bug.cpp

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// SPDX-License-Identifier: BSD-3-Clause
//
// bug.cpp
//
// Copyright (C) 1996 Limit Point Systems, Inc.
//
// Author: Curtis Janssen <cljanss@limitpt.com>
// Maintainer: LPS
//
// This file is part of the SC Toolkit.
//
// The SC Toolkit is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// The SC Toolkit 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 Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with the SC Toolkit; see the file COPYING.LIB.  If not, write to
// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
//
// The U.S. Government is granted a limited license as per AL 91-7.
//
 
#include "bug.h"
 
#include <unistd.h>
#include <cfenv>
#include <csignal>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <iterator>
#include <sstream>
 
#include "backtrace.h"
 
// usually in signal.h, but not always.
#ifndef NSIG
#define NSIG 100
#endif
 
using namespace std;
using namespace ttg;
 
namespace ttg {
  void initialize_fpe() {
#if defined(__APPLE__) && defined(__MACH__)
 
    // Public domain polyfill for feenableexcept on OS X
    // http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c
 
#ifndef HAVE_FEENABLEEXCEPT
    auto feenableexcept = [](int excepts) -> int {
      static fenv_t fenv;
      const auto new_excepts = excepts & FE_ALL_EXCEPT;
 
      if (fegetenv(&fenv)) {
        return -1;
      }
#if defined(__x86_64__)
      // previous masks
      const unsigned int old_excepts = fenv.__control & FE_ALL_EXCEPT;
 
      // unmask
      fenv.__control &= ~new_excepts;
      fenv.__mxcsr &= ~(new_excepts << 7);
#elif defined(__arm64__)
      if (new_excepts & FE_INVALID) fenv.__fpcr |= __fpcr_trap_invalid;
      if (new_excepts & FE_DIVBYZERO) fenv.__fpcr |= __fpcr_trap_divbyzero;
      if (new_excepts & FE_OVERFLOW) fenv.__fpcr |= __fpcr_trap_overflow;
      if (new_excepts & FE_UNDERFLOW) fenv.__fpcr |= __fpcr_trap_underflow;
      if (new_excepts & FE_INEXACT) fenv.__fpcr |= __fpcr_trap_inexact;
#else
#error "MacOS on unknown architecture"
#endif
      return fesetenv(&fenv);
    };
#define HAVE_FEENABLEEXCEPT 1
#endif  // not defined HAVE_FEENABLEEXCEPT
 
#ifndef HAVE_FEDISABLEEXCEPT
    auto fedisableexcept = [](int excepts) -> int {
      static fenv_t fenv;
      const auto new_excepts = excepts & FE_ALL_EXCEPT;
      // all previous masks
 
      if (fegetenv(&fenv)) {
        return -1;
      }
#if defined(__x86_64__)
      const unsigned int old_excepts = fenv.__control & FE_ALL_EXCEPT;
 
      // mask
      fenv.__control |= new_excepts;
      fenv.__mxcsr |= new_excepts << 7;
#elif defined(__arm64__)
      if (new_excepts & FE_INVALID) fenv.__fpcr &= ~__fpcr_trap_invalid;
      if (new_excepts & FE_DIVBYZERO) fenv.__fpcr &= ~__fpcr_trap_divbyzero;
      if (new_excepts & FE_OVERFLOW) fenv.__fpcr &= ~__fpcr_trap_overflow;
      if (new_excepts & FE_UNDERFLOW) fenv.__fpcr &= ~__fpcr_trap_underflow;
      if (new_excepts & FE_INEXACT) fenv.__fpcr &= ~__fpcr_trap_inexact;
#else
#error "MacOS on unknown architecture"
#endif
 
      return fesetenv(&fenv);
    };
 
#define HAVE_FEDISABLEEXCEPT 1
#endif  // not defined HAVE_FEDISABLEEXCEPT
#endif  // mac
 
#ifdef HAVE_FEENABLEEXCEPT
    // this uses a glibc extension to trap on individual exceptions
    int enable_excepts = 0;
#ifdef FE_DIVBYZERO
    enable_excepts |= FE_DIVBYZERO;
#endif
#ifdef FE_INVALID
    enable_excepts |= FE_INVALID;
#endif
#ifdef FE_OVERFLOW
    enable_excepts |= FE_OVERFLOW;
#endif
    feenableexcept(enable_excepts);
#endif
 
#ifdef HAVE_FEDISABLEEXCEPT
    // this uses a glibc extension to not trap on individual exceptions
    int disable_excepts = 0;
#ifdef FE_UNDERFLOW
    disable_excepts |= FE_UNDERFLOW;
#endif
#ifdef FE_INEXACT
    disable_excepts |= FE_INEXACT;
#endif
    fedisableexcept(disable_excepts);
#endif
  }
}
 
// static variables
 
static Debugger *signals[NSIG];
 
// Debugger class definition
 
std::shared_ptr<Debugger> Debugger::default_debugger_(nullptr);
 
Debugger::Debugger(const char *exec) {
  init();
 
  debug_ = true;
  traceback_ = true;
  exit_on_signal_ = true;
  sleep_ = false;
  wait_for_debugger_ = true;
  default_cmd();
  prefix_ = "";
  handle_sigint_ = false;
  handle_defaults();
 
  set_exec(exec);
  resolve_cmd_alias();
}
 
Debugger::~Debugger() {
  for (int i = 0; i < NSIG; i++) {
    if (mysigs_[i]) signals[i] = nullptr;
  }
  delete[] mysigs_;
}
 
void Debugger::init() {
  exec_.resize(0);
  prefix_.resize(0);
  cmd_.resize(0);
  sleep_ = 0;
 
  exit_on_signal_ = 1;
  traceback_ = 1;
  debug_ = 1;
  wait_for_debugger_ = 1;
 
  mysigs_ = new int[NSIG];
  for (int i = 0; i < NSIG; i++) {
    mysigs_[i] = 0;
  }
}
 
namespace {
  static void handler(int sig) {
    if (signals[sig]) signals[sig]->got_signal(sig);
  }
}  // namespace
 
void Debugger::handle(int sig) {
  if (sig >= NSIG) return;
  typedef void (*handler_type)(int);
  signal(sig, (handler_type)handler);
  signals[sig] = this;
  mysigs_[sig] = 1;
}
 
void Debugger::release(int sig) {
  if (sig >= NSIG) return;
  signal(sig, SIG_DFL);
  signals[sig] = nullptr;
  mysigs_[sig] = 0;
}
 
void Debugger::handle_defaults() {
#ifdef SIGSEGV
  handle(SIGSEGV);
#endif
#ifdef SIGFPE
  handle(SIGFPE);
#endif
#ifdef SIGQUIT
  handle(SIGQUIT);
#endif
#ifdef SIGIOT
  handle(SIGIOT);
#endif
#ifdef SIGINT
  if (handle_sigint_) handle(SIGINT);
#endif
#ifdef SIGHUP
  handle(SIGHUP);
#endif
#ifdef SIGBUS
  handle(SIGBUS);
#endif
#ifdef SIGABRT
  handle(SIGABRT);
#endif
#ifdef SIGTRAP
  handle(SIGTRAP);
#endif
}
 
void Debugger::set_exec(const char *exec) {
  if (exec) {
    exec_ = exec;
  } else {
    exec_.resize(0);
  }
}
 
void Debugger::set_prefix(const char *p) {
  if (p) {
    prefix_ = p;
  } else {
    prefix_.resize(0);
  }
}
 
void Debugger::set_prefix(int i) {
  char p[128];
  sprintf(p, "%3d: ", i);
  set_prefix(p);
}
 
void Debugger::default_cmd() {
  int has_x11_display = (getenv("DISPLAY") != 0);
 
  if (has_x11_display) {
    set_cmd("gdb_xterm");
  } else {
    set_cmd(0);
  }
}
 
void Debugger::resolve_cmd_alias() {
  if (cmd_ == "gdb_xterm") {
    cmd_ = "xterm -title \"$(PREFIX)$(EXEC)\" -e gdb -ex \"set variable debugger_ready_=1\" --pid=$(PID) $(EXEC) &";
  } else if (cmd_ == "lldb_xterm") {
    cmd_ = "xterm -title \"$(PREFIX)$(EXEC)\" -e lldb -p $(PID) -o \"expr debugger_ready_=1\" &";
  }
}
 
void Debugger::set_cmd(const char *cmd) {
  if (cmd) {
    cmd_ = cmd;
    resolve_cmd_alias();
  } else {
    cmd_.resize(0);
  }
}
 
void Debugger::debug(const char *reason) {
  std::cout << prefix_ << "Debugger::debug: ";
  if (reason)
    std::cout << reason;
  else
    std::cout << "no reason given";
  std::cout << endl;
 
  if (!cmd_.empty()) {
    int pid = getpid();
    // contruct the command name
    std::string cmd = cmd_;
    std::string::size_type pos;
    std::string pidvar("$(PID)");
    while ((pos = cmd.find(pidvar)) != std::string::npos) {
      std::string pidstr;
      pidstr += std::to_string(pid);
      cmd.replace(pos, pidvar.size(), pidstr);
    }
    std::string execvar("$(EXEC)");
    while ((pos = cmd.find(execvar)) != std::string::npos) {
      cmd.replace(pos, execvar.size(), exec_);
    }
    std::string prefixvar("$(PREFIX)");
    while ((pos = cmd.find(prefixvar)) != std::string::npos) {
      cmd.replace(pos, prefixvar.size(), prefix_);
    }
 
    // start the debugger
    // before starting the debugger de-register signal handler for SIGTRAP to let the debugger take over
    release(SIGTRAP);
    std::cout << prefix_ << "Debugger: starting \"" << cmd << "\"" << endl;
    debugger_ready_ = 0;
    const auto system_retvalue = system(cmd.c_str());
    if (system_retvalue != 0) {  // call to system() failed
      std::cout << prefix_ << "Failed debugger launch: system() did not succeed ..." << endl;
    } else {  // call to system() succeeded
      // wait until the debugger is ready
      if (sleep_) {
        std::cout << prefix_ << "Sleeping " << sleep_ << " seconds to wait for debugger ..." << endl;
        sleep(sleep_);
      }
      if (wait_for_debugger_) {
        std::string make_ready_message;
        if (cmd_.find(" gdb ") != std::string::npos || cmd_.find(" lldb ") != std::string::npos) {
          make_ready_message =
              " configure debugging session (set breakpoints/watchpoints, etc.) then type 'c' to continue running";
        }
 
        std::cout << prefix_ << ": waiting for the user ..." << make_ready_message << endl;
        while (!debugger_ready_)
          ;
      }
    }
  } else {  // empty command = wait for the user to attach manually
    std::cout << prefix_ << ": waiting for the user to attach a debugger to process " << getpid() << " ... " << endl;
    debugger_ready_ = 0;
    while (!debugger_ready_)
      ;
  }
}
 
void Debugger::got_signal(int sig) {
  const char *signame;
  if (sig == SIGSEGV)
    signame = "SIGSEGV";
  else if (sig == SIGFPE)
    signame = "SIGFPE";
  else if (sig == SIGHUP)
    signame = "SIGHUP";
  else if (sig == SIGINT)
    signame = "SIGINT";
  else if (sig == SIGABRT)
    signame = "SIGABRT";
#ifdef SIGBUS
  else if (sig == SIGBUS)
    signame = "SIGBUS";
#endif
  else if (sig == SIGTRAP)
    signame = "SIGTRAP";
  else
    signame = "UNKNOWN SIGNAL";
 
  if (traceback_) {
    traceback(signame);
  }
  if (debug_) {
    debug(signame);
  }
 
  if (exit_on_signal_) {
    std::cout << prefix_ << "Debugger: exiting" << endl;
    exit(1);
  } else {
    std::cout << prefix_ << "Debugger: continuing" << endl;
  }
 
  // handle(sig);
}
 
void Debugger::set_debug_on_signal(int v) { debug_ = v; }
 
void Debugger::set_traceback_on_signal(int v) { traceback_ = v; }
 
void Debugger::set_wait_for_debugger(int v) { wait_for_debugger_ = v; }
 
void Debugger::set_exit_on_signal(int v) { exit_on_signal_ = v; }
 
void Debugger::set_default_debugger(const std::shared_ptr<Debugger> &d) { default_debugger_ = d; }
 
std::shared_ptr<Debugger> Debugger::default_debugger() { return default_debugger_; }
 
#define SIMPLE_STACK (defined(linux) && defined(i386)) || (defined(__OSF1__) && defined(i860))
 
void Debugger::traceback(const char *reason) { Debugger::__traceback(prefix_, reason); }
 
void Debugger::__traceback(const std::string &prefix, const char *reason) {
  detail::Backtrace result(prefix);
  const size_t nframes_to_skip = 2;
#if defined(HAVE_LIBUNWIND)
  std::cout << prefix << "Debugger::traceback(using libunwind):";
#elif defined(HAVE_BACKTRACE)  // !HAVE_LIBUNWIND
  std::cout << prefix << "Debugger::traceback(using backtrace):";
#else                          // !HAVE_LIBUNWIND && !HAVE_BACKTRACE
#if defined(SIMPLE_STACK)
  std::cout << prefix << "Debugger::traceback:";
#else
  std::cout << prefix << "traceback not available for this arch" << endl;
  return;
#endif  // SIMPLE_STACK
#endif  // HAVE_LIBUNWIND, HAVE_BACKTRACE
 
  if (reason)
    std::cout << reason;
  else
    std::cout << "no reason given";
  std::cout << endl;
 
  if (result.empty())
    std::cout << prefix << "backtrace returned no state information" << std::endl;
  else
    std::cout << result.str(nframes_to_skip) << std::endl;
}
 
 
namespace ttg {
  void launch_debugger(int rank, const char *exec_name, const char *cmd) {
    using ttg::Debugger;
    auto debugger = std::make_shared<Debugger>();
    Debugger::set_default_debugger(debugger);
    debugger->set_exec(exec_name);
    debugger->set_prefix(rank);
    debugger->set_cmd("lldb_xterm");
    debugger->debug("start");
 
    //  initialize_watchpoints();
  }
 
  void launch_lldb(int rank, const char *exec_name) { launch_debugger(rank, exec_name, "lldb_xterm"); }
  void launch_gdb(int rank, const char *exec_name) { launch_debugger(rank, exec_name, "gdb_xterm"); }
}  // namespace ttg
 
// Local Variables:
// mode: c++
// c-file-style: "CLJ"
// End: