git: skeleton of a new extension to _directly_ operate on git repos
This is based in part of work I did years ago in hgit, but it's mostly
new code since I'm using pygit2 instead of dulwich and the hg storage
interfaces have improved. Some cleanup of old hgit code by Pulkit,
which I greatly appreciate.
test-git-interop.t does not cover a whole lot of cases, but it
passes. It includes status, diff, making a new commit, and `hg annotate`
working on the git repository.
This is _not_ (yet) production quality code: this is an
experiment. Known technical debt lurking in this implementation:
* Writing bookmarks just totally ignores transactions.
* The way progress is threaded down into the gitstore is awful.
* Ideally we'd find a way to incrementally reindex DAGs. I'm not sure
how to do that efficiently, so we might need a "known only fast-forwards"
mode on the DAG indexer for use on `hg commit` and friends.
* We don't even _try_ to do anything reasonable for `hg pull` or `hg push`.
* Mercurial need an interface for the changelog type.
Tests currently require git 2.24 as far as I'm aware: `git status` has
some changed output that I didn't try and handle in a compatible way.
This patch has produced some interesting cleanups, most recently on
the manifest type. I expect continuing down this road will produce
other meritorious cleanups throughout our code.
Differential Revision: https://phab.mercurial-scm.org/D6734
# blobstore.py - local and remote (speaking Git-LFS protocol) blob storages
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import contextlib
import errno
import hashlib
import json
import os
import re
import socket
from mercurial.i18n import _
from mercurial.pycompat import getattr
from mercurial import (
encoding,
error,
httpconnection as httpconnectionmod,
node,
pathutil,
pycompat,
url as urlmod,
util,
vfs as vfsmod,
worker,
)
from mercurial.utils import stringutil
from ..largefiles import lfutil
# 64 bytes for SHA256
_lfsre = re.compile(br'\A[a-f0-9]{64}\Z')
class lfsvfs(vfsmod.vfs):
def join(self, path):
"""split the path at first two characters, like: XX/XXXXX..."""
if not _lfsre.match(path):
raise error.ProgrammingError(b'unexpected lfs path: %s' % path)
return super(lfsvfs, self).join(path[0:2], path[2:])
def walk(self, path=None, onerror=None):
"""Yield (dirpath, [], oids) tuple for blobs under path
Oids only exist in the root of this vfs, so dirpath is always ''.
"""
root = os.path.normpath(self.base)
# when dirpath == root, dirpath[prefixlen:] becomes empty
# because len(dirpath) < prefixlen.
prefixlen = len(pathutil.normasprefix(root))
oids = []
for dirpath, dirs, files in os.walk(
self.reljoin(self.base, path or b''), onerror=onerror
):
dirpath = dirpath[prefixlen:]
# Silently skip unexpected files and directories
if len(dirpath) == 2:
oids.extend(
[dirpath + f for f in files if _lfsre.match(dirpath + f)]
)
yield (b'', [], oids)
class nullvfs(lfsvfs):
def __init__(self):
pass
def exists(self, oid):
return False
def read(self, oid):
# store.read() calls into here if the blob doesn't exist in its
# self.vfs. Raise the same error as a normal vfs when asked to read a
# file that doesn't exist. The only difference is the full file path
# isn't available in the error.
raise IOError(
errno.ENOENT,
pycompat.sysstr(b'%s: No such file or directory' % oid),
)
def walk(self, path=None, onerror=None):
return (b'', [], [])
def write(self, oid, data):
pass
class lfsuploadfile(httpconnectionmod.httpsendfile):
"""a file-like object that supports keepalive.
"""
def __init__(self, ui, filename):
super(lfsuploadfile, self).__init__(ui, filename, b'rb')
self.read = self._data.read
def _makeprogress(self):
return None # progress is handled by the worker client
class local(object):
"""Local blobstore for large file contents.
This blobstore is used both as a cache and as a staging area for large blobs
to be uploaded to the remote blobstore.
"""
def __init__(self, repo):
fullpath = repo.svfs.join(b'lfs/objects')
self.vfs = lfsvfs(fullpath)
if repo.ui.configbool(b'experimental', b'lfs.disableusercache'):
self.cachevfs = nullvfs()
else:
usercache = lfutil._usercachedir(repo.ui, b'lfs')
self.cachevfs = lfsvfs(usercache)
self.ui = repo.ui
def open(self, oid):
"""Open a read-only file descriptor to the named blob, in either the
usercache or the local store."""
return open(self.path(oid), 'rb')
def path(self, oid):
"""Build the path for the given blob ``oid``.
If the blob exists locally, the path may point to either the usercache
or the local store. If it doesn't, it will point to the local store.
This is meant for situations where existing code that isn't LFS aware
needs to open a blob. Generally, prefer the ``open`` method on this
class.
"""
# The usercache is the most likely place to hold the file. Commit will
# write to both it and the local store, as will anything that downloads
# the blobs. However, things like clone without an update won't
# populate the local store. For an init + push of a local clone,
# the usercache is the only place it _could_ be. If not present, the
# missing file msg here will indicate the local repo, not the usercache.
if self.cachevfs.exists(oid):
return self.cachevfs.join(oid)
return self.vfs.join(oid)
def download(self, oid, src, content_length):
"""Read the blob from the remote source in chunks, verify the content,
and write to this local blobstore."""
sha256 = hashlib.sha256()
size = 0
with self.vfs(oid, b'wb', atomictemp=True) as fp:
for chunk in util.filechunkiter(src, size=1048576):
fp.write(chunk)
sha256.update(chunk)
size += len(chunk)
# If the server advertised a length longer than what we actually
# received, then we should expect that the server crashed while
# producing the response (but the server has no way of telling us
# that), and we really don't need to try to write the response to
# the localstore, because it's not going to match the expected.
if content_length is not None and int(content_length) != size:
msg = (
b"Response length (%s) does not match Content-Length "
b"header (%d): likely server-side crash"
)
raise LfsRemoteError(_(msg) % (size, int(content_length)))
realoid = node.hex(sha256.digest())
if realoid != oid:
raise LfsCorruptionError(
_(b'corrupt remote lfs object: %s') % oid
)
self._linktousercache(oid)
def write(self, oid, data):
"""Write blob to local blobstore.
This should only be called from the filelog during a commit or similar.
As such, there is no need to verify the data. Imports from a remote
store must use ``download()`` instead."""
with self.vfs(oid, b'wb', atomictemp=True) as fp:
fp.write(data)
self._linktousercache(oid)
def linkfromusercache(self, oid):
"""Link blobs found in the user cache into this store.
The server module needs to do this when it lets the client know not to
upload the blob, to ensure it is always available in this store.
Normally this is done implicitly when the client reads or writes the
blob, but that doesn't happen when the server tells the client that it
already has the blob.
"""
if not isinstance(self.cachevfs, nullvfs) and not self.vfs.exists(oid):
self.ui.note(_(b'lfs: found %s in the usercache\n') % oid)
lfutil.link(self.cachevfs.join(oid), self.vfs.join(oid))
def _linktousercache(self, oid):
# XXX: should we verify the content of the cache, and hardlink back to
# the local store on success, but truncate, write and link on failure?
if not self.cachevfs.exists(oid) and not isinstance(
self.cachevfs, nullvfs
):
self.ui.note(_(b'lfs: adding %s to the usercache\n') % oid)
lfutil.link(self.vfs.join(oid), self.cachevfs.join(oid))
def read(self, oid, verify=True):
"""Read blob from local blobstore."""
if not self.vfs.exists(oid):
blob = self._read(self.cachevfs, oid, verify)
# Even if revlog will verify the content, it needs to be verified
# now before making the hardlink to avoid propagating corrupt blobs.
# Don't abort if corruption is detected, because `hg verify` will
# give more useful info about the corruption- simply don't add the
# hardlink.
if verify or node.hex(hashlib.sha256(blob).digest()) == oid:
self.ui.note(_(b'lfs: found %s in the usercache\n') % oid)
lfutil.link(self.cachevfs.join(oid), self.vfs.join(oid))
else:
self.ui.note(_(b'lfs: found %s in the local lfs store\n') % oid)
blob = self._read(self.vfs, oid, verify)
return blob
def _read(self, vfs, oid, verify):
"""Read blob (after verifying) from the given store"""
blob = vfs.read(oid)
if verify:
_verify(oid, blob)
return blob
def verify(self, oid):
"""Indicate whether or not the hash of the underlying file matches its
name."""
sha256 = hashlib.sha256()
with self.open(oid) as fp:
for chunk in util.filechunkiter(fp, size=1048576):
sha256.update(chunk)
return oid == node.hex(sha256.digest())
def has(self, oid):
"""Returns True if the local blobstore contains the requested blob,
False otherwise."""
return self.cachevfs.exists(oid) or self.vfs.exists(oid)
def _urlerrorreason(urlerror):
'''Create a friendly message for the given URLError to be used in an
LfsRemoteError message.
'''
inst = urlerror
if isinstance(urlerror.reason, Exception):
inst = urlerror.reason
if util.safehasattr(inst, b'reason'):
try: # usually it is in the form (errno, strerror)
reason = inst.reason.args[1]
except (AttributeError, IndexError):
# it might be anything, for example a string
reason = inst.reason
if isinstance(reason, pycompat.unicode):
# SSLError of Python 2.7.9 contains a unicode
reason = encoding.unitolocal(reason)
return reason
elif getattr(inst, "strerror", None):
return encoding.strtolocal(inst.strerror)
else:
return stringutil.forcebytestr(urlerror)
class lfsauthhandler(util.urlreq.basehandler):
handler_order = 480 # Before HTTPDigestAuthHandler (== 490)
def http_error_401(self, req, fp, code, msg, headers):
"""Enforces that any authentication performed is HTTP Basic
Authentication. No authentication is also acceptable.
"""
authreq = headers.get('www-authenticate', None)
if authreq:
scheme = authreq.split()[0]
if scheme.lower() != 'basic':
msg = _(b'the server must support Basic Authentication')
raise util.urlerr.httperror(
req.get_full_url(),
code,
encoding.strfromlocal(msg),
headers,
fp,
)
return None
class _gitlfsremote(object):
def __init__(self, repo, url):
ui = repo.ui
self.ui = ui
baseurl, authinfo = url.authinfo()
self.baseurl = baseurl.rstrip(b'/')
useragent = repo.ui.config(b'experimental', b'lfs.user-agent')
if not useragent:
useragent = b'git-lfs/2.3.4 (Mercurial %s)' % util.version()
self.urlopener = urlmod.opener(ui, authinfo, useragent)
self.urlopener.add_handler(lfsauthhandler())
self.retry = ui.configint(b'lfs', b'retry')
def writebatch(self, pointers, fromstore):
"""Batch upload from local to remote blobstore."""
self._batch(_deduplicate(pointers), fromstore, b'upload')
def readbatch(self, pointers, tostore):
"""Batch download from remote to local blostore."""
self._batch(_deduplicate(pointers), tostore, b'download')
def _batchrequest(self, pointers, action):
"""Get metadata about objects pointed by pointers for given action
Return decoded JSON object like {'objects': [{'oid': '', 'size': 1}]}
See https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md
"""
objects = [
{'oid': pycompat.strurl(p.oid()), 'size': p.size()}
for p in pointers
]
requestdata = pycompat.bytesurl(
json.dumps(
{'objects': objects, 'operation': pycompat.strurl(action),}
)
)
url = b'%s/objects/batch' % self.baseurl
batchreq = util.urlreq.request(pycompat.strurl(url), data=requestdata)
batchreq.add_header('Accept', 'application/vnd.git-lfs+json')
batchreq.add_header('Content-Type', 'application/vnd.git-lfs+json')
try:
with contextlib.closing(self.urlopener.open(batchreq)) as rsp:
rawjson = rsp.read()
except util.urlerr.httperror as ex:
hints = {
400: _(
b'check that lfs serving is enabled on %s and "%s" is '
b'supported'
)
% (self.baseurl, action),
404: _(b'the "lfs.url" config may be used to override %s')
% self.baseurl,
}
hint = hints.get(ex.code, _(b'api=%s, action=%s') % (url, action))
raise LfsRemoteError(
_(b'LFS HTTP error: %s') % stringutil.forcebytestr(ex),
hint=hint,
)
except util.urlerr.urlerror as ex:
hint = (
_(b'the "lfs.url" config may be used to override %s')
% self.baseurl
)
raise LfsRemoteError(
_(b'LFS error: %s') % _urlerrorreason(ex), hint=hint
)
try:
response = pycompat.json_loads(rawjson)
except ValueError:
raise LfsRemoteError(
_(b'LFS server returns invalid JSON: %s')
% rawjson.encode("utf-8")
)
if self.ui.debugflag:
self.ui.debug(b'Status: %d\n' % rsp.status)
# lfs-test-server and hg serve return headers in different order
headers = pycompat.bytestr(rsp.info()).strip()
self.ui.debug(b'%s\n' % b'\n'.join(sorted(headers.splitlines())))
if 'objects' in response:
response['objects'] = sorted(
response['objects'], key=lambda p: p['oid']
)
self.ui.debug(
b'%s\n'
% pycompat.bytesurl(
json.dumps(
response,
indent=2,
separators=('', ': '),
sort_keys=True,
)
)
)
def encodestr(x):
if isinstance(x, pycompat.unicode):
return x.encode('utf-8')
return x
return pycompat.rapply(encodestr, response)
def _checkforservererror(self, pointers, responses, action):
"""Scans errors from objects
Raises LfsRemoteError if any objects have an error"""
for response in responses:
# The server should return 404 when objects cannot be found. Some
# server implementation (ex. lfs-test-server) does not set "error"
# but just removes "download" from "actions". Treat that case
# as the same as 404 error.
if b'error' not in response:
if action == b'download' and action not in response.get(
b'actions', []
):
code = 404
else:
continue
else:
# An error dict without a code doesn't make much sense, so
# treat as a server error.
code = response.get(b'error').get(b'code', 500)
ptrmap = {p.oid(): p for p in pointers}
p = ptrmap.get(response[b'oid'], None)
if p:
filename = getattr(p, 'filename', b'unknown')
errors = {
404: b'The object does not exist',
410: b'The object was removed by the owner',
422: b'Validation error',
500: b'Internal server error',
}
msg = errors.get(code, b'status code %d' % code)
raise LfsRemoteError(
_(b'LFS server error for "%s": %s') % (filename, msg)
)
else:
raise LfsRemoteError(
_(b'LFS server error. Unsolicited response for oid %s')
% response[b'oid']
)
def _extractobjects(self, response, pointers, action):
"""extract objects from response of the batch API
response: parsed JSON object returned by batch API
return response['objects'] filtered by action
raise if any object has an error
"""
# Scan errors from objects - fail early
objects = response.get(b'objects', [])
self._checkforservererror(pointers, objects, action)
# Filter objects with given action. Practically, this skips uploading
# objects which exist in the server.
filteredobjects = [
o for o in objects if action in o.get(b'actions', [])
]
return filteredobjects
def _basictransfer(self, obj, action, localstore):
"""Download or upload a single object using basic transfer protocol
obj: dict, an object description returned by batch API
action: string, one of ['upload', 'download']
localstore: blobstore.local
See https://github.com/git-lfs/git-lfs/blob/master/docs/api/\
basic-transfers.md
"""
oid = obj[b'oid']
href = obj[b'actions'][action].get(b'href')
headers = obj[b'actions'][action].get(b'header', {}).items()
request = util.urlreq.request(pycompat.strurl(href))
if action == b'upload':
# If uploading blobs, read data from local blobstore.
if not localstore.verify(oid):
raise error.Abort(
_(b'detected corrupt lfs object: %s') % oid,
hint=_(b'run hg verify'),
)
for k, v in headers:
request.add_header(pycompat.strurl(k), pycompat.strurl(v))
try:
if action == b'upload':
request.data = lfsuploadfile(self.ui, localstore.path(oid))
request.get_method = lambda: 'PUT'
request.add_header('Content-Type', 'application/octet-stream')
request.add_header('Content-Length', request.data.length)
with contextlib.closing(self.urlopener.open(request)) as res:
contentlength = res.info().get(b"content-length")
ui = self.ui # Shorten debug lines
if self.ui.debugflag:
ui.debug(b'Status: %d\n' % res.status)
# lfs-test-server and hg serve return headers in different
# order
headers = pycompat.bytestr(res.info()).strip()
ui.debug(b'%s\n' % b'\n'.join(sorted(headers.splitlines())))
if action == b'download':
# If downloading blobs, store downloaded data to local
# blobstore
localstore.download(oid, res, contentlength)
else:
blocks = []
while True:
data = res.read(1048576)
if not data:
break
blocks.append(data)
response = b"".join(blocks)
if response:
ui.debug(b'lfs %s response: %s' % (action, response))
except util.urlerr.httperror as ex:
if self.ui.debugflag:
self.ui.debug(
b'%s: %s\n' % (oid, ex.read())
) # XXX: also bytes?
raise LfsRemoteError(
_(b'LFS HTTP error: %s (oid=%s, action=%s)')
% (stringutil.forcebytestr(ex), oid, action)
)
except util.urlerr.urlerror as ex:
hint = _(b'attempted connection to %s') % pycompat.bytesurl(
util.urllibcompat.getfullurl(request)
)
raise LfsRemoteError(
_(b'LFS error: %s') % _urlerrorreason(ex), hint=hint
)
finally:
if request.data:
request.data.close()
def _batch(self, pointers, localstore, action):
if action not in [b'upload', b'download']:
raise error.ProgrammingError(b'invalid Git-LFS action: %s' % action)
response = self._batchrequest(pointers, action)
objects = self._extractobjects(response, pointers, action)
total = sum(x.get(b'size', 0) for x in objects)
sizes = {}
for obj in objects:
sizes[obj.get(b'oid')] = obj.get(b'size', 0)
topic = {
b'upload': _(b'lfs uploading'),
b'download': _(b'lfs downloading'),
}[action]
if len(objects) > 1:
self.ui.note(
_(b'lfs: need to transfer %d objects (%s)\n')
% (len(objects), util.bytecount(total))
)
def transfer(chunk):
for obj in chunk:
objsize = obj.get(b'size', 0)
if self.ui.verbose:
if action == b'download':
msg = _(b'lfs: downloading %s (%s)\n')
elif action == b'upload':
msg = _(b'lfs: uploading %s (%s)\n')
self.ui.note(
msg % (obj.get(b'oid'), util.bytecount(objsize))
)
retry = self.retry
while True:
try:
self._basictransfer(obj, action, localstore)
yield 1, obj.get(b'oid')
break
except socket.error as ex:
if retry > 0:
self.ui.note(
_(b'lfs: failed: %r (remaining retry %d)\n')
% (stringutil.forcebytestr(ex), retry)
)
retry -= 1
continue
raise
# Until https multiplexing gets sorted out
if self.ui.configbool(b'experimental', b'lfs.worker-enable'):
oids = worker.worker(
self.ui,
0.1,
transfer,
(),
sorted(objects, key=lambda o: o.get(b'oid')),
)
else:
oids = transfer(sorted(objects, key=lambda o: o.get(b'oid')))
with self.ui.makeprogress(
topic, unit=_(b"bytes"), total=total
) as progress:
progress.update(0)
processed = 0
blobs = 0
for _one, oid in oids:
processed += sizes[oid]
blobs += 1
progress.update(processed)
self.ui.note(_(b'lfs: processed: %s\n') % oid)
if blobs > 0:
if action == b'upload':
self.ui.status(
_(b'lfs: uploaded %d files (%s)\n')
% (blobs, util.bytecount(processed))
)
elif action == b'download':
self.ui.status(
_(b'lfs: downloaded %d files (%s)\n')
% (blobs, util.bytecount(processed))
)
def __del__(self):
# copied from mercurial/httppeer.py
urlopener = getattr(self, 'urlopener', None)
if urlopener:
for h in urlopener.handlers:
h.close()
getattr(h, "close_all", lambda: None)()
class _dummyremote(object):
"""Dummy store storing blobs to temp directory."""
def __init__(self, repo, url):
fullpath = repo.vfs.join(b'lfs', url.path)
self.vfs = lfsvfs(fullpath)
def writebatch(self, pointers, fromstore):
for p in _deduplicate(pointers):
content = fromstore.read(p.oid(), verify=True)
with self.vfs(p.oid(), b'wb', atomictemp=True) as fp:
fp.write(content)
def readbatch(self, pointers, tostore):
for p in _deduplicate(pointers):
with self.vfs(p.oid(), b'rb') as fp:
tostore.download(p.oid(), fp, None)
class _nullremote(object):
"""Null store storing blobs to /dev/null."""
def __init__(self, repo, url):
pass
def writebatch(self, pointers, fromstore):
pass
def readbatch(self, pointers, tostore):
pass
class _promptremote(object):
"""Prompt user to set lfs.url when accessed."""
def __init__(self, repo, url):
pass
def writebatch(self, pointers, fromstore, ui=None):
self._prompt()
def readbatch(self, pointers, tostore, ui=None):
self._prompt()
def _prompt(self):
raise error.Abort(_(b'lfs.url needs to be configured'))
_storemap = {
b'https': _gitlfsremote,
b'http': _gitlfsremote,
b'file': _dummyremote,
b'null': _nullremote,
None: _promptremote,
}
def _deduplicate(pointers):
"""Remove any duplicate oids that exist in the list"""
reduced = util.sortdict()
for p in pointers:
reduced[p.oid()] = p
return reduced.values()
def _verify(oid, content):
realoid = node.hex(hashlib.sha256(content).digest())
if realoid != oid:
raise LfsCorruptionError(
_(b'detected corrupt lfs object: %s') % oid,
hint=_(b'run hg verify'),
)
def remote(repo, remote=None):
"""remotestore factory. return a store in _storemap depending on config
If ``lfs.url`` is specified, use that remote endpoint. Otherwise, try to
infer the endpoint, based on the remote repository using the same path
adjustments as git. As an extension, 'http' is supported as well so that
``hg serve`` works out of the box.
https://github.com/git-lfs/git-lfs/blob/master/docs/api/server-discovery.md
"""
lfsurl = repo.ui.config(b'lfs', b'url')
url = util.url(lfsurl or b'')
if lfsurl is None:
if remote:
path = remote
elif util.safehasattr(repo, b'_subtoppath'):
# The pull command sets this during the optional update phase, which
# tells exactly where the pull originated, whether 'paths.default'
# or explicit.
path = repo._subtoppath
else:
# TODO: investigate 'paths.remote:lfsurl' style path customization,
# and fall back to inferring from 'paths.remote' if unspecified.
path = repo.ui.config(b'paths', b'default') or b''
defaulturl = util.url(path)
# TODO: support local paths as well.
# TODO: consider the ssh -> https transformation that git applies
if defaulturl.scheme in (b'http', b'https'):
if defaulturl.path and defaulturl.path[:-1] != b'/':
defaulturl.path += b'/'
defaulturl.path = (defaulturl.path or b'') + b'.git/info/lfs'
url = util.url(bytes(defaulturl))
repo.ui.note(_(b'lfs: assuming remote store: %s\n') % url)
scheme = url.scheme
if scheme not in _storemap:
raise error.Abort(_(b'lfs: unknown url scheme: %s') % scheme)
return _storemap[scheme](repo, url)
class LfsRemoteError(error.StorageError):
pass
class LfsCorruptionError(error.Abort):
"""Raised when a corrupt blob is detected, aborting an operation
It exists to allow specialized handling on the server side."""