zoneminder/src/zm_signal.cpp

//
// ZoneMinder Signal Handling Implementation, $Date$, $Revision$
// Copyright (C) 2001-2008 Philip Coombes
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//

#include "zm_signal.h"

#include "zm.h"
#include "zm_logger.h"
#include <cstring>

#define TRACE_SIZE 16

bool zm_reload = false;
bool zm_terminate = false;
bool zm_panic = false;

RETSIGTYPE zm_hup_handler(int signal) {
  // Shouldn't do complex things in signal handlers, logging is complex and can block due to mutexes.
  //Info("Got signal %d (%s), reloading", signal, strsignal(signal));
  zm_reload = true;
}

RETSIGTYPE zm_term_handler(int signal) {
  // Shouldn't do complex things in signal handlers, logging is complex and can block due to mutexes.
  //Info("Got signal %d (%s), exiting", signal, strsignal(signal));
  zm_terminate = true;
}

#if ( HAVE_SIGINFO_T && HAVE_UCONTEXT_T )
RETSIGTYPE zm_die_handler(int signal, siginfo_t * info, void *context)
#else
RETSIGTYPE zm_die_handler(int signal)
#endif
{
  zm_terminate = true;
  if (zm_panic)
    Fatal("Got signal %d (%s), crashing", signal, strsignal(signal));
  zm_panic = true;
  Error("Got signal %d (%s), crashing", signal, strsignal(signal));
#if (defined(__i386__) || defined(__x86_64__))
  // Get more information if available
#if ( HAVE_SIGINFO_T && HAVE_UCONTEXT_T )
  void *ip = nullptr;
  void *cr2 = nullptr;
  if ( info && context ) {
    Debug(1,
          "Signal information: number %d code %d errno %d pid %d uid %d status %d",
          signal, info->si_code, info->si_errno, info->si_pid,
          info->si_uid, info->si_status);

    ucontext_t *uc = (ucontext_t *) context;
    cr2 = info->si_addr;
#if defined(__x86_64__)
#if defined(__FreeBSD_kernel__) || defined(__FreeBSD__)
    ip = (void *)(uc->uc_mcontext.mc_rip);
#elif defined(__OpenBSD__)
    ip = (void *)(uc->sc_rip);
#else
    ip = (void *)(uc->uc_mcontext.gregs[REG_RIP]);
#endif
#else
#if defined(__FreeBSD_kernel__) || defined(__FreeBSD__)
    ip = (void *)(uc->uc_mcontext.mc_eip);
#else
    ip = (void *)(uc->uc_mcontext.gregs[REG_EIP]);
#endif
#endif				// defined(__x86_64__)

    // Print the signal address and instruction pointer if available
    if ( ip ) {
      Error("Signal address is %p, from %p", cr2, ip);
    } else {
      Error("Signal address is %p, no instruction pointer", cr2);
    }
  }
#endif				// ( HAVE_SIGINFO_T && HAVE_UCONTEXT_T )
#endif                          // (defined(__i386__) || defined(__x86_64__)


  // Print backtrace if enabled and available
#if ( !defined(ZM_NO_CRASHTRACE) && HAVE_DECL_BACKTRACE && HAVE_DECL_BACKTRACE_SYMBOLS )
  void *trace[TRACE_SIZE];
  int trace_size = 0;
  trace_size = backtrace(trace, TRACE_SIZE);

  char cmd[1024] = "addr2line -Cfip -e ";
  char *cmd_ptr = cmd + strlen(cmd);
  cmd_ptr += snprintf(cmd_ptr, sizeof(cmd) - (cmd_ptr - cmd), "%s", self);

  char **messages = backtrace_symbols(trace, trace_size);
  char *ofs_ptr;
  char *end_ptr;
  bool found_offset = false;

  // Print the full backtrace
  for (int i = 0; i < trace_size; i++) {
    Error("Backtrace %u: %s", i, messages[i]);
    if (strstr(messages[i], self) == nullptr)
      continue;
    ofs_ptr = strstr(messages[i], "(+0x");
    if (ofs_ptr == nullptr)
      continue;
    ofs_ptr += 2;
    end_ptr = strchr(ofs_ptr, ')');
    if (end_ptr == nullptr)
      continue;
    found_offset = true;
    int rc = snprintf(cmd_ptr, sizeof(cmd) - (cmd_ptr - cmd), " %.*s", static_cast<int>(end_ptr - ofs_ptr), ofs_ptr);
    if (rc < 0 || static_cast<size_t>(rc) > sizeof(cmd) - (cmd_ptr - cmd))
      break;
    cmd_ptr += rc;
  }
  free(messages);

  if (found_offset) {
    Error("Backtrace complete, please install debug symbols (typically zoneminder-dbg)");
    Error("and execute the following command for more information:");
    Error("%s", cmd);
  }
#endif				// ( !defined(ZM_NO_CRASHTRACE) && HAVE_DECL_BACKTRACE && HAVE_DECL_BACKTRACE_SYMBOLS )
  // Icon: Don't exit, setting zm_terminate should cause the exit to happen in a timely manner.
  // The main reason not to here is to make valgrind traces quieter because logger gets free while other threads
  // are still running and trying to log.
  //exit(signal);
}

void zmSetHupHandler(SigHandler * handler) {
  sigset_t block_set;
  sigemptyset(&block_set);
  struct sigaction action, old_action;

  action.sa_handler = (SigHandler *) handler;
  action.sa_mask = block_set;
  action.sa_flags = SA_RESTART;
  sigaction(SIGHUP, &action, &old_action);
}

void zmSetTermHandler(SigHandler * handler) {
  sigset_t block_set;
  sigemptyset(&block_set);
  struct sigaction action, old_action;

  action.sa_handler = (SigHandler *) handler;
  action.sa_mask = block_set;
  action.sa_flags = SA_RESTART;
  sigaction(SIGTERM, &action, &old_action);
  sigaction(SIGINT, &action, &old_action);
  sigaction(SIGQUIT, &action, &old_action);
}

void zmSetDieHandler(SigHandler * handler) {
  sigset_t block_set;
  sigemptyset(&block_set);
  struct sigaction action, old_action;

  action.sa_mask = block_set;
#if ( HAVE_SIGINFO_T && HAVE_UCONTEXT_T )
  action.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
  action.sa_flags = SA_SIGINFO;
#else
  action.sa_handler = (SigHandler *) handler;
  action.sa_flags = 0;
#endif

  sigaction(SIGBUS, &action, &old_action);
  sigaction(SIGSEGV, &action, &old_action);
  sigaction(SIGABRT, &action, &old_action);
  sigaction(SIGILL, &action, &old_action);
  sigaction(SIGFPE, &action, &old_action);
}

void zmSetDefaultHupHandler() {
  zmSetHupHandler((SigHandler *) zm_hup_handler);
}

void zmSetDefaultTermHandler() {
  zmSetTermHandler((SigHandler *) zm_term_handler);
}

void zmSetDefaultDieHandler() {
  if ( config.dump_cores ) {
    // Do nothing
  } else {
    zmSetDieHandler((SigHandler *) zm_die_handler);
  }
}