/* Functions for memory limit warnings.
   Copyright (C) 1990, 1992, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
                 2008, 2009, 2010  Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */

#ifdef emacs
#include <config.h>
#include <setjmp.h>
#include "lisp.h"
#endif

#include "mem-limits.h"

#ifdef HAVE_GETRLIMIT
#include <sys/resource.h>
#endif

/*
  Level number of warnings already issued.
  0 -- no warnings issued.
  1 -- 75% warning already issued.
  2 -- 85% warning already issued.
  3 -- 95% warning issued; keep warning frequently.
*/
enum warnlevel { not_warned, warned_75, warned_85, warned_95 };

static enum warnlevel warnlevel;

/* Function to call to issue a warning;
   0 means don't issue them.  */
static void (*warn_function) (const char *);

/* Start of data space; can be changed by calling malloc_init.  */
static POINTER data_space_start;

/* Number of bytes of writable memory we can expect to be able to get.  */
static unsigned long lim_data;


#if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
static void
get_lim_data (void)
{
  struct rlimit rlimit;

  getrlimit (RLIMIT_AS, &rlimit);
  if (rlimit.rlim_cur == RLIM_INFINITY)
    lim_data = -1;
  else
    lim_data = rlimit.rlim_cur;
}

#else /* not HAVE_GETRLIMIT */

#ifdef USG

static void
get_lim_data (void)
{
  extern long ulimit ();

  lim_data = -1;

  /* Use the ulimit call, if we seem to have it.  */
#if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
  lim_data = ulimit (3, 0);
#endif

  /* If that didn't work, just use the macro's value.  */
#ifdef ULIMIT_BREAK_VALUE
  if (lim_data == -1)
    lim_data = ULIMIT_BREAK_VALUE;
#endif

  lim_data -= (long) data_space_start;
}

#else /* not USG */
#ifdef WINDOWSNT

static void
get_lim_data (void)
{
  extern unsigned long reserved_heap_size;
  lim_data = reserved_heap_size;
}

#else
#if !defined (BSD4_2) && !defined (__osf__)

#ifdef MSDOS
void
get_lim_data (void)
{
  _go32_dpmi_meminfo info;
  unsigned long lim1, lim2;

  _go32_dpmi_get_free_memory_information (&info);
  /* DPMI server of Windows NT and its descendants reports in
     info.available_memory a much lower amount that is really
     available, which causes bogus "past 95% of memory limit"
     warnings.  Try to overcome that via circumstantial evidence.  */
  lim1 = info.available_memory;
  lim2 = info.available_physical_pages;
  /* DPMI Spec: "Fields that are unavailable will hold -1."  */
  if ((long)lim1 == -1L)
    lim1 = 0;
  if ((long)lim2 == -1L)
    lim2 = 0;
  else
    lim2 *= 4096;
  /* Surely, the available memory is at least what we have physically
     available, right?  */
  if (lim1 >= lim2)
    lim_data = lim1;
  else
    lim_data = lim2;
  /* Don't believe they will give us more that 0.5 GB.   */
  if (lim_data > 512U * 1024U * 1024U)
    lim_data = 512U * 1024U * 1024U;
}

unsigned long
ret_lim_data (void)
{
  get_lim_data ();
  return lim_data;
}
#else /* not MSDOS */
static void
get_lim_data (void)
{
  lim_data = vlimit (LIM_DATA, -1);
}
#endif /* not MSDOS */

#else /* BSD4_2 */

static void
get_lim_data (void)
{
  struct rlimit XXrlimit;

  getrlimit (RLIMIT_DATA, &XXrlimit);
#ifdef RLIM_INFINITY
  lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
#else
  lim_data = XXrlimit.rlim_cur;	/* soft limit */
#endif
}
#endif /* BSD4_2 */
#endif /* not WINDOWSNT */
#endif /* not USG */
#endif /* not HAVE_GETRLIMIT */

/* Verify amount of memory available, complaining if we're near the end. */

static void
check_memory_limits (void)
{
#ifdef REL_ALLOC
  extern POINTER (*real_morecore) ();
#endif
  extern POINTER (*__morecore) ();

  register POINTER cp;
  unsigned long five_percent;
  unsigned long data_size;
  enum warnlevel new_warnlevel;

  if (lim_data == 0)
    get_lim_data ();
  five_percent = lim_data / 20;

  /* Find current end of memory and issue warning if getting near max */
#ifdef REL_ALLOC
  if (real_morecore)
    cp = (char *) (*real_morecore) (0);
  else
#endif
  cp = (char *) (*__morecore) (0);
  data_size = (char *) cp - (char *) data_space_start;

  if (!warn_function)
    return;

  /* What level of warning does current memory usage demand?  */
  new_warnlevel
    = (data_size > five_percent * 19) ? warned_95
    : (data_size > five_percent * 17) ? warned_85
    : (data_size > five_percent * 15) ? warned_75
    : not_warned;

  /* If we have gone up a level, give the appropriate warning.  */
  if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
    {
      warnlevel = new_warnlevel;
      switch (warnlevel)
	{
	case warned_75:
	  (*warn_function) ("Warning: past 75% of memory limit");
	  break;

	case warned_85:
	  (*warn_function) ("Warning: past 85% of memory limit");
	  break;

	case warned_95:
	  (*warn_function) ("Warning: past 95% of memory limit");
	}
    }
  /* Handle going down in usage levels, with some hysteresis.  */
  else
    {
      /* If we go down below 70% full, issue another 75% warning
	 when we go up again.  */
      if (data_size < five_percent * 14)
	warnlevel = not_warned;
      /* If we go down below 80% full, issue another 85% warning
	 when we go up again.  */
      else if (warnlevel > warned_75 && data_size < five_percent * 16)
	warnlevel = warned_75;
      /* If we go down below 90% full, issue another 95% warning
	 when we go up again.  */
      else if (warnlevel > warned_85 && data_size < five_percent * 18)
	warnlevel = warned_85;
    }

  if (EXCEEDS_LISP_PTR (cp))
    (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
}

#if !defined(CANNOT_DUMP) || !defined(SYSTEM_MALLOC)
/* Some systems that cannot dump also cannot implement these.  */

/*
 *	Return the address of the start of the data segment prior to
 *	doing an unexec.  After unexec the return value is undefined.
 *	See crt0.c for further information and definition of data_start.
 *
 *	Apparently, on BSD systems this is etext at startup.  On
 *	USG systems (swapping) this is highly mmu dependent and
 *	is also dependent on whether or not the program is running
 *	with shared text.  Generally there is a (possibly large)
 *	gap between end of text and start of data with shared text.
 *
 */

POINTER
start_of_data (void)
{
#ifdef BSD_SYSTEM
  extern char etext;
  return (POINTER)(&etext);
#elif defined DATA_START
  return ((POINTER) DATA_START);
#elif defined ORDINARY_LINK
  /*
   * This is a hack.  Since we're not linking crt0.c or pre_crt0.c,
   * data_start isn't defined.  We take the address of environ, which
   * is known to live at or near the start of the system crt0.c, and
   * we don't sweat the handful of bytes that might lose.
   */
  extern char **environ;
  return ((POINTER) &environ);
#else
  extern int data_start;
  return ((POINTER) &data_start);
#endif
}
#endif /* (not CANNOT_DUMP or not SYSTEM_MALLOC) */

/* Enable memory usage warnings.
   START says where the end of pure storage is.
   WARNFUN specifies the function to call to issue a warning.  */

void
memory_warnings (POINTER start, void (*warnfun) (const char *))
{
  extern void (* __after_morecore_hook) (void);     /* From gmalloc.c */

  if (start)
    data_space_start = start;
  else
    data_space_start = start_of_data ();

  warn_function = warnfun;
  __after_morecore_hook = check_memory_limits;

  /* Force data limit to be recalculated on each run.  */
  lim_data = 0;
}

/* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
   (do not change this comment) */