exceptions.cc

cygwin, 著名的在win32下模拟unix操作系统的东东

/* exceptions.cc

   Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <imagehlp.h>
#include <errno.h>
#include <stdlib.h>

#include "exceptions.h"
#include "sync.h"
#include "sigproc.h"
#include "pinfo.h"
#include "cygerrno.h"
#include "perthread.h"
#include "shared_info.h"
#include "perprocess.h"
#include "security.h"

#define CALL_HANDLER_RETRY 20

char debugger_command[2 * MAX_PATH + 20];

extern "C" {
static int handle_exceptions (EXCEPTION_RECORD *, void *, CONTEXT *, void *);
extern void sigreturn ();
extern void sigdelayed ();
extern void sigdelayed0 ();
extern void siglast ();
extern DWORD __no_sig_start, __no_sig_end;
};

extern DWORD sigtid;

extern HANDLE hExeced;
extern DWORD dwExeced;

static BOOL WINAPI ctrl_c_handler (DWORD);
static void signal_exit (int) __attribute__ ((noreturn));
static char windows_system_directory[1024];
static size_t windows_system_directory_length;

/* This is set to indicate that we have already exited.  */

static NO_COPY int exit_already = 0;
static NO_COPY muto *mask_sync = NULL;

HMODULE NO_COPY cygwin_hmodule;

NO_COPY static struct
{
  unsigned int code;
  const char *name;
} status_info[] =
{
#define X(s) s, #s
  { X (STATUS_ABANDONED_WAIT_0) },
  { X (STATUS_ACCESS_VIOLATION) },
  { X (STATUS_ARRAY_BOUNDS_EXCEEDED) },
  { X (STATUS_BREAKPOINT) },
  { X (STATUS_CONTROL_C_EXIT) },
  { X (STATUS_DATATYPE_MISALIGNMENT) },
  { X (STATUS_FLOAT_DENORMAL_OPERAND) },
  { X (STATUS_FLOAT_DIVIDE_BY_ZERO) },
  { X (STATUS_FLOAT_INEXACT_RESULT) },
  { X (STATUS_FLOAT_INVALID_OPERATION) },
  { X (STATUS_FLOAT_OVERFLOW) },
  { X (STATUS_FLOAT_STACK_CHECK) },
  { X (STATUS_FLOAT_UNDERFLOW) },
  { X (STATUS_GUARD_PAGE_VIOLATION) },
  { X (STATUS_ILLEGAL_INSTRUCTION) },
  { X (STATUS_INTEGER_DIVIDE_BY_ZERO) },
  { X (STATUS_INTEGER_OVERFLOW) },
  { X (STATUS_INVALID_DISPOSITION) },
  { X (STATUS_IN_PAGE_ERROR) },
  { X (STATUS_NONCONTINUABLE_EXCEPTION) },
  { X (STATUS_NO_MEMORY) },
  { X (STATUS_PENDING) },
  { X (STATUS_PRIVILEGED_INSTRUCTION) },
  { X (STATUS_SINGLE_STEP) },
  { X (STATUS_STACK_OVERFLOW) },
  { X (STATUS_TIMEOUT) },
  { X (STATUS_USER_APC) },
  { X (STATUS_WAIT_0) },
  { 0, 0 }
#undef X
};

/* Initialization code.  */

#ifdef __i386__

// Set up the exception handler for the current thread.  The PowerPC & Mips
// use compiler generated tables to set up the exception handlers for each
// region of code, and the kernel walks the call list until it finds a region
// of code that handles exceptions.  The x86 on the other hand uses segment
// register fs, offset 0 to point to the current exception handler.

asm (".equ __except_list,0");

extern exception_list *_except_list asm ("%fs:__except_list");

static void
init_exception_handler (exception_list *el)
{
  el->handler = handle_exceptions;
  el->prev = _except_list;
  _except_list = el;
}
#endif

void
early_stuff_init ()
{
  (void) SetConsoleCtrlHandler (ctrl_c_handler, FALSE);
  if (!SetConsoleCtrlHandler (ctrl_c_handler, TRUE))
    system_printf ("SetConsoleCtrlHandler failed, %E");

  /* Initialize global security attribute stuff */

  sec_none.nLength = sec_none_nih.nLength =
  sec_all.nLength = sec_all_nih.nLength = sizeof (SECURITY_ATTRIBUTES);
  sec_none.bInheritHandle = sec_all.bInheritHandle = TRUE;
  sec_none_nih.bInheritHandle = sec_all_nih.bInheritHandle = FALSE;
  sec_none.lpSecurityDescriptor = sec_none_nih.lpSecurityDescriptor = NULL;
  sec_all.lpSecurityDescriptor = sec_all_nih.lpSecurityDescriptor =
    get_null_sd ();
}

extern "C" void
init_exceptions (exception_list *el)
{
  init_exception_handler (el);
}

extern "C" void
error_start_init (const char *buf)
{
  if (!buf || !*buf)
    {
      debugger_command[0] = '\0';
      return;
    }

  char pgm[MAX_PATH + 1];
  if (!GetModuleFileName (NULL, pgm, MAX_PATH))
    strcpy (pgm, "cygwin1.dll");
  for (char *p = strchr (pgm, '\\'); p; p = strchr (p, '\\'))
    *p = '/';

  __small_sprintf (debugger_command, "%s %s", buf, pgm);
}

static void
open_stackdumpfile ()
{
  if (myself->progname[0])
    {
      const char *p;
      /* write to progname.stackdump if possible */
      if (!myself->progname[0])
	p = "unknown";
      else if ((p = strrchr (myself->progname, '\\')))
	p++;
      else
	p = myself->progname;
      char corefile[strlen (p) + sizeof (".stackdump")];
      __small_sprintf (corefile, "%s.stackdump", p);
      HANDLE h = CreateFile (corefile, GENERIC_WRITE, 0, &sec_none_nih,
			     CREATE_ALWAYS, 0, 0);
      if (h != INVALID_HANDLE_VALUE)
	{
	  if (!myself->ppid_handle)
	    system_printf ("Dumping stack trace to %s", corefile);
	  else
	    debug_printf ("Dumping stack trace to %s", corefile);
	  SetStdHandle (STD_ERROR_HANDLE, h);
	}
    }
}

/* Utilities for dumping the stack, etc.  */

static void
exception (EXCEPTION_RECORD *e,  CONTEXT *in)
{
  const char *exception_name = NULL;

  if (e)
    {
      for (int i = 0; status_info[i].name; i++)
	{
	  if (status_info[i].code == e->ExceptionCode)
	    {
	      exception_name = status_info[i].name;
	      break;
	    }
	}
    }

#ifdef __i386__
#define HAVE_STATUS
  if (exception_name)
    small_printf ("Exception: %s at eip=%08x\r\n", exception_name, in->Eip);
  else
    small_printf ("Exception %d at eip=%08x\r\n", e->ExceptionCode, in->Eip);
  small_printf ("eax=%08x ebx=%08x ecx=%08x edx=%08x esi=%08x edi=%08x\r\n",
	      in->Eax, in->Ebx, in->Ecx, in->Edx, in->Esi, in->Edi);
  small_printf ("ebp=%08x esp=%08x program=%s\r\n",
	      in->Ebp, in->Esp, myself->progname);
  small_printf ("cs=%04x ds=%04x es=%04x fs=%04x gs=%04x ss=%04x\r\n",
	      in->SegCs, in->SegDs, in->SegEs, in->SegFs, in->SegGs, in->SegSs);
#endif

#ifndef HAVE_STATUS
  system_printf ("Had an exception");
#endif
}

#ifdef __i386__
/* Print a stack backtrace. */

#define HAVE_STACK_TRACE

/* A class for manipulating the stack. */
class stack_info
{
  int walk ();			/* Uses the "old" method */
  char *next_offset () {return *((char **) sf.AddrFrame.Offset);}
  bool needargs;
  DWORD dummy_frame;
public:
  STACKFRAME sf;		 /* For storing the stack information */
  void init (DWORD, bool, bool); /* Called the first time that stack info is needed */

  /* Postfix ++ iterates over the stack, returning zero when nothing is left. */
  int operator ++(int) { return this->walk (); }
};

/* The number of parameters used in STACKFRAME */
#define NPARAMS (sizeof (thestack.sf.Params) / sizeof (thestack.sf.Params[0]))

/* This is the main stack frame info for this process. */
static NO_COPY stack_info thestack;
static signal_dispatch sigsave;

/* Initialize everything needed to start iterating. */
void
stack_info::init (DWORD ebp, bool wantargs, bool goodframe)
{
# define debp ((DWORD *) ebp)
  memset (&sf, 0, sizeof (sf));
  if (!goodframe)
    sf.AddrFrame.Offset = ebp;
  else
    {
      dummy_frame = ebp;
      sf.AddrFrame.Offset = (DWORD) &dummy_frame;
    }
  sf.AddrReturn.Offset = debp[1];
  sf.AddrFrame.Mode = AddrModeFlat;
  needargs = wantargs;
# undef debp
}

/* Walk the stack by looking at successive stored 'bp' frames.
   This is not foolproof. */
int
stack_info::walk ()
{
  char **ebp;
  if ((ebp = (char **) next_offset ()) == NULL)
    return 0;

  sf.AddrFrame.Offset = (DWORD) ebp;
  sf.AddrPC.Offset = sf.AddrReturn.Offset;

  if (!sf.AddrPC.Offset)
    return 0;		/* stack frames are exhausted */

  /* The return address always follows the stack pointer */
  sf.AddrReturn.Offset = (DWORD) *++ebp;

  if (needargs)
    /* The arguments follow the return address */
    for (unsigned i = 0; i < NPARAMS; i++)
      sf.Params[i] = (DWORD) *++ebp;

  return 1;
}

static void
stackdump (DWORD ebp, int open_file, bool isexception)
{
  extern unsigned long rlim_core;

  if (rlim_core == 0UL)
    return;

  if (open_file)
    open_stackdumpfile ();

  int i;

  thestack.init (ebp, 1, !isexception);	/* Initialize from the input CONTEXT */
  small_printf ("Stack trace:\r\nFrame     Function  Args\r\n");
  for (i = 0; i < 16 && thestack++; i++)
    {
      small_printf ("%08x  %08x ", thestack.sf.AddrFrame.Offset,
		    thestack.sf.AddrPC.Offset);
      for (unsigned j = 0; j < NPARAMS; j++)
	small_printf ("%s%08x", j == 0 ? " (" : ", ", thestack.sf.Params[j]);
      small_printf (")\r\n");
    }
  small_printf ("End of stack trace%s",
	      i == 16 ? " (more stack frames may be present)" : "");
}

/* Temporary (?) function for external callers to get a stack dump */
extern "C" void
cygwin_stackdump ()
{
  CONTEXT c;
  c.ContextFlags = CONTEXT_FULL;
  GetThreadContext (GetCurrentThread (), &c);
  stackdump (c.Ebp, 0, 0);
}

#define TIME_TO_WAIT_FOR_DEBUGGER 10000

extern "C" int
try_to_debug (bool waitloop)
{
  debug_printf ("debugger_command '%s'", debugger_command);
  if (*debugger_command == '\0' || being_debugged ())
    return 0;

  __small_sprintf (strchr (debugger_command, '\0'), " %u", GetCurrentProcessId ());

  SetThreadPriority (hMainThread, THREAD_PRIORITY_HIGHEST);
  PROCESS_INFORMATION pi = {NULL, 0, 0, 0};

  STARTUPINFO si = {0, NULL, NULL, NULL, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL, NULL, NULL, NULL};
  si.lpReserved = NULL;
  si.lpDesktop = NULL;
  si.dwFlags = 0;
  si.cb = sizeof (si);

  /* FIXME: need to know handles of all running threads to
     suspend_all_threads_except (current_thread_id);
  */

  /* if any of these mutexes is owned, we will fail to start any cygwin app
     until trapped app exits */

  ReleaseMutex (title_mutex);

  /* prevent recursive exception handling */
  char* rawenv = GetEnvironmentStrings () ;
  for (char* p = rawenv; *p != '\0'; p = strchr (p, '\0') + 1)
    {
      if (strncmp (p, "CYGWIN=", sizeof ("CYGWIN=") - 1) == 0)
	{
	  char* q = strstr (p, "error_start") ;
	  /* replace 'error_start=...' with '_rror_start=...' */
	  if (q) *q = '_' ;
	  SetEnvironmentVariable ("CYGWIN", p + sizeof ("CYGWIN=")) ;
	  break ;
	}
    }

  BOOL dbg;
  dbg = CreateProcess (NULL,
		       debugger_command,
		       NULL,
		       NULL,
		       FALSE,
		       CREATE_NEW_CONSOLE | CREATE_NEW_PROCESS_GROUP,
		       NULL,
		       NULL,
		       &si,
		       &pi);

  if (!dbg)
    system_printf ("Failed to start debugger: %E");
  else
    {
      SetThreadPriority (hMainThread, THREAD_PRIORITY_IDLE);
      if (!waitloop)
	return 1;
      while (!being_debugged ())
	/* spin */;
      Sleep (4000);
      small_printf ("*** continuing from debugger call\n");
    }

  /* FIXME: need to know handles of all running threads to
    resume_all_threads_except (current_thread_id);
  */
  return 0;
}

/* Main exception handler. */

static int
handle_exceptions (EXCEPTION_RECORD *e, void *, CONTEXT *in, void *)
{
  int sig;
  static int NO_COPY debugging = 0;
  static int NO_COPY recursed = 0;

  if (debugging && ++debugging < 500000)
    {
      SetThreadPriority (hMainThread, THREAD_PRIORITY_NORMAL);
      return 0;
    }

  /* If we've already exited, don't do anything here.  Returning 1