#!/usr/bin/env python

#
# Ceph - scalable distributed file system
#
# Copyright (C) 2011 New Dream Network
#
# This is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License version 2.1, as published by the Free Software
# Foundation.  See file COPYING.
#

"""
obsync.py: the object synchronizer
"""

from boto.s3.connection import OrdinaryCallingFormat
from boto.s3.connection import SubdomainCallingFormat
from boto.s3.connection import S3Connection
from boto.s3.key import Key
from optparse import OptionParser
from sys import stderr
from lxml import etree
import base64
import boto
import errno
import hashlib
import mimetypes
import os
from StringIO import StringIO
import re
import shutil
import string
import sys
import tempfile
import time
import traceback
import xattr

try:
    import cloudfiles
except ImportError:
    cloudfiles = None

# Command-line options
global opts

# Translation table mapping users in the source to users in the destination.
global xuser

###### Usage #######
USAGE = """
obsync synchronizes S3, swift and local objects. The source and destination
can both be local or both remote.

Examples:
# copy contents of s3 bucket to disk
SRC_AKEY=... SRC_SKEY=... \
obsync -v --src-type=s3 --src-host=myhost --src-bucket=mybucket \
--dst-type=file --dst-path=mydir

# copy contents of mydir to a swift container
DST_AKEY=... DST_SKEY=... \
obsync -v --src-type=file --src-path=mydir --dst-type=swift \
--dst-authurl=myauthurl --dst-bucket=mycontainer

# synchronize two S3 buckets
SRC_AKEY=... SRC_SKEY=... \
DST_AKEY=... DST_SKEY=... \
obsync -v --src-type=s3 --src-host=oldhost --src-bucket=mybucket \
--dst-type=s3 --dst-host=newhost --dst-bucket=mybucket \
--xuser bob=robert --xuser joe=joseph

Note: You must specify an AWS access key and secret access key when accessing
S3. When accessing swift use your username as the access key and your api
key as the secret key. obsync honors these environment variables:
SRC_AKEY          Access key for the source URL
SRC_SKEY          Secret access key for the source URL
DST_AKEY          Access key for the destination URL
DST_SKEY          Secret access key for the destination URL
SRC_SECURE        If set, we'll use https to talk to the s3 source.
DST_SECURE        If set, we'll use https to talk to the s3 destination.
AKEY              Access key for both source and dest
SKEY              Secret access key for both source and dest
DST_CONSISTENCY   Set to 'eventual' if the destination is eventually consistent

If these environment variables are not given, we will fall back on libboto
defaults.

Note: if python-cloudfiles is not installed, swift stores will not be able
to be synced.
"""
###### Constants #######
ACL_XATTR = "rados.acl"
META_XATTR_PREFIX = "rados.meta."
CONTENT_TYPE_XATTR = "rados.content_type"

def vvprint(s):
    if (opts.more_verbose):
        print s

###### Exception classes #######
class ObsyncException(Exception):
    def __init__(self, ty, e):
        if (isinstance(e, str)):
            # from a string
            self.tb = "".join(traceback.format_stack())
            self.comment = e
        else:
            # from another exception
            self.tb = traceback.format_exc(100000)
            self.comment = None
        self.ty = ty

""" A temporary obsync exception.
The user may want to retry the operation that failed.
We can create one of these from a string or from another exception.
"""
class ObsyncTemporaryException(ObsyncException):
    def __init__(self, e):
        ObsyncException.__init__(self, "temporary", e)

""" A permanent obsync exception.
We can create one of these from a string or from another exception.
"""
class ObsyncPermanentException(ObsyncException):
    def __init__(self, e):
        ObsyncException.__init__(self, "permanent", e)

""" An exception we encountered while parsing input arguments.
"""
class ObsyncArgumentParsingException(ObsyncException):
    def __init__(self, e):
        ObsyncException.__init__(self, "argument_parsing", e)

""" Print out some exception information and exit the program.
Normally, this function expects to see Obsync exceptions. If a random exception
slips through, we treat it as an unknown error type.
"""
def print_obsync_exception_and_abort(e, origin):
    if (isinstance(e, ObsyncException)):
        if (isinstance(e, ObsyncArgumentParsingException)):
            print >>stderr, USAGE
        else:
            print >>stderr, e.tb
        if (e.comment != None):
            print >>stderr, e.comment
        print >>stderr, ("ERROR TYPE: %s, ORIGIN: %s" % (e.ty, origin))
        sys.exit(1)
    else:
        traceback.print_exc(100000, stderr)
        print >>stderr, "ERROR TYPE: unknown, ORIGIN: %s" % origin
        sys.exit(1)

###### Extended Attributes #######
def test_xattr_support(path):
    test_file = path + "/$TEST"
    f = open(test_file, 'w')
    f.close
    try:
        xattr.set(test_file, "test", "123", namespace=xattr.NS_USER)
        if xattr.get(test_file, "test", namespace=xattr.NS_USER) !=  "123":
            raise ObsyncPermanentException("test_xattr_support: failed to set an xattr and " + \
                "read it back.")
    except IOError, e:
        print >>stderr, "**** ERRROR: You do not appear to have xattr support " + \
            "at %s ****" % pa
        raise ObsyncPermanentException(exc)
    finally:
        os.unlink(test_file)

def xattr_is_metadata(k):
    # miscellaneous user-defined metadata
    if (k[:len(META_XATTR_PREFIX)] == META_XATTR_PREFIX):
        return True
    # content-type
    elif (k == CONTENT_TYPE_XATTR):
        return True
    return False

###### Helper functions #######
def mkdir_p(path):
    try:
        os.makedirs(path)
    except OSError, exc:
        if exc.errno != errno.EEXIST:
            raise ObsyncTemporaryException(exc)
        if (not os.path.isdir(path)):
            raise ObsyncTemporaryException(exc)

def bytes_to_str(b):
    return ''.join(["%02x"% ord(x) for x in b]).strip()

def get_md5(f, block_size=2**20):
    md5 = hashlib.md5()
    while True:
        data = f.read(block_size)
        if not data:
            break
        md5.update(data)
    return "%s" % md5.hexdigest()

def strip_prefix(prefix, s):
    if not (s[0:len(prefix)] == prefix):
        return None
    return s[len(prefix):]

def etag_to_md5(etag):
    if (etag[:1] == '"'):
        start = 1
    else:
        start = 0
    if (etag[-1:] == '"'):
        end = -1
    else:
        end = None
    return etag[start:end]

def getenv(a, b):
    if os.environ.has_key(a):
        return os.environ[a]
    elif b and os.environ.has_key(b):
        return os.environ[b]
    else:
        return None

# Escaping functions.
#
# Valid names for local files are a little different than valid object
# names for S3. So these functions are needed to translate.
#
# Basically, in local names, every sequence starting with a dollar sign is
# reserved as a special escape sequence. If you want to create an S3 object
# with a dollar sign in the name, the local file should have a double dollar
# sign ($$).
#
# TODO: translate local files' control characters into escape sequences.
# Most S3 clients (boto included) cannot handle control characters in S3 object
# names.
# TODO: check for invalid utf-8 in local file names. Ideally, escape it, but
# if not, just reject the local file name. S3 object names must be valid
# utf-8.
#
# ----------        -----------
# In S3             Locally
# ----------        -----------
# foo/              foo$slash
#
# $money            $$money
#
# obj-with-acl      obj-with-acl
#                  .obj-with-acl$acl
def s3_name_to_local_name(s3_name):
    s3_name = re.sub(r'\$', "$$", s3_name)
    if (s3_name[-1:] == "/"):
        s3_name = s3_name[:-1] + "$slash"
    return s3_name

def local_name_to_s3_name(local_name):
    local_name = re.sub(r'\$slash', "/", local_name)
    mre = re.compile("[$][^$]")
    if mre.match(local_name):
        raise ObsyncPermanentException("Local name contains a dollar sign escape \
sequence we don't understand.")
    local_name = re.sub(r'\$\$', "$", local_name)
    return local_name

###### ACLs #######

# for buckets: allow list
# for object: allow grantee to read object data and metadata
READ = 1

# for buckets: allow create, overwrite, or deletion of any object in the bucket
WRITE = 2

# for buckets: allow grantee to read the bucket ACL
# for objects: allow grantee to read the object ACL
READ_ACP = 4

# for buckets: allow grantee to write the bucket ACL
# for objects: allow grantee to write the object ACL
WRITE_ACP = 8

# all of the above
FULL_CONTROL = READ | WRITE | READ_ACP | WRITE_ACP

ACL_TYPE_CANON_USER = "canon:"
ACL_TYPE_EMAIL_USER = "email:"
ACL_TYPE_GROUP = "group:"
ALL_ACL_TYPES = [ ACL_TYPE_CANON_USER, ACL_TYPE_EMAIL_USER, ACL_TYPE_GROUP ]

S3_GROUP_AUTH_USERS = ACL_TYPE_GROUP +  "AuthenticatedUsers"
S3_GROUP_ALL_USERS = ACL_TYPE_GROUP +  "AllUsers"
S3_GROUP_LOG_DELIVERY = ACL_TYPE_GROUP +  "LogDelivery"

NS = "http://s3.amazonaws.com/doc/2006-03-01/"
NS2 = "http://www.w3.org/2001/XMLSchema-instance"

def get_user_type(utype):
    for ut in [ ACL_TYPE_CANON_USER, ACL_TYPE_EMAIL_USER, ACL_TYPE_GROUP ]:
        if utype[:len(ut)] == ut:
            return ut
    raise ObsyncPermanentException("unknown user type for user %s" % utype)

def strip_user_type(utype):
    for ut in [ ACL_TYPE_CANON_USER, ACL_TYPE_EMAIL_USER, ACL_TYPE_GROUP ]:
        if utype[:len(ut)] == ut:
            return utype[len(ut):]
    raise ObsyncPermanentException("unknown user type for user %s" % utype)

def grantee_attribute_to_user_type(utype):
    if (utype == "Canonical User"):
        return ACL_TYPE_CANON_USER
    elif (utype == "CanonicalUser"):
        return ACL_TYPE_CANON_USER
    elif (utype == "Group"):
        return ACL_TYPE_GROUP
    elif (utype == "Email User"):
        return ACL_TYPE_EMAIL_USER
    elif (utype == "EmailUser"):
        return ACL_TYPE_EMAIL_USER
    else:
        raise ObsyncPermanentException("unknown user type for user %s" % utype)

def user_type_to_attr(t):
    if (t == ACL_TYPE_CANON_USER):
        return "CanonicalUser"
    elif (t == ACL_TYPE_GROUP):
        return "Group"
    elif (t ==  ACL_TYPE_EMAIL_USER):
        return "EmailUser"
    else:
        raise ObsyncPermanentException("unknown user type %s" % t)

def add_user_type(user):
    """ All users that are not specifically marked as something else
are treated as canonical users"""
    for atype in ALL_ACL_TYPES:
        if (user[:len(atype)] == atype):
            return user
    return ACL_TYPE_CANON_USER + user

class AclGrant(object):
    def __init__(self, user_id, display_name, permission):
        self.user_id = user_id
        self.display_name = display_name
        self.permission = permission
    def translate_users(self, xusers):
        # Keep in mind that xusers contains user_ids of the form "type:value"
        # So typical contents might be like { canon:XYZ => canon.123 }
        if (xusers.has_key(self.user_id)):
            self.user_id = xusers[self.user_id]
            # It's not clear what the new pretty-name should be, so just leave it blank.
            self.display_name = None
    def equals(self, rhs):
        if (self.user_id != rhs.user_id):
            return False
        if (self.permission != rhs.permission):
            return False
        # ignore display_name
        return True

class AclPolicy(object):
    def __init__(self, owner_id, owner_display_name, grants):
        self.owner_id = owner_id
        self.owner_display_name = owner_display_name
        self.grants = grants  # dict of { string -> ACLGrant }
    @staticmethod
    def create_default(owner_id):
        grants = { }
        grants[ACL_TYPE_CANON_USER + owner_id] = \
            AclGrant(ACL_TYPE_CANON_USER + owner_id, None, "FULL_CONTROL")
        return AclPolicy(owner_id, None, grants)
    @staticmethod
    def from_xml(s):
        root = etree.parse(StringIO(s))
        owner_id_node = root.find("{%s}Owner/{%s}ID" % (NS,NS))
        owner_id = owner_id_node.text
        owner_display_name_node = root.find("{%s}Owner/{%s}DisplayName" \
                                        % (NS,NS))
        if (owner_display_name_node != None):
            owner_display_name = owner_display_name_node.text
        else:
            owner_display_name = None
        grantlist = root.findall("{%s}AccessControlList/{%s}Grant" \
            % (NS,NS))
        grants = { }
        for g in grantlist:
            grantee = g.find("{%s}Grantee" % NS)
            user_id = grantee.find("{%s}ID" % NS).text
            if (grantee.attrib.has_key("type")):
                user_type = grantee.attrib["type"]
            else:
                user_type = grantee.attrib["{%s}type" % NS2]
            display_name_node = grantee.find("{%s}DisplayName" % NS)
            if (display_name_node != None):
                display_name = grantee.find("{%s}DisplayName" % NS).text
            else:
                display_name = None
            permission = g.find("{%s}Permission" % NS).text
            grant_user_id = grantee_attribute_to_user_type(user_type) + user_id
            grants[grant_user_id] = AclGrant(grant_user_id, display_name, permission)
        return AclPolicy(owner_id, owner_display_name, grants)
    def to_xml(self):
        root = etree.Element("AccessControlPolicy", nsmap={None: NS})
        owner = etree.SubElement(root, "Owner")
        id_elem = etree.SubElement(owner, "ID")
        id_elem.text = self.owner_id
        if (self.owner_display_name and self.owner_display_name != ""):
            display_name_elem = etree.SubElement(owner, "DisplayName")
            display_name_elem.text = self.owner_display_name
        access_control_list = etree.SubElement(root, "AccessControlList")
        for k,g in self.grants.items():
            grant_elem = etree.SubElement(access_control_list, "Grant")
            grantee_elem = etree.SubElement(grant_elem, "{%s}Grantee" % NS,
                nsmap={None: NS, "xsi" : NS2})
            grantee_elem.set("{%s}type" % NS2, user_type_to_attr(get_user_type(g.user_id)))
            user_id_elem = etree.SubElement(grantee_elem, "{%s}ID" % NS)
            user_id_elem.text = strip_user_type(g.user_id)
            if (g.display_name != None):
                display_name_elem = etree.SubElement(grantee_elem, "{%s}DisplayName" % NS)
                display_name_elem.text = g.display_name
            permission_elem = etree.SubElement(grant_elem, "{%s}Permission" % NS)
            permission_elem.text = g.permission
        return etree.tostring(root, encoding="UTF-8")
    def translate_users(self, xusers):
        # Owner ids are always expressed in terms of canonical user id
        if (xusers.has_key(ACL_TYPE_CANON_USER + self.owner_id)):
            self.owner_id = \
                strip_user_type(xusers[ACL_TYPE_CANON_USER + self.owner_id])
            self.owner_display_name = ""
        for k,g in self.grants.items():
            g.translate_users(xusers)
    def get_all_users(self):
        """ Get a list of all user ids referenced in this ACL """
        users = {}
        users[ACL_TYPE_CANON_USER + self.owner_id] = 1
        for k,g in self.grants.items():
            users[k] = 1
        return users.keys()
    def set_owner(self, owner_id):
        self.owner_id = owner_id
        self.owner_display_name = ""
    def equals(self, rhs):
        if (self.owner_id != rhs.owner_id):
            return False
        for k,g in self.grants.items():
            if (not rhs.grants.has_key(k)):
                return False
            if (not g.equals(rhs.grants[k])):
                return False
        for l,r in rhs.grants.items():
            if (not self.grants.has_key(l)):
                return False
            if (not r.equals(self.grants[l])):
                return False
        return True

def compare_xml(xml1, xml2):
    tree1 = etree.parse(StringIO(xml1))
    out1 = etree.tostring(tree1, encoding="UTF-8")
    tree2 = etree.parse(StringIO(xml2))
    out2 = etree.tostring(tree2, encoding="UTF-8")
    out1 = out1.replace("xsi:type", "type")
    out2 = out2.replace("xsi:type", "type")
    if out1 != out2:
        print "out1 = %s" % out1
        print "out2 = %s" % out2
        raise ObsyncPermanentException("compare xml failed")

#<?xml version="1.0" encoding="UTF-8"?>
def test_acl_policy():
    test1_xml = \
"<AccessControlPolicy xmlns=\"http://s3.amazonaws.com/doc/2006-03-01/\">" + \
"<Owner><ID>foo</ID><DisplayName>MrFoo</DisplayName></Owner><AccessControlList>" + \
"<Grant><Grantee xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" " + \
"xsi:type=\"CanonicalUser\"><ID>bar</ID>" + \
"<DisplayName>display-name</DisplayName></Grantee>" + \
"<Permission>FULL_CONTROL</Permission></Grant></AccessControlList></AccessControlPolicy>"
    test1 = AclPolicy.from_xml(test1_xml)
    compare_xml(test1_xml, test1.to_xml())

###### Object #######
class Object(object):
    def __init__(self, name, md5, size, meta):
        self.name = name
        self.md5 = md5
        self.size = int(size)
        self.meta = meta
    def equals(self, rhs):
        if (self.name != rhs.name):
            vvprint("EQUALS: self.name = %s, rhs.name = %s" % (self.name, rhs.name))
            return False
        if (self.md5 != rhs.md5):
            vvprint("EQUALS: self.md5 = %s, rhs.md5 = %s" % (self.md5, rhs.md5))
            return False
        if (self.size != rhs.size):
            vvprint("EQUALS: self.size = %d, rhs.size = %d" % (self.size, rhs.size))
            return False
        for k,v in self.meta.items():
            if (not rhs.meta.has_key(k)):
                vvprint("EQUALS: rhs.meta lacks key %s" % k)
                return False
            if (rhs.meta[k] != v):
                vvprint("EQUALS: self.meta[%s] = %s, rhs.meta[%s] = %s" % \
                    (k, v, k, rhs.meta[k]))
                return False
        for k,v in rhs.meta.items():
            if (not self.meta.has_key(k)):
                vvprint("EQUALS: self.meta lacks key %s" % k)
                return False
        vvprint("EQUALS: the objects are equal.")
        return True
    def local_name(self):
        return s3_name_to_local_name(self.name)
    def local_path(self, base):
        return base + "/" + s3_name_to_local_name(self.name)
    @staticmethod
    def from_file(obj_name, path):
        f = open(path, 'r')
        try:
            md5 = get_md5(f)
        finally:
            f.close()
        size = os.path.getsize(path)
        meta = {}
        try:
            xlist = xattr.get_all(path, namespace=xattr.NS_USER)
        except IOError, e:
            if e.errno == 2:
                return meta
            else:
                raise ObsyncTemporaryException(e)
        for k,v in xlist:
            if xattr_is_metadata(k):
                meta[k] = v
        #print "Object.from_file: path="+path+",md5=" + bytes_to_str(md5) +",size=" + str(size)
        return Object(obj_name, md5, size, meta)

###### Store #######
class Store(object):
    @staticmethod
    def make_store(type, is_dst, create, akey, skey, **kwargs):
        if (type == 's3'):
            if (is_dst):
                is_secure = os.environ.has_key("DST_SECURE")
            else:
                is_secure = os.environ.has_key("SRC_SECURE")
            return S3Store(kwargs['host'], kwargs['bucket'], kwargs['prefix'], create, akey, skey, is_secure)
        elif (type == 'swift'):
            return SwiftStore(kwargs['host'], kwargs['bucket'], kwargs['prefix'], create, akey, skey, False)
        elif (type == 'file'):
            return FileStore(kwargs['path'], create)
        raise ObsyncPermanentException('Unknown store type: "%s"' %type)

###### LocalCopy ######
class LocalCopy(object):
    def __init__(self, obj_name, path, path_is_temp):
        self.obj_name = obj_name
        self.path = path
        self.path_is_temp = path_is_temp
    def remove(self):
        if ((self.path_is_temp == True) and (self.path != None)):
            os.unlink(self.path)
        self.path = None
        self.path_is_temp = False
    def __del__(self):
        self.remove()

class LocalAcl(object):
    @staticmethod
    def from_xml(obj_name, xml):
        acl_policy = AclPolicy.from_xml(xml)
        return LocalAcl(obj_name, acl_policy)
    @staticmethod
    def get_empty(obj_name):
        return LocalAcl(obj_name, None)
    def __init__(self, obj_name, acl_policy):
        self.obj_name = obj_name
        self.acl_policy = acl_policy
    def equals(self, rhs):
        """ Compare two LocalAcls """
        if (self.acl_policy == None):
            return (rhs.acl_policy == None)
        if (rhs.acl_policy == None):
            return (self.acl_policy == None)
        return self.acl_policy.equals(rhs.acl_policy)
    def translate_users(self, xusers):
        """ Translate the users in this ACL """
        if (self.acl_policy == None):
            return
        self.acl_policy.translate_users(xusers)
    def set_owner(self, owner_id):
        if (self.acl_policy == None):
            return
        self.acl_policy.set_owner(owner_id)
    def write_to_xattr(self, file_name):
        """ Write this ACL to an extended attribute """
        if (self.acl_policy == None):
            return
        xml = self.acl_policy.to_xml()
        xattr.set(file_name, ACL_XATTR, xml, namespace=xattr.NS_USER)

###### S3 store #######
def s3_key_to_meta(k):
    meta = {}
    if (k.__dict__.has_key("content_type")):
        meta[CONTENT_TYPE_XATTR] = k.content_type
    for k,v in k.metadata.items():
        meta[META_XATTR_PREFIX + k] = v
    return meta

def meta_to_s3_key(key, meta):
    for k,v in meta.items():
        if (k == CONTENT_TYPE_XATTR):
            key.set_metadata("Content-Type", v)
        elif (k[:len(META_XATTR_PREFIX)] == META_XATTR_PREFIX):
            k_name = k[len(META_XATTR_PREFIX):]
            key.set_metadata(k_name, v)
        else:
            raise ObsyncPermanentException("can't understand meta entry: %s" % k)

class S3StoreIterator(object):
    """S3Store iterator"""
    def __init__(self, bucket, blrs):
        self.bucket = bucket
        self.blrs = blrs
    def __iter__(self):
        return self
    def next(self):
        # This will raise StopIteration when there are no more objects to
        # iterate on
        key = self.blrs.next()
        # Issue a HEAD request to get content-type and other metadata
        k = self.bucket.get_key(key.name)
        ret = Object(key.name, etag_to_md5(key.etag), key.size, s3_key_to_meta(k))
        return ret

class S3Store(Store):
    def __init__(self, host, bucket_name, object_prefix, create, akey, skey, is_secure):
        self.host = host
        self.bucket_name = bucket_name
        self.key_prefix = object_prefix

        self.conn = S3Connection(calling_format=OrdinaryCallingFormat(),
                host=self.host, is_secure=is_secure,
                aws_access_key_id=akey, aws_secret_access_key=skey)

        self.bucket = self.conn.lookup(self.bucket_name)
        if (self.bucket == None):
            if (create):
                if (opts.dry_run):
                    raise ObsyncPermanentException("logic error: this should be unreachable.")
                self.bucket = self.conn.create_bucket(bucket_name = self.bucket_name)
            else:
                # Hrm, try again using Subdomain method.  This works
                # around PermanentRedirect.
                self.conn = S3Connection(calling_format=SubdomainCallingFormat(),
                                         host=self.host, is_secure=is_secure,
                                         aws_access_key_id=akey, aws_secret_access_key=skey)
                self.bucket = self.conn.lookup(self.bucket_name)
                if (self.bucket == None):
                    raise ObsyncPermanentException("%s: no such bucket as %s" % \
                                                       (host, self.bucket_name))

    def __str__(self):
        return "s3://" + self.host + "/" + self.bucket_name + "/" + self.key_prefix

    def get_acl(self, obj):
        acl_xml = self.bucket.get_xml_acl(obj.name)
        return LocalAcl.from_xml(obj.name, acl_xml)

    def make_local_copy(self, obj):
        k = Key(self.bucket)
        k.key = obj.name
        temp_file = tempfile.NamedTemporaryFile(mode='w+b', delete=False).name
        try:
            k.get_contents_to_filename(temp_file)
        except Exception, e:
            os.unlink(temp_file)
            raise ObsyncTemporaryException(e)
        return LocalCopy(obj.name, temp_file, True)

    def all_objects(self):
        blrs = self.bucket.list(prefix = self.key_prefix)
        return S3StoreIterator(self.bucket, blrs.__iter__())

    def locate_object(self, obj):
        k = self.bucket.get_key(obj.name)
        if (k == None):
            return None
        return Object(obj.name, etag_to_md5(k.etag), k.size, s3_key_to_meta(k))

    def upload(self, local_copy, src_acl, obj):
        if (opts.more_verbose):
            print "S3Store.UPLOAD: local_copy.path='" + local_copy.path + "' " + \
                "obj='" + obj.name + "'"
        if (opts.dry_run):
            return
        k = Key(self.bucket)
        k.key = obj.name
        meta_to_s3_key(k, obj.meta)
        k.set_contents_from_filename(local_copy.path)
        if (src_acl.acl_policy != None):
            xml = src_acl.acl_policy.to_xml()
            try:
                def fn():
                    self.bucket.set_xml_acl(xml, k)
                do_with_s3_retries(fn)
            except boto.exception.S3ResponseError, e:
                print >>stderr, "ERROR SETTING ACL on object '" + sobj.name + "'"
                print >>stderr
                print >>stderr, "************* ACL: *************"
                print >>stderr, str(xml)
                print >>stderr, "********************************"
                raise ObsyncTemporaryException(e)

    def remove(self, obj):
        if (opts.dry_run):
            return
        self.bucket.delete_key(obj.name)
        if (opts.more_verbose):
            print "S3Store: removed %s" % obj.name

# Some S3 servers offer "eventual consistency."
# What this means is that after a change has been made, like the creation of an
# object, it takes some time for this change to become visible to everyone.
# This potentially includes the client making the change.
#
# This means we need to implement a retry mechanism for certain operations.
# For example, setting the ACL on a newly created object may fail with an
# "object not found" error if the object creation hasn't yet become visible to
# us.
def do_with_s3_retries(fn):
    if (os.environ.has_key("DST_CONSISTENCY") and
            os.environ["DST_CONSISTENCY"] == "eventual"):
        sleep_times = [5, 10, 60, -1]
    else:
        sleep_times = [-1]
    for stime in sleep_times:
        try:
            fn()
            return
        except boto.exception.S3ResponseError, e:
            if (stime == -1):
                raise ObsyncTemporaryException(e)
            if (opts.verbose):
                print "encountered s3 response error: ",
            if (opts.more_verbose):
                print str(e) + ": ",
            if (opts.verbose):
                print "retrying operation after " + str(stime) + \
                    " second delay"
            time.sleep(stime)

###### Swift store #######
def swift_object_to_meta(obj):
    meta = {}
    if (obj.__dict__.has_key("content_type")):
        meta[CONTENT_TYPE_XATTR] = obj.content_type
    for k,v in obj.metadata.items():
        meta[META_XATTR_PREFIX + k] = v
    return meta

def meta_to_swift_object(obj, meta):
    for k,v in meta.items():
        if (k == CONTENT_TYPE_XATTR):
            obj.metadata["Content-Type"] = v
        elif (k[:len(META_XATTR_PREFIX)] == META_XATTR_PREFIX):
            k_name = k[len(META_XATTR_PREFIX):]
            obj.metadata[k_name] = v
        else:
            raise ObsyncPermanentException("can't understand meta entry: %s" % k)
        obj.sync_metadata()

class SwiftStoreIterator(object):
    """SwiftStore iterator"""
    def __init__(self, container, object_list):
        self.container = container
        self.generator = (o for o in object_list)
    def __iter__(self):
        return self
    def next(self):
        # This will raise StopIteration when there are no more objects to
        # iterate on
        obj = self.generator.next()
        obj = self.container.get_object(obj.name)
        ret = Object(obj.name, etag_to_md5(obj._etag), obj.size, swift_object_to_meta(obj))
        return ret

class SwiftStore(Store):
    def __init__(self, authurl, container_name, object_prefix, create, akey, skey, is_secure):
        self.host = authurl
        self.container_name = container_name
        self.object_prefix = object_prefix

        self.conn = cloudfiles.get_connection(username=akey, api_key=skey,
            authurl=self.host)
        try:
            self.container = self.conn.get_container(self.container_name)
        except cloudfiles.errors.NoSuchContainer:
            self.container = None

        if (self.container == None):
            if (create):
                if (opts.dry_run):
                    raise ObsyncPermanentException("logic error: this should be unreachable.")
                self.container = self.conn.create_container(self.container_name)
            else:
                raise ObsyncPermanentException("%s: no such container as %s" % \
                    (self.host, self.container_name))

    def __str__(self):
        return "swift://" + self.host + "/" + self.container_name + "/" + self.object_prefix

    def get_acl(self, obj):
        raise NotImplementedError # We always use --no-preserve-acls right now
    def make_local_copy(self, obj):
        o = self.container.get_object(obj.name)
        temp_file = tempfile.NamedTemporaryFile(mode='w+b', delete=False).name
        try:
            o.save_to_filename(temp_file)
        except Exception, e:
            os.unlink(temp_file)
            raise ObsyncTemporaryException(e)
        return LocalCopy(obj.name, temp_file, True)

    def all_objects(self):
        object_list = self.container.get_objects(prefix = self.object_prefix)
        return SwiftStoreIterator(self.container, object_list)

    def locate_object(self, obj):
        try:
            o = self.container.get_object(obj.name)
        except cloudfiles.errors.NoSuchObject:
            return None
        return Object(obj.name, etag_to_md5(o._etag), o.size, swift_object_to_meta(o))

    def upload(self, local_copy, src_acl, obj):
        if (opts.more_verbose):
            print "SwiftStore.UPLOAD: local_copy.path='" + local_copy.path + "' " + \
                "obj='" + obj.name + "'"
        if (opts.dry_run):
            return
        o = self.container.create_object(obj.name)
        o.load_from_filename(local_copy.path)
        meta_to_swift_object(o, obj.meta)
        if (src_acl.acl_policy != None):
            #FIXME: no acls for swift yet
            pass

    def remove(self, obj):
        if (opts.dry_run):
            return
        self.container.delete_object(obj.name)
        if (opts.more_verbose):
            print "SwiftStore: removed %s" % obj.name

###### FileStore #######
class FileStoreIterator(object):
    """FileStore iterator"""
    def __init__(self, base):
        self.base = base
        if (opts.follow_symlinks):
            self.generator = os.walk(base, followlinks=True)
        else:
            self.generator = os.walk(base)
        self.path = ""
        self.files = []
    def __iter__(self):
        return self
    def next(self):
        while True:
            if (len(self.files) == 0):
                self.path, dirs, self.files = self.generator.next()
                continue
            path = self.path + "/" + self.files[0]
            self.files = self.files[1:]
            # Ignore non-files when iterating.
            if (not os.path.isfile(path)):
                continue
            obj_name = local_name_to_s3_name(path[len(self.base)+1:])
            return Object.from_file(obj_name, path)

class FileStore(Store):
    def __init__(self, url, create):
        # Parse the file url
        self.base = url
        if (self.base[-1:] == '/'):
            self.base = self.base[:-1]
        if (create):
            if (opts.dry_run):
                raise ObsyncPermanentException("logic error: this should be unreachable.")
            mkdir_p(self.base)
        elif (not os.path.isdir(self.base)):
            raise ObsyncPermanentException("NonexistentStore")
        Store.__init__(self, "file://" + url)
        test_xattr_support(self.base)
    def __str__(self):
        return "file://" + self.base
    def get_acl(self, obj):
        try:
            xml = xattr.get(obj.local_path(self.base), ACL_XATTR,
                            namespace=xattr.NS_USER)
        except IOError, e:
            #print "failed to get XML ACL from %s" % obj.local_name()
            if e.errno == 61:
                return LocalAcl.get_empty(obj.name)
            raise ObsyncPermanentException(e)
        return LocalAcl.from_xml(obj.name, xml)
    def make_local_copy(self, obj):
        return LocalCopy(obj.name, obj.local_path(self.base), False)
    def all_objects(self):
        return FileStoreIterator(self.base)
    def locate_object(self, obj):
        path = obj.local_path(self.base)
        found = os.path.isfile(path)
        if (opts.more_verbose):
            if (found):
                print "FileStore::locate_object: found object '" + \
                    obj.name + "'"
            else:
                print "FileStore::locate_object: did not find object '" + \
                    obj.name + "'"
        if (not found):
            return None
        return Object.from_file(obj.name, path)
    def upload(self, local_copy, src_acl, obj):
        if (opts.more_verbose):
            print "FileStore.UPLOAD: local_copy.path='" + local_copy.path + "' " + \
                "obj='" + obj.name + "'"
        if (opts.dry_run):
            return
        s = local_copy.path
        lname = obj.local_name()
        d = self.base + "/" + lname
        mkdir_p(os.path.dirname(d))
        shutil.copy(s, d)
        src_acl.write_to_xattr(d)
        # Store metadata in extended attributes
        for k,v in obj.meta.items():
            xattr.set(d, k, v, namespace=xattr.NS_USER)
    def remove(self, obj):
        if (opts.dry_run):
            return
        os.unlink(self.base + "/" + obj.name)
        if (opts.more_verbose):
            print "FileStore: removed %s" % obj.name

###### Functions #######
def delete_unreferenced(src, dst):
    """ delete everything from dst that is not referenced in src """
    if (opts.more_verbose):
        print "handling deletes."
    currently_handling = "destination"
    try:
        dst_all_objects = dst.all_objects()
        while True:
            dobj = dst_all_objects.next()
            currently_handling = "source"
            sobj = src.locate_object(dobj)
            currently_handling = "destination"
            if (sobj == None):
                dst.remove(dobj)
    except StopIteration:
        pass
    except Exception, e:
        print_obsync_exception_and_abort(e, currently_handling)

def xuser_cb(opt, opt_str, value, parser):
    """ handle an --xuser argument """
    equals = value.find(r'=')
    if equals == -1:
        raise ObsyncArgumentParsingException("Error parsing --xuser: You must \
give both a source and destination user name, like so:\n\
--xuser SOURCE_USER=DEST_USER\n\
\n\
This will translate the user SOURCE_USER in the source to the user DEST_USER \n\
in the destination.")
    src_user = value[:equals]
    dst_user = value[equals+1:]
    if ((len(src_user) == 0) or (len(dst_user) == 0)):
        raise ObsyncArgumentParsingException("Error parsing --xuser: \
can't have a zero-length user name.")
    src_user = add_user_type(src_user)
    dst_user = add_user_type(dst_user)
    if (xuser.has_key(src_user)):
        raise ObsyncArgumentParsingException("Error parsing --xuser: \
we are already translating \"%s\" to \"%s\"; we cannot translate it \
to \"%s\"" % (src_user, xuser[src_user], dst_user))
    xuser[src_user] = dst_user

############Begin#############
try:
    currently_handling = "unknown"
    parser = OptionParser(USAGE)
    parser.add_option("--src-type", dest="src_type", type="string",
        action="store", help="type of data  store for source. Can be " + \
        "'file', 's3', or 'swift'")
    parser.add_option("--src-path", dest="src_path", type="string",
        action="store", help="local file path for source")
    parser.add_option("--src-host", dest="src_host", type="string",
        action="store", help="host to connect to for source data")
    parser.add_option("--src-authurl", dest="src_authurl", type="string",
        action="store", help="authurl to connect to for source data")
    parser.add_option("--src-bucket", dest="src_bucket", type="string",
        action="store", help="source bucket")
    parser.add_option("--src-prefix", dest="src_prefix", type="string",
        action="store", help="object prefix for the source")
    parser.add_option("--dst-type", dest="dst_type", type="string",
        action="store", help="type of data  store for destination. Can be " + \
        "'file', 's3', or 'swift'")
    parser.add_option("--dst-path", dest="dst_path", type="string",
        action="store", help="local file path for destination")
    parser.add_option("--dst-host", dest="dst_host", type="string",
        action="store", help="host to connect to for destination data")
    parser.add_option("--dst-authurl", dest="dst_authurl", type="string",
        action="store", help="authurl to connect to for destination data")
    parser.add_option("--dst-bucket", dest="dst_bucket", type="string",
        action="store", help="destination bucket")
    parser.add_option("--dst-prefix", dest="dst_prefix", type="string",
        action="store", help="object prefix for the destination")
    parser.add_option("-n", "--dry-run", action="store_true", \
        dest="dry_run", default=False)
    parser.add_option("-c", "--create-dest", action="store_true", \
        dest="create", help="create the destination if it doesn't already exist")
    parser.add_option("--delete-before", action="store_true", \
        dest="delete_before", help="delete objects that aren't in SOURCE from \
    DESTINATION before transferring any objects")
    parser.add_option("--boto-retries", dest="boto_retries", type="int",
        help="set number of times we'll retry the same S3 operation")
    parser.add_option("-d", "--delete-after", action="store_true", \
        dest="delete_after", help="delete objects that aren't in SOURCE from \
    DESTINATION after doing all transfers.")
    parser.add_option("-L", "--follow-symlinks", action="store_true", \
        dest="follow_symlinks", help="follow symlinks (please avoid symlink " + \
        "loops when using this option!)")
    parser.add_option("--no-preserve-acls", action="store_true", \
        dest="no_preserve_acls", help="don't preserve ACLs when copying objects.")
    parser.add_option("-v", "--verbose", action="store_true", \
        dest="verbose", help="be verbose")
    parser.add_option("-V", "--more-verbose", action="store_true", \
        dest="more_verbose", help="be really, really verbose (developer mode)")
    parser.add_option("-x", "--xuser", type="string", nargs=1, action="callback", \
        dest="SRC=DST", callback=xuser_cb, help="set up a user tranlation. You \
    can specify multiple user translations with multiple --xuser arguments.")
    parser.add_option("--force", action="store_true", \
        dest="force", help="overwrite all destination objects, even if they \
    appear to be the same as the source objects.")
    parser.add_option("--unit", action="store_true", \
        dest="run_unit_tests", help="run unit tests and quit")
    xuser = {}
    (opts, args) = parser.parse_args()
    if (opts.run_unit_tests):
        test_acl_policy()
        sys.exit(0)

    if opts.boto_retries != None:
        if not boto.config.has_section('Boto'):
            boto.config.add_section('Boto')
        boto.config.set('Boto', 'num_retries', str(opts.boto_retries))

    if (not opts.src_type):
        raise ObsyncArgumentParsingException("src-type is required!")
    if (opts.src_type == 'file'):
        if (opts.src_host or opts.src_bucket or opts.src_prefix or opts.src_authurl):
            raise ObsyncArgumentParsingException("host, bucket, prefix, and " + \
                "authurl not required for local file stores.")
        if (not opts.src_path):
            raise ObsyncArgumentParsingException("src-path is required!")
    else:
        if (opts.src_type == 's3'):
            if (opts.src_authurl):
                raise ObsyncArgumentParsingException("src-authurl is not used for s3 stores!")
            if (not opts.src_host):
                raise ObsyncArgumentParsingException("src-host is required for s3 stores!")
        if (opts.src_type == 'swift'):
            if not cloudfiles:
                raise ObsyncArgumentParsingException("cloudfiles library not found. Swift syncing unavailable")
            if (not opts.src_authurl):
                raise ObsyncArgumentParsingException("src-authurl is required for swift stores!")
            if (opts.src_host):
                raise ObsyncArgumentParsingException("src-host is not used for swift stores!")
        if (not opts.src_bucket):
            raise ObsyncArgumentParsingException("src-bucket is required!")

    if (not opts.dst_type):
        raise ObsyncArgumentParsingException("dst-type is required!")
    if (opts.dst_type == 'file'):
        if (opts.dst_host or opts.dst_bucket or opts.dst_prefix or opts.dst_authurl):
            raise ObsyncArgumentParsingException("host, bucket, prefix, and " + \
                "authurl not required for local file stores.")
        if (not opts.dst_path):
            raise ObsyncArgumentParsingException("dst-path is required!")
    else:
        if (opts.dst_type == 's3'):
            if (opts.dst_authurl):
                raise ObsyncArgumentParsingException("dst-authurl is not used for s3 stores!")
            if (not opts.dst_host):
                raise ObsyncArgumentParsingException("dst-host is required for s3 stores!")
        if (opts.dst_type == 'swift'):
            if not cloudfiles:
                raise ObsyncArgumentParsingException("cloudfiles library not found. Swift syncing unavailable")
            if (not opts.dst_authurl):
                raise ObsyncArgumentParsingException("dst-authurl is required for swift stores!")
            if (opts.dst_host):
                raise ObsyncArgumentParsingException("dst-host is not used for swift stores!")
        if (not opts.dst_bucket):
            raise ObsyncArgumentParsingException("dst-bucket is required!")

    if opts.src_authurl:
        opts.src_host = opts.src_authurl
    if opts.dst_authurl:
        opts.dst_host = opts.dst_authurl
    opts.preserve_acls = not opts.no_preserve_acls
    if (opts.create and opts.dry_run):
        raise ObsyncArgumentParsingException("You can't run with both \
--create-dest and --dry-run! By definition, a dry run never changes anything.")

    if (opts.more_verbose):
        print >>stderr, "User translations:"
        for k,v in xuser.items():
            print >>stderr, "\"%s\" ==> \"%s\"" % (k, v)
        print >>stderr, ""
    if (opts.more_verbose):
        opts.verbose = True
        boto.set_stream_logger("stdout")
        boto.log.info("Enabling verbose boto logging.")
    if (opts.delete_before and opts.delete_after):
        raise ObsyncArgumentParsingException("It doesn't make sense to \
specify both --delete-before and --delete-after.")

    currently_handling = "source"
    if (opts.more_verbose):
        print "SOURCE: %s, %s, %s (%s)" % (opts.src_host, opts.src_bucket,
                opts.src_prefix, opts.src_type)
    try:
        src = Store.make_store(opts.src_type, False, False,
                getenv("SRC_AKEY", "AKEY"), getenv("SRC_SKEY", "SKEY"),
                host=opts.src_host, bucket=opts.src_bucket,
                prefix=opts.src_prefix, path=opts.src_path)
    except ObsyncException, e:
        if (e.comment == "NonexistentStore"):
            e.comment = "Fatal error: Source " + opts.src_host + " does " +\
                "not appear to exist."
        raise

    currently_handling = "destination"
    if (opts.more_verbose):
        print "DESTINATION: %s, %s, %s (%s)" % (opts.dst_host, opts.dst_bucket,
                opts.dst_prefix, opts.dst_type)
    try:
        dst = Store.make_store(opts.dst_type, True, opts.create,
                getenv("DST_AKEY", "AKEY"), getenv("DST_SKEY", "SKEY"),
                host=opts.dst_host, bucket=opts.dst_bucket,
                prefix=opts.dst_prefix, path=opts.dst_path)
    except ObsyncException, e:
        if (e.comment == "NonexistentStore"):
            e.comment = "Fatal error: Destination does not exist. Run " + \
                "with -c or --create-dest to create it automatically."
        raise

    if (opts.delete_before):
        delete_unreferenced(src, dst)

    currently_handling = "source"
    src_all_objects = src.all_objects()
    while True:
        currently_handling = "source"
        try:
            sobj = src_all_objects.next()
        except StopIteration:
            break
        if (opts.more_verbose):
            print "handling " + sobj.name
        pline = ""
        currently_handling = "destination"
        dobj = dst.locate_object(sobj)
        upload = False
        src_acl = None
        dst_acl = None
        if (opts.force):
            if (opts.verbose):
                pline += "F " + sobj.name
            upload = True
        elif (dobj == None):
            if (opts.verbose):
                pline += "+ " + sobj.name
            upload = True
        elif not sobj.equals(dobj):
            if (opts.verbose):
                pline += "> " + sobj.name
            upload = True
        elif (opts.preserve_acls):
            # Do the ACLs match?
            currently_handling = "source"
            src_acl = src.get_acl(sobj)
            currently_handling = "destination"
            dst_acl = dst.get_acl(dobj)
            currently_handling = "source"
            src_acl.translate_users(xuser)
            #src_acl.set_owner()
            if (not src_acl.equals(dst_acl)):
                upload = True
                if (opts.verbose):
                    pline += "^ %s" % sobj.name
        else:
            if (opts.verbose):
                pline += ". " + sobj.name
        if (upload):
            if (not opts.preserve_acls):
                # Just default to an empty ACL
                src_acl = LocalAcl.get_empty(sobj.name)
            else:
                if (src_acl == None):
                    currently_handling = "source"
                    src_acl = src.get_acl(sobj)
                    src_acl.translate_users(xuser)
                    #src_acl.set_owner()
            currently_handling = "source"
            local_copy = src.make_local_copy(sobj)
            try:
                currently_handling = "destination"
                dst.upload(local_copy, src_acl, sobj)
            finally:
                local_copy.remove()
        if (pline != ""):
            print pline

    if (opts.delete_after):
        delete_unreferenced(src, dst)
except Exception, e:
    print_obsync_exception_and_abort(e, currently_handling)

if (opts.more_verbose):
    print "finished."
sys.exit(0)