GitConfigParser now respects and merges 'include' sections

We implement it as described in this article:
http://stackoverflow.com/questions/1557183/is-it-possible-to-include-a-file-in-your-gitconfig

Thus we handle

* cycles
* relative and absolute include paths
* write-backs in case of writable GitConfigParser instances

Fixes #201

5 files changed, 143 insertions, 17 deletions

diff --git a/.gitmodules b/.gitmodules
index 612c39d9..4a3f37c2 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "gitdb"]
-	path = git/ext/gitdb
 	url = https://github.com/gitpython-developers/gitdb.git
+	path = git/ext/gitdb
diff --git a/git/config.py b/git/config.py
index 5828a1c1..4c4cb491 100644
--- a/git/config.py
+++ b/git/config.py
@@ -15,6 +15,7 @@ except ImportError:
 import inspect
 import logging
 import abc
+import os
 
 from git.odict import OrderedDict
 from git.util import LockFile
@@ -164,7 +165,7 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
     # list of RawConfigParser methods able to change the instance
     _mutating_methods_ = ("add_section", "remove_section", "remove_option", "set")
 
-    def __init__(self, file_or_files, read_only=True):
+    def __init__(self, file_or_files, read_only=True, merge_includes=True):
         """Initialize a configuration reader to read the given file_or_files and to
         possibly allow changes to it by setting read_only False
 
@@ -173,7 +174,13 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
 
         :param read_only:
             If True, the ConfigParser may only read the data , but not change it.
-            If False, only a single file path or file object may be given."""
+            If False, only a single file path or file object may be given. We will write back the changes
+            when they happen, or when the ConfigParser is released. This will not happen if other
+            configuration files have been included
+        :param merge_includes: if True, we will read files mentioned in [include] sections and merge their
+            contents into ours. This makes it impossible to write back an individual configuration file.
+            Thus, if you want to modify a single conifguration file, turn this off to leave the original
+            dataset unaltered when reading it."""
         cp.RawConfigParser.__init__(self, dict_type=OrderedDict)
 
         # Used in python 3, needs to stay in sync with sections for underlying implementation to work
@@ -183,6 +190,7 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
         self._file_or_files = file_or_files
         self._read_only = read_only
         self._is_initialized = False
+        self._merge_includes = merge_includes
         self._lock = None
 
         if not read_only:
@@ -313,7 +321,6 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
                     if not e:
                         e = cp.ParsingError(fpname)
                     e.append(lineno, repr(line))
-                    print(lineno, line)
                     continue
             else:
                 line = line.rstrip()
@@ -329,6 +336,9 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
         if e:
             raise e
 
+    def _has_includes(self):
+        return self._merge_includes and self.has_section('include')
+
     def read(self):
         """Reads the data stored in the files we have been initialized with. It will
         ignore files that cannot be read, possibly leaving an empty configuration
@@ -337,18 +347,25 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
         :raise IOError: if a file cannot be handled"""
         if self._is_initialized:
             return
+        self._is_initialized = True
 
-        files_to_read = self._file_or_files
-        if not isinstance(files_to_read, (tuple, list)):
-            files_to_read = [files_to_read]
-
-        for file_object in files_to_read:
-            fp = file_object
+        if not isinstance(self._file_or_files, (tuple, list)):
+            files_to_read = [self._file_or_files]
+        else:
+            files_to_read = list(self._file_or_files)
+        # end assure we have a copy of the paths to handle
+
+        seen = set(files_to_read)
+        num_read_include_files = 0
+        while files_to_read:
+            file_path = files_to_read.pop(0)
+            fp = file_path
             close_fp = False
+
             # assume a path if it is not a file-object
-            if not hasattr(file_object, "seek"):
+            if not hasattr(fp, "seek"):
                 try:
-                    fp = open(file_object, 'rb')
+                    fp = open(file_path, 'rb')
                     close_fp = True
                 except IOError:
                     continue
@@ -360,8 +377,33 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
                 if close_fp:
                     fp.close()
             # END read-handling
-        # END  for each file object to read
-        self._is_initialized = True
+
+            # Read includes and append those that we didn't handle yet
+            # We expect all paths to be normalized and absolute (and will assure that is the case)
+            if self._has_includes():
+                for _, include_path in self.items('include'):
+                    if not os.path.isabs(include_path):
+                        if not close_fp:
+                            continue
+                        # end ignore relative paths if we don't know the configuration file path
+                        assert os.path.isabs(file_path), "Need absolute paths to be sure our cycle checks will work"
+                        include_path = os.path.join(os.path.dirname(file_path), include_path)
+                    # end make include path absolute
+                    include_path = os.path.normpath(include_path)
+                    if include_path in seen or not os.access(include_path, os.R_OK):
+                        continue
+                    seen.add(include_path)
+                    files_to_read.append(include_path)
+                    num_read_include_files += 1
+                # each include path in configuration file
+            # end handle includes
+        # END for each file object to read
+
+        # If there was no file included, we can safely write back (potentially) the configuration file
+        # without altering it's meaning
+        if num_read_include_files == 0:
+            self._merge_includes = False
+        # end
 
     def _write(self, fp):
         """Write an .ini-format representation of the configuration state in
@@ -379,6 +421,10 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
         for name, value in self._sections.items():
             write_section(name, value)
 
+    def items(self, section_name):
+        """:return: list((option, value), ...) pairs of all items in the given section"""
+        return [(k, v) for k, v in super(GitConfigParser, self).items(section_name) if k != '__name__']
+
     @needs_values
     def write(self):
         """Write changes to our file, if there are changes at all
@@ -387,6 +433,17 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
             a file lock"""
         self._assure_writable("write")
 
+        if isinstance(self._file_or_files, (list, tuple)):
+            raise AssertionError("Cannot write back if there is not exactly a single file to write to, have %i files"
+                                 % len(self._file_or_files))
+        # end assert multiple files
+
+        if self._has_includes():
+            log.debug("Skipping write-back of confiuration file as include files were merged in." +
+                      "Set merge_includes=False to prevent this.")
+            return
+        # end
+
         fp = self._file_or_files
         close_fp = False
 
diff --git a/git/repo/base.py b/git/repo/base.py
index f5ed2479..155a674f 100644
--- a/git/repo/base.py
+++ b/git/repo/base.py
@@ -359,11 +359,11 @@ class Repo(object):
             return "/etc/gitconfig"
         elif config_level == "user":
             config_home = os.environ.get("XDG_CONFIG_HOME") or os.path.join(os.environ.get("HOME", '~'), ".config")
-            return os.path.expanduser(join(config_home, "git", "config"))
+            return os.path.normpath(os.path.expanduser(join(config_home, "git", "config")))
         elif config_level == "global":
             return os.path.normpath(os.path.expanduser("~/.gitconfig"))
         elif config_level == "repository":
-            return join(self.git_dir, "config")
+            return os.path.normpath(join(self.git_dir, "config"))
 
         raise ValueError("Invalid configuration level: %r" % config_level)
 
diff --git a/git/test/fixtures/git_config b/git/test/fixtures/git_config
index ff8e7114..c9945cd5 100644
--- a/git/test/fixtures/git_config
+++ b/git/test/fixtures/git_config
@@ -27,3 +27,6 @@
 [branch "mainline_performance"]
 	remote = mainline
 	merge = refs/heads/master
+[include]
+	path = doesntexist.cfg
+	abspath = /usr/bin/foodoesntexist.bar
\ No newline at end of file
diff --git a/git/test/test_config.py b/git/test/test_config.py
index 6851b2a1..9a44d9e3 100644
--- a/git/test/test_config.py
+++ b/git/test/test_config.py
@@ -7,8 +7,9 @@
 from git.test.lib import (
     TestCase,
     fixture_path,
-    assert_equal
+    assert_equal,
 )
+from gitdb.test.lib import with_rw_directory
 from git import (
     GitConfigParser
 )
@@ -16,6 +17,7 @@ from git.compat import (
     string_types,
 )
 import io
+import os
 from copy import copy
 from git.config import cp
 
@@ -127,3 +129,67 @@ class TestBase(TestCase):
 
         # it raises if there is no default though
         self.failUnlessRaises(cp.NoSectionError, r_config.get_value, "doesnt", "exist")
+
+    @with_rw_directory
+    def test_config_include(self, rw_dir):
+        def write_test_value(cw, value):
+            cw.set_value(value, 'value', value)
+        # end
+
+        def check_test_value(cr, value):
+            assert cr.get_value(value, 'value') == value
+        # end
+
+        # PREPARE CONFIG FILE A
+        fpa = os.path.join(rw_dir, 'a')
+        cw = GitConfigParser(fpa, read_only=False)
+        write_test_value(cw, 'a')
+
+        fpb = os.path.join(rw_dir, 'b')
+        fpc = os.path.join(rw_dir, 'c')
+        cw.set_value('include', 'relative_path_b', 'b')
+        cw.set_value('include', 'doesntexist', 'foobar')
+        cw.set_value('include', 'relative_cycle_a_a', 'a')
+        cw.set_value('include', 'absolute_cycle_a_a', fpa)
+        cw.release()
+        assert os.path.exists(fpa)
+
+        # PREPARE CONFIG FILE B
+        cw = GitConfigParser(fpb, read_only=False)
+        write_test_value(cw, 'b')
+        cw.set_value('include', 'relative_cycle_b_a', 'a')
+        cw.set_value('include', 'absolute_cycle_b_a', fpa)
+        cw.set_value('include', 'relative_path_c', 'c')
+        cw.set_value('include', 'absolute_path_c', fpc)
+        cw.release()
+
+        # PREPARE CONFIG FILE C
+        cw = GitConfigParser(fpc, read_only=False)
+        write_test_value(cw, 'c')
+        cw.release()
+
+        cr = GitConfigParser(fpa, read_only=True)
+        for tv in ('a', 'b', 'c'):
+            check_test_value(cr, tv)
+        # end for each test to verify
+        assert len(cr.items('include')) == 8, "Expected all include sections to be merged"
+        cr.release()
+
+        # test writable config writers - assure write-back doesn't involve includes
+        cw = GitConfigParser(fpa, read_only=False, merge_includes=True)
+        tv = 'x'
+        write_test_value(cw, tv)
+        cw.release()
+
+        cr = GitConfigParser(fpa, read_only=True)
+        self.failUnlessRaises(cp.NoSectionError, check_test_value, cr, tv)
+        cr.release()
+
+        # But can make it skip includes alltogether, and thus allow write-backs
+        cw = GitConfigParser(fpa, read_only=False, merge_includes=False)
+        write_test_value(cw, tv)
+        cw.release()
+
+        cr = GitConfigParser(fpa, read_only=True)
+        check_test_value(cr, tv)
+        cr.release()