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diff --git a/ganarchy/git.py b/ganarchy/git.py
new file mode 100644
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+++ b/ganarchy/git.py
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+# This file is part of GAnarchy - decentralized project hub
+# Copyright (C) 2020  Soni L.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Git abstraction.
+"""
+
+# Errors are raised when we can't provide an otherwise valid result.
+# For example, we return 0 for counts instead of raising, but raise
+# instead of returning empty strings for commit hashes and messages.
+
+import subprocess
+
+class GitError(LookupError):
+    """Raised when a git operation fails, generally due to a
+    missing commit or branch, or network connection issues.
+    """
+    pass
+
+class Git:
+    def __init__(self, path):
+        self.path = path
+        self.base = ("git", "-C", path)
+
+    def check_history(self, local_head, commit):
+        """Checks if the local head contains commit in its history.
+        Raises if it doesn't.
+
+        Args:
+            local_head (str): Name of local head.
+            commit (str): Commit hash.
+
+        Raises:
+            GitError: If an error occurs.
+        """
+        try:
+            subprocess.check_call(
+                self.base + ("merge-base", "--is-ancestor", commit, local_head),
+                stdout=subprocess.DEVNULL,
+                stderr=subprocess.DEVNULL
+            )
+        except subprocess.CalledProcessError as e:
+            raise GitError from e
+
+    def force_fetch(self, url, remote_head, local_head):
+        """Fetches a remote head into a local head.
+        
+        If the local head already exists, it is replaced.
+
+        Args:
+            url (str): Remote url.
+            remote_head (str): Name of remote head.
+            local_head (str): Name of local head.
+
+        Raises:
+            GitError: If an error occurs.
+        """
+        try:
+            subprocess.check_output(
+                base + ("fetch", "-q", url, "+" + remote_head + ":" + local_head),
+                stderr=subprocess.STDOUT
+            )
+        except subprocess.CalledProcessError as e:
+            raise GitError from e
+
+    def get_count(self, first_hash, last_hash):
+        """Returns a count of the commits added since ``first_hash``
+        up to ``last_hash``.
+
+        Args:
+            first_hash (str): A commit.
+            last_hash (str): Another commit.
+
+        Returns:
+            int: A count of commits added between the hashes, or 0
+            if an error occurs.
+        """
+        try:
+            res = subprocess.check_output(
+                base + ("rev-list", "--count", first_hash + ".." + last_hash, "--"),
+                stderr=subprocess.DEVNULL
+            ).decode("utf-8").strip()
+            return int(res)
+        except subprocess.CalledProcessError as e:
+            return 0
+
+    def get_hash(self, target):
+        """Returns the commit hash for a given target.
+
+        Args:
+            target (str): a refspec.
+
+        Raises:
+            GitError: If an error occurs.
+        """
+        try:
+            return subprocess.check_output(
+                self.base + ("show", target, "-s", "--format=format:%H", "--"),
+                stderr=subprocess.DEVNULL
+            ).decode("utf-8")
+        except subprocess.CalledProcessError as e:
+            raise GitError from e
+
+    def get_commit_message(self, target):
+        """Returns the commit message for a given target.
+
+        Args:
+            target (str): a refspec.
+
+        Raises:
+            GitError: If an error occurs.
+        """
+        try:
+            return subprocess.check_output(
+                self.base + ("show", target, "-s", "--format=format:%B", "--"),
+                stderr=subprocess.DEVNULL
+            ).decode("utf-8", "replace")
+        except subprocess.CalledProcessError as e:
+            raise GitError from e