330 lines
9.8 KiB
Python
330 lines
9.8 KiB
Python
import argparse
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import collections
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import configparser
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from datetime import datetime
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from fnmatch import fnmatch
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import hashlib
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from math import ceil
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import os
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import re
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import sys
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import zlib
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argparser = argparse.ArgumentParser(description="The stupidest content tracker")
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argsubparsers = argparser.add_subparsers(title="Commands", dest="command")
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argsubparsers.required = True
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def main(argv=sys.argv[1:]):
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args = argparser.parse_args(argv)
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match args.command:
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case "add" : cmd_add(args)
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case "cat-file" : cmd_cat_file(args)
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case "check-ignore" : cmd_check_ignore(args)
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case "checkout" : cmd_checkout(args)
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case "commit" : cmd_commit(args)
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case "hash-object" : cmd_hash_object(args)
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case "init" : cmd_init(args)
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case "log" : cmd_log(args)
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case "ls-files" : cmd_ls_files(args)
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case "ls-tree" : cmd_ls_tree(args)
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case "rev-parse" : cmd_rev_parse(args)
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case "rm" : cmd_rm(args)
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case "show-ref" : cmd_show_ref(args)
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case "status" : cmd_status(args)
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case "tag" : cmd_tag(args)
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case _ : print("Bad command.")
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class GitRepository (object):
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"""A git repo"""
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worktree = None
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gitdir = None
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conf = None
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def __init__(self, path, force=False):
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self.worktree = path
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self.gitdir = os.path.join(path, ".git")
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if not (force or os.path.isdir(self.gitdir)):
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raise Exception(f"Not a git repository {path}")
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# Read configuration file in .git/config
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self.conf = configparser.ConfigParser()
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cf = GitRepository.repo_file(self, "config")
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if cf and os.path.exists(cf):
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self.conf.read([cf])
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elif not force:
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raise Exception("Configuration file missing")
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if not force:
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vers = int(self.conf.get("core", "repositoryformatversion"))
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if vers != 0:
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raise Exception(f"Unsupported repositoryformatversion {vers}")
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def repo_path(repo, *path):
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"""Compute path under repo's gitdir."""
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return os.path.join(repo.gitdir, *path)
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def repo_file(repo, *path, mkdir=False):
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"""Same as repo_path, but create dirname(*path) if absent. For
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example, repo_file(r, \"refs\", \"remotes\", \"origin\", \"HEAD\") will create
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.git/refs/remotes/origin."""
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if GitRepository.repo_dir(repo, *path[:-1], mkdir=mkdir):
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return GitRepository.repo_path(repo, *path)
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def repo_dir(repo, *path, mkdir=False):
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"""Same as repo_path, bt mkdir *path if absent if mkdir"""
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path = GitRepository.repo_path(repo, *path)
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if (os.path.exists(path)):
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if (os.path.isdir(path)):
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return path
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else:
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raise Exception(f"Not a directory {path}")
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if mkdir:
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os.makedirs(path)
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return path
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else:
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return None
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def repo_create(path):
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"""Create a new repository at path."""
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repo = GitRepository(path, True)
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# First, we make sure the path either doesn't exist or is an
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# empty dir.
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if os.path.exists(repo.worktree):
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if not os.path.isdir(repo.worktree):
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raise Exception(f"{path} is not a directory!")
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if os.path.exists(repo.gitdir) and os.listdir(repo.gitdir):
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raise Exception(f"{path} is not empty!")
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else:
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os.makedirs(repo.worktree)
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assert GitRepository.repo_dir(repo, "branches", mkdir=True)
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assert GitRepository.repo_dir(repo, "objects", mkdir=True)
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assert GitRepository.repo_dir(repo, "refs", "tags", mkdir=True)
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assert GitRepository.repo_dir(repo, "refs", "heads", mkdir=True)
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# .git/description
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with open(GitRepository.repo_file(repo, "description"), "w") as f:
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f.write("Unnamed repository; edit this file 'description' to name the repository")
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with open(GitRepository.repo_file(repo, "HEAD"), "w") as f:
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f.write("ref: refs/heads/master\n")
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with open(GitRepository.repo_file(repo, "config"), "w") as f:
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config = repo_default_config()
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config.write(f)
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return repo
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def repo_default_config():
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ret = configparser.ConfigParser()
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ret.add_section("core")
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ret.set("core", "repositoryformatVersion", "0")
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ret.set("core", "filemode", "false")
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ret.set("core", "bare", "false")
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return ret
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argsp = argsubparsers.add_parser("init", help="Initialize a new, empty repository.")
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argsp.add_argument("path",
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metavar="directory",
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nargs="?",
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default=".",
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help="Where to create the repository.")
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def cmd_init(args):
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repo_create(args.path)
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def repo_find(path=".", required=True):
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path = os.path.realpath(path)
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if os.path.isdir(os.path.join(path, ".git")):
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return GitRepository(path)
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# If we haven't returned, recurse in parent
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parent = os.path.realpath(os.path.join(path, ".."))
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match os.name:
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case "nt":
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is_root = os.path.splitdrive(path)[1] == "\\"
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case "posix":
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# If parent==path, then path is root.
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is_root = parent == path
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case _:
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raise Exception(f"Unsupported os {os.name}")
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if is_root:
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if required:
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raise Exception("No git directory.")
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else:
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return None
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# Recursive case
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return repo_find(parent, required)
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argsp = argsubparsers.add_parser("status", help="Get the status of the repo")
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argsp.add_argument("path",
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metavar="directory",
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nargs="?",
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default=".",
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help="Which directory")
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def cmd_status(args):
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# TODO: actually get status
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print(repo_find(args.path).worktree)
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class GitObject (object):
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def __init__(self, data=None):
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if data != None:
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self.deserialize(data)
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else:
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self.init()
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def serialize(self, repo):
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"""This function MUST be implemented by subclasses.
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It must read the object's contents from self.data, a byte string, and
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do whatever it takes to convert it into a meaningful representation. What exactly that means depends on each subclass."""
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raise Exception("Unimplemented!")
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def deserialize(self, repo):
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raise Exception("Unimplemented!")
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def init(self):
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pass # other implementations might do something here
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def object_read(repo, sha):
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"""Read object sha from Git repository repo. Return a
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GitObject whose exact type depends on the object."""
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path = GitRepository.repo_file(repo, "objects", sha[0:2], sha[2:])
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if not os.path.isfile(path):
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return None
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with open(path, "rb") as f:
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raw = zlib.decompress(f.read())
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# Read object type
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x = raw.find(b' ')
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fmt = raw[0:x]
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# Read and validate object size
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y = raw.find(b'\x00', x)
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size = int(raw[x:y].decode("ascii"))
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if size != len(raw)-y-1:
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raise Exception(f"Malformed object {sha}: bad length")
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match fmt:
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case b'commit' : c=GitCommit
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case b'tree' : c=GitTree
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case b'tag' : c=GitTag
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case b'blob' : c=GitBlob
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case _:
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raise Exception(f"Unknown type {fmt.decode('ascii')} for object {sha}")
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return c(raw[y+1:])
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def object_write(obj, repo=None):
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data = obj.serialize()
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# Add header
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result = obj.fmt + b' ' + str(len(data)).encode() + b'\x00' + data
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# Compute hash
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sha = hashlib.sha1(result).hexdigest()
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if repo:
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# Compute path
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path=GitRepository.repo_file(repo, "objects", sha[0:2], sha[2:], mkdir=True)
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if not os.path.exists(path):
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with open(path, 'wb') as f:
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f.write(zlib.compress(result))
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return sha
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class GitBlob(GitObject):
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fmt=b'blob'
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def serialize(self):
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return self.blobdata
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def deserialize(self, data):
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self.blobdata = data
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argsp = argsubparsers.add_parser("cat-file",
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help="Provide content of repository objects")
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argsp.add_argument("type",
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metavar="type",
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choices=["blob", "commit", "tag", "tree"],
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help="Specify the type")
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argsp.add_argument("object",
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metavar="object",
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help="The object to display")
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def cmd_cat_file(args):
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repo = repo_find()
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cat_file(repo, args.object, fmt=args.type.encode())
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def cat_file(repo, obj, fmt=None):
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obj = object_read(repo, object_find(repo, obj, fmt=fmt))
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sys.stdout.buffer.write(obj.serialize())
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def object_find(repo, name, fmt=None, follow=True):
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return name
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argsp = argsubparsers.add_parser(
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"hash-object",
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help="Compute object ID an optionally creates a blob from a file")
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argsp.add_argument("-t",
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metavar="type",
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dest="type",
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choices=["blob", "commit", "tag", "tree"],
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default="blob",
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help="Specify the type")
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argsp.add_argument("-w",
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dest="write",
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action="store_true",
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help="Actually write the object into the database")
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argsp.add_argument("path",
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help="Read object from <file>")
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def cmd_hash_object(args):
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if args.write:
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repo = repo_find()
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else:
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repo = None
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with open(args.path, "rb") as fd:
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sha = object_hash(fd, args.type.encode(), repo)
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print(sha)
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def object_hash(fd, fmt, repo=None):
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"""Hash object, writing it to repo if provided"""
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data = fd.read()
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match fmt:
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case b'commit' : obj=GitCommit(data)
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case b'tree' : obj=GitTree(data)
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case b'tag' : obj=GitTag(data)
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case b'blob' : obj=GitBlob(data)
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case _ : raise Exception(f"Unknown type {fmt}")
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return object_write(obj, repo)
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