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