#ifdef HAS_UNIX_SEGMENT_HACK

#include <signal.h>
#include <setjmp.h>

/*
 * baseaddr( ) returns the base address of the data segment on most Unix
 * systems.  It's an ugly hack for info that should be provided by the OS.
 */

/* Does anyone use a pagesize < 256 bytes??  I'll bet not;
 * too small doesn't hurt
 */

#define LOG2_PAGESIZE	8

static jmp_buf	env;

static SIGNAL_TYPE
fault( )
{
        sysv_signal(SIGSEGV, (SIGNAL_FUNCTION) fault);	/* SysV style */
	longjmp(env, 1);
}

static void *
baseaddr( )
{
	char *low, *high, *at;
	char *sbrk( );
	long x;
	SIGNAL_TYPE	(*orig_signal)( );

	if (getenv("SPICE_NO_DATASEG_CHECK"))
		return 0;

	low = 0;
	high = (char *) ((unsigned long) sbrk(0) & ~((1 << LOG2_PAGESIZE) - 1));

		orig_signal = sysv_signal(SIGSEGV, (SIGNAL_FUNCTION) fault);

	do {

		at = (char *) ((((long)low >> LOG2_PAGESIZE)
			+ ((long)high >> LOG2_PAGESIZE))
			<< (LOG2_PAGESIZE - 1));
#  ifdef notdef
		at = (char *) ((((int) low + (int) high) / 2 + 0x7ff)
			& ~(long) 0xfff);
			/* nearest page */
#  endif
#  ifdef notdef
		printf(
		"high = %#8x    low = %#8x     at = %#8x\n",
			high, low, at);
#  endif

		if (at == low || at == high) {
			break;
		}

		if (setjmp(env)) {
			low = at;
			continue;
		} else
			x = *at;

		if (setjmp(env)) {
			low = at;
			continue;
		} else
			*at = x;

		high = at;

	} while (1);

#  ifdef notdef
	printf ("start is at %#x, end is at %#x\n", high, sbrk(0));
#  endif
	(void) signal(SIGSEGV, (SIGNAL_FUNCTION) orig_signal);
	return (void *) high;
}

#  ifdef notdef
main( )
{
	printf("testing\n");
	printf("baseaddr: %#8x  topaddr: %#8x\n", baseaddr( ), sbrk(0));
}
#  endif

#else

static void *
baseaddr( )
{
	return 0;
}

#endif