1 /* $Header: /p/tcsh/cvsroot/tcsh/tc.alloc.c,v 3.56 2016/03/08 12:47:43 christos Exp $ */
3 * tc.alloc.c (Caltech) 2/21/82
4 * Chris Kingsley, kingsley@cit-20.
6 * This is a very fast storage allocator. It allocates blocks of a small
7 * number of different sizes, and keeps free lists of each size. Blocks that
8 * don't exactly fit are passed up to the next larger size. In this
9 * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
10 * This is designed for use in a program that uses vast quantities of memory,
11 * but bombs when it runs out.
14 * Copyright (c) 1980, 1991 The Regents of the University of California.
15 * All rights reserved.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
25 * 3. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
45 #if defined(HAVE_SBRK) && !defined(__APPLE__)
49 RCSID("$tcsh: tc.alloc.c,v 3.56 2016/03/08 12:47:43 christos Exp $")
54 static char *memtop = NULL; /* PWP: top of current memory */
55 static char *membot = NULL; /* PWP: bottom of allocatable memory */
60 # define malloc fmalloc
62 # define calloc fcalloc
63 # define realloc frealloc
64 #endif /* WINNT_NATIVE */
66 #if !defined(DEBUG) || defined(SYSMALLOC)
70 static const char msg[] = "Out of memory\n";
72 TCSH_IGNORE(write(didfds ? 2 : SHDIAG, msg, strlen(msg)));
83 * Lots of os routines are busted and try to free invalid pointers.
84 * Although our free routine is smart enough and it will pick bad
85 * pointers most of the time, in cases where we know we are going to get
86 * a bad pointer, we'd rather leak.
93 typedef unsigned char U_char; /* we don't really have signed chars */
94 typedef unsigned int U_int;
95 typedef unsigned short U_short;
96 typedef unsigned long U_long;
100 * The overhead on a block is at least 4 bytes. When free, this space
101 * contains a pointer to the next free block, and the bottom two bits must
102 * be zero. When in use, the first byte is set to MAGIC, and the second
103 * byte is the size index. The remaining bytes are for alignment.
104 * If range checking is enabled and the size of the block fits
105 * in two bytes, then the top two bytes hold the size of the requested block
106 * plus the range checking words, and the header word MINUS ONE.
110 #define MEMALIGN(a) (((a) + ROUNDUP) & ~ROUNDUP)
113 union overhead *ov_next; /* when free */
115 U_char ovu_magic; /* magic number */
116 U_char ovu_index; /* bucket # */
118 U_short ovu_size; /* actual block size */
119 U_int ovu_rmagic; /* range magic number */
122 #define ov_magic ovu.ovu_magic
123 #define ov_index ovu.ovu_index
124 #define ov_size ovu.ovu_size
125 #define ov_rmagic ovu.ovu_rmagic
128 #define MAGIC 0xfd /* magic # on accounting info */
129 #define RMAGIC 0x55555555 /* magic # on range info */
131 #define RSLOP sizeof (U_int)
144 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
145 * smallest allocatable block is 8 bytes. The overhead information
146 * precedes the data area returned to the user.
148 #define NBUCKETS ((sizeof(long) << 3) - 3)
149 static union overhead *nextf[NBUCKETS] IZERO_STRUCT;
152 * nmalloc[i] is the difference between the number of mallocs and frees
153 * for a given block size.
155 static U_int nmalloc[NBUCKETS] IZERO_STRUCT;
158 static int findbucket (union overhead *, int);
159 static void morecore (int);
164 # define CHECK(a, str, p) \
167 xprintf(" (memtop = %p membot = %p)\n", memtop, membot); \
171 # define CHECK(a, str, p) \
174 xprintf(" (memtop = %p membot = %p)\n", memtop, membot); \
180 malloc(size_t nbytes)
188 * Convert amount of memory requested into closest block size stored in
189 * hash buckets which satisfies request. Account for space used per block
194 * SunOS localtime() overwrites the 9th byte on an 8 byte malloc()....
195 * so we get one more...
196 * From Michael Schroeder: This is not true. It depends on the
197 * timezone string. In Europe it can overwrite the 13th byte on a
199 * So we punt and we always allocate an extra byte.
204 nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead)) + nbytes + RSLOP);
205 shiftr = (nbytes - 1) >> 2;
207 /* apart from this loop, this is O(1) */
208 while ((shiftr >>= 1) != 0)
211 * If nothing in hash bucket right now, request more memory from the
214 if (nextf[bucket] == NULL)
216 if ((p = nextf[bucket]) == NULL) {
222 xprintf(CGETS(19, 1, "nbytes=%zu: Out of memory\n"), nbytes);
226 return ((memalign_t) 0);
228 /* remove from linked list */
229 nextf[bucket] = nextf[bucket]->ov_next;
231 p->ov_index = bucket;
235 * Record allocated size of block and bound space with magic numbers.
237 p->ov_size = (p->ov_index <= 13) ? nbytes - 1 : 0;
238 p->ov_rmagic = RMAGIC;
239 *((U_int *) (((caddr_t) p) + nbytes - RSLOP)) = RMAGIC;
241 return ((memalign_t) (((caddr_t) p) + MEMALIGN(sizeof(union overhead))));
244 return ((memalign_t) 0);
246 return ((memalign_t) 0);
252 * Allocate more memory to the indicated bucket.
258 int rnu; /* 2^rnu bytes will be requested */
259 int nblks; /* become nblks blocks of the desired size */
265 * Insure memory is allocated on a page boundary. Should make getpageize
268 op = (union overhead *) sbrk(0);
269 memtop = (char *) op;
272 if ((long) op & 0x3ff) {
273 memtop = sbrk((int) (1024 - ((long) op & 0x3ff)));
274 memtop += (long) (1024 - ((long) op & 0x3ff));
277 /* take 2k unless the block is bigger than that */
278 rnu = (bucket <= 8) ? 11 : bucket + 3;
279 nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
280 memtop = sbrk(1 << rnu); /* PWP */
281 op = (union overhead *) memtop;
285 memtop += (long) (1 << rnu);
287 * Round up to minimum allocation size boundary and deduct from block count
290 if (((U_long) op) & ROUNDUP) {
291 op = (union overhead *) (((U_long) op + (ROUNDUP + 1)) & ~ROUNDUP);
295 * Add new memory allocated to that on free list for this hash bucket.
298 siz = 1 << (bucket + 3);
299 while (--nblks > 0) {
300 op->ov_next = (union overhead *) (((caddr_t) op) + siz);
301 op = (union overhead *) (((caddr_t) op) + siz);
316 * the don't free flag is there so that we avoid os bugs in routines
317 * that free invalid pointers!
319 if (cp == NULL || dont_free)
321 CHECK(!memtop || !membot,
322 CGETS(19, 2, "free(%p) called before any allocations."), cp);
323 CHECK(cp > (ptr_t) memtop,
324 CGETS(19, 3, "free(%p) above top of memory."), cp);
325 CHECK(cp < (ptr_t) membot,
326 CGETS(19, 4, "free(%p) below bottom of memory."), cp);
327 op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
328 CHECK(op->ov_magic != MAGIC,
329 CGETS(19, 5, "free(%p) bad block."), cp);
332 if (op->ov_index <= 13)
333 CHECK(*(U_int *) ((caddr_t) op + op->ov_size + 1 - RSLOP) != RMAGIC,
334 CGETS(19, 6, "free(%p) bad range check."), cp);
336 CHECK(op->ov_index >= NBUCKETS,
337 CGETS(19, 7, "free(%p) bad block index."), cp);
339 op->ov_next = nextf[size];
351 calloc(size_t i, size_t j)
359 /* Stop gcc 5.x from optimizing malloc+memset = calloc */
363 return ((memalign_t) cp);
366 return ((memalign_t) 0);
368 return ((memalign_t) 0);
373 * When a program attempts "storage compaction" as mentioned in the
374 * old malloc man page, it realloc's an already freed block. Usually
375 * this is the last block it freed; occasionally it might be farther
376 * back. We have to search all the free lists for the block in order
377 * to determine its bucket: 1st we make one pass thru the lists
378 * checking only the first block in each; if that fails we search
379 * ``realloc_srchlen'' blocks in each list for a match (the variable
380 * is extern so the caller can modify it). If that fails we just copy
381 * however many bytes was given to realloc() and hope it's not huge.
384 /* 4 should be plenty, -1 =>'s whole list */
385 static int realloc_srchlen = 4;
389 realloc(ptr_t cp, size_t nbytes)
399 return (malloc(nbytes));
400 op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
401 if (op->ov_magic == MAGIC) {
407 * Already free, doing "compaction".
409 * Search for the old block of memory on the free list. First, check the
410 * most common case (last element free'd), then (this failing) the last
411 * ``realloc_srchlen'' items free'd. If all lookups fail, then assume
412 * the size of the memory block being realloc'd is the smallest
415 if ((i = findbucket(op, 1)) < 0 &&
416 (i = findbucket(op, realloc_srchlen)) < 0)
419 onb = MEMALIGN(nbytes + MEMALIGN(sizeof(union overhead)) + RSLOP);
421 /* avoid the copy if same size block */
422 if (was_alloced && (onb <= (U_int) (1 << (i + 3))) &&
423 (onb > (U_int) (1 << (i + 2)))) {
425 /* JMR: formerly this wasn't updated ! */
426 nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead))+nbytes+RSLOP);
427 *((U_int *) (((caddr_t) op) + nbytes - RSLOP)) = RMAGIC;
428 op->ov_rmagic = RMAGIC;
429 op->ov_size = (op->ov_index <= 13) ? nbytes - 1 : 0;
431 return ((memalign_t) cp);
433 if ((res = malloc(nbytes)) == NULL)
434 return ((memalign_t) NULL);
435 if (cp != res) { /* common optimization */
437 * christos: this used to copy nbytes! It should copy the
438 * smaller of the old and new size
440 onb = (1 << (i + 3)) - MEMALIGN(sizeof(union overhead)) - RSLOP;
441 (void) memmove(res, cp, onb < nbytes ? onb : nbytes);
445 return ((memalign_t) res);
448 return ((memalign_t) 0);
450 return ((memalign_t) 0);
455 * On linux, _nss_nis_setnetgrent() calls this function to determine
456 * the usable size of the pointer passed, but this is not a portable
457 * API, so we cannot use our malloc replacement without providing one.
458 * Thanks a lot glibc!
465 size_t malloc_usable_size(M_U_S_CONST void *);
467 malloc_usable_size(M_U_S_CONST void *ptr)
469 const union overhead *op = (const union overhead *)
470 (((const char *) ptr) - MEMALIGN(sizeof(*op)));
471 if (op->ov_magic == MAGIC)
472 return 1 << (op->ov_index + 3);
480 * Search ``srchlen'' elements of each free list for a block whose
481 * header starts at ``freep''. If srchlen is -1 search the whole list.
482 * Return bucket number, or -1 if not found.
485 findbucket(union overhead *freep, int srchlen)
491 for (i = 0; i < NBUCKETS; i++) {
493 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
505 #else /* SYSMALLOC */
508 ** ``Protected versions'' of malloc, realloc, calloc, and free
512 ** 1. malloc(0) is bad
514 ** 3. realloc(0, n) is bad
515 ** 4. realloc(n, 0) is bad
517 ** Also we call our error routine if we run out of memory.
529 #endif /* USE_SBRK */
531 if ((ptr = malloc(n)) == NULL)
534 if (memtop < ((char *) ptr) + n)
535 memtop = ((char *) ptr) + n;
538 #endif /* !USE_SBRK */
539 return ((memalign_t) ptr);
543 srealloc(ptr_t p, size_t n)
552 #endif /* USE_SBRK */
554 if ((ptr = (p ? realloc(p, n) : malloc(n))) == NULL)
557 if (memtop < ((char *) ptr) + n)
558 memtop = ((char *) ptr) + n;
561 #endif /* !USE_SBRK */
562 return ((memalign_t) ptr);
566 scalloc(size_t s, size_t n)
576 #endif /* USE_SBRK */
578 if ((ptr = malloc(n)) == NULL)
584 if (memtop < ((char *) ptr) + n)
585 memtop = ((char *) ptr) + n;
588 #endif /* !USE_SBRK */
590 return ((memalign_t) ptr);
600 #endif /* SYSMALLOC */
603 * mstats - print out statistics about malloc
605 * Prints two lines of numbers, one showing the length of the free list
606 * for each size category, the second showing the number of mallocs -
607 * frees for each size category.
611 showall(Char **v, struct command *c)
616 int totfree = 0, totused = 0;
618 xprintf(CGETS(19, 8, "%s current memory allocation:\nfree:\t"), progname);
619 for (i = 0; i < NBUCKETS; i++) {
620 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
623 totfree += j * (1 << (i + 3));
625 xprintf("\n%s:\t", CGETS(19, 9, "used"));
626 for (i = 0; i < NBUCKETS; i++) {
627 xprintf(" %4d", nmalloc[i]);
628 totused += nmalloc[i] * (1 << (i + 3));
630 xprintf(CGETS(19, 10, "\n\tTotal in use: %d, total free: %d\n"),
632 xprintf(CGETS(19, 11,
633 "\tAllocated memory from 0x%lx to 0x%lx. Real top at 0x%lx\n"),
634 (unsigned long) membot, (unsigned long) memtop,
635 (unsigned long) sbrk(0));
636 #else /* SYSMALLOC */
637 #ifndef HAVE_MALLINFO
640 #endif /* USE_SBRK */
641 xprintf(CGETS(19, 12, "Allocated memory from 0x%lx to 0x%lx (%ld).\n"),
642 (unsigned long) membot, (unsigned long) memtop,
643 (unsigned long) (memtop - membot));
644 #else /* HAVE_MALLINFO */
648 xprintf(CGETS(19, 13, "%s current memory allocation:\n"), progname);
649 xprintf(CGETS(19, 14, "Total space allocated from system: %d\n"), mi.arena);
650 xprintf(CGETS(19, 15, "Number of non-inuse chunks: %d\n"), mi.ordblks);
651 xprintf(CGETS(19, 16, "Number of mmapped regions: %d\n"), mi.hblks);
652 xprintf(CGETS(19, 17, "Total space in mmapped regions: %d\n"), mi.hblkhd);
653 xprintf(CGETS(19, 18, "Total allocated space: %d\n"), mi.uordblks);
654 xprintf(CGETS(19, 19, "Total non-inuse space: %d\n"), mi.fordblks);
655 xprintf(CGETS(19, 20, "Top-most, releasable space: %d\n"), mi.keepcost);
656 #endif /* HAVE_MALLINFO */
657 #endif /* SYSMALLOC */