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github.com_openSUSE_osc/osc/gitea_api/tardiff.py

96 lines
3.2 KiB
Python

import os
import shutil
import subprocess
from typing import Iterator
from . import git
GIT_EMPTY_COMMIT = "4b825dc642cb6eb9a060e54bf8d69288fbee4904"
class TarDiff:
def __init__(self, path):
self.git = git.Git(path)
os.makedirs(self.path, exist_ok=True)
self.git.init(initial_branch="empty", quiet=True, mute_stderr=True)
# the git repo is switched to this branch by default to hide the files from disk
self.git.commit("empty branch", allow_empty=True)
@property
def path(self):
return self.git.abspath
def _get_branch_name(self, filename: str, checksum: str) -> str:
filename = os.path.basename(filename)
return f"{filename}-{checksum}"
def add_archive(self, filename: str, checksum: str, data: Iterator[bytes]) -> str:
"""
Create a branch with expanded archive.
The easiest way of obtaining the `checksum` is via running `git lfs ls-files --long`.
"""
# make sure we don't use the path anywhere
filename = os.path.basename(filename)
branch = self._get_branch_name(filename, checksum)
# detect if a branch exists and is not empty; do nothing if it's the case
if self.git.branch_exists(branch) and self.git.commit_count(branch) > 0:
return branch
# create an empty branch
self.git.switch(branch, orphan=True)
# TODO: mute stdout
# remove any existing contents but ".git" directory
for fn in os.listdir(self.path):
if fn == ".git":
continue
shutil.rmtree(os.path.join(self.path, fn))
# extract archive
# We use bsdtar, because tar cannot determine compression from stdin automatically.
# Stripping the first path component works fine for regular source archives with %{name}/%{version}/ prefix
# but it may need an improvement for other archives.
proc = subprocess.Popen(
["bsdtar", "xf", "-", "--strip-components=1"],
stdin=subprocess.PIPE,
cwd=self.path,
)
assert proc.stdin is not None
for chunk in data:
proc.stdin.write(chunk)
proc.communicate()
assert proc.returncode == 0
# add files and commit
self.git.add(["--all"])
self.git.commit(msg=f"import {filename} with checksum {checksum}")
self.git.switch("empty")
# TODO: git gc?
return branch
def diff_archives(self, src_filename, src_checksum, dst_filename, dst_checksum) -> Iterator[bytes]:
if src_filename:
src_filename = os.path.basename(src_filename)
src_branch = self._get_branch_name(src_filename, src_checksum)
src_branch = f"refs/heads/{src_branch}"
else:
src_filename = "/dev/null"
src_branch = GIT_EMPTY_COMMIT
if dst_filename:
dst_filename = os.path.basename(dst_filename)
dst_branch = self._get_branch_name(dst_filename, dst_checksum)
dst_branch = f"refs/heads/{dst_branch}"
else:
dst_filename = "/dev/null"
dst_branch = GIT_EMPTY_COMMIT
yield from self.git.diff(src_branch, dst_branch, src_prefix=src_filename, dst_prefix=dst_filename)