438 lines
12 KiB
C
438 lines
12 KiB
C
/*
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* Copyright (c) 1983 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)malloc.c 5.11 (Berkeley) 2/23/91";
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#endif /* LIBC_SCCS and not lint */
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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-10) bytes long.
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* This is designed for use in a virtual memory environment.
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*/
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#define IN_MALLOC_WRAPPER
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#define NO_OPCODES
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#include "std.h"
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#include "main.h"
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#undef NULL
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#define NULL 0
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#ifdef _SEQUENT_
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typedef unsigned char u_char;
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typedef unsigned short u_short;
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typedef unsigned int u_int;
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#endif
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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 then a second word holds the size of the
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* requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
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* The order of elements is critical: ov_magic must overlay the low order
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* bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
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*/
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union overhead {
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union overhead *ov_next; /* when free */
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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_rmagic; /* range magic number */
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u_int ovu_size; /* actual block size */
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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_rmagic ovu.ovu_rmagic
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#define ov_size ovu.ovu_size
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};
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#define MAGIC 0xef /* magic # on accounting info */
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#define RMAGIC 0x5555 /* magic # on range info */
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#ifdef RCHECK
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#define RSLOP sizeof (u_short)
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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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static int pagesz; /* page size */
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static int pagebucket; /* page size bucket */
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static void morecore (int);
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static int findbucket (union overhead *, int);
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void *sbrkx(long);
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#ifdef DO_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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#endif
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#if defined(DEBUG) || defined(RCHECK)
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#ifdef __STDC__
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#define ASSERT(p) if (!(p)) botch(#p)
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#else
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#define ASSERT(p) if (!(p)) botch("?")
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#endif
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static int botch (char * s)
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{
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debug_message("\r\nassertion botched: %s\r\n", s);
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(void) fflush(stderr); /* just in case user buffered it */
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abort();
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return 0;
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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 malloc
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/* linux */
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#undef malloc
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#endif
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void *bsdmalloc_malloc (size_t nbytes)
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{
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register union overhead *op;
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register long bucket, n;
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register unsigned amt;
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/*
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* First time malloc is called, setup page size and align break pointer
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* so all data will be page aligned.
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*/
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if (pagesz == 0) {
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#ifdef MEMPAGESIZE
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pagesz = n = MEMPAGESIZE;
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#else
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pagesz = n = getpagesize();
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#endif
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op = (union overhead *) sbrkx(0);
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n = n - sizeof(*op) - ((long) op & (n - 1));
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if (n < 0)
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n += pagesz;
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if (n) {
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if ((char *)sbrkx(n) == (char *) -1)
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return (NULL);
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}
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bucket = 0;
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amt = 8;
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while (pagesz > amt) {
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amt <<= 1;
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bucket++;
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}
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pagebucket = bucket;
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}
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/*
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* Convert amount of memory requested into closest block size stored in
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* hash buckets which satisfies request. Account for space used per block
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* for accounting.
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*/
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if (nbytes <= (n = pagesz - sizeof(*op) - RSLOP)) {
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#ifndef RCHECK
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amt = 8; /* size of first bucket */
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bucket = 0;
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#else
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amt = 16; /* size of first bucket */
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bucket = 1;
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#endif
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n = -(sizeof(*op) + RSLOP);
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} else {
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amt = pagesz;
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bucket = pagebucket;
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}
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while (nbytes > amt + n) {
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amt <<= 1;
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if (amt == 0)
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return (NULL);
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bucket++;
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}
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/*
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* If nothing in hash bucket right now, request more memory from the
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* system.
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*/
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if ((op = nextf[bucket]) == NULL) {
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morecore(bucket);
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if ((op = nextf[bucket]) == NULL)
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return (NULL);
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}
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/* remove from linked list */
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nextf[bucket] = op->ov_next;
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op->ov_magic = MAGIC;
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op->ov_index = bucket;
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#ifdef DO_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 bound space with magic numbers.
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*/
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op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
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op->ov_rmagic = RMAGIC;
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*(u_short *) ((caddr_t) (op + 1) + op->ov_size) = RMAGIC;
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#endif
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return ((char *) (op + 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 void
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morecore (int bucket)
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{
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register union overhead *op;
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register int sz; /* size of desired block */
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int amt; /* amount to allocate */
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int nblks; /* how many blocks we get */
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/*
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* sbrk_size <= 0 only for big, FLUFFY, requests (about 2^30 bytes on a
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* VAX, I think) or for a negative arg.
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*/
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sz = 1 << (bucket + 3);
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#ifdef DEBUG
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ASSERT(sz > 0);
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#else
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if (sz <= 0)
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return;
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#endif
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if (sz < pagesz) {
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amt = pagesz;
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nblks = amt / sz;
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} else {
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amt = sz + pagesz;
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nblks = 1;
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}
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op = (union overhead *) sbrkx(amt);
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/* no more room! */
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if ((long) op == -1)
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return;
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/*
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* Add new memory allocated to that on free list for this hash bucket.
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*/
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nextf[bucket] = op;
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while (--nblks > 0) {
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op->ov_next = (union overhead *) ((caddr_t) op + sz);
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op = (union overhead *) ((caddr_t) op + sz);
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}
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}
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INLINE void
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bsdmalloc_free (void * cp)
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{
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register int size;
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register union overhead *op;
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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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return; /* sanity */
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#endif
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#ifdef RCHECK
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ASSERT(op->ov_rmagic == RMAGIC);
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ASSERT(*(u_short *) ((caddr_t) (op + 1) + op->ov_size) == RMAGIC);
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#endif
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size = op->ov_index;
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ASSERT(size < NBUCKETS);
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op->ov_next = nextf[size]; /* also clobbers ov_magic */
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nextf[size] = op;
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#ifdef DO_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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* ``realloc_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 realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
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void *bsdmalloc_realloc (void * cp, size_t nbytes)
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{
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register u_int onb;
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register int i;
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union overhead *op;
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char *res;
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int was_alloced = 0;
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if (cp == NULL)
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return (bsdmalloc_malloc(nbytes));
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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 free list. First, check
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* the most common case (last element free'd), then (this failing)
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* the last ``realloc_srchlen'' items free'd. If all lookups fail,
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* then assume the size of the memory block being realloc'd is the
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* largest possible (so that all "nbytes" of new memory are copied
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* into). Note that this could cause a memory fault if the old area
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* was tiny, and the moon is gibbous. However, that is very
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* unlikely.
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*/
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if ((i = findbucket(op, 1)) < 0 &&
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(i = findbucket(op, realloc_srchlen)) < 0)
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i = NBUCKETS;
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}
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onb = 1 << (i + 3);
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if (onb < pagesz)
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onb -= sizeof(*op) + RSLOP;
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else
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onb += pagesz - 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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if (i) {
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i = 1 << (i + 2);
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if (i < pagesz)
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i -= sizeof(*op) + RSLOP;
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else
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i += pagesz - sizeof(*op) - RSLOP;
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}
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if (nbytes <= onb && nbytes > i) {
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#ifdef RCHECK
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op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
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*(u_short *) ((caddr_t) (op + 1) + op->ov_size) = RMAGIC;
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#endif
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return (cp);
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} else
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bsdmalloc_free(cp);
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}
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if ((res = bsdmalloc_malloc(nbytes)) == NULL)
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return (NULL);
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if (cp != res) /* common optimization if "compacting" */
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memcpy(res, cp, (nbytes < onb) ? nbytes : onb);
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return (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 (union overhead * freep, 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 DO_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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show_mstats (outbuffer_t * ob, 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, totused = 0;
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outbuf_addv(ob, "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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outbuf_addv(ob, " %d", j);
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totfree += j * (1 << (i + 3));
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}
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outbuf_add(ob, "\nused:\t");
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for (i = 0; i < NBUCKETS; i++) {
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outbuf_addv(ob, " %d", nmalloc[i]);
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totused += nmalloc[i] * (1 << (i + 3));
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}
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outbuf_addv(ob, "\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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/* calloc was originally in its own source file */
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#ifdef calloc
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/* linux */
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#undef calloc
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#endif
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INLINE void *bsdmalloc_calloc (size_t num, register size_t size)
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{
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register void *p;
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size *= num;
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if ((p = bsdmalloc_malloc(size)))
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memset(p, 0, size);
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return (p);
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}
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