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-rw-r--r--lib/libc/stdlib/malloc.c420
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diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
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+/*
+ * Copyright (c) 1983, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)malloc.c 8.1 (Berkeley) 6/4/93";
+#endif /* LIBC_SCCS and not lint */
+
+/*
+ * 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-10) bytes long.
+ * This is designed for use in a virtual memory environment.
+ */
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define NULL 0
+
+static void morecore();
+static int findbucket();
+
+/*
+ * 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 then a second word holds the size of the
+ * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
+ * The order of elements is critical: ov_magic must overlay the low order
+ * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
+ */
+union overhead {
+ union overhead *ov_next; /* when free */
+ struct {
+ u_char ovu_magic; /* magic number */
+ u_char ovu_index; /* bucket # */
+#ifdef RCHECK
+ u_short ovu_rmagic; /* range magic number */
+ u_int ovu_size; /* actual block size */
+#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
+
+#if defined(DEBUG) || defined(RCHECK)
+#define ASSERT(p) if (!(p)) botch("p")
+#include <stdio.h>
+static
+botch(s)
+ char *s;
+{
+ fprintf(stderr, "\r\nassertion botched: %s\r\n", s);
+ (void) fflush(stderr); /* just in case user buffered it */
+ abort();
+}
+#else
+#define ASSERT(p)
+#endif
+
+void *
+malloc(nbytes)
+ size_t nbytes;
+{
+ register union overhead *op;
+ register int bucket, n;
+ register unsigned amt;
+
+ /*
+ * 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)
+ return (NULL);
+ }
+ bucket = 0;
+ amt = 8;
+ while (pagesz > amt) {
+ amt <<= 1;
+ bucket++;
+ }
+ pagebucket = bucket;
+ }
+ /*
+ * Convert amount of memory requested into 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;
+ if (amt == 0)
+ return (NULL);
+ 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
+ return ((char *)(op + 1));
+}
+
+/*
+ * Allocate more memory to the indicated bucket.
+ */
+static void
+morecore(bucket)
+ int bucket;
+{
+ register union overhead *op;
+ register int sz; /* size of desired block */
+ int amt; /* amount to allocate */
+ int nblks; /* how many blocks we get */
+
+ /*
+ * sbrk_size <= 0 only for big, FLUFFY, requests (about
+ * 2^30 bytes on a VAX, I think) or for a negative arg.
+ */
+ sz = 1 << (bucket + 3);
+#ifdef DEBUG
+ ASSERT(sz > 0);
+#else
+ if (sz <= 0)
+ return;
+#endif
+ 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);
+ }
+}
+
+void
+free(cp)
+ void *cp;
+{
+ register int size;
+ register union overhead *op;
+
+ if (cp == NULL)
+ return;
+ 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)
+ 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]; /* also clobbers ov_magic */
+ nextf[size] = op;
+#ifdef MSTATS
+ nmalloc[size]--;
+#endif
+}
+
+/*
+ * 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 */
+
+void *
+realloc(cp, nbytes)
+ void *cp;
+ size_t nbytes;
+{
+ register u_int onb;
+ register int i;
+ union overhead *op;
+ char *res;
+ int was_alloced = 0;
+
+ if (cp == NULL)
+ return (malloc(nbytes));
+ 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
+ * largest possible (so that all "nbytes" of new
+ * memory are copied into). Note that this could cause
+ * a memory fault if the old area was tiny, and the moon
+ * is gibbous. However, that is very unlikely.
+ */
+ if ((i = findbucket(op, 1)) < 0 &&
+ (i = findbucket(op, __realloc_srchlen)) < 0)
+ i = NBUCKETS;
+ }
+ 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
+ return(cp);
+ } else
+ free(cp);
+ }
+ if ((res = malloc(nbytes)) == NULL)
+ return (NULL);
+ if (cp != res) /* common optimization if "compacting" */
+ bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
+ 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
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