110 lines
4.6 KiB
Python
110 lines
4.6 KiB
Python
"""在独立微型进程中校准系统调用延迟，不附加正式或测试应用。"""
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import hashlib
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import json
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import os
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from pathlib import Path
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import signal
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import subprocess
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import sys
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import time
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CHILD = r'''
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import json, os, sys, time
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from pathlib import Path
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root = Path(sys.argv[1])
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while not (root / 'gate').exists():
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time.sleep(0.01)
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fd = os.open(root, os.O_RDONLY | os.O_DIRECTORY)
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start = time.monotonic()
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os.rename('unrelated.tmp', 'unrelated.json', src_dir_fd=fd, dst_dir_fd=fd)
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(root / 'unrelated-result.json').write_text(json.dumps({'seconds': time.monotonic() - start}))
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(root / 'ready').touch()
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start = time.monotonic()
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os.rename('candidate.tmp', 'config.json', src_dir_fd=fd, dst_dir_fd=fd)
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(root / 'done.json').write_text(json.dumps({'seconds': time.monotonic() - start}))
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os.close(fd)
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'''
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def wait_until(predicate, timeout=10):
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deadline = time.monotonic() + timeout
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while time.monotonic() < deadline:
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if predicate():
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return
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time.sleep(0.02)
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raise AssertionError('校准等待超时')
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def tracer_pid(pid):
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lines = Path('/proc/' + str(pid) + '/status').read_text().splitlines()
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return int(next(line.split(':')[1] for line in lines if line.startswith('TracerPid:')))
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def calibrate(root, phase):
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assert phase in ('enter', 'exit')
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root.mkdir(mode=0o700)
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for name, value in [('config.json', 'old'), ('candidate.tmp', 'new'), ('unrelated.tmp', 'other')]:
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(root / name).write_text(value)
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child = subprocess.Popen([sys.executable, '-c', CHILD, str(root)],
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stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
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trace = None
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details = {'phase': phase, 'passed': False}
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try:
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with (root / 'trace.stderr').open('w') as errors:
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trace = subprocess.Popen(['strace', '-f', '-ttt', '-T', '-yy',
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'-e', 'trace=rename,renameat,renameat2', '-P', 'config.json',
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'-e', 'inject=rename,renameat,renameat2:delay_' + phase + '=3s',
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'-o', str(root / 'trace.log'), '-p', str(child.pid)],
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stdout=subprocess.DEVNULL, stderr=errors)
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wait_until(lambda: tracer_pid(child.pid) == trace.pid)
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wait_until(lambda: 'attached' in (root / 'trace.stderr').read_text())
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(root / 'gate').touch()
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wait_until(lambda: (root / 'ready').exists())
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unrelated = json.loads((root / 'unrelated-result.json').read_text())
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assert unrelated['seconds'] < 1, '路径过滤没有排除无关替换'
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time.sleep(0.4)
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observed = (root / 'config.json').read_text()
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assert observed == ('old' if phase == 'enter' else 'new'), '延迟边界不符合预期'
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assert 'renameat(' in (root / 'trace.log').read_text(), '延迟期间没有可观测的调用记录'
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assert not (root / 'done.json').exists(), '替换调用未处于延迟窗口'
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assert child.wait(timeout=10) == 0
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assert trace.wait(timeout=5) == 0
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duration = json.loads((root / 'done.json').read_text())['seconds']
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assert 2.5 <= duration <= 8
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assert (root / 'config.json').read_text() == 'new'
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details.update(passed=True, unrelated_seconds=unrelated['seconds'],
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target_seconds=duration, observed_during_delay=observed,
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child_exited=True, tracer_exited=True,
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trace_sha256=hashlib.sha256((root / 'trace.log').read_bytes()).hexdigest())
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finally:
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# 只回收本函数亲自创建的子进程，不接收外部 PID，也不删除任何证据。
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if child.poll() is None:
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child.kill()
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child.wait(timeout=10)
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if trace is not None and trace.poll() is None:
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trace.send_signal(signal.SIGTERM)
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trace.wait(timeout=10)
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(root / 'result.json').write_text(json.dumps(details, indent=2), encoding='utf-8')
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return details
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def main():
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assert os.geteuid() == 0
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root = Path('/var/tmp') / ('smail-review-fault-calibration-' + time.strftime('%Y%m%d-%H%M%S'))
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root.mkdir(mode=0o700)
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result = {'root': str(root), 'passed': False}
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try:
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result['strace_version'] = subprocess.check_output(['strace', '-V'], text=True).splitlines()[0]
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result['ptrace_scope'] = Path('/proc/sys/kernel/yama/ptrace_scope').read_text().strip()
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result['cases'] = [calibrate(root / phase, phase) for phase in ('enter', 'exit')]
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result['passed'] = True
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finally:
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(root / 'result.json').write_text(json.dumps(result, indent=2), encoding='utf-8')
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print(json.dumps(result, indent=2), flush=True)
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if __name__ == '__main__':
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main()
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