    # Git attributes
+    #
+    def get_attr(self, path, name, flags=0):
+        """Retrieve an attribute for a file by path
+
+        Arguments
+
+        path
+            The path of the file to look up attributes for, relative to the
+            workdir root
+        name
+            The name of the attribute to look up
+        flags
+            A combination of GIT_ATTR_CHECK_ flags which determine the
+            lookup order
+
+        Returns either a boolean, None (if the value is unspecified) or string
+        with the value of the attribute.
+        """
+
+        cvalue = ffi.new('char **')
+        err = C.git_attr_get(cvalue, self._repo, flags, to_bytes(path), to_bytes(name))
+        check_error(err)
+
+        # Now let's see if we can figure out what the value is
+        attr_kind = C.git_attr_value(cvalue[0])
+        if attr_kind == C.GIT_ATTR_UNSPECIFIED_T:
+            return None
+        elif attr_kind == C.GIT_ATTR_TRUE_T:
+            return True
+        elif attr_kind == C.GIT_ATTR_FALSE_T:
+            return False
+        elif attr_kind == C.GIT_ATTR_VALUE_T:
+            return ffi.string(cvalue[0]).decode('utf-8')
+
+        assert False, "the attribute value from libgit2 is invalid"

test/test_attributes.py

@@ -0,0 +1,65 @@
+# -*- coding: UTF-8 -*-
+#
+# Copyright 2010-2014 The pygit2 contributors
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License, version 2,
+# as published by the Free Software Foundation.
+#
+# In addition to the permissions in the GNU General Public License,
+# the authors give you unlimited permission to link the compiled
+# version of this file into combinations with other programs,
+# and to distribute those combinations without any restriction
+# coming from the use of this file.  (The General Public License
+# restrictions do apply in other respects; for example, they cover
+# modification of the file, and distribution when not linked into
+# a combined executable.)
+#
+# This file 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; see the file COPYING.  If not, write to
+# the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+
+# Import from the future
+from __future__ import absolute_import
+from __future__ import unicode_literals, print_function
+
+# Import from the Standard Library
+import binascii
+import unittest
+import tempfile
+import os
+from os.path import join, realpath
+import sys
+
+# Import from pygit2
+from pygit2 import GIT_OBJ_ANY, GIT_OBJ_BLOB, GIT_OBJ_COMMIT
+from pygit2 import init_repository, clone_repository, discover_repository
+from pygit2 import Oid, Reference, hashfile
+import pygit2
+from . import utils
+
+try:
+    import __pypy__
+except ImportError:
+    __pypy__ = None
+
+class RepositorySignatureTest(utils.RepoTestCase):
+
+    def test_no_attr(self):
+        self.assertIsNone(self.repo.get_attr('file', 'foo'))
+
+        with open(join(self.repo.workdir, '.gitattributes'), 'w+') as f:
+            print('*.py  text\n', file=f)
+            print('*.jpg -text\n', file=f)
+            print('*.sh  eol=lf\n', file=f)
+
+        self.assertIsNone(self.repo.get_attr('file.py', 'foo'))
+        self.assertTrue(self.repo.get_attr('file.py', 'text'))
+        self.assertFalse(self.repo.get_attr('file.jpg', 'text'))
+        self.assertEqual("lf", self.repo.get_attr('file.sh', 'eol'))