1 /* dynamic memory allocation for GNU.
2 Copyright (C) 1985, 1987 Free Software Foundation, Inc.
6 BECAUSE THIS PROGRAM IS LICENSED FREE OF CHARGE, WE PROVIDE ABSOLUTELY
7 NO WARRANTY, TO THE EXTENT PERMITTED BY APPLICABLE STATE LAW. EXCEPT
8 WHEN OTHERWISE STATED IN WRITING, FREE SOFTWARE FOUNDATION, INC,
9 RICHARD M. STALLMAN AND/OR OTHER PARTIES PROVIDE THIS PROGRAM "AS IS"
10 WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
11 BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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13 AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE
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17 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW WILL RICHARD M.
18 STALLMAN, THE FREE SOFTWARE FOUNDATION, INC., AND/OR ANY OTHER PARTY
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24 A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS) THIS
25 PROGRAM, EVEN IF YOU HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
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28 GENERAL PUBLIC LICENSE TO COPY
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84 4. You may not copy, sublicense, distribute or transfer this program
85 except as expressly provided under this License Agreement. Any attempt
86 otherwise to copy, sublicense, distribute or transfer this program is void and
87 your rights to use the program under this License agreement shall be
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94 Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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98 our free software and of promoting the sharing and reuse of software.
100 In other words, you are welcome to use, share and improve this program.
101 You are forbidden to forbid anyone else to use, share and improve
102 what you give them. Help stamp out software-hoarding! */
104 /* Synched up with: Not synched with FSF. */
107 * @(#)nmalloc.c 1 (Caltech) 2/21/82
109 * U of M Modified: 20 Jun 1983 ACT: strange hacks for Emacs
111 * Nov 1983, Mike@BRL, Added support for 4.1C/4.2 BSD.
113 * This is a very fast storage allocator. It allocates blocks of a small
114 * number of different sizes, and keeps free lists of each size. Blocks
115 * that don't exactly fit are passed up to the next larger size. In this
116 * implementation, the available sizes are (2^n)-4 (or -16) bytes long.
117 * This is designed for use in a program that uses vast quantities of
118 * memory, but bombs when it runs out. To make it a little better, it
119 * warns the user when he starts to get near the end.
121 * June 84, ACT: modified rcheck code to check the range given to malloc,
122 * rather than the range determined by the 2-power used.
124 * Jan 85, RMS: calls malloc_warning to issue warning on nearly full.
125 * No longer Emacs-specific; can serve as all-purpose malloc for GNU.
126 * You should call malloc_init to reinitialize after loading dumped Emacs.
127 * Call malloc_stats to get info on memory stats if MSTATS turned on.
128 * realloc knows how to return same block given, just changing its size,
129 * if the power of 2 is correct.
133 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
134 * smallest allocatable block is 8 bytes. The overhead information will
135 * go in the first int of the block, and the returned pointer will point
139 * nmalloc[i] is the difference between the number of mallocs and frees
140 * for a given block size.
145 /* config.h specifies which kind of system this is. */
149 /* Determine which kind of system this is. */
165 #endif /* not emacs */
169 /* Define getpagesize () if the system does not. */
170 #include "ui/getpagesize.h"
178 #include <sys/vlimit.h> /* warn the user when near the end */
180 #else /* if BSD4_2 */
181 #include <sys/time.h>
182 #include <sys/resource.h>
187 /* not sure where this for NetBSD should really go
188 and it probably applies to other systems */
189 #if !defined(__NetBSD__) && !defined(__bsdi__) && !defined(__OpenBSD__)
190 extern void *sbrk(ptrdiff_t);
193 #endif /* __NetBSD__ or __OpenBSD__ */
197 #endif /* __STDC__ */
199 extern char *start_of_data(void);
202 #define start_of_data() &etext
206 #define start_of_data() &etext
209 #define ISALLOC ((char) 0xf7) /* magic byte that implies allocation */
210 #define ISFREE ((char) 0x54) /* magic byte that implies free block */
211 /* this is for error checking only */
212 #define ISMEMALIGN ((char) 0xd6) /* Stored before the value returned by
213 memalign, with the rest of the word
214 being the distance to the true
215 beginning of the block. */
219 /* These two are for user programs to look at, when they are interested. */
221 unsigned int malloc_sbrk_used; /* amount of data space used now */
222 unsigned int malloc_sbrk_unused; /* amount more we can have */
224 /* start of data space; can be changed by calling init_malloc */
225 static char *data_space_start;
228 static int nmalloc[30];
229 static int nmal, nfre;
232 /* If range checking is not turned on, all we have is a flag indicating
233 whether memory is allocated, an index in nextf[], and a size field; to
234 realloc() memory we copy either size bytes or 1<<(index+3) bytes depending
235 on whether the former can hold the exact size (given the value of
236 'index'). If range checking is on, we always need to know how much space
237 is allocated, so the 'size' field is never used. */
240 char mh_alloc; /* ISALLOC or ISFREE */
241 char mh_index; /* index in nextf[] */
242 /* Remainder are valid only when block is allocated */
243 unsigned short mh_size; /* size, if < 0x10000 */
245 unsigned mh_nbytes; /* number of bytes allocated */
246 int mh_magic4; /* should be == MAGIC4 */
250 /* Access free-list pointer of a block.
251 It is stored at block + 4.
252 This is not a field in the mhead structure
253 because we want sizeof (struct mhead)
254 to describe the overhead for when the block is in use,
255 and we do not want the free-list pointer to count in that. */
258 (*(struct mhead **) (sizeof (char *) + (char *) (a)))
262 /* To implement range checking, we write magic values in at the beginning and
263 end of each allocated block, and make sure they are undisturbed whenever a
264 free or a realloc occurs. */
265 /* Written in each of the 4 bytes following the block's real space */
267 /* Written in the 4 bytes before the block's real space */
268 #define MAGIC4 0x55555555
269 #define ASSERT(p) if (!(p)) botch("p"); else
270 #define EXTRA 4 /* 4 bytes extra for MAGIC1s */
276 /* nextf[i] is free list of blocks of size 2**(i + 3) */
278 static struct mhead *nextf[30];
280 /* busy[i] is nonzero while allocation of block size i is in progress. */
282 static char busy[30];
284 /* Number of bytes of writable memory we can expect to be able to get */
285 #ifdef _RLIM_T_DECLARED
286 extern rlim_t lim_data;
288 extern unsigned long lim_data;
291 /* Level number of warnings already issued.
292 0 -- no warnings issued.
293 1 -- 75% warning already issued.
294 2 -- 85% warning already issued.
296 static int warnlevel;
298 /* Function to call to issue a warning;
299 0 means don't issue them. */
300 static void (*warnfunction) ();
302 /* nonzero once initial bunch of free blocks made */
307 static void getpool(void);
309 /* Cause reinitialization based on job parameters;
310 also declare where the end of pure storage is. */
311 void malloc_init(start, warnfun)
316 data_space_start = start;
319 warnfunction = warnfun;
322 /* Return the maximum size to which MEM can be realloc'd
323 without actually requiring copying. */
325 int malloc_usable_size(mem)
328 int blocksize = 8 << (((struct mhead *)mem) - 1)->mh_index;
330 return blocksize - sizeof(struct mhead) - EXTRA;
333 static void get_lim_data();
335 static void morecore(nu) /* ask system for more memory */
336 int nu; /* size index to get more of */
345 /* ?? There was a suggestion not to block SIGILL, somehow for GDB's sake. */
346 oldmask = sigsetmask(-1);
350 if (!data_space_start) {
351 data_space_start = start_of_data();
357 /* On initial startup, get two blocks of each size up to 1k bytes */
364 /* Find current end of memory and issue warning if getting near max */
367 siz = cp - data_space_start;
372 if (siz > (lim_data / 4) * 3) {
375 ("Warning: past 75% of memory limit");
379 if (siz > (lim_data / 20) * 17) {
382 ("Warning: past 85% of memory limit");
386 if (siz > (lim_data / 20) * 19) {
389 ("Warning: past 95% of memory limit");
394 if ((int)cp & 0x3ff) /* land on 1K boundaries */
395 sbrk(1024 - ((int)cp & 0x3ff));
397 /* Take at least 2k, and figure out how many blocks of the desired size
398 we're about to get */
401 nblks = 1 << ((siz = 8) - nu);
403 if ((cp = sbrk(1 << (siz + 3))) == (char *)-1) {
409 return; /* no more room! */
411 malloc_sbrk_used = siz;
412 malloc_sbrk_unused = lim_data - siz;
414 if ((int)cp & 7) { /* shouldn't happen, but just in case */
415 cp = (char *)(((int)cp + 8) & ~7);
419 /* save new header and link the nblks blocks together */
420 nextf[nu] = (struct mhead *)cp;
423 ((struct mhead *)cp)->mh_alloc = ISFREE;
424 ((struct mhead *)cp)->mh_index = nu;
427 CHAIN((struct mhead *)cp) = (struct mhead *)(cp + siz);
430 CHAIN((struct mhead *)cp) = 0;
439 static void getpool(void)
444 if ((int)cp & 0x3ff) /* land on 1K boundaries */
445 sbrk(1024 - ((int)cp & 0x3ff));
447 /* Record address of start of space allocated by malloc. */
448 if (_malloc_base == 0)
451 /* Get 2k of storage */
454 if (cp == (char *)-1)
457 /* Divide it into an initial 8-word block
458 plus one block of size 2**nu for nu = 3 ... 10. */
460 CHAIN(cp) = nextf[0];
461 nextf[0] = (struct mhead *)cp;
462 ((struct mhead *)cp)->mh_alloc = ISFREE;
463 ((struct mhead *)cp)->mh_index = 0;
466 for (nu = 0; nu < 7; nu++) {
467 CHAIN(cp) = nextf[nu];
468 nextf[nu] = (struct mhead *)cp;
469 ((struct mhead *)cp)->mh_alloc = ISFREE;
470 ((struct mhead *)cp)->mh_index = nu;
475 char *malloc(n) /* get a block */
482 /* Figure out how many bytes are required, rounding up to the nearest
483 multiple of 8, then figure out which nestf[] area to use.
484 Both the beginning of the header and the beginning of the
485 block should be on an eight byte boundary. */
486 nbytes = (n + ((sizeof *p + 7) & ~7) + EXTRA + 7) & ~7;
488 unsigned int shiftr = (nbytes - 1) >> 2;
494 /* In case this is reentrant use of malloc from signal handler,
495 pick a block size that no other malloc level is currently
496 trying to allocate. That's the easiest harmless way not to
497 interfere with the other level of execution. */
502 /* If there are no blocks of the appropriate size, go get some */
503 /* COULD SPLIT UP A LARGER BLOCK HERE ... ACT */
504 if (nextf[nunits] == 0)
507 /* Get one block off the list, and set the new list head */
508 if ((p = nextf[nunits]) == 0) {
512 nextf[nunits] = CHAIN(p);
515 /* Check for free block clobbered */
516 /* If not for this check, we would gobble a clobbered free chain ptr */
517 /* and bomb out on the NEXT allocate of this size block */
518 if (p->mh_alloc != ISFREE || p->mh_index != nunits)
520 botch("block on free list clobbered");
521 #else /* not rcheck */
523 #endif /* not rcheck */
525 /* Fill in the info, and if range checking, set up the magic numbers */
526 p->mh_alloc = ISALLOC;
529 p->mh_magic4 = MAGIC4;
531 /* Get the location n after the beginning of the user's space. */
532 char *m = (char *)p + ((sizeof *p + 7) & ~7) + n;
534 *m++ = MAGIC1, *m++ = MAGIC1, *m++ = MAGIC1, *m = MAGIC1;
536 #else /* not rcheck */
538 #endif /* not rcheck */
543 return (char *)p + ((sizeof *p + 7) & ~7);
556 p = (struct mhead *)(ap - ((sizeof *p + 7) & ~7));
557 if (p->mh_alloc == ISMEMALIGN) {
559 p = (struct mhead *)(ap - ((sizeof *p + 7) & ~7));
562 if (p->mh_alloc != ISALLOC)
566 if (p->mh_alloc != ISALLOC) {
567 if (p->mh_alloc == ISFREE)
569 ("free: Called with already freed block argument\n");
571 botch("free: Called with bad argument\n");
574 ASSERT(p->mh_magic4 == MAGIC4);
576 ASSERT(*ap++ == MAGIC1);
577 ASSERT(*ap++ == MAGIC1);
578 ASSERT(*ap++ == MAGIC1);
579 ASSERT(*ap == MAGIC1);
583 int nunits = p->mh_index;
585 ASSERT(nunits <= 29);
586 p->mh_alloc = ISFREE;
588 /* Protect against signal handlers calling malloc. */
590 /* Put this block on the free list. */
591 CHAIN(p) = nextf[nunits];
602 char *realloc(mem, n)
613 p = (struct mhead *)(mem - ((sizeof *p + 7) & ~7));
614 nunits = p->mh_index;
615 ASSERT(p->mh_alloc == ISALLOC);
617 ASSERT(p->mh_magic4 == MAGIC4);
619 char *m = mem + (tocopy = p->mh_nbytes);
620 ASSERT(*m++ == MAGIC1);
621 ASSERT(*m++ == MAGIC1);
622 ASSERT(*m++ == MAGIC1);
623 ASSERT(*m == MAGIC1);
625 #else /* not rcheck */
626 if (p->mh_index >= 13)
627 tocopy = (1 << (p->mh_index + 3)) - ((sizeof *p + 7) & ~7);
630 #endif /* not rcheck */
632 /* See if desired size rounds to same power of 2 as actual size. */
633 nbytes = (n + ((sizeof *p + 7) & ~7) + EXTRA + 7) & ~7;
635 /* If ok, use the same block, just marking its size as changed. */
636 if (nbytes > (4 << nunits) && nbytes <= (8 << nunits)) {
638 char *m = mem + tocopy;
649 #else /* not rcheck */
651 #endif /* not rcheck */
660 if ((new = malloc(n)) == 0)
662 memcpy(new, mem, tocopy);
668 char *memalign(alignment, size)
669 unsigned alignment, size;
671 char *ptr = malloc(size + alignment);
677 /* If entire block has the desired alignment, just accept it. */
678 if (((int)ptr & (alignment - 1)) == 0)
680 /* Otherwise, get address of byte in the block that has that alignment. */
681 aligned = (char *)(((int)ptr + alignment - 1) & -alignment);
683 /* Store a suitable indication of how to free the block,
684 so that free can find the true beginning of it. */
685 p = (struct mhead *)aligned - 1;
686 p->mh_size = aligned - ptr;
687 p->mh_alloc = ISMEMALIGN;
692 /* This runs into trouble with getpagesize on HPUX.
693 Patching out seems cleaner than the ugly fix needed. */
697 return memalign(getpagesize(), size);
699 #endif /* not __hpux */
702 /* Return statistics describing allocation of blocks of size 2**n. */
704 struct mstats_value {
710 struct mstats_value malloc_stats(size)
713 struct mstats_value v;
719 if (size < 0 || size >= 30) {
725 v.blocksize = 1 << (size + 3);
726 v.nused = nmalloc[size];
728 for (p = nextf[size]; p; p = CHAIN(p))
733 int malloc_mem_used(void)
740 for (i = 0; i < 30; i++) {
741 int allocation_size = 1 << (i + 3);
744 size_used += nmalloc[i] * allocation_size;
750 int malloc_mem_free(void)
757 for (i = 0; i < 30; i++) {
758 int allocation_size = 1 << (i + 3);
761 for (p = nextf[i]; p; p = CHAIN(p))
762 size_unused += allocation_size;
770 * This function returns the total number of bytes that the process
771 * will be allowed to allocate via the sbrk(2) system call. On
772 * BSD systems this is the total space allocatable to stack and
773 * data. On USG systems this is the data space only.
778 static void get_lim_data(void)
780 #ifdef ULIMIT_BREAK_VALUE
781 lim_data = ULIMIT_BREAK_VALUE;
783 lim_data = ulimit(3, 0);
786 lim_data -= (long)data_space_start;
792 static void get_lim_data(void)
794 lim_data = vlimit(LIM_DATA, -1);
799 static void get_lim_data(void)
801 struct rlimit XXrlimit;
803 getrlimit(RLIMIT_DATA, &XXrlimit);
805 lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
807 lim_data = XXrlimit.rlim_cur; /* soft limit */