/*********************                                                        */
/*! \file util.cpp
 ** \verbatim
 ** Original author: mdeters
 ** Major contributors: none
 ** Minor contributors (to current version): acsys, cconway
 ** This file is part of the CVC4 prototype.
 ** Copyright (c) 2009, 2010, 2011  The Analysis of Computer Systems Group (ACSys)
 ** Courant Institute of Mathematical Sciences
 ** New York University
 ** See the file COPYING in the top-level source directory for licensing
 ** information.\endverbatim
 **
 ** \brief Utilities for the main driver.
 **
 ** Utilities for the main driver.
 **/

#include <cstdio>
#include <cstdlib>
#include <cerrno>
#include <exception>
#include <string.h>
#include <signal.h>
#include <sys/resource.h>
#include <unistd.h>

#include "util/exception.h"
#include "options/options.h"
#include "util/statistics.h"
#include "util/tls.h"
#include "smt/smt_engine.h"

#include "cvc4autoconfig.h"
#include "main/main.h"
#include "main/command_executor.h"

using CVC4::Exception;
using namespace std;

namespace CVC4 {

#ifdef CVC4_DEBUG
  extern CVC4_THREADLOCAL(const char*) s_debugLastException;
#endif /* CVC4_DEBUG */

namespace main {

size_t cvc4StackSize;
void* cvc4StackBase;

/**
 * If true, will not spin on segfault even when CVC4_DEBUG is on.
 * Useful for nightly regressions, noninteractive performance runs
 * etc.
 */
bool segvNoSpin = false;

/** Handler for SIGXCPU, i.e., timeout. */
void timeout_handler(int sig, siginfo_t* info, void*) {
  fprintf(stderr, "CVC4 interrupted by timeout.\n");
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  abort();
}

/** Handler for SIGINT, i.e., when the user hits control C. */
void sigint_handler(int sig, siginfo_t* info, void*) {
  fprintf(stderr, "CVC4 interrupted by user.\n");
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  abort();
}

/** Handler for SIGSEGV (segfault). */
void segv_handler(int sig, siginfo_t* info, void* c) {
  uintptr_t extent = reinterpret_cast<uintptr_t>(cvc4StackBase) - cvc4StackSize;
  uintptr_t addr = reinterpret_cast<uintptr_t>(info->si_addr);
#ifdef CVC4_DEBUG
  fprintf(stderr, "CVC4 suffered a segfault in DEBUG mode.\n");
  cerr << "Offending address is " << info->si_addr << endl;
  //cerr << "base is " << (void*)cvc4StackBase << endl;
  //cerr << "size is " << cvc4StackSize << endl;
  //cerr << "extent is " << (void*)extent << endl;
  if(addr >= extent && addr <= extent + 10*1024) {
    cerr << "Looks like this is likely due to stack overflow." << endl
         << "You might consider increasing the limit with `ulimit -s' or equivalent." << endl;
  } else if(addr < 10*1024) {
    cerr << "Looks like a NULL pointer was dereferenced." << endl;
  }

  if(segvNoSpin) {
    fprintf(stderr, "No-spin requested, aborting...\n");
    if((*pOptions)[options::statistics] && pExecutor != NULL) {
      pExecutor->flushStatistics(cerr);
    }
    abort();
  } else {
    fprintf(stderr, "Spinning so that a debugger can be connected.\n");
    cerr << "Try:  gdb " << progName << " " << getpid() << endl;
    for(;;) {
      sleep(60);
    }
  }
#else /* CVC4_DEBUG */
  fprintf(stderr, "CVC4 suffered a segfault.\n");
  cerr << "Offending address is " << info->si_addr << endl;
  if(addr >= extent && addr <= extent + 10*1024) {
    cerr << "Looks like this is likely due to stack overflow." << endl
         << "You might consider increasing the limit with `ulimit -s' or equivalent." << endl;
  } else if(addr < 10*1024) {
    cerr << "Looks like a NULL pointer was dereferenced." << endl;
  }
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  abort();
#endif /* CVC4_DEBUG */
}

/** Handler for SIGILL (illegal instruction). */
void ill_handler(int sig, siginfo_t* info, void*) {
#ifdef CVC4_DEBUG
  fprintf(stderr, "CVC4 executed an illegal instruction in DEBUG mode.\n");
  if(segvNoSpin) {
    fprintf(stderr, "No-spin requested, aborting...\n");
    if((*pOptions)[options::statistics] && pExecutor != NULL) {
      pExecutor->flushStatistics(cerr);
    }
    abort();
  } else {
    fprintf(stderr, "Spinning so that a debugger can be connected.\n");
    fprintf(stderr, "Try:  gdb %s %u\n", progName, getpid());
    for(;;) {
      sleep(60);
    }
  }
#else /* CVC4_DEBUG */
  fprintf(stderr, "CVC4 executed an illegal instruction.\n");
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  abort();
#endif /* CVC4_DEBUG */
}

static terminate_handler default_terminator;

void cvc4unexpected() {
#ifdef CVC4_DEBUG
  fprintf(stderr, "\n"
          "CVC4 threw an \"unexpected\" exception (one that wasn't properly "
          "specified\nin the throws() specifier for the throwing function)."
          "\n\n");
  if(CVC4::s_debugLastException == NULL) {
    fprintf(stderr,
            "The exception is unknown (maybe it's not a CVC4::Exception).\n\n");
  } else {
    fprintf(stderr, "The exception is:\n%s\n\n",
            static_cast<const char*>(CVC4::s_debugLastException));
  }
  if(segvNoSpin) {
    fprintf(stderr, "No-spin requested.\n");
    if((*pOptions)[options::statistics] && pExecutor != NULL) {
      pExecutor->flushStatistics(cerr);
    }
    set_terminate(default_terminator);
  } else {
    fprintf(stderr, "Spinning so that a debugger can be connected.\n");
    fprintf(stderr, "Try:  gdb %s %u\n", progName, getpid());
    for(;;) {
      sleep(60);
    }
  }
#else /* CVC4_DEBUG */
  fprintf(stderr, "CVC4 threw an \"unexpected\" exception.\n");
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  set_terminate(default_terminator);
#endif /* CVC4_DEBUG */
}

void cvc4terminate() {
#ifdef CVC4_DEBUG
  fprintf(stderr, "\n"
          "CVC4 was terminated by the C++ runtime.\n"
          "Perhaps an exception was thrown during stack unwinding.  "
          "(Don't do that.)\n");
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  default_terminator();
#else /* CVC4_DEBUG */
  fprintf(stderr,
          "CVC4 was terminated by the C++ runtime.\n"
          "Perhaps an exception was thrown during stack unwinding.\n");
  if((*pOptions)[options::statistics] && pExecutor != NULL) {
    pExecutor->flushStatistics(cerr);
  }
  default_terminator();
#endif /* CVC4_DEBUG */
}

/** Initialize the driver.  Sets signal handlers for SIGINT and SIGSEGV. */
void cvc4_init() throw(Exception) {
  stack_t ss;
  ss.ss_sp = malloc(SIGSTKSZ);
  if(ss.ss_sp == NULL) {
    throw Exception("Can't malloc() space for a signal stack");
  }
  ss.ss_size = SIGSTKSZ;
  ss.ss_flags = 0;
  if(sigaltstack(&ss, NULL) == -1) {
    throw Exception(string("sigaltstack() failure: ") + strerror(errno));
  }
  struct rlimit limit;
  if(getrlimit(RLIMIT_STACK, &limit)) {
    throw Exception(string("getrlimit() failure: ") + strerror(errno));
  }
  if(limit.rlim_cur != limit.rlim_max) {
    limit.rlim_cur = limit.rlim_max;
    if(setrlimit(RLIMIT_STACK, &limit)) {
      throw Exception(string("setrlimit() failure: ") + strerror(errno));
    }
    if(getrlimit(RLIMIT_STACK, &limit)) {
      throw Exception(string("getrlimit() failure: ") + strerror(errno));
    }
  }
  cvc4StackSize = limit.rlim_cur;
  cvc4StackBase = &ss;

  struct sigaction act1;
  act1.sa_sigaction = sigint_handler;
  act1.sa_flags = SA_SIGINFO;
  sigemptyset(&act1.sa_mask);
  if(sigaction(SIGINT, &act1, NULL)) {
    throw Exception(string("sigaction(SIGINT) failure: ") + strerror(errno));
  }

  struct sigaction act2;
  act2.sa_sigaction = timeout_handler;
  act2.sa_flags = SA_SIGINFO;
  sigemptyset(&act2.sa_mask);
  if(sigaction(SIGXCPU, &act2, NULL)) {
    throw Exception(string("sigaction(SIGXCPU) failure: ") + strerror(errno));
  }

  struct sigaction act3;
  act3.sa_sigaction = segv_handler;
  act3.sa_flags = SA_SIGINFO | SA_ONSTACK;
  sigemptyset(&act3.sa_mask);
  if(sigaction(SIGSEGV, &act3, NULL)) {
    throw Exception(string("sigaction(SIGSEGV) failure: ") + strerror(errno));
  }

  struct sigaction act4;
  act4.sa_sigaction = segv_handler;
  act4.sa_flags = SA_SIGINFO;
  sigemptyset(&act4.sa_mask);
  if(sigaction(SIGILL, &act4, NULL)) {
    throw Exception(string("sigaction(SIGILL) failure: ") + strerror(errno));
  }

  set_unexpected(cvc4unexpected);
  default_terminator = set_terminate(cvc4terminate);
}

}/* CVC4::main namespace */
}/* CVC4 namespace */