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#!/usr/bin/env python
# Example of sparse streams usage
#
# Authors:
# Michal Privoznik <mprivozn@redhat.com>
import libvirt, sys, os
def bytesWriteHandler(stream, buf, opaque):
fd = opaque
return os.write(fd, buf)
def bytesReadHandler(stream, nbytes, opaque):
fd = opaque
return os.read(fd, nbytes)
def recvSkipHandler(stream, length, opaque):
fd = opaque
cur = os.lseek(fd, length, os.SEEK_CUR)
return os.ftruncate(fd, cur)
def sendSkipHandler(stream, length, opaque):
fd = opaque
return os.lseek(fd, length, os.SEEK_CUR)
def holeHandler(stream, opaque):
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, st, filename):
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, st, filename):
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
if len(sys.argv) != 5:
print("Usage: ", sys.argv[0], " URI --upload/--download VOLUME FILE")
print("Either uploads local FILE to libvirt VOLUME, or downloads libvirt ")
print("VOLUME into local FILE while preserving FILE/VOLUME sparseness")
sys.exit(1)
conn = libvirt.open(sys.argv[1])
vol = conn.storageVolLookupByKey(sys.argv[3])
st = conn.newStream()
if sys.argv[2] == "--download":
download(vol, st, sys.argv[4])
elif sys.argv[2] == "--upload":
upload(vol, st, sys.argv[4])
else:
print("Unknown operation: %s " % sys.argv[1])
sys.exit(1)
st.finish()
conn.close()
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