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https://gitlab.com/libvirt/libvirt-python.git
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118 lines
3.6 KiB
Python
Executable File
118 lines
3.6 KiB
Python
Executable File
#!/usr/bin/env python3
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# Example of sparse streams usage
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#
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# Authors:
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# Michal Privoznik <mprivozn@redhat.com>
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import libvirt, sys, os
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def bytesWriteHandler(stream: libvirt.virStream, buf: bytes, opaque: int) -> int:
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fd = opaque
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return os.write(fd, buf)
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def bytesReadHandler(stream: libvirt.virStream, nbytes: int, opaque: int) -> bytes:
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fd = opaque
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return os.read(fd, nbytes)
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def recvSkipHandler(stream: libvirt.virStream, length: int, opaque: int) -> None:
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fd = opaque
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cur = os.lseek(fd, length, os.SEEK_CUR)
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return os.ftruncate(fd, cur)
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def sendSkipHandler(stream: libvirt.virStream, length: int, opaque: int) -> int:
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fd = opaque
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return os.lseek(fd, length, os.SEEK_CUR)
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def holeHandler(stream: libvirt.virStream, opaque: int):
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fd = opaque
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cur = os.lseek(fd, 0, os.SEEK_CUR)
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try:
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data = os.lseek(fd, cur, os.SEEK_DATA)
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except OSError as e:
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if e.errno != 6:
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raise e
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else:
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data = -1
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# There are three options:
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# 1) data == cur; @cur is in data
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# 2) data > cur; @cur is in a hole, next data at @data
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# 3) data < 0; either @cur is in trailing hole, or @cur is beyond EOF.
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if data < 0:
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# case 3
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inData = False
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eof = os.lseek(fd, 0, os.SEEK_END)
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if (eof < cur):
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raise RuntimeError("Current position in file after EOF: %d" % cur)
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sectionLen = eof - cur
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else:
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if (data > cur):
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# case 2
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inData = False
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sectionLen = data - cur
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else:
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# case 1
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inData = True
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# We don't know where does the next hole start. Let's find out.
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# Here we get the same options as above
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hole = os.lseek(fd, data, os.SEEK_HOLE)
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if hole < 0:
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# case 3. But wait a second. There is always a trailing hole.
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# Do the best what we can here
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raise RuntimeError("No trailing hole")
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if (hole == data):
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# case 1. Again, this is suspicious. The reason we are here is
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# because we are in data. But at the same time we are in a
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# hole. WAT?
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raise RuntimeError("Impossible happened")
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else:
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# case 2
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sectionLen = hole - data
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os.lseek(fd, cur, os.SEEK_SET)
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return [inData, sectionLen]
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def download(vol: libvirt.virStorageVol, st: libvirt.virStream, filename: str) -> None:
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offset = 0
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length = 0
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fd = os.open(filename, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, mode=0o0660)
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vol.download(st, offset, length, libvirt.VIR_STORAGE_VOL_DOWNLOAD_SPARSE_STREAM)
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st.sparseRecvAll(bytesWriteHandler, recvSkipHandler, fd)
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os.close(fd)
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def upload(vol: libvirt.virStorageVol, st: libvirt.virStream, filename: str) -> None:
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offset = 0
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length = 0
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fd = os.open(filename, os.O_RDONLY)
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vol.upload(st, offset, length, libvirt.VIR_STORAGE_VOL_UPLOAD_SPARSE_STREAM)
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st.sparseSendAll(bytesReadHandler, holeHandler, sendSkipHandler, fd)
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os.close(fd)
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# main
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if len(sys.argv) != 5:
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print("Usage: ", sys.argv[0], " URI --upload/--download VOLUME FILE")
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print("Either uploads local FILE to libvirt VOLUME, or downloads libvirt ")
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print("VOLUME into local FILE while preserving FILE/VOLUME sparseness")
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sys.exit(1)
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conn = libvirt.open(sys.argv[1])
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vol = conn.storageVolLookupByKey(sys.argv[3])
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st = conn.newStream()
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if sys.argv[2] == "--download":
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download(vol, st, sys.argv[4])
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elif sys.argv[2] == "--upload":
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upload(vol, st, sys.argv[4])
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else:
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print("Unknown operation: %s " % sys.argv[1])
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sys.exit(1)
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st.finish()
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conn.close()
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