UnixSignalHandlers.cc

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#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <cstdio>
#include <cstring>

#include "FWCore/Utilities/interface/UnixSignalHandlers.h"
#include "FWCore/Utilities/interface/DebugMacros.h"

#if !defined(NSIG)
#if defined(_NSIG)
#define NSIG _NSIG
#elif defined(__DARWIN_NSIG)
#define NSIG __DARWIN_NSIG
#endif
#endif

namespace edm {

  //--------------------------------------------------------------

  volatile std::atomic<bool> shutdown_flag{false};

  extern "C" {
  void ep_sigusr2(int, siginfo_t*, void*) {
    FDEBUG(1) << "in sigusr2 handler\n";
    shutdown_flag.store(true);
  }
  }
#define MUST_BE_ZERO(fun)                                           \
  if ((fun) != 0) {                                                 \
    perror("UnixSignalHandlers::setupSignal: sig function failed"); \
    abort();                                                        \
  }

  //--------------------------------------------------------------

  void disableAllSigs(sigset_t* oldset) {
    sigset_t myset;
    // all blocked for now
    MUST_BE_ZERO(sigfillset(&myset));
    MUST_BE_ZERO(pthread_sigmask(SIG_SETMASK, &myset, oldset));
  }

  //--------------------------------------------------------------

  void disableRTSigs() {
#if defined(__linux__)
    // ignore all the RT signals
    sigset_t myset;
    MUST_BE_ZERO(sigemptyset(&myset));

    struct sigaction tmpact;
    memset(&tmpact, 0, sizeof(tmpact));
    tmpact.sa_handler = SIG_IGN;

    for (int num = SIGRTMIN; num <= SIGRTMAX; ++num) {
      // signal 38 is used by Intel Amplifier
      if (num == 38)
        continue;

      MUST_BE_ZERO(sigaddset(&myset, num));
      MUST_BE_ZERO(sigaction(num, &tmpact, nullptr));
    }

    MUST_BE_ZERO(pthread_sigmask(SIG_BLOCK, &myset, nullptr));
#endif
  }

  //--------------------------------------------------------------

  void reenableSigs(sigset_t* oldset) {
    // reenable the signals
    MUST_BE_ZERO(pthread_sigmask(SIG_SETMASK, oldset, nullptr));
  }

  //--------------------------------------------------------------

  void enableSignal(sigset_t* newset, const int signum) {
    // enable the specified signal
    MUST_BE_ZERO(sigaddset(newset, signum));
  }

  //--------------------------------------------------------------

  void disableSignal(sigset_t* newset, const int signum) {
    // disable the specified signal
    MUST_BE_ZERO(sigdelset(newset, signum));
  }

  //--------------------------------------------------------------

  void installCustomHandler(const int signum, CFUNC func) {
    sigset_t oldset;
    edm::disableAllSigs(&oldset);
#if defined(__linux__)
    edm::disableRTSigs();
#endif
    edm::installSig(signum, func);
    edm::reenableSigs(&oldset);
  }

  //--------------------------------------------------------------

  void installSig(const int signum, CFUNC func) {
    // set up my RT signal now
    struct sigaction act;
    memset(&act, 0, sizeof(act));
    act.sa_sigaction = func;
    act.sa_flags = SA_RESTART;

    // get my signal number
    int mysig = signum;
    if (mysig == SIGKILL) {
      perror("Cannot install handler for KILL signal");
      return;
    } else if (mysig == SIGSTOP) {
      perror("Cannot install handler for STOP signal");
      return;
    }

    if (sigaction(mysig, &act, nullptr) != 0) {
      perror("sigaction failed");
      abort();
    }

    sigset_t newset;
    MUST_BE_ZERO(sigemptyset(&newset));
    MUST_BE_ZERO(sigaddset(&newset, mysig));
    MUST_BE_ZERO(pthread_sigmask(SIG_UNBLOCK, &newset, nullptr));
  }

  //--------------------------------------------------------------

  void sigInventory() {
    sigset_t tmpset, oldset;
    //    Make a full house set of signals, except for SIGKILL = 9
    //    and SIGSTOP = 19 which cannot be blocked
    MUST_BE_ZERO(sigfillset(&tmpset));
    MUST_BE_ZERO(sigdelset(&tmpset, SIGKILL));
    MUST_BE_ZERO(sigdelset(&tmpset, SIGSTOP));
    //    Swap it with the current sigset_t
    MUST_BE_ZERO(pthread_sigmask(SIG_SETMASK, &tmpset, &oldset));
    //    Now see what's included in the set
    for (int k = 1; k < NSIG; ++k) {
      std::cerr << "sigismember is " << sigismember(&tmpset, k) << " for signal " << std::setw(2) << k
#if defined(__linux__)
                << " (" << strsignal(k) << ")"
#endif
                << std::endl;
    }
    //    Finally put the original sigset_t back
    MUST_BE_ZERO(pthread_sigmask(SIG_SETMASK, &oldset, &tmpset));
  }

}  // end of namespace edm