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import os
import signal
import socket
import subprocess
import sys
import ptrace.debugger
from ptrace.debugger import (
ProcessSignal,
ProcessExit,
NewProcessEvent,
)
# -------- scheduler via unix socket --------
def read_next_tid(sock, processes):
"""
Read the next thread ID to schedule from a controller over a socket.
Blocks until a valid TID is received.
"""
while True:
data = sock.recv(64)
if not data:
continue # ignore empty reads
try:
tid = int(data.strip())
except ValueError:
print(f"Invalid scheduler value: {data!r}")
continue
if tid in processes:
print(f"Scheduler selected TID {tid}")
return processes[tid]
print(f"TID {tid} not active, waiting for a valid one …")
# -------- wait until first clone --------
def run_until_first_clone(debugger, process):
process.cont()
while True:
try:
sig = debugger.waitSignals()
sig.process.cont(sig.signum)
except NewProcessEvent as event:
new_proc = event.process
print(f"First clone: TID {new_proc.pid}")
return
except ProcessExit as event:
print(f"Process {event.process.pid} exited before cloning")
raise
# -------- main tracer --------
def trace(pid, sched_socket_path):
debugger = ptrace.debugger.PtraceDebugger()
debugger.traceClone()
debugger.traceFork()
debugger.traceExec()
print(f"Attach process {pid}")
proc0 = debugger.addProcess(pid, False)
# Create listening scheduling socket
if os.path.exists(sched_socket_path):
os.unlink(sched_socket_path)
srv = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
srv.bind(sched_socket_path)
srv.listen(1)
print(f"Waiting for scheduler connection on {sched_socket_path}")
conn, _ = srv.accept()
print("Scheduler connected")
# 1) run until clone
run_until_first_clone(debugger, proc0)
# 2) attach all existing threads after clone
for tid_str in os.listdir(f"/proc/{pid}/task"):
tid = int(tid_str)
if tid not in debugger.dict:
try:
debugger.addProcess(tid, False)
except Exception as e:
print(f"Failed to attach TID {tid}: {e}")
# 3) main loop: scheduler picks TID → run it to next syscall
while len(debugger.list) != 0:
proc = read_next_tid(conn, debugger.dict)
tid = proc.pid
try:
proc.syscall() # continue until syscall entry/exit
proc.waitSyscall()
ip = proc.getInstrPointer()
print(f"TID {tid} syscall-stop at {hex(ip)}")
except ProcessSignal as ev:
ev.process.cont(ev.signum)
except ProcessExit as ev:
print(f"Thread {ev.process.pid} exited (exitcode={ev.exitcode})")
try:
ev.process.detach()
except Exception:
pass
debugger.deleteProcess(ev.process)
except Exception as e:
print(f"TID {tid} exception: {e}")
try:
proc.detach()
except Exception:
pass
debugger.deleteProcess(proc)
# detect new threads
for p in list(debugger.list):
t = p.pid
if t not in debugger.dict:
debugger.dict[t] = p
conn.close()
srv.close()
debugger.quit()
# -------- entry point --------
def quoted(s: str) -> str:
return f'"{s}"'
if __name__ == "__main__":
env = os.environ.copy()
qemu = [
"qemu-x86_64",
"/nix/store/dmpq06y392i752zwhcna07kb2x5l58l5-memcached-static-x86_64-unknown-linux-musl-1.6.37/bin/memcached",
"-p", "11211",
"-t", "4",
"-vv",
]
sched_path = "/tmp/memcached_scheduler.sock"
proc = subprocess.Popen(qemu, env=env)
try:
trace(proc.pid, sched_path)
except Exception as e:
print(f"Got exception: {e}")
proc.kill()
exit(2)
exit(0)
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