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#!/usr/bin/env python3
# Fetch a file from the guest via the QEMU guest agent protocol
# (/tmp/qemu-guest-agent.sock, the virtio-serial QGA chardev - the same
# socket vgpu_vm.py exec uses). Usage: qga_fetch.py <guest_path> <host_path> [chunk]
#
# Robustness (r1490): the r1489 evidence capture fetched nothing because the
# guest-side frame was still being written / the agent answered late. Retry
# the open a few times, tolerate error replies with a clear diagnostic, use a
# long socket timeout, and write to a temporary file so a partial transfer is
# never mistaken for a complete capture.
import base64
import json
import os
import socket
import sys
import time
if len(sys.argv) < 3:
print("usage: qga_fetch.py <guest_path> <host_path> [chunk]", file=sys.stderr)
sys.exit(2)
GUEST = sys.argv[1]
HOST = sys.argv[2]
CHUNK = int(sys.argv[3]) if len(sys.argv) > 3 else 1 << 20
SOCK = "/tmp/qemu-guest-agent.sock"
TRIES = 6
TMP = HOST + ".part"
def recv_line(s):
buf = b""
while b"\n" not in buf:
chunk = s.recv(65536)
if not chunk:
break
buf += chunk
return buf.split(b"\n", 1)[0]
def cmd(s, obj):
s.sendall((json.dumps(obj) + "\r\n").encode())
line = recv_line(s)
return json.loads(line)
def open_guest():
last = None
for i in range(TRIES):
try:
s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
s.settimeout(120.0)
s.connect(SOCK)
r = cmd(s, {"execute": "guest-file-open",
"arguments": {"path": GUEST, "mode": "r"}})
if "return" in r:
return s, r["return"], None
last = f"guest-file-open error: {r.get('error')}"
except Exception as e: # noqa: BLE001 - diagnostic surface
last = f"guest-file-open exception: {e}"
try:
s.close()
except Exception:
pass
time.sleep(1.5)
if i + 1 < TRIES:
print(f"retry {i + 1}/{TRIES}: {last}", file=sys.stderr)
return None, None, last
s, h, err = open_guest()
if s is None:
print(f"FETCH-FAIL {GUEST} -> {HOST}: {err}", file=sys.stderr)
sys.exit(1)
print(f"handle={h}")
total = 0
try:
with open(TMP, "wb") as out:
while True:
r = cmd(s, {"execute": "guest-file-read",
"arguments": {"handle": h, "count": CHUNK}})
if "return" not in r:
raise RuntimeError(f"guest-file-read error: {r.get('error')}")
d = r["return"]
buf = base64.b64decode(d.get("buf-b64", ""))
if buf:
out.write(buf)
total += len(buf)
print(f"\r{total}", end="", flush=True)
if d.get("eof"):
break
cmd(s, {"execute": "guest-file-close", "arguments": {"handle": h}})
except Exception as e: # noqa: BLE001
print(f"\nFETCH-FAIL {GUEST} -> {HOST}: {e}", file=sys.stderr)
try:
if os.path.exists(TMP):
os.unlink(TMP)
except OSError:
pass
sys.exit(1)
finally:
try:
s.close()
except Exception:
pass
os.replace(TMP, HOST)
print(f"\nFETCHED {total} bytes -> {HOST}")
sys.exit(0)
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