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#!/usr/bin/env python3
"""
Either uploads local FILE to libvirt VOLUME, or downloads libvirt
VOLUME into local FILE while preserving FILE/VOLUME sparseness
"""
# Example of sparse streams usage
#
# Authors:
# Michal Privoznik <mprivozn@redhat.com>
import libvirt
import os
from argparse import ArgumentParser
def bytesWriteHandler(stream: libvirt.virStream, buf: bytes, opaque: int) -> int:
fd = opaque
return os.write(fd, buf)
def bytesReadHandler(stream: libvirt.virStream, nbytes: int, opaque: int) -> bytes:
fd = opaque
return os.read(fd, nbytes)
def recvSkipHandler(stream: libvirt.virStream, length: int, opaque: int) -> None:
fd = opaque
cur = os.lseek(fd, length, os.SEEK_CUR)
return os.ftruncate(fd, cur)
def sendSkipHandler(stream: libvirt.virStream, length: int, opaque: int) -> int:
fd = opaque
return os.lseek(fd, length, os.SEEK_CUR)
def holeHandler(stream: libvirt.virStream, opaque: int):
fd = opaque
cur = os.lseek(fd, 0, os.SEEK_CUR)
try:
data = os.lseek(fd, cur, os.SEEK_DATA)
except OSError as e:
if e.errno != 6:
raise e
else:
data = -1
# There are three options:
# 1) data == cur; @cur is in data
# 2) data > cur; @cur is in a hole, next data at @data
# 3) data < 0; either @cur is in trailing hole, or @cur is beyond EOF.
if data < 0:
# case 3
inData = False
eof = os.lseek(fd, 0, os.SEEK_END)
if (eof < cur):
raise RuntimeError("Current position in file after EOF: %d" % cur)
sectionLen = eof - cur
else:
if (data > cur):
# case 2
inData = False
sectionLen = data - cur
else:
# case 1
inData = True
# We don't know where does the next hole start. Let's find out.
# Here we get the same options as above
hole = os.lseek(fd, data, os.SEEK_HOLE)
if hole < 0:
# case 3. But wait a second. There is always a trailing hole.
# Do the best what we can here
raise RuntimeError("No trailing hole")
if (hole == data):
# case 1. Again, this is suspicious. The reason we are here is
# because we are in data. But at the same time we are in a
# hole. WAT?
raise RuntimeError("Impossible happened")
else:
# case 2
sectionLen = hole - data
os.lseek(fd, cur, os.SEEK_SET)
return [inData, sectionLen]
def download(vol: libvirt.virStorageVol, st: libvirt.virStream, filename: str) -> None:
offset = 0
length = 0
fd = os.open(filename, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, mode=0o0660)
vol.download(st, offset, length, libvirt.VIR_STORAGE_VOL_DOWNLOAD_SPARSE_STREAM)
st.sparseRecvAll(bytesWriteHandler, recvSkipHandler, fd)
os.close(fd)
def upload(vol: libvirt.virStorageVol, st: libvirt.virStream, filename: str) -> None:
offset = 0
length = 0
fd = os.open(filename, os.O_RDONLY)
vol.upload(st, offset, length, libvirt.VIR_STORAGE_VOL_UPLOAD_SPARSE_STREAM)
st.sparseSendAll(bytesReadHandler, holeHandler, sendSkipHandler, fd)
os.close(fd)
# main
parser = ArgumentParser(description=__doc__)
parser.add_argument("uri")
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument("--upload", action="store_const", const=upload, dest="operation")
group.add_argument("--download", action="store_const", const=download, dest="operation")
parser.add_argument("volume")
parser.add_argument("file")
args = parser.parse_args()
conn = libvirt.open(args.uri)
vol = conn.storageVolLookupByKey(args.volume)
st = conn.newStream()
args.operation(vol, st, args.file)
st.finish()
conn.close()
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