view src/malloc.c @ 665:fdefd0186b75

[xemacs-hg @ 2001-09-20 06:28:42 by ben] The great integral types renaming. The purpose of this is to rationalize the names used for various integral types, so that they match their intended uses and follow consist conventions, and eliminate types that were not semantically different from each other. The conventions are: -- All integral types that measure quantities of anything are signed. Some people disagree vociferously with this, but their arguments are mostly theoretical, and are vastly outweighed by the practical headaches of mixing signed and unsigned values, and more importantly by the far increased likelihood of inadvertent bugs: Because of the broken "viral" nature of unsigned quantities in C (operations involving mixed signed/unsigned are done unsigned, when exactly the opposite is nearly always wanted), even a single error in declaring a quantity unsigned that should be signed, or even the even more subtle error of comparing signed and unsigned values and forgetting the necessary cast, can be catastrophic, as comparisons will yield wrong results. -Wsign-compare is turned on specifically to catch this, but this tends to result in a great number of warnings when mixing signed and unsigned, and the casts are annoying. More has been written on this elsewhere. -- All such quantity types just mentioned boil down to EMACS_INT, which is 32 bits on 32-bit machines and 64 bits on 64-bit machines. This is guaranteed to be the same size as Lisp objects of type `int', and (as far as I can tell) of size_t (unsigned!) and ssize_t. The only type below that is not an EMACS_INT is Hashcode, which is an unsigned value of the same size as EMACS_INT. -- Type names should be relatively short (no more than 10 characters or so), with the first letter capitalized and no underscores if they can at all be avoided. -- "count" == a zero-based measurement of some quantity. Includes sizes, offsets, and indexes. -- "bpos" == a one-based measurement of a position in a buffer. "Charbpos" and "Bytebpos" count text in the buffer, rather than bytes in memory; thus Bytebpos does not directly correspond to the memory representation. Use "Membpos" for this. -- "Char" refers to internal-format characters, not to the C type "char", which is really a byte. -- For the actual name changes, see the script below. I ran the following script to do the conversion. (NOTE: This script is idempotent. You can safely run it multiple times and it will not screw up previous results -- in fact, it will do nothing if nothing has changed. Thus, it can be run repeatedly as necessary to handle patches coming in from old workspaces, or old branches.) There are two tags, just before and just after the change: `pre-integral-type-rename' and `post-integral-type-rename'. When merging code from the main trunk into a branch, the best thing to do is first merge up to `pre-integral-type-rename', then apply the script and associated changes, then merge from `post-integral-type-change' to the present. (Alternatively, just do the merging in one operation; but you may then have a lot of conflicts needing to be resolved by hand.) Script `fixtypes.sh' follows: ----------------------------------- cut ------------------------------------ files="*.[ch] s/*.h m/*.h config.h.in ../configure.in Makefile.in.in ../lib-src/*.[ch] ../lwlib/*.[ch]" gr Memory_Count Bytecount $files gr Lstream_Data_Count Bytecount $files gr Element_Count Elemcount $files gr Hash_Code Hashcode $files gr extcount bytecount $files gr bufpos charbpos $files gr bytind bytebpos $files gr memind membpos $files gr bufbyte intbyte $files gr Extcount Bytecount $files gr Bufpos Charbpos $files gr Bytind Bytebpos $files gr Memind Membpos $files gr Bufbyte Intbyte $files gr EXTCOUNT BYTECOUNT $files gr BUFPOS CHARBPOS $files gr BYTIND BYTEBPOS $files gr MEMIND MEMBPOS $files gr BUFBYTE INTBYTE $files gr MEMORY_COUNT BYTECOUNT $files gr LSTREAM_DATA_COUNT BYTECOUNT $files gr ELEMENT_COUNT ELEMCOUNT $files gr HASH_CODE HASHCODE $files ----------------------------------- cut ------------------------------------ `fixtypes.sh' is a Bourne-shell script; it uses 'gr': ----------------------------------- cut ------------------------------------ #!/bin/sh # Usage is like this: # gr FROM TO FILES ... # globally replace FROM with TO in FILES. FROM and TO are regular expressions. # backup files are stored in the `backup' directory. from="$1" to="$2" shift 2 echo ${1+"$@"} | xargs global-replace "s/$from/$to/g" ----------------------------------- cut ------------------------------------ `gr' in turn uses a Perl script to do its real work, `global-replace', which follows: ----------------------------------- cut ------------------------------------ : #-*- Perl -*- ### global-modify --- modify the contents of a file by a Perl expression ## Copyright (C) 1999 Martin Buchholz. ## Copyright (C) 2001 Ben Wing. ## Authors: Martin Buchholz <martin@xemacs.org>, Ben Wing <ben@xemacs.org> ## Maintainer: Ben Wing <ben@xemacs.org> ## Current Version: 1.0, May 5, 2001 # This program 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 2, or (at your option) # any later version. # # This program 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 XEmacs; see the file COPYING. If not, write to the Free # Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA # 02111-1307, USA. eval 'exec perl -w -S $0 ${1+"$@"}' if 0; use strict; use FileHandle; use Carp; use Getopt::Long; use File::Basename; (my $myName = $0) =~ s@.*/@@; my $usage=" Usage: $myName [--help] [--backup-dir=DIR] [--line-mode] [--hunk-mode] PERLEXPR FILE ... Globally modify a file, either line by line or in one big hunk. Typical usage is like this: [with GNU print, GNU xargs: guaranteed to handle spaces, quotes, etc. in file names] find . -name '*.[ch]' -print0 | xargs -0 $0 's/\bCONST\b/const/g'\n [with non-GNU print, xargs] find . -name '*.[ch]' -print | xargs $0 's/\bCONST\b/const/g'\n The file is read in, either line by line (with --line-mode specified) or in one big hunk (with --hunk-mode specified; it's the default), and the Perl expression is then evalled with \$_ set to the line or hunk of text, including the terminating newline if there is one. It should destructively modify the value there, storing the changed result in \$_. Files in which any modifications are made are backed up to the directory specified using --backup-dir, or to `backup' by default. To disable this, use --backup-dir= with no argument. Hunk mode is the default because it is MUCH MUCH faster than line-by-line. Use line-by-line only when it matters, e.g. you want to do a replacement only once per line (the default without the `g' argument). Conversely, when using hunk mode, *ALWAYS* use `g'; otherwise, you will only make one replacement in the entire file! "; my %options = (); $Getopt::Long::ignorecase = 0; &GetOptions ( \%options, 'help', 'backup-dir=s', 'line-mode', 'hunk-mode', ); die $usage if $options{"help"} or @ARGV <= 1; my $code = shift; die $usage if grep (-d || ! -w, @ARGV); sub SafeOpen { open ((my $fh = new FileHandle), $_[0]); confess "Can't open $_[0]: $!" if ! defined $fh; return $fh; } sub SafeClose { close $_[0] or confess "Can't close $_[0]: $!"; } sub FileContents { my $fh = SafeOpen ("< $_[0]"); my $olddollarslash = $/; local $/ = undef; my $contents = <$fh>; $/ = $olddollarslash; return $contents; } sub WriteStringToFile { my $fh = SafeOpen ("> $_[0]"); binmode $fh; print $fh $_[1] or confess "$_[0]: $!\n"; SafeClose $fh; } foreach my $file (@ARGV) { my $changed_p = 0; my $new_contents = ""; if ($options{"line-mode"}) { my $fh = SafeOpen $file; while (<$fh>) { my $save_line = $_; eval $code; $changed_p = 1 if $save_line ne $_; $new_contents .= $_; } } else { my $orig_contents = $_ = FileContents $file; eval $code; if ($_ ne $orig_contents) { $changed_p = 1; $new_contents = $_; } } if ($changed_p) { my $backdir = $options{"backup-dir"}; $backdir = "backup" if !defined ($backdir); if ($backdir) { my ($name, $path, $suffix) = fileparse ($file, ""); my $backfulldir = $path . $backdir; my $backfile = "$backfulldir/$name"; mkdir $backfulldir, 0755 unless -d $backfulldir; print "modifying $file (original saved in $backfile)\n"; rename $file, $backfile; } WriteStringToFile ($file, $new_contents); } } ----------------------------------- cut ------------------------------------ In addition to those programs, I needed to fix up a few other things, particularly relating to the duplicate definitions of types, now that some types merged with others. Specifically: 1. in lisp.h, removed duplicate declarations of Bytecount. The changed code should now look like this: (In each code snippet below, the first and last lines are the same as the original, as are all lines outside of those lines. That allows you to locate the section to be replaced, and replace the stuff in that section, verifying that there isn't anything new added that would need to be kept.) --------------------------------- snip ------------------------------------- /* Counts of bytes or chars */ typedef EMACS_INT Bytecount; typedef EMACS_INT Charcount; /* Counts of elements */ typedef EMACS_INT Elemcount; /* Hash codes */ typedef unsigned long Hashcode; /* ------------------------ dynamic arrays ------------------- */ --------------------------------- snip ------------------------------------- 2. in lstream.h, removed duplicate declaration of Bytecount. Rewrote the comment about this type. The changed code should now look like this: --------------------------------- snip ------------------------------------- #endif /* The have been some arguments over the what the type should be that specifies a count of bytes in a data block to be written out or read in, using Lstream_read(), Lstream_write(), and related functions. Originally it was long, which worked fine; Martin "corrected" these to size_t and ssize_t on the grounds that this is theoretically cleaner and is in keeping with the C standards. Unfortunately, this practice is horribly error-prone due to design flaws in the way that mixed signed/unsigned arithmetic happens. In fact, by doing this change, Martin introduced a subtle but fatal error that caused the operation of sending large mail messages to the SMTP server under Windows to fail. By putting all values back to be signed, avoiding any signed/unsigned mixing, the bug immediately went away. The type then in use was Lstream_Data_Count, so that it be reverted cleanly if a vote came to that. Now it is Bytecount. Some earlier comments about why the type must be signed: This MUST BE SIGNED, since it also is used in functions that return the number of bytes actually read to or written from in an operation, and these functions can return -1 to signal error. Note that the standard Unix read() and write() functions define the count going in as a size_t, which is UNSIGNED, and the count going out as an ssize_t, which is SIGNED. This is a horrible design flaw. Not only is it highly likely to lead to logic errors when a -1 gets interpreted as a large positive number, but operations are bound to fail in all sorts of horrible ways when a number in the upper-half of the size_t range is passed in -- this number is unrepresentable as an ssize_t, so code that checks to see how many bytes are actually written (which is mandatory if you are dealing with certain types of devices) will get completely screwed up. --ben */ typedef enum lstream_buffering --------------------------------- snip ------------------------------------- 3. in dumper.c, there are four places, all inside of switch() statements, where XD_BYTECOUNT appears twice as a case tag. In each case, the two case blocks contain identical code, and you should *REMOVE THE SECOND* and leave the first.
author ben
date Thu, 20 Sep 2001 06:31:11 +0000
parents b39c14581166
children 13e47461d509
line wrap: on
line source

/* dynamic memory allocation for GNU.
   Copyright (C) 1985, 1987 Free Software Foundation, Inc.

		       NO WARRANTY

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/* Synched up with: Not synched with FSF. */


/*
 * @(#)nmalloc.c 1 (Caltech) 2/21/82
 *
 *	U of M Modified: 20 Jun 1983 ACT: strange hacks for Emacs
 *
 *	Nov 1983, Mike@BRL, Added support for 4.1C/4.2 BSD.
 *
 * This is a very fast storage allocator.  It allocates blocks of a small 
 * number of different sizes, and keeps free lists of each size.  Blocks
 * that don't exactly fit are passed up to the next larger size.  In this 
 * implementation, the available sizes are (2^n)-4 (or -16) bytes long.
 * This is designed for use in a program that uses vast quantities of
 * memory, but bombs when it runs out.  To make it a little better, it
 * warns the user when he starts to get near the end.
 *
 * June 84, ACT: modified rcheck code to check the range given to malloc,
 * rather than the range determined by the 2-power used.
 *
 * Jan 85, RMS: calls malloc_warning to issue warning on nearly full.
 * No longer Emacs-specific; can serve as all-purpose malloc for GNU.
 * You should call malloc_init to reinitialize after loading dumped Emacs.
 * Call malloc_stats to get info on memory stats if MSTATS turned on.
 * realloc knows how to return same block given, just changing its size,
 * if the power of 2 is correct.
 */

/*
 * nextf[i] is the pointer to the next free block of size 2^(i+3).  The
 * smallest allocatable block is 8 bytes.  The overhead information will
 * go in the first int of the block, and the returned pointer will point
 * to the second.
 *
#ifdef MSTATS
 * nmalloc[i] is the difference between the number of mallocs and frees
 * for a given block size.
#endif MSTATS
 */

#ifdef emacs
/* config.h specifies which kind of system this is.  */
#include <config.h>
#else

/* Determine which kind of system this is.  */
#include <signal.h>
#ifndef SIGTSTP
#ifndef USG
#define USG
#endif
#else /* SIGTSTP */
#ifdef SIGIO
#define BSD4_2
#endif /* SIGIO */
#endif /* SIGTSTP */

#if defined(hpux)
#define USG
#endif

#endif /* not emacs */

#include <stddef.h>

/* Define getpagesize () if the system does not.  */
#include "getpagesize.h"

#ifdef HAVE_ULIMIT_H
#include <ulimit.h>
#endif

#ifndef BSD4_2
#ifndef USG
#include <sys/vlimit.h>		/* warn the user when near the end */
#endif /* not USG */
#else /* if BSD4_2 */
#include <sys/time.h>
#include <sys/resource.h>
#endif /* BSD4_2 */

#ifdef __STDC__
#ifndef HPUX
/* not sure where this for NetBSD should really go
   and it probably applies to other systems */
#if !defined(__NetBSD__) && !defined(__bsdi__) && !defined(__OpenBSD__)
extern void *sbrk (ptrdiff_t);
#else
extern char *sbrk ();
#endif /* __NetBSD__ or __OpenBSD__ */
#endif /* HPUX */
#else
extern void *sbrk ();
#endif /* __STDC__ */

extern char *start_of_data (void);

#ifdef BSD
#define start_of_data() &etext
#endif

#ifndef emacs
#define start_of_data() &etext
#endif

#define ISALLOC ((char) 0xf7)	/* magic byte that implies allocation */
#define ISFREE ((char) 0x54)	/* magic byte that implies free block */
				/* this is for error checking only */
#define ISMEMALIGN ((char) 0xd6)  /* Stored before the value returned by
				     memalign, with the rest of the word
				     being the distance to the true
				     beginning of the block.  */

extern char etext;

/* These two are for user programs to look at, when they are interested.  */

Bytecount malloc_sbrk_used;       /* amount of data space used now */
Bytecount malloc_sbrk_unused;     /* amount more we can have */

/* start of data space; can be changed by calling init_malloc */
static char *data_space_start;

#ifdef MSTATS
static int nmalloc[30];
static int nmal, nfre;
#endif /* MSTATS */

/* If range checking is not turned on, all we have is a flag indicating
   whether memory is allocated, an index in nextf[], and a size field; to
   realloc() memory we copy either size bytes or 1<<(index+3) bytes depending
   on whether the former can hold the exact size (given the value of
   'index').  If range checking is on, we always need to know how much space
   is allocated, so the 'size' field is never used. */

struct mhead {
	char     mh_alloc;	/* ISALLOC or ISFREE */
	char     mh_index;	/* index in nextf[] */
/* Remainder are valid only when block is allocated */
	unsigned short mh_size;	/* size, if < 0x10000 */
#ifdef rcheck
	unsigned mh_nbytes;	/* number of bytes allocated */
	int      mh_magic4;	/* should be == MAGIC4 */
#endif /* rcheck */
};

/* Access free-list pointer of a block.
  It is stored at block + 4.
  This is not a field in the mhead structure
  because we want sizeof (struct mhead)
  to describe the overhead for when the block is in use,
  and we do not want the free-list pointer to count in that.  */

#define CHAIN(a) \
  (*(struct mhead **) (sizeof (char *) + (char *) (a)))

#ifdef rcheck

/* To implement range checking, we write magic values in at the beginning and
   end of each allocated block, and make sure they are undisturbed whenever a
   free or a realloc occurs. */
/* Written in each of the 4 bytes following the block's real space */
#define MAGIC1 0x55
/* Written in the 4 bytes before the block's real space */
#define MAGIC4 0x55555555
#define ASSERT(p) if (!(p)) botch("p"); else
#define EXTRA  4		/* 4 bytes extra for MAGIC1s */
#else
#define ASSERT(p)
#define EXTRA  0
#endif /* rcheck */


/* nextf[i] is free list of blocks of size 2**(i + 3)  */

static struct mhead *nextf[30];

/* busy[i] is nonzero while allocation of block size i is in progress.  */

static char busy[30];

/* Number of bytes of writable memory we can expect to be able to get */
extern unsigned int lim_data;

/* Level number of warnings already issued.
  0 -- no warnings issued.
  1 -- 75% warning already issued.
  2 -- 85% warning already issued.
*/
static int warnlevel;

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

/* nonzero once initial bunch of free blocks made */
static int gotpool;

char *_malloc_base;

static void getpool (void);

/* Cause reinitialization based on job parameters;
  also declare where the end of pure storage is. */
void
malloc_init (start, warnfun)
     char *start;
     void (*warnfun) ();
{
  if (start)
    data_space_start = start;
  lim_data = 0;
  warnlevel = 0;
  warnfunction = warnfun;
}

/* Return the maximum size to which MEM can be realloc'd
   without actually requiring copying.  */

int
malloc_usable_size (mem)
     char *mem;
{
  int blocksize = 8 << (((struct mhead *) mem) - 1) -> mh_index;

  return blocksize - sizeof (struct mhead) - EXTRA;
}

static void get_lim_data ();

static void
morecore (nu)			/* ask system for more memory */
     int nu;		/* size index to get more of  */
{
  char *cp;
  int nblks;
  unsigned int siz;
  int oldmask;

#ifdef BSD
#ifndef BSD4_1
  /* ?? There was a suggestion not to block SIGILL, somehow for GDB's sake.  */
  oldmask = sigsetmask (-1);
#endif
#endif

  if (!data_space_start)
    {
      data_space_start = start_of_data ();
    }

  if (lim_data == 0)
    get_lim_data ();

 /* On initial startup, get two blocks of each size up to 1k bytes */
  if (!gotpool)
    { getpool (); getpool (); gotpool = 1; }

  /* Find current end of memory and issue warning if getting near max */

  cp = sbrk (0);
  siz = cp - data_space_start;

  if (warnfunction)
    switch (warnlevel)
      {
      case 0: 
	if (siz > (lim_data / 4) * 3)
	  {
	    warnlevel++;
	    (*warnfunction) ("Warning: past 75% of memory limit");
	  }
	break;
      case 1: 
	if (siz > (lim_data / 20) * 17)
	  {
	    warnlevel++;
	    (*warnfunction) ("Warning: past 85% of memory limit");
	  }
	break;
      case 2: 
	if (siz > (lim_data / 20) * 19)
	  {
	    warnlevel++;
	    (*warnfunction) ("Warning: past 95% of memory limit");
	  }
	break;
      }

  if ((int) cp & 0x3ff)	/* land on 1K boundaries */
    sbrk (1024 - ((int) cp & 0x3ff));

 /* Take at least 2k, and figure out how many blocks of the desired size
    we're about to get */
  nblks = 1;
  if ((siz = nu) < 8)
    nblks = 1 << ((siz = 8) - nu);

  if ((cp = sbrk (1 << (siz + 3))) == (char *) -1)
    {
#ifdef BSD
#ifndef BSD4_1
      sigsetmask (oldmask);
#endif
#endif
      return;			/* no more room! */
    }
  malloc_sbrk_used = siz;
  malloc_sbrk_unused = lim_data - siz;

  if ((int) cp & 7)
    {		/* shouldn't happen, but just in case */
      cp = (char *) (((int) cp + 8) & ~7);
      nblks--;
    }

 /* save new header and link the nblks blocks together */
  nextf[nu] = (struct mhead *) cp;
  siz = 1 << (nu + 3);
  while (1)
    {
      ((struct mhead *) cp) -> mh_alloc = ISFREE;
      ((struct mhead *) cp) -> mh_index = nu;
      if (--nblks <= 0) break;
      CHAIN ((struct mhead *) cp) = (struct mhead *) (cp + siz);
      cp += siz;
    }
  CHAIN ((struct mhead *) cp) = 0;

#ifdef BSD
#ifndef BSD4_1
  sigsetmask (oldmask);
#endif
#endif
}

static void
getpool (void)
{
  int nu;
  char *cp = sbrk (0);

  if ((int) cp & 0x3ff)	/* land on 1K boundaries */
    sbrk (1024 - ((int) cp & 0x3ff));

  /* Record address of start of space allocated by malloc.  */
  if (_malloc_base == 0)
    _malloc_base = cp;

  /* Get 2k of storage */

  cp = sbrk (04000);
  if (cp == (char *) -1)
    return;

  /* Divide it into an initial 8-word block
     plus one block of size 2**nu for nu = 3 ... 10.  */

  CHAIN (cp) = nextf[0];
  nextf[0] = (struct mhead *) cp;
  ((struct mhead *) cp) -> mh_alloc = ISFREE;
  ((struct mhead *) cp) -> mh_index = 0;
  cp += 8;

  for (nu = 0; nu < 7; nu++)
    {
      CHAIN (cp) = nextf[nu];
      nextf[nu] = (struct mhead *) cp;
      ((struct mhead *) cp) -> mh_alloc = ISFREE;
      ((struct mhead *) cp) -> mh_index = nu;
      cp += 8 << nu;
    }
}

char *
malloc (n)		/* get a block */
     unsigned n;
{
  struct mhead *p;
  unsigned int nbytes;
  int nunits = 0;

  /* Figure out how many bytes are required, rounding up to the nearest
     multiple of 8, then figure out which nestf[] area to use.
     Both the beginning of the header and the beginning of the
     block should be on an eight byte boundary.  */
  nbytes = (n + ((sizeof (*p) + 7) & ~7) + EXTRA + 7) & ~7;
  {
    unsigned int   shiftr = (nbytes - 1) >> 2;

    while (shiftr >>= 1)
      nunits++;
  }

  /* In case this is reentrant use of malloc from signal handler,
     pick a block size that no other malloc level is currently
     trying to allocate.  That's the easiest harmless way not to
     interfere with the other level of execution.  */
  while (busy[nunits]) nunits++;
  busy[nunits] = 1;

  /* If there are no blocks of the appropriate size, go get some */
  /* COULD SPLIT UP A LARGER BLOCK HERE ... ACT */
  if (nextf[nunits] == 0)
    morecore (nunits);

  /* Get one block off the list, and set the new list head */
  if ((p = nextf[nunits]) == 0)
    {
      busy[nunits] = 0;
      return 0;
    }
  nextf[nunits] = CHAIN (p);
  busy[nunits] = 0;

  /* Check for free block clobbered */
  /* If not for this check, we would gobble a clobbered free chain ptr */
  /* and bomb out on the NEXT allocate of this size block */
  if (p -> mh_alloc != ISFREE || p -> mh_index != nunits)
#ifdef rcheck
    botch ("block on free list clobbered");
#else /* not rcheck */
    abort ();
#endif /* not rcheck */

  /* Fill in the info, and if range checking, set up the magic numbers */
  p -> mh_alloc = ISALLOC;
#ifdef rcheck
  p -> mh_nbytes = n;
  p -> mh_magic4 = MAGIC4;
  {
    /* Get the location n after the beginning of the user's space.  */
    char *m = (char *) p + ((sizeof (*p) + 7) & ~7) + n;

    *m++ = MAGIC1, *m++ = MAGIC1, *m++ = MAGIC1, *m = MAGIC1;
  }
#else /* not rcheck */
  p -> mh_size = n;
#endif /* not rcheck */
#ifdef MSTATS
  nmalloc[nunits]++;
  nmal++;
#endif /* MSTATS */
  return (char *) p + ((sizeof (*p) + 7) & ~7);
}

void
free (mem)
     char *mem;
{
  struct mhead *p;
  {
    char *ap = mem;

    if (ap == 0)
      return;

    p = (struct mhead *) (ap - ((sizeof (*p) + 7) & ~7));
    if (p -> mh_alloc == ISMEMALIGN)
      {
	ap -= p->mh_size;
	p = (struct mhead *) (ap - ((sizeof (*p) + 7) & ~7));
      }

#ifndef rcheck
    if (p -> mh_alloc != ISALLOC)
      abort ();

#else /* rcheck */
    if (p -> mh_alloc != ISALLOC)
      {
	if (p -> mh_alloc == ISFREE)
	  botch ("free: Called with already freed block argument\n");
	else
	  botch ("free: Called with bad argument\n");
      }

    ASSERT (p -> mh_magic4 == MAGIC4);
    ap += p -> mh_nbytes;
    ASSERT (*ap++ == MAGIC1); ASSERT (*ap++ == MAGIC1);
    ASSERT (*ap++ == MAGIC1); ASSERT (*ap   == MAGIC1);
#endif /* rcheck */
  }
  {
    int nunits = p -> mh_index;

    ASSERT (nunits <= 29);
    p -> mh_alloc = ISFREE;

    /* Protect against signal handlers calling malloc.  */
    busy[nunits] = 1;
    /* Put this block on the free list.  */
    CHAIN (p) = nextf[nunits];
    nextf[nunits] = p;
    busy[nunits] = 0;

#ifdef MSTATS
    nmalloc[nunits]--;
    nfre++;
#endif /* MSTATS */
  }
}

char *
realloc (mem, n)
     char *mem;
     unsigned n;
{
  struct mhead *p;
  unsigned int tocopy;
  unsigned int nbytes;
  int nunits;

  if (mem == 0)
    return malloc (n);
  p = (struct mhead *) (mem - ((sizeof (*p) + 7) & ~7));
  nunits = p -> mh_index;
  ASSERT (p -> mh_alloc == ISALLOC);
#ifdef rcheck
  ASSERT (p -> mh_magic4 == MAGIC4);
  {
    char *m = mem + (tocopy = p -> mh_nbytes);
    ASSERT (*m++ == MAGIC1); ASSERT (*m++ == MAGIC1);
    ASSERT (*m++ == MAGIC1); ASSERT (*m   == MAGIC1);
  }
#else /* not rcheck */
  if (p -> mh_index >= 13)
    tocopy = (1 << (p -> mh_index + 3)) - ((sizeof (*p) + 7) & ~7);
  else
    tocopy = p -> mh_size;
#endif /* not rcheck */

  /* See if desired size rounds to same power of 2 as actual size. */
  nbytes = (n + ((sizeof (*p) + 7) & ~7) + EXTRA + 7) & ~7;

  /* If ok, use the same block, just marking its size as changed.  */
  if (nbytes > (4 << nunits) && nbytes <= (8 << nunits))
    {
#ifdef rcheck
      char *m = mem + tocopy;
      *m++ = 0;  *m++ = 0;  *m++ = 0;  *m++ = 0;
      p-> mh_nbytes = n;
      m = mem + n;
      *m++ = MAGIC1;  *m++ = MAGIC1;  *m++ = MAGIC1;  *m++ = MAGIC1;
#else /* not rcheck */
      p -> mh_size = n;
#endif /* not rcheck */
      return mem;
    }

  if (n < tocopy)
    tocopy = n;
  {
    char *new;

    if ((new = malloc (n)) == 0)
      return 0;
    memcpy (new, mem, tocopy);
    free (mem);
    return new;
  }
}


char *
memalign (alignment, size)
     unsigned alignment, size;
{
  char *ptr = malloc (size + alignment);
  char *aligned;
  struct mhead *p;

  if (ptr == 0)
    return 0;
  /* If entire block has the desired alignment, just accept it.  */
  if (((int) ptr & (alignment - 1)) == 0)
    return ptr;
  /* Otherwise, get address of byte in the block that has that alignment.  */
  aligned = (char *) (((int) ptr + alignment - 1) & -alignment);

  /* Store a suitable indication of how to free the block,
     so that free can find the true beginning of it.  */
  p = (struct mhead *) aligned - 1;
  p -> mh_size = aligned - ptr;
  p -> mh_alloc = ISMEMALIGN;
  return aligned;
}

#ifndef __hpux
/* This runs into trouble with getpagesize on HPUX.
   Patching out seems cleaner than the ugly fix needed.  */
char *
valloc (size)
unsigned size;
{
  return memalign (getpagesize (), size);
}
#endif /* not __hpux */

#ifdef MSTATS
/* Return statistics describing allocation of blocks of size 2**n. */

struct mstats_value
  {
    int blocksize;
    int nfree;
    int nused;
  };

struct mstats_value
malloc_stats (size)
     int size;
{
  struct mstats_value v;
  int i;
  struct mhead *p;

  v.nfree = 0;

  if (size < 0 || size >= 30)
    {
      v.blocksize = 0;
      v.nused = 0;
      return v;
    }

  v.blocksize = 1 << (size + 3);
  v.nused = nmalloc[size];

  for (p = nextf[size]; p; p = CHAIN (p))
    v.nfree++;

  return v;
}
int
malloc_mem_used (void)
{
  int i;
  int size_used;

  size_used = 0;
  
  for (i = 0; i < 30; i++)
    {
      int allocation_size = 1 << (i + 3);
      struct mhead *p;
      
      size_used += nmalloc[i] * allocation_size;
    }

  return size_used;
}

int 
malloc_mem_free (void)
{
  int i;
  int size_unused;

  size_unused = 0;
  
  for (i = 0; i < 30; i++)
    {
      int allocation_size = 1 << (i + 3);
      struct mhead *p;
      
      for (p = nextf[i]; p ; p = CHAIN (p))
	size_unused += allocation_size;
    }

  return size_unused;
}
#endif /* MSTATS */

/*
 *	This function returns the total number of bytes that the process
 *	will be allowed to allocate via the sbrk(2) system call.  On
 *	BSD systems this is the total space allocatable to stack and
 *	data.  On USG systems this is the data space only.
 */

#ifdef USG

static void
get_lim_data (void)
{
#ifdef ULIMIT_BREAK_VALUE
  lim_data = ULIMIT_BREAK_VALUE;
#else
  lim_data = ulimit (3, 0);
#endif

  lim_data -= (long) data_space_start;
}

#else /* not USG */
#ifndef BSD4_2

static void
get_lim_data (void)
{
  lim_data = vlimit (LIM_DATA, -1);
}

#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 USG */