sigproc.cc

来自「cygwin, 著名的在win32下模拟unix操作系统的东东」· CC 代码 · 共 1,312 行 · 第 1/3 页

/* Get or create a process specific semaphore used in message passing.
 */
static HANDLE __stdcall
getsem (_pinfo *p, const char *str, int init, int max)
{
  HANDLE h;

  if (p != NULL)
    {
      if (!proc_can_be_signalled (p))
	{
	  set_errno (ESRCH);
	  return NULL;
	}
      int wait = 1000;
      /* Wait for new process to generate its semaphores. */
      sigproc_printf ("pid %d, ppid %d, wait %d, initializing %x", p->pid, p->ppid, wait,
		  ISSTATE (p, PID_INITIALIZING));
      for (int i = 0; ISSTATE (p, PID_INITIALIZING) && i < wait; i++)
	low_priority_sleep (1);
    }

  SetLastError (0);
  if (p == NULL)
    {
      char sa_buf[1024];

      DWORD winpid = GetCurrentProcessId ();
      h = CreateSemaphore (sec_user_nih (sa_buf), init, max,
			   str = shared_name (str, winpid));
      p = myself;
      if (!h)
	{
	  system_printf ("can't create semaphore %s, %E", str);
	  __seterrno ();
	}
    }
  else
    {
      h = OpenSemaphore (SEMAPHORE_ALL_ACCESS, FALSE,
			 shared_name (str, p->dwProcessId));

      if (!h)
	{
	  if (GetLastError () == ERROR_FILE_NOT_FOUND && !proc_exists (p))
	    set_errno (ESRCH);	/* No such process */
	  else
	    set_errno (EPERM);	/* Couldn't access the semaphore --
				   different cygwin DLL maybe? */
	}
    }

  return h;
}

/* Remove a zombie from zombies by swapping it with the last child in the list.
 */
static void __stdcall
remove_zombie (int ci)
{
  sigproc_printf ("removing %d, pid %d, nzombies %d", ci, zombies[ci]->pid,
		  nzombies);

  if (zombies[ci])
    {
      ForceCloseHandle1 (zombies[ci]->hProcess, childhProc);
      ForceCloseHandle1 (zombies[ci]->pid_handle, pid_handle);
      zombies[ci].release ();
    }

  if (ci < --nzombies)
    zombies[ci] = zombies[nzombies];

  return;
}

/* Check status of child process vs. waitq member.
 *
 * parent_w is the pointer to the parent of the waitq member in question.
 * child is the subprocess being considered.
 *
 * Returns
 *   1 if stopped or terminated child matches parent_w->next criteria
 *  -1 if a non-stopped/terminated child matches parent_w->next criteria
 *   0 if child does not match parent_w->next criteria
 */
static int __stdcall
stopped_or_terminated (waitq *parent_w, _pinfo *child)
{
  int potential_match;
  waitq *w = parent_w->next;

  sigproc_printf ("considering pid %d", child->pid);
  if (w->pid == -1)
    potential_match = 1;
  else if (w->pid == 0)
    potential_match = child->pgid == myself->pgid;
  else if (w->pid < 0)
    potential_match = child->pgid == -w->pid;
  else
    potential_match = (w->pid == child->pid);

  if (!potential_match)
    return 0;

  BOOL terminated;

  if ((terminated = child->process_state == PID_ZOMBIE) ||
      ((w->options & WUNTRACED) && child->stopsig))
    {
      parent_w->next = w->next;	/* successful wait.  remove from wait queue */
      w->pid = child->pid;

      if (!terminated)
	{
	  sigproc_printf ("stopped child");
	  w->status = (child->stopsig << 8) | 0x7f;
	  child->stopsig = 0;
	}
      else /* Should only get here when child has been moved to the zombies array */
	{
	  DWORD status;
	  if (!GetExitCodeProcess (child->hProcess, &status))
	    status = 0xffff;
	  if (status & EXIT_SIGNAL)
	    w->status = (status >> 8) & 0xff;	/* exited due to signal */
	  else
	    w->status = (status & 0xff) << 8;	/* exited via "exit ()" */

	  add_rusage (&myself->rusage_children, &child->rusage_children);
	  add_rusage (&myself->rusage_children, &child->rusage_self);

	  if (w->rusage)
	    {
	      add_rusage ((struct rusage *) w->rusage, &child->rusage_children);
	      add_rusage ((struct rusage *) w->rusage, &child->rusage_self);
	    }
	}

      if (!SetEvent (w->ev))	/* wake up wait4 () immediately */
	system_printf ("couldn't wake up wait event %p, %E", w->ev);
      return 1;
    }

  return -potential_match;
}

static void
talktome ()
{
  winpids pids;
  for (unsigned i = 0; i < pids.npids; i++)
    if (pids[i]->hello_pid == myself->pid)
      pids[i]->commune_recv ();
}

/* Process signals by waiting for a semaphore to become signaled.
 * Then scan an in-memory array representing queued signals.
 * Executes in a separate thread.
 *
 * Signals sent from this process are sent a completion signal so
 * that returns from kill/raise do not occur until the signal has
 * has been handled, as per POSIX.
 */
static DWORD WINAPI
wait_sig (VOID *self)
{
  /* Initialization */
  (void) SetThreadPriority (GetCurrentThread (), WAIT_SIG_PRIORITY);

  /* sigcatch_nosync       - semaphore incremented by sig_dispatch_pending and
   *			     by foreign processes to force an examination of
   *			     the sigtodo array.
   * sigcatch_main	   - ditto for local main thread.
   * sigcatch_nonmain      - ditto for local non-main threads.
   *
   * sigcomplete_main	   - event used to signal main thread on signal
   *			     completion
   * sigcomplete_nonmain   - semaphore signaled for non-main thread on signal
   *			     completion
   */
  sigcatch_nosync = getsem (NULL, "sigcatch", 0, MAXLONG);
  sigcatch_nonmain = CreateSemaphore (&sec_none_nih, 0, MAXLONG, NULL);
  sigcatch_main = CreateSemaphore (&sec_none_nih, 0, MAXLONG, NULL);
  sigcomplete_nonmain = CreateSemaphore (&sec_none_nih, 0, MAXLONG, NULL);
  sigcomplete_main = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
  sigproc_printf ("sigcatch_nonmain %p, sigcatch_main %p", sigcatch_nonmain, sigcatch_main);
  sigCONT = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);

  /* Setting dwProcessId flags that this process is now capable of receiving
   * signals.  Prior to this, dwProcessId was set to the windows pid of
   * of the original windows process which spawned us unless this was a
   * "toplevel" process.
   */
  myself->dwProcessId = GetCurrentProcessId ();
  myself->process_state |= PID_ACTIVE;
  myself->process_state &= ~PID_INITIALIZING;

  ProtectHandle (sigcatch_nosync);
  ProtectHandle (sigcatch_nonmain);
  ProtectHandle (sigcatch_main);
  ProtectHandle (sigcomplete_nonmain);
  ProtectHandle (sigcomplete_main);

  /* If we've been execed, then there is still a stub left in the previous
   * windows process waiting to see if it's started a cygwin process or not.
   * Signalling subproc_ready indicates that we are a cygwin process.
   */
  if (child_proc_info && child_proc_info->type == PROC_EXEC)
    {
      debug_printf ("subproc_ready %p", child_proc_info->subproc_ready);
      if (!SetEvent (child_proc_info->subproc_ready))
	system_printf ("SetEvent (subproc_ready) failed, %E");
      ForceCloseHandle1 (child_proc_info->subproc_ready, subproc_ready);
      /* Initialize an "indirect" pid block so that if someone looks up this
	 process via its Windows PID it will be redirected to the appropriate
	 Cygwin PID shared memory block. */
      static pinfo NO_COPY myself_identity;
      myself_identity.init (cygwin_pid (myself->dwProcessId), PID_EXECED);
    }

  SetEvent (wait_sig_inited);
  sigtid = GetCurrentThreadId ();

  HANDLE catchem[] = {sigcatch_main, sigcatch_nonmain, sigcatch_nosync};
  sigproc_printf ("Ready.  dwProcessid %d", myself->dwProcessId);
  for (;;)
    {
      DWORD rc = WaitForMultipleObjects (3, catchem, FALSE, sig_loop_wait);
      (void) SetThreadPriority (GetCurrentThread (), WAIT_SIG_PRIORITY);

      /* sigproc_terminate sets sig_loop_wait to zero to indicate that
       * this thread should terminate.
       */
      if (rc == WAIT_TIMEOUT)
	{
	  if (!sig_loop_wait)
	    break;			// Exiting
	  else
	    continue;
	}

      if (rc == WAIT_FAILED)
	{
	  if (sig_loop_wait != 0)
	    system_printf ("WFMO failed, %E");
	  break;
	}

      rc -= WAIT_OBJECT_0;
      sigproc_printf ("awake");
      /* A sigcatch semaphore has been signaled.  Scan the sigtodo
       * array looking for any unprocessed signals.
       */
      pending_signals = -1;
      int saw_pending_signals = 0;
      int saw_sigchld = 0;
      for (int sig = -__SIGOFFSET; sig < NSIG; sig++)
	{
	  while (InterlockedDecrement (myself->getsigtodo (sig)) >= 0)
	    {
	      if (sig == SIGCHLD)
		saw_sigchld = 1;

	      if (sig > 0 && sig != SIGKILL && sig != SIGSTOP &&
		  (sigismember (&myself->getsigmask (), sig) ||
		   main_vfork->pid ||
		   (sig != SIGCONT && ISSTATE (myself, PID_STOPPED))))
		{
		  sigproc_printf ("signal %d blocked", sig);
		  break;
		}

	      /* Found a signal to process */
	      sigproc_printf ("processing signal %d", sig);
	      switch (sig)
		{
		case __SIGFLUSH:
		  /* just forcing the loop */
		  break;

		/* Internal signal to turn on stracing. */
		case __SIGSTRACE:
		  strace.hello ();
		  break;

		case __SIGCOMMUNE:
		  talktome ();
		  break;

		/* A normal UNIX signal */
		default:
		  sigproc_printf ("Got signal %d", sig);
		  sig_handle (sig, rc != 2);
		  /* Need to decrement again to offset increment below since
		     we really do want to decrement in this case. */
		  InterlockedDecrement (myself->getsigtodo (sig));
		  goto nextsig;		/* FIXME: shouldn't this allow the loop to continue? */
		}
	    }

	nextsig:
	  /* Decremented too far. */
	  if (InterlockedIncrement (myself->getsigtodo (sig)) > 0)
	    saw_pending_signals = 1;
	}

      if (pending_signals < 0 && !saw_pending_signals)
	pending_signals = 0;

      if (saw_sigchld)
	proc_subproc (PROC_CLEARWAIT, 0);

      /* Signal completion of signal handling depending on which semaphore
       * woke up the WaitForMultipleObjects above.
       */
      switch (rc)
	{
	case 0:
	  SetEvent (sigcomplete_main);
	  sigproc_printf ("set main thread completion event");
	  break;
	case 1:
	  ReleaseSemaphore (sigcomplete_nonmain, 1, NULL);
	  break;
	default:
	  /* Signal from another process.  No need to synchronize. */
	  break;
	}
      sigproc_printf ("looping");
    }

  sigproc_printf ("done");
  ExitThread (0);
}

/* Wait for subprocesses to terminate. Executes in a separate thread. */
static DWORD WINAPI
wait_subproc (VOID *)
{
  sigproc_printf ("starting");
  int errloop = 0;

  for (;;)
    {
      DWORD rc = WaitForMultipleObjects (nchildren + 1, events, FALSE,
					 proc_loop_wait);
      if (rc == WAIT_TIMEOUT)
	if (!proc_loop_wait)
	  break;			// Exiting
	else
	  continue;

      if (rc == WAIT_FAILED)
	{
	  if (!proc_loop_wait)
	    break;

	  /* It's ok to get an ERROR_INVALID_HANDLE since another thread may have
	     closed a handle in the children[] array.  So, we try looping a couple
	     of times to stabilize. FIXME - this is not foolproof.  Probably, this
	     thread should be responsible for closing the children. */
	  if (!errloop++)
	    proc_subproc (PROC_NOTHING, 0);	// Just synchronize and continue
	  if (errloop < 10)
	    continue;

	  system_printf ("wait failed. nchildren %d, wait %d, %E",
			nchildren, proc_loop_wait);

	  for (int i = 0; i <= nchildren; i++)
	    if ((rc = WaitForSingleObject (events[i], 0)) == WAIT_OBJECT_0 ||
		rc == WAIT_TIMEOUT)
	      continue;
	    else if (i == 0)
		system_printf ("nchildren %d, event[%d] %p, %E", nchildren, i, events[i]);
	    else
	      {
		system_printf ("nchildren %d, event[%d] %p, pchildren[%d] %p, events[0] %p, %E",
			       nchildren, i, events[i], i - 1, (_pinfo *) pchildren[i - 1], events[0]);
		system_printf ("pid %d, dwProcessId %u, hProcess %p, progname '%s'",
			       pchildren[i - 1]->pid, pchildren[i - 1]->dwProcessId,
			       pchildren[i - 1]->hProcess, pchildren[i - 1]->progname);
	      }
	  break;
	}

      errloop = 0;
      rc -= WAIT_OBJECT_0;
      if (rc-- != 0)
	{
	  rc = proc_subproc (PROC_CHILDTERMINATED, rc);
	  if (!proc_loop_wait)		// Don't bother if wait_subproc is
	    break;			//  exiting

	  /* Send a SIGCHLD to myself.   We do this here, rather than in proc_subproc
	     to avoid the proc_subproc lock since the signal thread will eventually
	     be calling proc_subproc and could unnecessarily block. */
	  if (rc)
	    sig_send (myself_nowait, SIGCHLD);
	}
      sigproc_printf ("looping");
    }

  ForceCloseHandle (events[0]);
  events[0] = NULL;
  sigproc_printf ("done");
  ExitThread (0);
}

extern "C" {
/* Provide a stack frame when calling WaitFor* functions */

#undef WaitForSingleObject

DWORD __stdcall
WFSO (HANDLE hHandle, DWORD dwMilliseconds)
{
  DWORD ret;
  sigframe thisframe (mainthread);
  ret = WaitForSingleObject (hHandle, dwMilliseconds);
  return ret;
}

#undef WaitForMultipleObjects

DWORD __stdcall
WFMO (DWORD nCount, CONST HANDLE *lpHandles, BOOL fWaitAll, DWORD dwMilliseconds)
{
  DWORD ret;
  sigframe thisframe (mainthread);
  ret = WaitForMultipleObjects (nCount, lpHandles, fWaitAll, dwMilliseconds);
  return ret;
}
}