# 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 import (

    encoding,

    error,

    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):

        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 = []

                                            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 ('', [], 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.

    def walk(self, path=None, onerror=None):

    def write(self, oid, data):

        pass

class filewithprogress(object):

    """a file-like object that supports __len__ and read.

    Useful to provide progress information for how many bytes are read.

    """

    def __init__(self, fp, callback):

        self._fp = fp

        self._callback = callback # func(readsize)

        fp.seek(0, os.SEEK_END)

        self._len = fp.tell()

        fp.seek(0)

    def __len__(self):

        return self._len

    def read(self, size):

        if self._fp is None:

            return b''

        data = self._fp.read(size)

        if data:

            if self._callback:

                self._callback(len(data))

        else:

            self._fp.close()

            self._fp = None

        return data

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):

        self.vfs = lfsvfs(fullpath)

            self.cachevfs = nullvfs()

        else:

            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."""

        # 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):

    def download(self, oid, src):

        """Read the blob from the remote source in chunks, verify the content,

        and write to this local blobstore."""

        sha256 = hashlib.sha256()

            for chunk in util.filechunkiter(src, size=1048576):

                fp.write(chunk)

                sha256.update(chunk)

            realoid = node.hex(sha256.digest())

            if realoid != oid:

                                         % 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."""

            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)):

            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)):

            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:

                lfutil.link(self.cachevfs.join(oid), self.vfs.join(oid))

        else:

            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, '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 _gitlfsremote(object):

    def __init__(self, repo, url):

        ui = repo.ui

        self.ui = ui

        baseurl, authinfo = url.authinfo()

        if not useragent:

        self.urlopener = urlmod.opener(ui, authinfo, useragent)

    def writebatch(self, pointers, fromstore):

        """Batch upload from local to remote blobstore."""

    def readbatch(self, pointers, tostore):

        """Batch download from remote to local blostore."""

    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': p.oid(), 'size': p.size()} for p in pointers]

        requestdata = json.dumps({

            'objects': objects,

            'operation': action,

        })

        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 = {

                       'supported') % (self.baseurl, action),

                       % self.baseurl,

            }

        except util.urlerr.urlerror as ex:

                    % self.baseurl)

                                 hint=hint)

        try:

            response = json.loads(rawjson)

        except ValueError:

        if self.ui.debugflag:

            # lfs-test-server and hg serve return headers in different order

            if 'objects' in response:

                response['objects'] = sorted(response['objects'],

                                             key=lambda p: p['oid'])

            self.ui.debug('%s\n'

                          % json.dumps(response, indent=2,

                                       separators=('', ': '), sort_keys=True))

        return 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.

                    code = 404

                else:

                    continue

            else:

                # An error dict without a code doesn't make much sense, so

                # treat as a server error.

            ptrmap = {p.oid(): p for p in pointers}

            if p:

                errors = {

                }

                                     % (filename, msg))

            else:

                raise LfsRemoteError(

    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

        self._checkforservererror(pointers, objects, action)

        # Filter objects with given action. Practically, this skips uploading

        # objects which exist in the server.

        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 = pycompat.bytestr(obj['oid'])

        href = pycompat.bytestr(obj['actions'][action].get('href'))

        headers = obj['actions'][action].get('header', {}).items()

        request = util.urlreq.request(href)

            # If uploading blobs, read data from local blobstore.

            if not localstore.verify(oid):

            request.data = filewithprogress(localstore.open(oid), None)

            request.get_method = lambda: 'PUT'

            request.add_header('Content-Type', 'application/octet-stream')

        for k, v in headers:

            request.add_header(k, v)

        response = b''

        try:

            with contextlib.closing(self.urlopener.open(request)) as req:

                ui = self.ui  # Shorten debug lines

                if self.ui.debugflag:

                    # lfs-test-server and hg serve return headers in different

                    # order

                    # If downloading blobs, store downloaded data to local

                    # blobstore

                    localstore.download(oid, req)

                else:

                    while True:

                        data = req.read(1048576)

                        if not data:

                            break

                        response += data

                    if response:

        except util.urlerr.httperror as ex:

            if self.ui.debugflag:

        except util.urlerr.urlerror as ex:

                                 hint=hint)

    def _batch(self, pointers, localstore, action):

        response = self._batchrequest(pointers, action)

        objects = self._extractobjects(response, pointers, action)

        sizes = {}

        for obj in objects:

        if len(objects) > 1:

                         % (len(objects), util.bytecount(total)))

        def transfer(chunk):

            for obj in chunk:

                if self.ui.verbose:

                                 util.bytecount(objsize)))

                retry = self.retry

                while True:

                    try:

                        self._basictransfer(obj, action, localstore)