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Tiny clone of pacman in python
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README.md

pacman.py

Tiny clone of pacman to fetch arch packages binary cache. Best used with something like LFN or LFS Note: mount and su executables are setuid, but you will get weird permission errors with them unless you chown :root ./root/usr/bin/su or similar.

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cache.py
import os
# Printing
def print_replace(text: str, end: str = '\n'):
print('\x1b[?7l', end='', flush=True) # Disable wrap
print('\x1b[2K', end='', flush=True) # Clear line
print(text, end=end, flush=True) # Print line
print('\x1b[?7h', end='', flush=True) # Enable wrap
def sizeof_fmt(size: int, suffix: str = 'B'):
# Source: https://stackoverflow.com/questions/1094841/get-a-human-readable-version-of-a-file-size
num = size
for unit in ('', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi'):
if abs(num) < 1024.0:
return f'{num:3.1f}{unit}{suffix}'
num /= 1024.0
return f'{num:.1f}Yi{suffix}'
def progress_bar(value: int, max: int, label: str, filesize: bool = True):
WIDTH = 20
chars = int(value / max * WIDTH)
def fmt(val: int) -> str:
if filesize: return sizeof_fmt(val)
else: return str(val)
bar = f'[{'=' * chars}{' ' * (WIDTH - chars)}]'
print_replace(f'{fmt(value)} / {fmt(max)} {bar} {label}', end='\r')
# Download
from typing import IO
def download(url: str, file: IO[bytes]):
# Source: https://stackoverflow.com/questions/15644964/python-progress-bar-and-downloads (slightly modified)
import requests
response = requests.get(url, stream=True)
content_length = response.headers.get('content-length')
if content_length is None:
file.write(response.content)
else:
content_length = int(content_length)
downloaded = 0
for data in response.iter_content(chunk_size=4096):
file.write(data)
downloaded += len(data)
progress_bar(downloaded, content_length, f'Downloading {url}')
print_replace(f'Downloaded {url}')
def extract(file: IO[bytes], target_dir: str):
# Source: https://stackoverflow.com/questions/3667865/python-tarfile-progress-output
import tarfile
def track_progress(members: list[tarfile.TarInfo]):
for idx, member in enumerate(members):
progress_bar(idx + 1, len(members), f'Extracting {member.name}')
yield member
with tarfile.open(fileobj=file) as tarball:
tarball.extractall(target_dir, members=track_progress(tarball.getmembers()))
print_replace(f'Extracted {os.path.basename(target_dir)}')
def download_and_extract(url: str, target_dir: str, zst=False):
from io import BytesIO
with BytesIO() as pipe1:
download(url, pipe1)
pipe1.seek(0)
if zst:
with BytesIO() as pipe2:
import zstandard
unzstd = zstandard.ZstdDecompressor()
unzstd.copy_stream(pipe1, pipe2)
pipe2.seek(0)
extract(pipe2, target_dir)
else:
extract(pipe1, target_dir)
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pacman.py
import platform
import os
import cache
ARCH = platform.uname().machine
MIRROR = 'https://mirrors.edge.kernel.org/archlinux'
PACKAGE_CACHE_PATH = './packages'
if not os.path.isdir(PACKAGE_CACHE_PATH):
for repo in ['core', 'extra']:
path = os.path.join(PACKAGE_CACHE_PATH, repo)
cache.download_and_extract(f'{MIRROR}/{repo}/os/{ARCH}/{repo}.db.tar.gz', path)
def split_version(package):
split = len(package)
split = min(split, package.index('<') if '<' in package else len(package))
split = min(split, package.index('>') if '>' in package else len(package))
split = min(split, package.index('=') if '=' in package else len(package))
package, version = package[:split], package[split:]
return package, version
package_info = {}
for repo in os.listdir(PACKAGE_CACHE_PATH):
for package in os.listdir(os.path.join(PACKAGE_CACHE_PATH, repo)):
with open(os.path.join(PACKAGE_CACHE_PATH, repo, package, 'desc'), 'r') as file:
info = {}
info['repo'] = repo
section = None
for line in file.readlines():
line = line.strip()
if line == '': continue
if line[0] == '%' and line[-1] == '%':
section = line[1:-1]
info[section] = []
else:
info[section].append(line)
for entry in info['NAME'] + (info['PROVIDES'] if 'PROVIDES' in info else []):
entry, _ = split_version(entry)
if entry not in package_info: package_info[entry] = []
package_info[entry].append(info)
pending_packages = set()
def install(name, target_dir, mirror=MIRROR, arch=ARCH):
if not name in package_info:
raise RuntimeError(f'package {name} not found')
packages = package_info[name]
for package in packages:
if package['NAME'][0] in pending_packages: return
if os.path.isfile(os.path.join(target_dir, 'installed', package['NAME'][0])): return
if len(packages) == 1:
package = packages[0]
else:
names = [package['NAME'][0] for package in packages]
while True:
print(f'Select a package for {name}:\n{'\n'.join([f' {idx + 1}) {name}' for idx, name in enumerate(names)])}')
choice = input('Input (default 1): ')
if choice.strip() == '':
package = packages[0]
break
try:
package = packages[int(choice) - 1]
break
except ValueError: pass
pending_packages.add(package['NAME'][0])
for dep in (package['DEPENDS'] if 'DEPENDS' in package else []):
dep, _ = split_version(dep)
try:
install(dep, target_dir, mirror, arch)
except RuntimeError as e:
e.add_note(f'while evaluating dependencies of {name}')
raise e
url = f'{mirror}/{package['repo']}/os/{arch}/{package['FILENAME'][0]}'
cache.download_and_extract(url, target_dir, True)
open(os.path.join(target_dir, 'installed', package['NAME'][0]), 'a').close()
pending_packages.remove(package['NAME'][0])
import argparse
parser = argparse.ArgumentParser(description='Arch linux from scratch :)')
parser.add_argument('target', type=str, help='target path')
parser.add_argument('packages', metavar='N', type=str, nargs='+', help='packages to install')
args = parser.parse_args()
os.makedirs(os.path.join(args.target, 'installed'), exist_ok=True)
for package in args.packages:
install(package, args.target)
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