os_dep.c

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    unsigned long       mapsize; 
    unsigned long       reserved;
};

#define O32_FLAGS(x)    (x).flags
#define OBJREAD         0x0001L
#define OBJWRITE        0x0002L
#define OBJINVALID      0x0080L
#define O32_SIZE(x)     (x).size
#define O32_BASE(x)     (x).base

# else  /* IBM's compiler */

/* A kludge to get around what appears to be a header file bug */
# ifndef WORD
#   define WORD unsigned short
# endif
# ifndef DWORD
#   define DWORD unsigned long
# endif

# define EXE386 1
# include <newexe.h>
# include <exe386.h>

# endif  /* __IBMC__ */

# define INCL_DOSEXCEPTIONS
# define INCL_DOSPROCESS
# define INCL_DOSERRORS
# define INCL_DOSMODULEMGR
# define INCL_DOSMEMMGR
# include <os2.h>


/* Disable and enable signals during nontrivial allocations	*/

void GC_disable_signals(void)
{
    ULONG nest;
    
    DosEnterMustComplete(&nest);
    if (nest != 1) ABORT("nested GC_disable_signals");
}

void GC_enable_signals(void)
{
    ULONG nest;
    
    DosExitMustComplete(&nest);
    if (nest != 0) ABORT("GC_enable_signals");
}


# else

#  if !defined(PCR) && !defined(AMIGA) && !defined(MSWIN32) \
      && !defined(MSWINCE) \
      && !defined(MACOS) && !defined(DJGPP) && !defined(DOS4GW) \
      && !defined(NOSYS) && !defined(ECOS)

#   if defined(sigmask) && !defined(UTS4) && !defined(HURD)
	/* Use the traditional BSD interface */
#	define SIGSET_T int
#	define SIG_DEL(set, signal) (set) &= ~(sigmask(signal))
#	define SIG_FILL(set)  (set) = 0x7fffffff
    	  /* Setting the leading bit appears to provoke a bug in some	*/
    	  /* longjmp implementations.  Most systems appear not to have	*/
    	  /* a signal 32.						*/
#	define SIGSETMASK(old, new) (old) = sigsetmask(new)
#   else
	/* Use POSIX/SYSV interface	*/
#	define SIGSET_T sigset_t
#	define SIG_DEL(set, signal) sigdelset(&(set), (signal))
#	define SIG_FILL(set) sigfillset(&set)
#	define SIGSETMASK(old, new) sigprocmask(SIG_SETMASK, &(new), &(old))
#   endif

static GC_bool mask_initialized = FALSE;

static SIGSET_T new_mask;

static SIGSET_T old_mask;

static SIGSET_T dummy;

#if defined(PRINTSTATS) && !defined(THREADS)
# define CHECK_SIGNALS
  int GC_sig_disabled = 0;
#endif

void GC_disable_signals()
{
    if (!mask_initialized) {
    	SIG_FILL(new_mask);

	SIG_DEL(new_mask, SIGSEGV);
	SIG_DEL(new_mask, SIGILL);
	SIG_DEL(new_mask, SIGQUIT);
#	ifdef SIGBUS
	    SIG_DEL(new_mask, SIGBUS);
#	endif
#	ifdef SIGIOT
	    SIG_DEL(new_mask, SIGIOT);
#	endif
#	ifdef SIGEMT
	    SIG_DEL(new_mask, SIGEMT);
#	endif
#	ifdef SIGTRAP
	    SIG_DEL(new_mask, SIGTRAP);
#	endif 
	mask_initialized = TRUE;
    }
#   ifdef CHECK_SIGNALS
	if (GC_sig_disabled != 0) ABORT("Nested disables");
	GC_sig_disabled++;
#   endif
    SIGSETMASK(old_mask,new_mask);
}

void GC_enable_signals()
{
#   ifdef CHECK_SIGNALS
	if (GC_sig_disabled != 1) ABORT("Unmatched enable");
	GC_sig_disabled--;
#   endif
    SIGSETMASK(dummy,old_mask);
}

#  endif  /* !PCR */

# endif /*!OS/2 */

/* Ivan Demakov: simplest way (to me) */
#if defined (DOS4GW)
  void GC_disable_signals() { }
  void GC_enable_signals() { }
#endif

/* Find the page size */
word GC_page_size;

# if defined(MSWIN32) || defined(MSWINCE)
  void GC_setpagesize()
  {
    GetSystemInfo(&GC_sysinfo);
    GC_page_size = GC_sysinfo.dwPageSize;
  }

# else
#   if defined(MPROTECT_VDB) || defined(PROC_VDB) || defined(USE_MMAP) \
       || defined(USE_MUNMAP)
	void GC_setpagesize()
	{
	    GC_page_size = GETPAGESIZE();
	}
#   else
	/* It's acceptable to fake it. */
	void GC_setpagesize()
	{
	    GC_page_size = HBLKSIZE;
	}
#   endif
# endif

/* 
 * Find the base of the stack. 
 * Used only in single-threaded environment.
 * With threads, GC_mark_roots needs to know how to do this.
 * Called with allocator lock held.
 */
# if defined(MSWIN32) || defined(MSWINCE)
# define is_writable(prot) ((prot) == PAGE_READWRITE \
			    || (prot) == PAGE_WRITECOPY \
			    || (prot) == PAGE_EXECUTE_READWRITE \
			    || (prot) == PAGE_EXECUTE_WRITECOPY)
/* Return the number of bytes that are writable starting at p.	*/
/* The pointer p is assumed to be page aligned.			*/
/* If base is not 0, *base becomes the beginning of the 	*/
/* allocation region containing p.				*/
word GC_get_writable_length(ptr_t p, ptr_t *base)
{
    MEMORY_BASIC_INFORMATION buf;
    word result;
    word protect;
    
    result = VirtualQuery(p, &buf, sizeof(buf));
    if (result != sizeof(buf)) ABORT("Weird VirtualQuery result");
    if (base != 0) *base = (ptr_t)(buf.AllocationBase);
    protect = (buf.Protect & ~(PAGE_GUARD | PAGE_NOCACHE));
    if (!is_writable(protect)) {
        return(0);
    }
    if (buf.State != MEM_COMMIT) return(0);
    return(buf.RegionSize);
}

ptr_t GC_get_stack_base()
{
    int dummy;
    ptr_t sp = (ptr_t)(&dummy);
    ptr_t trunc_sp = (ptr_t)((word)sp & ~(GC_page_size - 1));
    word size = GC_get_writable_length(trunc_sp, 0);
   
    return(trunc_sp + size);
}


# endif /* MS Windows */

# ifdef BEOS
# include <kernel/OS.h>
ptr_t GC_get_stack_base(){
	thread_info th;
	get_thread_info(find_thread(NULL),&th);
	return th.stack_end;
}
# endif /* BEOS */


# ifdef OS2

ptr_t GC_get_stack_base()
{
    PTIB ptib;
    PPIB ppib;
    
    if (DosGetInfoBlocks(&ptib, &ppib) != NO_ERROR) {
    	GC_err_printf0("DosGetInfoBlocks failed\n");
    	ABORT("DosGetInfoBlocks failed\n");
    }
    return((ptr_t)(ptib -> tib_pstacklimit));
}

# endif /* OS2 */

# ifdef AMIGA
#   define GC_AMIGA_SB
#   include "AmigaOS.c"
#   undef GC_AMIGA_SB
# endif /* AMIGA */

# if defined(NEED_FIND_LIMIT) || defined(UNIX_LIKE)

#   ifdef __STDC__
	typedef void (*handler)(int);
#   else
	typedef void (*handler)();
#   endif

#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1) \
    || defined(HURD) || defined(NETBSD)
	static struct sigaction old_segv_act;
#	if defined(IRIX5) || defined(HPUX) \
	|| defined(HURD) || defined(NETBSD)
	    static struct sigaction old_bus_act;
#	endif
#   else
        static handler old_segv_handler, old_bus_handler;
#   endif
    
#   ifdef __STDC__
      void GC_set_and_save_fault_handler(handler h)
#   else
      void GC_set_and_save_fault_handler(h)
      handler h;
#   endif
    {
#	if defined(SUNOS5SIGS) || defined(IRIX5)  \
        || defined(OSF1) || defined(HURD) || defined(NETBSD)
	  struct sigaction	act;

	  act.sa_handler	= h;
#	  if 0 /* Was necessary for Solaris 2.3 and very temporary 	*/
	       /* NetBSD bugs.						*/
            act.sa_flags          = SA_RESTART | SA_NODEFER;
#         else
            act.sa_flags          = SA_RESTART;
#	  endif

	  (void) sigemptyset(&act.sa_mask);
#	  ifdef GC_IRIX_THREADS
		/* Older versions have a bug related to retrieving and	*/
		/* and setting a handler at the same time.		*/
	        (void) sigaction(SIGSEGV, 0, &old_segv_act);
	        (void) sigaction(SIGSEGV, &act, 0);
	        (void) sigaction(SIGBUS, 0, &old_bus_act);
	        (void) sigaction(SIGBUS, &act, 0);
#	  else
	        (void) sigaction(SIGSEGV, &act, &old_segv_act);
#		if defined(IRIX5) \
		   || defined(HPUX) || defined(HURD) || defined(NETBSD)
		    /* Under Irix 5.x or HP/UX, we may get SIGBUS.	*/
		    /* Pthreads doesn't exist under Irix 5.x, so we	*/
		    /* don't have to worry in the threads case.		*/
		    (void) sigaction(SIGBUS, &act, &old_bus_act);
#		endif
#	  endif	/* GC_IRIX_THREADS */
#	else
    	  old_segv_handler = signal(SIGSEGV, h);
#	  ifdef SIGBUS
	    old_bus_handler = signal(SIGBUS, h);
#	  endif
#	endif
    }
# endif /* NEED_FIND_LIMIT || UNIX_LIKE */

# ifdef NEED_FIND_LIMIT
  /* Some tools to implement HEURISTIC2	*/
#   define MIN_PAGE_SIZE 256	/* Smallest conceivable page size, bytes */
    /* static */ JMP_BUF GC_jmp_buf;
    
    /*ARGSUSED*/
    void GC_fault_handler(sig)
    int sig;
    {
        LONGJMP(GC_jmp_buf, 1);
    }

    void GC_setup_temporary_fault_handler()
    {
	GC_set_and_save_fault_handler(GC_fault_handler);
    }
    
    void GC_reset_fault_handler()
    {
#       if defined(SUNOS5SIGS) || defined(IRIX5) \
	   || defined(OSF1) || defined(HURD) || defined(NETBSD)
	  (void) sigaction(SIGSEGV, &old_segv_act, 0);
#	  if defined(IRIX5) \
	     || defined(HPUX) || defined(HURD) || defined(NETBSD)
	      (void) sigaction(SIGBUS, &old_bus_act, 0);
#	  endif
#       else
  	  (void) signal(SIGSEGV, old_segv_handler);
#	  ifdef SIGBUS
	    (void) signal(SIGBUS, old_bus_handler);
#	  endif
#       endif
    }

    /* Return the first nonaddressible location > p (up) or 	*/
    /* the smallest location q s.t. [q,p) is addressable (!up).	*/
    /* We assume that p (up) or p-1 (!up) is addressable.	*/
    ptr_t GC_find_limit(p, up)
    ptr_t p;
    GC_bool up;
    {
        static VOLATILE ptr_t result;
    		/* Needs to be static, since otherwise it may not be	*/
    		/* preserved across the longjmp.  Can safely be 	*/
    		/* static since it's only called once, with the		*/
    		/* allocation lock held.				*/


	GC_setup_temporary_fault_handler();
	if (SETJMP(GC_jmp_buf) == 0) {
	    result = (ptr_t)(((word)(p))
			      & ~(MIN_PAGE_SIZE-1));
	    for (;;) {
 	        if (up) {
		    result += MIN_PAGE_SIZE;
 	        } else {
		    result -= MIN_PAGE_SIZE;
 	        }
		GC_noop1((word)(*result));
	    }
	}
	GC_reset_fault_handler();
 	if (!up) {
	    result += MIN_PAGE_SIZE;
 	}
	return(result);
    }
# endif

#if defined(ECOS) || defined(NOSYS)
  ptr_t GC_get_stack_base()
  {
    return STACKBOTTOM;
  }
#endif

#ifdef HPUX_STACKBOTTOM

#include <sys/param.h>
#include <sys/pstat.h>

  ptr_t GC_get_register_stack_base(void)
  {
    struct pst_vm_status vm_status;

    int i = 0;
    while (pstat_getprocvm(&vm_status, sizeof(vm_status), 0, i++) == 1) {
      if (vm_status.pst_type == PS_RSESTACK) {
        return (ptr_t) vm_status.pst_vaddr;
      }
    }

    /* old way to get the register stackbottom */
    return (ptr_t)(((word)GC_stackbottom - BACKING_STORE_DISPLACEMENT - 1)
                   & ~(BACKING_STORE_ALIGNMENT - 1));
  }

#endif /* HPUX_STACK_BOTTOM */

#ifdef LINUX_STACKBOTTOM

#include <sys/types.h>
#include <sys/stat.h>

# define STAT_SKIP 27   /* Number of fields preceding startstack	*/
			/* field in /proc/self/stat			*/

#ifdef USE_LIBC_PRIVATES
# pragma weak __libc_stack_end
  extern ptr_t __libc_stack_end;
#endif

# ifdef IA64
    /* Try to read the backing store base from /proc/self/maps.	*/
    /* We look for the writable mapping with a 0 major device,  */
    /* which is	as close to our frame as possible, but below it.*/
    static word backing_store_base_from_maps(char *maps)
    {
      char prot_buf[5];
      char *buf_ptr = maps;
      word start, end;
      unsigned int maj_dev;
      word current_best = 0;
      word dummy;
  
      for (;;) {
        buf_ptr = GC_parse_map_entry(buf_ptr, &start, &end, prot_buf, &maj_dev);
	if (buf_ptr == NULL) return current_best;
	if (prot_buf[1] == 'w' && maj_dev == 0) {
	    if (end < (word)(&dummy) && start > current_best) current_best = start;
	}
      }
      return current_best;
    }