fix(watcher): enforce time limit by wall clock instead of RLIMIT_CPU - #311
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ZnPdCo wants to merge 4 commits into
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fix(watcher): enforce time limit by wall clock instead of RLIMIT_CPU#311ZnPdCo wants to merge 4 commits into
ZnPdCo wants to merge 4 commits into
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RLIMIT_CPU limits CPU time while the judge measures user time, and a program that merely sleeps never hits it, so a sleep-only program could run forever. The watcher now receives the extra wall-clock grace (argv[12], ms) from the main process and enforces timeLimit + extraTime with timerfd + pidfd (Linux) / kqueue (macOS), killing the child on timeout and reporting TLE. The sandbox stays in the main process (bwrap), which only keeps a 1s backstop against a hung watcher.
RLIMIT_CPU limits CPU time while the judge measures user time, and a program that merely sleeps never hits it, so a sleep-only program could run forever. The watcher now receives the extra wall-clock grace (argv[12], ms) from the main process and enforces timeLimit + extraTime with timerfd + pidfd (Linux) / kqueue (macOS & BSD), killing the child on timeout and reporting TLE. The sandbox stays in the main process (bwrap), which only keeps a 1s backstop against a hung watcher.
…m/ZnPdCo/Project_LemonLime into fix/watcher-wall-clock-time-limit
The watcher now waits for the child with clone3 + CLONE_PIDFD, which requires Linux 5.3+. Distros with older kernels (Ubuntu 18.04, Debian 10, Mint 19.3, Deepin 15.11, openSUSE Leap 15.1) can no longer run the watcher, so remove them from the tested list and keep NOI Linux 2 as the baseline.
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RLIMIT_CPU 限制 CPU time，而主程序仅测量 user time，这会导致部分程序提前结束运行。同时，
sleep这类没有产生 cpu time 的程序会显示成内部错误，不美观。现在 watcher 从主进程接收 extra wall-clock 限制，并使用 timerfd + pidfd 或 kqueue 来进行时间限制。超时后杀死子进程，并报告 TLE。
这个 pr 是 #306 的一个子 pr，由于 #306 进行的「沙箱移进 watcher」的重构仍待商榷，所以这里先把这个 bug 修复抽离出来。