signal.cpp

#include "config.h"
#include "vm.hpp"
#include "signal.hpp"
#include "configuration.hpp"

#include "builtin/module.hpp"
#include "builtin/array.hpp"

#include "builtin/array.hpp"
#include "builtin/module.hpp"
#include "builtin/class.hpp"

#include <string>
#include <iostream>
#include <fcntl.h>

#include "builtin/thread.hpp"

#include "dtrace/dtrace.h"

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

#ifdef USE_EXECINFO
#include <execinfo.h>
#endif

#ifdef RBX_WINDOWS
#include "windows_compat.h"
#else
#include <dlfcn.h>
#include <sys/utsname.h>
#include <sys/select.h>
#endif

namespace rubinius {
  static SignalHandler* signal_handler_ = 0;

  // Used by the segfault reporter. Calculated up front to avoid
  // crashing inside the crash handler.
  static struct utsname machine_info;
  static char report_path[PATH_MAX];

  Object* signal_handler_tramp(STATE) {
    state->shared().signal_handler()->perform(state);
    GCTokenImpl gct;
    state->gc_dependent(gct, 0);
    return cNil;
  }

  SignalHandler::SignalHandler(STATE, Configuration& config)
    : AuxiliaryThread()
    , shared_(state->shared())
    , target_(state->vm())
    , self_(NULL)
    , queued_signals_(0)
    , paused_(false)
    , exit_(false)
    , thread_(state)
  {
    signal_handler_ = this;

    shared_.auxiliary_threads()->register_thread(this);
    shared_.set_signal_handler(this);

    for(int i = 0; i < NSIG; i++) {
      pending_signals_[i] = 0;
    }

    worker_lock_.init();
    worker_cond_.init();
    pause_cond_.init();

    setup_default_handlers(config.report_path.value);

    start_thread(state);
  }

  SignalHandler::~SignalHandler() {
    shared_.auxiliary_threads()->unregister_thread(this);
  }

  void SignalHandler::start_thread(STATE) {
    SYNC(state);
    if(self_) return;
    utilities::thread::Mutex::LockGuard lg(worker_lock_);
    self_ = state->shared().new_vm();
    paused_ = false;
    exit_ = false;
    thread_.set(Thread::create(state, self_, G(thread), signal_handler_tramp, true));
    run(state);
  }

  void SignalHandler::stop_thread(STATE) {
    SYNC(state);
    if(!self_) return;

    pthread_t os = self_->os_thread();
    {
      utilities::thread::Mutex::LockGuard lg(worker_lock_);
      // Thread might have already been stopped
      exit_ = true;
      worker_cond_.signal();
    }

    void* return_value;
    pthread_join(os, &return_value);
    self_ = NULL;
  }

  void SignalHandler::shutdown(STATE) {
    for(std::list<int>::iterator i = watched_signals_.begin();
        i != watched_signals_.end();
        ++i)
    {
      signal(*i, SIG_DFL);
    }

    stop_thread(state);
  }

  void SignalHandler::before_exec(STATE) {
    stop_thread(state);
  }

  void SignalHandler::after_exec(STATE) {
    start_thread(state);
  }

  void SignalHandler::before_fork(STATE) {
    utilities::thread::Mutex::LockGuard lg(worker_lock_);
    while(!paused_ && self_->run_state() == ManagedThread::eRunning) {
      pause_cond_.wait(worker_lock_);
    }
  }

  void SignalHandler::after_fork_parent(STATE) {
    utilities::thread::Mutex::LockGuard lg(worker_lock_);
    pause_cond_.signal();
  }

  void SignalHandler::after_fork_child(STATE) {
    worker_lock_.init();
    worker_cond_.init();
    pause_cond_.init();

    if(self_) {
      VM::discard(state, self_);
      self_ = NULL;
    }

    start_thread(state);
  }

  void SignalHandler::run(STATE) {
    int error = thread_.get()->fork_attached(state);
    if(error) rubinius::bug("Unable to start signal handler thread");
  }

  void SignalHandler::perform(STATE) {
#ifndef RBX_WINDOWS
    sigset_t set;
    sigfillset(&set);
    pthread_sigmask(SIG_BLOCK, &set, NULL);
#endif

    GCTokenImpl gct;
    const char* thread_name = "rbx.signal";
    self_->set_name(thread_name);

    RUBINIUS_THREAD_START(thread_name, state->vm()->thread_id(), 1);

    state->vm()->thread->hard_unlock(state, gct, 0);

    while(!exit_) {
      {
        utilities::thread::Mutex::LockGuard lg(worker_lock_);
        if(exit_) break;
        state->gc_independent(gct, 0);
        paused_ = true;
        pause_cond_.signal();
        worker_cond_.wait(worker_lock_);
        // If we should exit now, don't try to become
        // dependent first but break and exit the thread
        if(exit_) break;
      }
      state->gc_dependent(gct, 0);
      {
        utilities::thread::Mutex::LockGuard lg(worker_lock_);
        if(exit_) break;
        paused_ = false;
      }

      target_->wakeup(state, gct, 0);
    }
    RUBINIUS_THREAD_STOP(thread_name, state->vm()->thread_id(), 1);
  }

  void SignalHandler::signal_tramp(int sig) {
    signal_handler_->handle_signal(sig);
  }

  void SignalHandler::handle_signal(int sig) {
    if(exit_) return;

    queued_signals_ = 1;
    pending_signals_[sig] = 1;

    target_->set_check_local_interrupts();

    if(target_->should_interrupt_with_signal()) {
      if(!pthread_equal(pthread_self(), target_->os_thread())) {
#ifdef RBX_WINDOWS
        // TODO: Windows
#else
        pthread_kill(target_->os_thread(), SIGVTALRM);
#endif
      }
    }

    worker_cond_.signal();
  }

  void SignalHandler::add_signal(STATE, int sig, HandlerType type) {
    SYNC(state);
    utilities::thread::Mutex::LockGuard lg(worker_lock_);

#ifndef RBX_WINDOWS
    struct sigaction action;

    if(type == eDefault) {
      action.sa_handler = SIG_DFL;
      watched_signals_.remove(sig);
    } else if(type == eIgnore) {
      action.sa_handler = SIG_IGN;
      watched_signals_.push_back(sig);
    } else {
      action.sa_handler = signal_tramp;
      watched_signals_.push_back(sig);
    }

    action.sa_flags = 0;
    sigfillset(&action.sa_mask);

    sigaction(sig, &action, NULL);
#endif
  }

  bool SignalHandler::deliver_signals(STATE, CallFrame* call_frame) {
    queued_signals_ = 0;

    for(int i = 0; i < NSIG; i++) {
      if(pending_signals_[i] > 0) {
        pending_signals_[i] = 0;

        Array* args = Array::create(state, 1);
        args->set(state, 0, Fixnum::from(i));

        // Check whether the send raised an exception and
        // stop running the handlers if that happens
        if(!G(rubinius)->send(state, call_frame,
               state->symbol("received_signal"), args, cNil)) {
          if(state->thread_state()->raise_reason() == cException ||
             state->thread_state()->raise_reason() == cExit) {
            return false;
          }
        }
      }
    }

    return true;
  }

  static void null_func(int sig) {}

  static void safe_write(int fd, const char* str, int len=0) {
    if(!len) len = strlen(str);
    if(write(fd, str, len) == 0) exit(101);
  }

  static void write_sig(int fd, int sig) {
    switch(sig) {
    case SIGSEGV:
      safe_write(fd, "SIGSEGV");
      break;
    case SIGBUS:
      safe_write(fd, "SIGBUS");
      break;
    case SIGILL:
      safe_write(fd, "SIGILL");
      break;
    case SIGABRT:
      safe_write(fd, "SIGABRT");
      break;
    case SIGFPE:
      safe_write(fd, "SIGFPE");
      break;
    default:
      safe_write(fd, "UNKNOWN");
      break;
    }
  }

  static void segv_handler(int sig) {
    void* array[64];
    size_t size;
    int fd = STDERR_FILENO;
    char* pause_env = getenv("RBX_PAUSE_ON_CRASH");

    if(pause_env) {
      long timeout = strtol(pause_env, NULL, 10);
      if(timeout <= 0) {
        timeout = 60;
      } else {
        timeout *= 60;
      }
      std::cerr << "\n========== CRASH (" << getpid();
      std::cerr << "), pausing for " << timeout << " seconds to attach debugger\n";
      sleep(timeout);
    }

    // If there is a report_path setup..
    if(report_path[0]) {
      fd = open(report_path, O_WRONLY | O_CREAT | O_TRUNC, 0666);
      // If we can't open this path, use stderr.
      if(fd == -1) fd = STDERR_FILENO;
    }

    // print out all the frames to stderr
    static const char header[] =
      "Rubinius Crash Report #rbxcrashreport\n\n"
      "Error: signal ";

    safe_write(fd, header, sizeof(header));
    write_sig(fd, sig);

    safe_write(fd, "\n\n[[Backtrace]]\n");

    // get void*'s for all entries on the stack
    size = backtrace(array, 64);

    backtrace_symbols_fd(array, size, fd);

    // Try to get the output to flush...
    safe_write(fd, "\n[[System Info]]\n");
    safe_write(fd, "sysname: ");
    safe_write(fd, machine_info.sysname);
    safe_write(fd, "\n");
    safe_write(fd, "nodename: ");
    safe_write(fd, machine_info.nodename);
    safe_write(fd, "\n");
    safe_write(fd, "release: ");
    safe_write(fd, machine_info.release);
    safe_write(fd, "\n");
    safe_write(fd, "version: ");
    safe_write(fd, machine_info.version);
    safe_write(fd, "\n");
    safe_write(fd, "machine: ");
    safe_write(fd, machine_info.machine);
    safe_write(fd, "\n");

    // If we didn't write to stderr, then close the file down and
    // write info to stderr about reporting the error.
    if(fd != STDERR_FILENO) {
      close(fd);
      safe_write(STDERR_FILENO, "\n---------------------------------------------\n");
      safe_write(STDERR_FILENO, "CRASH: A fatal error has occurred.\n\nBacktrace:\n");
      backtrace_symbols_fd(array, size, 2);
      safe_write(STDERR_FILENO, "\n\n");
      safe_write(STDERR_FILENO, "Wrote full error report to: ");
      safe_write(STDERR_FILENO, report_path);
      safe_write(STDERR_FILENO, "\nRun 'rbx report' to submit this crash report!\n");
    }

    raise(sig);
  }

  void SignalHandler::setup_default_handlers(std::string path) {
#ifndef RBX_WINDOWS
    report_path[0] = 0;

    // Calculate the report_path
    if(path.rfind("/") == std::string::npos) {
      if(char* home = getenv("HOME")) {
        snprintf(report_path, PATH_MAX, "%s/.rbx", home);

        pid_t pid = getpid();

        bool use_dir = false;
        struct stat s;
        if(stat(report_path, &s) != 0) {
          if(mkdir(report_path, S_IRWXU) == 0) use_dir = true;
        } else if(S_ISDIR(s.st_mode)) {
          use_dir = true;
        }

        if(use_dir) {
          snprintf(report_path + strlen(report_path), PATH_MAX, "/%s_%d",
                   path.c_str(), pid);
        } else {
          snprintf(report_path, PATH_MAX, "%s/.%s_%d", home, path.c_str(), pid);
        }
      }
    }

    if(!report_path[0]) {
      strncpy(report_path, path.c_str(), PATH_MAX-1);
    }

    // Test that we can actually use this path.
    int fd = open(report_path, O_RDONLY | O_CREAT, 0666);
    if(!fd) {
      char buf[RBX_STRERROR_BUFSIZE];
      char* err = RBX_STRERROR(errno, buf, RBX_STRERROR_BUFSIZE);
      std::cerr << "Unable to use " << report_path << " for crash reports.\n";
      std::cerr << "Unable to open path: " << err << "\n";

      // Don't use the home dir path even, just use stderr
      report_path[0] = 0;
    } else {
      close(fd);
      unlink(report_path);
    }

    // Get the machine info.
    uname(&machine_info);

    struct sigaction action;
    action.sa_handler = null_func;
    action.sa_flags = 0;
    sigfillset(&action.sa_mask);
    sigaction(SIGVTALRM, &action, NULL);

    // Some extensions expect SIGALRM to be defined, because MRI does.
    // We'll just use a noop for it.
    action.sa_handler = null_func;
    sigaction(SIGALRM, &action, NULL);

    // Ignore sigpipe.
    action.sa_handler = SIG_IGN;
    sigaction(SIGPIPE, &action, NULL);

#ifdef USE_EXECINFO
    // If we have execinfo, setup some crash handlers
    if(!getenv("DISABLE_SEGV")) {
      action.sa_handler = segv_handler;
      sigaction(SIGSEGV, &action, NULL);
      sigaction(SIGBUS,  &action, NULL);
      sigaction(SIGILL,  &action, NULL);
      sigaction(SIGFPE,  &action, NULL);
      sigaction(SIGABRT, &action, NULL);
    }
#endif  // USE_EXEC_INFO
#else
    signal(SIGTERM, quit_handler);
#endif  // ifndef RBX_WINDOWS
  }
}