# 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(Exception):
"""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 create(self):
"""Creates the local repo.
Can safely be called on an existing repo.
"""
subprocess.call(self.base + ("init", "-q"))
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.run(
self.base + ("merge-base", "--is-ancestor", commit, local_head),
check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE
)
except subprocess.CalledProcessError as e:
raise GitError("check history") from e
def check_branchname(self, branchname):
"""Checks if the given branchname is a valid branch name.
Raises if it isn't.
Args:
branchname (str): Name of branch.
Raises:
GitError: If an error occurs.
"""
try:
# TODO check that this rstrip is safe
out = subprocess.run(
self.base + ("check-ref-format", "--branch", branchname),
check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE
).stdout.decode("utf-8").rstrip('\r\n')
# protect against @{-1}/@{-n} ("previous checkout operation")
# is also fairly future-proofed, I hope?
if out != branchname:
raise GitError("check branchname", out, branchname)
except subprocess.CalledProcessError as e:
raise GitError("check branchname") 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.run(
self.base + ("fetch", "-q", url, "+" + remote_head + ":" + local_head),
check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE
)
except subprocess.CalledProcessError as e:
raise GitError(e.output) 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.run(
self.base + ("rev-list", "--count", first_hash + ".." + last_hash, "--"),
check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE
).stdout.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.run(
self.base + ("show", target, "-s", "--format=format:%H", "--"),
check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE
).stdout.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.run(
self.base + ("show", target, "-s", "--format=format:%B", "--"),
check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE
).stdout.decode("utf-8", "replace")
except subprocess.CalledProcessError as e:
raise GitError("") from e
