⟦151cc7e34⟧

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#ifndef lint
static char rcsid[] =
	"$Header: allocate.c,v 2.9 88/01/13 18:45:34 deboor Exp $";

static char notice[] =
	"This program is in the public domain and is available for unlimited \
distribution as long as this notice is enclosed.";
#endif
/*
** for memory allocation with single punt() calls!
**
** $Source: /c/support/deboor/usr/src/old/vmh/RCS/allocate.c,v $
** $Revision: 2.9 $
** $Author: deboor $
**
** FUNCTIONS:
**	_Calloc		front end for calloc() -- no NULL returns
**	_Free		non-useful front-end for free()
**	_Malloc		front-end for malloc() -- no NULL returns
**	abortcatch	non-useful abort() handler [abort won't be handled]
**	free		signal-blocking free() routine
**	malloc		signal-blocking malloc() routine
**	newstr		return copy of passed-in string
**	realloc		signal-blocking reallocation routine
*/

# include "vmh.h"

char	*calloc();
/*
** the following is taken from the standard 4.3 C library. I need
** to have it to be able to block signals when people like curses
** and stdio are using it. sigh.
*/

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

/*
 * malloc.c (Caltech) 2/21/82
 * Chris Kingsley, kingsley@cit-20.
 *
 * 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 2^n-12) bytes long.
 * This is designed for use in a program that uses vast quantities of memory,
 * but bombs when it runs out. 
 */

#define	NULL 0

/*
 * The overhead on a block is at least 4 bytes.  When free, this space
 * contains a pointer to the next free block, and the bottom two bits must
 * be zero.  When in use, the first byte is set to MAGIC, and the second
 * byte is the size index.  The remaining bytes are for alignment.
 * If range checking is enabled and the size of the block fits
 * in two bytes, then the top two bytes hold the size of the requested block
 * plus the range checking words, and the header word MINUS ONE.
 */
union	overhead {
	union	overhead *ov_next;	/* when free */
	struct {
#ifndef RCHECK
		u_char	ovu_magic;	/* magic number */
		u_char	ovu_index;	/* bucket # */
#else
		u_int	ovu_size;	/* actual block size */
		u_char	ovu_magic;	/* magic number */
		u_char	ovu_index;	/* bucket # */
		u_short	ovu_rmagic;	/* range magic number */
#endif
	} ovu;
#define	ov_magic	ovu.ovu_magic
#define	ov_index	ovu.ovu_index
#define	ov_rmagic	ovu.ovu_rmagic
#define	ov_size		ovu.ovu_size
};

#define	MAGIC		0xef		/* magic # on accounting info */
#define RMAGIC		0x5555		/* magic # on range info */

#ifdef RCHECK
#define	RSLOP		sizeof (u_short)
#else
#define	RSLOP		0
#endif

/*
 * 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
 * precedes the data area returned to the user.
 */
#define	NBUCKETS 30
static	union overhead *nextf[NBUCKETS];
extern	char *sbrk();

static	int pagesz;			/* page size */
static	int pagebucket;			/* page size bucket */

#ifdef MSTATS
/*
 * nmalloc[i] is the difference between the number of mallocs and frees
 * for a given block size.
 */
static	u_int nmalloc[NBUCKETS];
#include <stdio.h>
#endif

#ifdef DEBUG
#define	ASSERT(p)   if (!(p)) botch("p")
static
botch(s)
	char *s;
{

	printf("assertion botched: %s\n", s);
	abort();
}
#else
#define	ASSERT(p)
#endif

char *
malloc(nbytes)
	unsigned nbytes;
{
  	register union overhead *op;
  	register int bucket;
	register unsigned amt, n;
	char	*sbrk();

	blocksig();

	/*
	 * First time malloc is called, setup page size and
	 * align break pointer so all data will be page aligned.
	 */
	if (pagesz == 0) {
		pagesz = n = getpagesize();
		op = (union overhead *)sbrk(0);
  		n = n - sizeof (*op) - ((int)op & (n - 1));
		if (n < 0)
			n += pagesz;
  		if (n) {
  			if (sbrk(n) == (char *)-1) {
				unblocksig();
				return (NULL);
			}
		}
		bucket = 0;
		amt = 8;
		while (pagesz > amt) {
			amt <<= 1;
			bucket++;
		}
		pagebucket = bucket;
	}
	/*
	 * Convert amount of memory requested into (void) closest block size
	 * stored in hash buckets which satisfies request.
	 * Account for space used per block for accounting.
	 */
	if (nbytes <= (n = pagesz - sizeof (*op) - RSLOP)) {
#ifndef RCHECK
		amt = 8;	/* size of first bucket */
		bucket = 0;
#else
		amt = 16;	/* size of first bucket */
		bucket = 1;
#endif
		n = -(sizeof (*op) + RSLOP);
	} else {
		amt = pagesz;
		bucket = pagebucket;
	}
	while (nbytes > amt + n) {
		amt <<= 1;
		bucket++;
	}
	/*
	 * If nothing in hash bucket right now,
	 * request more memory from the system.
	 */
  	if ((op = nextf[bucket]) == NULL) {
  		morecore(bucket);
  		if ((op = nextf[bucket]) == NULL)
  			return (NULL);
	}
	/* remove from linked list */
  	nextf[bucket] = op->ov_next;
	op->ov_magic = MAGIC;
	op->ov_index = bucket;
#ifdef MSTATS
  	nmalloc[bucket]++;
#endif
#ifdef RCHECK
	/*
	 * Record allocated size of block and
	 * bound space with magic numbers.
	 */
	op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
	op->ov_rmagic = RMAGIC;
  	*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
	unblocksig();

  	return ((char *)(op + 1));
}

/*
 * Allocate more memory to the indicated bucket.
 */
static
morecore(bucket)
	int bucket;
{
  	register union overhead *op;
	register int sz;		/* size of desired block */
  	register int amt;		/* amount to allocate */
  	register int nblks;		/* how many blocks we get */

	sz = 1 << (bucket + 3);
	if (sz < pagesz) {
		amt = pagesz;
  		nblks = amt / sz;
	} else {
		amt = sz + pagesz;
		nblks = 1;
	}
	op = (union overhead *)sbrk(amt);
	/* no more room! */
  	if ((int)op == -1)
  		return;
	/*
	 * Add new memory allocated to that on
	 * free list for this hash bucket.
	 */
  	nextf[bucket] = op;
  	while (--nblks > 0) {
		op->ov_next = (union overhead *)((caddr_t)op + sz);
		op = (union overhead *)((caddr_t)op + sz);
  	}
}

free(cp)
	char *cp;
{   
  	register int size;
	register union overhead *op;

  	if (cp == NULL)
  		return;

	blocksig();

	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
#ifdef DEBUG
  	ASSERT(op->ov_magic == MAGIC);		/* make sure it was in use */
#else
	if (op->ov_magic != MAGIC) {
		unblocksig();
		return;				/* sanity */
	}
#endif
#ifdef RCHECK
  	ASSERT(op->ov_rmagic == RMAGIC);
	ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
#endif
  	size = op->ov_index;
  	ASSERT(size < NBUCKETS);
	op->ov_next = nextf[size];
  	nextf[size] = op;
#ifdef MSTATS
  	nmalloc[size]--;
#endif
	unblocksig();
}

/*
 * When a program attempts "storage compaction" as mentioned in the
 * old malloc man page, it realloc's an already freed block.  Usually
 * this is the last block it freed; occasionally it might be farther
 * back.  We have to search all the free lists for the block in order
 * to determine its bucket: 1st we make one pass thru the lists
 * checking only the first block in each; if that fails we search
 * ``realloc_srchlen'' blocks in each list for a match (the variable
 * is extern so the caller can modify it).  If that fails we just copy
 * however many bytes was given to realloc() and hope it's not huge.
 */
int realloc_srchlen = 4;	/* 4 should be plenty, -1 =>'s whole list */

char *
realloc (cp, nbytes)
	char	*cp; 
	unsigned nbytes;
{   
  	register u_int onb, i;
	union overhead *op;
  	char *res;
	int was_alloced = 0;

  	if (cp == NULL)
  		return (malloc(nbytes));

	blocksig();

	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
	if (op->ov_magic == MAGIC) {
		was_alloced++;
		i = op->ov_index;
	} else {
		/*
		 * Already free, doing "compaction".
		 *
		 * Search for the old block of memory on the
		 * free list.  First, check the most common
		 * case (last element free'd), then (this failing)
		 * the last ``realloc_srchlen'' items free'd.
		 * If all lookups fail, then assume the size of
		 * the memory block being realloc'd is the
		 * smallest possible.
		 */
		if ((i = findbucket(op, 1)) < 0 &&
		    (i = findbucket(op, realloc_srchlen)) < 0)
#ifndef RCHECK
			i = 0;
#else
			i = 1;	/* smallest possible w/ RCHECK */
#endif
	}
	onb = 1 << (i + 3);
	if (onb < pagesz)
		onb -= sizeof (*op) + RSLOP;
	else
		onb += pagesz - sizeof (*op) - RSLOP;
	/* avoid the copy if same size block */
	if (was_alloced) {
		if (i) {
			i = 1 << (i + 2);
			if (i < pagesz)
				i -= sizeof (*op) + RSLOP;
			else
				i += pagesz - sizeof (*op) - RSLOP;
		}
		if (nbytes <= onb && nbytes > i) {
#ifdef RCHECK
			op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
			*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
			unblocksig();

			return(cp);
		} else
			free(cp);
	}
  	if ((res = malloc(nbytes)) == NULL) {
		unblocksig();
  		return (NULL);
	}
  	if (cp != res)			/* common optimization */
		Bcopy(cp, res, (nbytes < onb) ? nbytes : onb);

	unblocksig();

  	return (res);
}

/*
 * Search ``srchlen'' elements of each free list for a block whose
 * header starts at ``freep''.  If srchlen is -1 search the whole list.
 * Return bucket number, or -1 if not found.
 */
static
findbucket(freep, srchlen)
	union overhead *freep;
	int srchlen;
{
	register union overhead *p;
	register int i, j;

	for (i = 0; i < NBUCKETS; i++) {
		j = 0;
		for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
			if (p == freep)
				return (i);
			j++;
		}
	}
	return (-1);
}

#ifdef MSTATS
/*
 * mstats - print out statistics about malloc
 * 
 * Prints two lines of numbers, one showing the length of the free list
 * for each size category, the second showing the number of mallocs -
 * frees for each size category.
 */
mstats(s)
	char *s;
{
  	register int i, j;
  	register union overhead *p;
  	int totfree = 0,
  	totused = 0;

  	fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
  	for (i = 0; i < NBUCKETS; i++) {
  		for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
  			;
  		fprintf(stderr, " %d", j);
  		totfree += j * (1 << (i + 3));
  	}
  	fprintf(stderr, "\nused:\t");
  	for (i = 0; i < NBUCKETS; i++) {
  		fprintf(stderr, " %d", nmalloc[i]);
  		totused += nmalloc[i] * (1 << (i + 3));
  	}
  	fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
	    totused, totfree);
}
#endif
/*
** Free (p) caddr_t p;
**	free's a block of memory with obnoxious signals blocked.
**	this is now useless.
*/
_Free (p)
	caddr_t p;
{

	free ((char *) p);

}

/*
** char *
** Calloc (n, s) int n, s;
**	blocks annoying signals, calls calloc casting its own args to
**	unsigneds for lint's benefit. If it got the memory, unblocks the
**	signals and returns the pointer, else punt()'s with an oom error.
*/
char *
_Calloc (n, s)
	int	n,
		s;
{
	register char	*cp = (char *) calloc ((unsigned) n, (unsigned) s);

	if (cp == NULL)
		punt ("Out of memory in Calloc!");
	return (cp);
}

/*
** char *
** Malloc (s) int s;
**	blocks annoying signals which imply the possibility of calling
**	routines which use malloc (stdio, curses, etc.), calls malloc using
**	the size  s  given it. If it gets a non-null pointer, unblocks the
**	signals and returns the pointer, else calls punt() with an out-of-mem
**	error.
*/
char *
_Malloc (s)
	int	s;
{
	register char	*cp = (char *) malloc ((unsigned) s);

	if (cp == NULL)
		punt ("Out of memory in Malloc!");
	return (cp);
}

char *
newstr (str)
	register char *str;
{
	return (strcpy (Malloc (strlen(str)+1), str));
}

/* the mask of blocked signals from before a call to Calloc, Malloc or Free */
int		mask = 0;
int		blocked = 0;	/* malloc occasionally calls itself, I think */
				/* this keeps the signals from being blocked */
				/* permanently				     */
blocksig()
{
	if (!blocked)
		mask = sigblock(sigmask(SIGALRM)|sigmask(SIGQUIT)|sigmask(SIGTSTP));
	blocked = 1;
}

unblocksig()
{
	(void) sigsetmask (mask);
	blocked = 0;
}

/*
 * abort is used to print out info before the program goes down
 * can be very useful at times.
 */
abort()
{
#ifdef MSTATS
	mstats("at botch time:");
#endif
	punt("malloc botch");	/* leaves my terminal sane */
}
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