517 lines
13 KiB
C
517 lines
13 KiB
C
/* $RCSfile: malloc.c,v $$Revision: 1.1.1.1 $$Date: 1994/09/10 06:27:54 $
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*
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* $Log: malloc.c,v $
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* Revision 1.1.1.1 1994/09/10 06:27:54 gclarkii
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* Initial import of Perl 4.046 bmaked
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*
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* Revision 1.2 1993/08/24 17:57:39 nate
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* Fix for ALIGN macros in PERL that conflict with 4.4 macros
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*
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* Revision 1.1.1.1 1993/08/23 21:30:11 nate
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* PERL!
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*
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* Revision 4.0.1.4 92/06/08 14:28:38 lwall
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* patch20: removed implicit int declarations on functions
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* patch20: hash tables now split only if the memory is available to do so
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* patch20: realloc(0, size) now does malloc in case library routines call it
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*
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* Revision 4.0.1.3 91/11/05 17:57:40 lwall
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* patch11: safe malloc code now integrated into Perl's malloc when possible
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*
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* Revision 4.0.1.2 91/06/07 11:20:45 lwall
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* patch4: many, many itty-bitty portability fixes
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*
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* Revision 4.0.1.1 91/04/11 17:48:31 lwall
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* patch1: Configure now figures out malloc ptr type
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*
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* Revision 4.0 91/03/20 01:28:52 lwall
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* 4.0 baseline.
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*
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*/
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#ifndef lint
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/*SUPPRESS 592*/
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static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83";
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#ifdef DEBUGGING
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#define RCHECK
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#endif
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/*
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* malloc.c (Caltech) 2/21/82
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* Chris Kingsley, kingsley@cit-20.
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*
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* This is a very fast storage allocator. It allocates blocks of a small
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* number of different sizes, and keeps free lists of each size. Blocks that
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* don't exactly fit are passed up to the next larger size. In this
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* implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
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* This is designed for use in a program that uses vast quantities of memory,
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* but bombs when it runs out.
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*/
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#include "EXTERN.h"
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#include "../perl.h"
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static findbucket(), morecore();
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/* I don't much care whether these are defined in sys/types.h--LAW */
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#define u_char unsigned char
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#define u_int unsigned int
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#define u_short unsigned short
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/*
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* The overhead on a block is at least 4 bytes. When free, this space
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* contains a pointer to the next free block, and the bottom two bits must
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* be zero. When in use, the first byte is set to MAGIC, and the second
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* byte is the size index. The remaining bytes are for alignment.
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* If range checking is enabled and the size of the block fits
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* in two bytes, then the top two bytes hold the size of the requested block
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* plus the range checking words, and the header word MINUS ONE.
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*/
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union overhead {
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union overhead *ov_next; /* when free */
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#if ALIGN_BYTES > 4
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double strut; /* alignment problems */
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#endif
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struct {
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u_char ovu_magic; /* magic number */
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u_char ovu_index; /* bucket # */
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#ifdef RCHECK
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u_short ovu_size; /* actual block size */
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u_int ovu_rmagic; /* range magic number */
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#endif
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} ovu;
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#define ov_magic ovu.ovu_magic
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#define ov_index ovu.ovu_index
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#define ov_size ovu.ovu_size
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#define ov_rmagic ovu.ovu_rmagic
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};
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#define MAGIC 0xff /* magic # on accounting info */
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#define OLDMAGIC 0x7f /* same after a free() */
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#define RMAGIC 0x55555555 /* magic # on range info */
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#ifdef RCHECK
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#define RSLOP sizeof (u_int)
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#else
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#define RSLOP 0
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#endif
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/*
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* nextf[i] is the pointer to the next free block of size 2^(i+3). The
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* smallest allocatable block is 8 bytes. The overhead information
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* precedes the data area returned to the user.
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*/
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#define NBUCKETS 30
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static union overhead *nextf[NBUCKETS];
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extern char *sbrk();
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#ifdef MSTATS
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/*
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* nmalloc[i] is the difference between the number of mallocs and frees
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* for a given block size.
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*/
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static u_int nmalloc[NBUCKETS];
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#include <stdio.h>
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#endif
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#ifdef debug
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#define ASSERT(p) if (!(p)) botch("p"); else
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static void
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botch(s)
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char *s;
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{
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printf("assertion botched: %s\n", s);
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abort();
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}
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#else
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#define ASSERT(p)
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#endif
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#ifdef safemalloc
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static int an = 0;
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#endif
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MALLOCPTRTYPE *
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malloc(nbytes)
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register MEM_SIZE nbytes;
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{
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register union overhead *p;
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register int bucket = 0;
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register MEM_SIZE shiftr;
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#ifdef safemalloc
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#ifdef DEBUGGING
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MEM_SIZE size = nbytes;
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#endif
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#ifdef MSDOS
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if (nbytes > 0xffff) {
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fprintf(stderr, "Allocation too large: %lx\n", (long)nbytes);
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exit(1);
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}
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#endif /* MSDOS */
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#ifdef DEBUGGING
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if ((long)nbytes < 0)
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fatal("panic: malloc");
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#endif
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#endif /* safemalloc */
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/*
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* Convert amount of memory requested into
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* closest block size stored in hash buckets
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* which satisfies request. Account for
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* space used per block for accounting.
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*/
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nbytes += sizeof (union overhead) + RSLOP;
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nbytes = (nbytes + 3) &~ 3;
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shiftr = (nbytes - 1) >> 2;
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/* apart from this loop, this is O(1) */
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while (shiftr >>= 1)
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bucket++;
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/*
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* If nothing in hash bucket right now,
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* request more memory from the system.
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*/
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if (nextf[bucket] == NULL)
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morecore(bucket);
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if ((p = (union overhead *)nextf[bucket]) == NULL) {
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#ifdef safemalloc
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if (!nomemok) {
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fputs("Out of memory!\n", stderr);
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exit(1);
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}
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#else
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return (NULL);
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#endif
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}
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#ifdef safemalloc
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#ifdef DEBUGGING
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# if !(defined(I286) || defined(atarist))
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if (debug & 128)
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fprintf(stderr,"0x%x: (%05d) malloc %ld bytes\n",p+1,an++,(long)size);
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# else
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if (debug & 128)
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fprintf(stderr,"0x%lx: (%05d) malloc %ld bytes\n",p+1,an++,(long)size);
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# endif
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#endif
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#endif /* safemalloc */
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/* remove from linked list */
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#ifdef RCHECK
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if (*((int*)p) & (sizeof(union overhead) - 1))
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#if !(defined(I286) || defined(atarist))
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fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",*((int*)p),p);
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#else
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fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n",*((int*)p),p);
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#endif
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#endif
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nextf[bucket] = p->ov_next;
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p->ov_magic = MAGIC;
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p->ov_index= bucket;
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#ifdef MSTATS
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nmalloc[bucket]++;
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#endif
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#ifdef RCHECK
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/*
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* Record allocated size of block and
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* bound space with magic numbers.
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*/
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if (nbytes <= 0x10000)
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p->ov_size = nbytes - 1;
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p->ov_rmagic = RMAGIC;
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*((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
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#endif
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return ((MALLOCPTRTYPE *)(p + 1));
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}
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/*
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* Allocate more memory to the indicated bucket.
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*/
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static
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morecore(bucket)
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register int bucket;
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{
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register union overhead *op;
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register int rnu; /* 2^rnu bytes will be requested */
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register int nblks; /* become nblks blocks of the desired size */
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register MEM_SIZE siz;
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if (nextf[bucket])
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return;
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/*
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* Insure memory is allocated
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* on a page boundary. Should
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* make getpageize call?
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*/
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#ifndef atarist /* on the atari we dont have to worry about this */
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op = (union overhead *)sbrk(0);
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#ifndef I286
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if ((int)op & 0x3ff)
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(void)sbrk(1024 - ((int)op & 0x3ff));
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#else
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/* The sbrk(0) call on the I286 always returns the next segment */
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#endif
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#endif /* atarist */
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#if !(defined(I286) || defined(atarist))
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/* take 2k unless the block is bigger than that */
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rnu = (bucket <= 8) ? 11 : bucket + 3;
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#else
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/* take 16k unless the block is bigger than that
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(80286s like large segments!), probably good on the atari too */
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rnu = (bucket <= 11) ? 14 : bucket + 3;
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#endif
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nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
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if (rnu < bucket)
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rnu = bucket;
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op = (union overhead *)sbrk(1L << rnu);
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/* no more room! */
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if ((int)op == -1)
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return;
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/*
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* Round up to minimum allocation size boundary
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* and deduct from block count to reflect.
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*/
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#ifndef I286
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if ((int)op & 7) {
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op = (union overhead *)(((MEM_SIZE)op + 8) &~ 7);
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nblks--;
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}
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#else
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/* Again, this should always be ok on an 80286 */
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#endif
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/*
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* Add new memory allocated to that on
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* free list for this hash bucket.
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*/
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nextf[bucket] = op;
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siz = 1 << (bucket + 3);
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while (--nblks > 0) {
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op->ov_next = (union overhead *)((caddr_t)op + siz);
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op = (union overhead *)((caddr_t)op + siz);
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}
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}
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void
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free(mp)
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MALLOCPTRTYPE *mp;
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{
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register MEM_SIZE size;
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register union overhead *op;
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char *cp = (char*)mp;
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#ifdef safemalloc
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#ifdef DEBUGGING
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# if !(defined(I286) || defined(atarist))
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if (debug & 128)
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fprintf(stderr,"0x%x: (%05d) free\n",cp,an++);
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# else
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if (debug & 128)
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fprintf(stderr,"0x%lx: (%05d) free\n",cp,an++);
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# endif
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#endif
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#endif /* safemalloc */
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if (cp == NULL)
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return;
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op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
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#ifdef debug
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ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
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#else
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if (op->ov_magic != MAGIC) {
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warn("%s free() ignored",
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op->ov_magic == OLDMAGIC ? "Duplicate" : "Bad");
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return; /* sanity */
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}
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op->ov_magic = OLDMAGIC;
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#endif
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#ifdef RCHECK
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ASSERT(op->ov_rmagic == RMAGIC);
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if (op->ov_index <= 13)
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ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC);
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#endif
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ASSERT(op->ov_index < NBUCKETS);
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size = op->ov_index;
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op->ov_next = nextf[size];
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nextf[size] = op;
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#ifdef MSTATS
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nmalloc[size]--;
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#endif
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}
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/*
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* When a program attempts "storage compaction" as mentioned in the
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* old malloc man page, it realloc's an already freed block. Usually
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* this is the last block it freed; occasionally it might be farther
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* back. We have to search all the free lists for the block in order
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* to determine its bucket: 1st we make one pass thru the lists
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* checking only the first block in each; if that fails we search
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* ``reall_srchlen'' blocks in each list for a match (the variable
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* is extern so the caller can modify it). If that fails we just copy
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* however many bytes was given to realloc() and hope it's not huge.
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*/
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int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
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MALLOCPTRTYPE *
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realloc(mp, nbytes)
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MALLOCPTRTYPE *mp;
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MEM_SIZE nbytes;
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{
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register MEM_SIZE onb;
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union overhead *op;
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char *res;
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register int i;
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int was_alloced = 0;
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char *cp = (char*)mp;
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#ifdef safemalloc
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#ifdef DEBUGGING
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MEM_SIZE size = nbytes;
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#endif
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#ifdef MSDOS
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if (nbytes > 0xffff) {
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fprintf(stderr, "Reallocation too large: %lx\n", size);
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exit(1);
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}
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#endif /* MSDOS */
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if (!cp)
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return malloc(nbytes);
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#ifdef DEBUGGING
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if ((long)nbytes < 0)
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fatal("panic: realloc");
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#endif
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#endif /* safemalloc */
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op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
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if (op->ov_magic == MAGIC) {
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was_alloced++;
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i = op->ov_index;
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} else {
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/*
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* Already free, doing "compaction".
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*
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* Search for the old block of memory on the
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* free list. First, check the most common
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* case (last element free'd), then (this failing)
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* the last ``reall_srchlen'' items free'd.
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* If all lookups fail, then assume the size of
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* the memory block being realloc'd is the
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* smallest possible.
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*/
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if ((i = findbucket(op, 1)) < 0 &&
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(i = findbucket(op, reall_srchlen)) < 0)
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i = 0;
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}
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onb = (1L << (i + 3)) - sizeof (*op) - RSLOP;
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/* avoid the copy if same size block */
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if (was_alloced &&
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nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) {
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#ifdef RCHECK
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/*
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* Record new allocated size of block and
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* bound space with magic numbers.
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*/
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if (op->ov_index <= 13) {
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/*
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* Convert amount of memory requested into
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* closest block size stored in hash buckets
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* which satisfies request. Account for
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* space used per block for accounting.
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*/
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nbytes += sizeof (union overhead) + RSLOP;
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nbytes = (nbytes + 3) &~ 3;
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op->ov_size = nbytes - 1;
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*((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC;
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}
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#endif
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res = cp;
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}
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else {
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if ((res = (char*)malloc(nbytes)) == NULL)
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return (NULL);
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if (cp != res) /* common optimization */
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Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
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if (was_alloced)
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free(cp);
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}
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#ifdef safemalloc
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#ifdef DEBUGGING
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# if !(defined(I286) || defined(atarist))
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if (debug & 128) {
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fprintf(stderr,"0x%x: (%05d) rfree\n",res,an++);
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fprintf(stderr,"0x%x: (%05d) realloc %ld bytes\n",res,an++,(long)size);
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}
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# else
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if (debug & 128) {
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fprintf(stderr,"0x%lx: (%05d) rfree\n",res,an++);
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fprintf(stderr,"0x%lx: (%05d) realloc %ld bytes\n",res,an++,(long)size);
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}
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# endif
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#endif
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#endif /* safemalloc */
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return ((MALLOCPTRTYPE*)res);
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}
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/*
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* Search ``srchlen'' elements of each free list for a block whose
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* header starts at ``freep''. If srchlen is -1 search the whole list.
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* Return bucket number, or -1 if not found.
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*/
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static int
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findbucket(freep, srchlen)
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union overhead *freep;
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int srchlen;
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{
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register union overhead *p;
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register int i, j;
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for (i = 0; i < NBUCKETS; i++) {
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j = 0;
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for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
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if (p == freep)
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return (i);
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j++;
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}
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}
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return (-1);
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}
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#ifdef MSTATS
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/*
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* mstats - print out statistics about malloc
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*
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* Prints two lines of numbers, one showing the length of the free list
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* for each size category, the second showing the number of mallocs -
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* frees for each size category.
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*/
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void
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mstats(s)
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char *s;
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{
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register int i, j;
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register union overhead *p;
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int totfree = 0,
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totused = 0;
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fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
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for (i = 0; i < NBUCKETS; i++) {
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for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
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;
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fprintf(stderr, " %d", j);
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totfree += j * (1 << (i + 3));
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}
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fprintf(stderr, "\nused:\t");
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for (i = 0; i < NBUCKETS; i++) {
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fprintf(stderr, " %d", nmalloc[i]);
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totused += nmalloc[i] * (1 << (i + 3));
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}
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fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
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totused, totfree);
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}
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#endif
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#endif /* lint */
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