/*- * Copyright (c) 1983 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 = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/ static char *rcsid = "$Id: malloc.c,v 1.1.1.1 1998/03/07 19:24:35 jdp Exp $"; #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 #include #include #include #include #include #include #ifndef BSD #define MAP_COPY MAP_PRIVATE #define MAP_FILE 0 #define MAP_ANON 0 #endif #ifndef BSD /* Need do better than this */ #define NEED_DEV_ZERO 1 #endif #define NULL 0 static void morecore(); static int findbucket(); /* * Pre-allocate mmap'ed pages */ #define NPOOLPAGES (32*1024/pagesz) static caddr_t pagepool_start, pagepool_end; static int morepages(); /* * 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 #endif #if defined(MALLOC_DEBUG) || defined(RCHECK) #define ASSERT(p) if (!(p)) botch("p") #include static void 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 /* Debugging stuff */ extern void xprintf(const char *, ...); #define TRACE() xprintf("TRACE %s:%d\n", __FILE__, __LINE__) void * malloc(nbytes) size_t nbytes; { register union overhead *op; register int bucket; register long 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(); if (morepages(NPOOLPAGES) == 0) return NULL; op = (union overhead *)(pagepool_start); n = n - sizeof (*op) - ((long)op & (n - 1)); if (n < 0) n += pagesz; if (n) { pagepool_start += n; } 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 MALLOC_DEBUG ASSERT(sz > 0); #else if (sz <= 0) return; #endif if (sz < pagesz) { amt = pagesz; nblks = amt / sz; } else { amt = sz + pagesz; nblks = 1; } if (amt > pagepool_end - pagepool_start) if (morepages(amt/pagesz + NPOOLPAGES) == 0) return; op = (union overhead *)pagepool_start; pagepool_start += amt; /* * 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 MALLOC_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 int 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 static int morepages(n) int n; { int fd = -1; int offset; #ifdef NEED_DEV_ZERO fd = open("/dev/zero", O_RDWR, 0); if (fd == -1) perror("/dev/zero"); #endif if (pagepool_end - pagepool_start > pagesz) { caddr_t addr = (caddr_t) (((long)pagepool_start + pagesz - 1) & ~(pagesz - 1)); if (munmap(addr, pagepool_end - addr) != 0) warn("morepages: munmap %p", addr); } offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1)); if ((pagepool_start = mmap(0, n * pagesz, PROT_READ|PROT_WRITE, MAP_ANON|MAP_COPY, fd, 0)) == (caddr_t)-1) { xprintf("Cannot map anonymous memory"); return 0; } pagepool_end = pagepool_start + n * pagesz; pagepool_start += offset; #ifdef NEED_DEV_ZERO close(fd); #endif return n; }