1 /* $Header: /p/tcsh/cvsroot/tcsh/tc.alloc.c,v 3.46 2006/03/02 18:46:44 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
43 RCSID("$tcsh: tc.alloc.c,v 3.46 2006/03/02 18:46:44 christos Exp $")
48 static char *memtop = NULL; /* PWP: top of current memory */
49 static char *membot = NULL; /* PWP: bottom of allocatable memory */
54 # define malloc fmalloc
56 # define calloc fcalloc
57 # define realloc frealloc
58 #endif /* WINNT_NATIVE */
60 #if !defined(DEBUG) || defined(SYSMALLOC)
64 static const char msg[] = "Out of memory\n";
66 write(didfds ? 2 : SHDIAG, msg, strlen(msg));
77 * Lots of os routines are busted and try to free invalid pointers.
78 * Although our free routine is smart enough and it will pick bad
79 * pointers most of the time, in cases where we know we are going to get
80 * a bad pointer, we'd rather leak.
87 typedef unsigned char U_char; /* we don't really have signed chars */
88 typedef unsigned int U_int;
89 typedef unsigned short U_short;
90 typedef unsigned long U_long;
94 * The overhead on a block is at least 4 bytes. When free, this space
95 * contains a pointer to the next free block, and the bottom two bits must
96 * be zero. When in use, the first byte is set to MAGIC, and the second
97 * byte is the size index. The remaining bytes are for alignment.
98 * If range checking is enabled and the size of the block fits
99 * in two bytes, then the top two bytes hold the size of the requested block
100 * plus the range checking words, and the header word MINUS ONE.
104 #define MEMALIGN(a) (((a) + ROUNDUP) & ~ROUNDUP)
107 union overhead *ov_next; /* when free */
109 U_char ovu_magic; /* magic number */
110 U_char ovu_index; /* bucket # */
112 U_short ovu_size; /* actual block size */
113 U_int ovu_rmagic; /* range magic number */
116 #define ov_magic ovu.ovu_magic
117 #define ov_index ovu.ovu_index
118 #define ov_size ovu.ovu_size
119 #define ov_rmagic ovu.ovu_rmagic
122 #define MAGIC 0xfd /* magic # on accounting info */
123 #define RMAGIC 0x55555555 /* magic # on range info */
125 #define RSLOP sizeof (U_int)
134 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
135 * smallest allocatable block is 8 bytes. The overhead information
136 * precedes the data area returned to the user.
138 #define NBUCKETS ((sizeof(long) << 3) - 3)
139 static union overhead *nextf[NBUCKETS] IZERO_STRUCT;
142 * nmalloc[i] is the difference between the number of mallocs and frees
143 * for a given block size.
145 static U_int nmalloc[NBUCKETS] IZERO_STRUCT;
148 static int findbucket (union overhead *, int);
149 static void morecore (int);
154 # define CHECK(a, str, p) \
157 xprintf(" (memtop = %p membot = %p)\n", memtop, membot); \
161 # define CHECK(a, str, p) \
164 xprintf(" (memtop = %p membot = %p)\n", memtop, membot); \
170 malloc(size_t nbytes)
178 * Convert amount of memory requested into closest block size stored in
179 * hash buckets which satisfies request. Account for space used per block
184 * SunOS localtime() overwrites the 9th byte on an 8 byte malloc()....
185 * so we get one more...
186 * From Michael Schroeder: This is not true. It depends on the
187 * timezone string. In Europe it can overwrite the 13th byte on a
189 * So we punt and we always allocate an extra byte.
194 nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead)) + nbytes + RSLOP);
195 shiftr = (nbytes - 1) >> 2;
197 /* apart from this loop, this is O(1) */
198 while ((shiftr >>= 1) != 0)
201 * If nothing in hash bucket right now, request more memory from the
204 if (nextf[bucket] == NULL)
206 if ((p = nextf[bucket]) == NULL) {
212 xprintf(CGETS(19, 1, "nbytes=%zu: Out of memory\n"), nbytes);
216 return ((memalign_t) 0);
218 /* remove from linked list */
219 nextf[bucket] = nextf[bucket]->ov_next;
221 p->ov_index = bucket;
225 * Record allocated size of block and bound space with magic numbers.
227 p->ov_size = (p->ov_index <= 13) ? nbytes - 1 : 0;
228 p->ov_rmagic = RMAGIC;
229 *((U_int *) (((caddr_t) p) + nbytes - RSLOP)) = RMAGIC;
231 return ((memalign_t) (((caddr_t) p) + MEMALIGN(sizeof(union overhead))));
234 return ((memalign_t) 0);
236 return ((memalign_t) 0);
242 * Allocate more memory to the indicated bucket.
248 int rnu; /* 2^rnu bytes will be requested */
249 int nblks; /* become nblks blocks of the desired size */
255 * Insure memory is allocated on a page boundary. Should make getpageize
258 op = (union overhead *) sbrk(0);
259 memtop = (char *) op;
262 if ((long) op & 0x3ff) {
263 memtop = sbrk((int) (1024 - ((long) op & 0x3ff)));
264 memtop += (long) (1024 - ((long) op & 0x3ff));
267 /* take 2k unless the block is bigger than that */
268 rnu = (bucket <= 8) ? 11 : bucket + 3;
269 nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
270 memtop = sbrk(1 << rnu); /* PWP */
271 op = (union overhead *) memtop;
275 memtop += (long) (1 << rnu);
277 * Round up to minimum allocation size boundary and deduct from block count
280 if (((U_long) op) & ROUNDUP) {
281 op = (union overhead *) (((U_long) op + (ROUNDUP + 1)) & ~ROUNDUP);
285 * Add new memory allocated to that on free list for this hash bucket.
288 siz = 1 << (bucket + 3);
289 while (--nblks > 0) {
290 op->ov_next = (union overhead *) (((caddr_t) op) + siz);
291 op = (union overhead *) (((caddr_t) op) + siz);
306 * the don't free flag is there so that we avoid os bugs in routines
307 * that free invalid pointers!
309 if (cp == NULL || dont_free)
311 CHECK(!memtop || !membot,
312 CGETS(19, 2, "free(%p) called before any allocations."), cp);
313 CHECK(cp > (ptr_t) memtop,
314 CGETS(19, 3, "free(%p) above top of memory."), cp);
315 CHECK(cp < (ptr_t) membot,
316 CGETS(19, 4, "free(%p) below bottom of memory."), cp);
317 op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
318 CHECK(op->ov_magic != MAGIC,
319 CGETS(19, 5, "free(%p) bad block."), cp);
322 if (op->ov_index <= 13)
323 CHECK(*(U_int *) ((caddr_t) op + op->ov_size + 1 - RSLOP) != RMAGIC,
324 CGETS(19, 6, "free(%p) bad range check."), cp);
326 CHECK(op->ov_index >= NBUCKETS,
327 CGETS(19, 7, "free(%p) bad block index."), cp);
329 op->ov_next = nextf[size];
341 calloc(size_t i, size_t j)
350 return ((memalign_t) cp);
353 return ((memalign_t) 0);
355 return ((memalign_t) 0);
360 * When a program attempts "storage compaction" as mentioned in the
361 * old malloc man page, it realloc's an already freed block. Usually
362 * this is the last block it freed; occasionally it might be farther
363 * back. We have to search all the free lists for the block in order
364 * to determine its bucket: 1st we make one pass thru the lists
365 * checking only the first block in each; if that fails we search
366 * ``realloc_srchlen'' blocks in each list for a match (the variable
367 * is extern so the caller can modify it). If that fails we just copy
368 * however many bytes was given to realloc() and hope it's not huge.
371 /* 4 should be plenty, -1 =>'s whole list */
372 static int realloc_srchlen = 4;
376 realloc(ptr_t cp, size_t nbytes)
386 return (malloc(nbytes));
387 op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
388 if (op->ov_magic == MAGIC) {
394 * Already free, doing "compaction".
396 * Search for the old block of memory on the free list. First, check the
397 * most common case (last element free'd), then (this failing) the last
398 * ``realloc_srchlen'' items free'd. If all lookups fail, then assume
399 * the size of the memory block being realloc'd is the smallest
402 if ((i = findbucket(op, 1)) < 0 &&
403 (i = findbucket(op, realloc_srchlen)) < 0)
406 onb = MEMALIGN(nbytes + MEMALIGN(sizeof(union overhead)) + RSLOP);
408 /* avoid the copy if same size block */
409 if (was_alloced && (onb <= (U_int) (1 << (i + 3))) &&
410 (onb > (U_int) (1 << (i + 2)))) {
412 /* JMR: formerly this wasn't updated ! */
413 nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead))+nbytes+RSLOP);
414 *((U_int *) (((caddr_t) op) + nbytes - RSLOP)) = RMAGIC;
415 op->ov_rmagic = RMAGIC;
416 op->ov_size = (op->ov_index <= 13) ? nbytes - 1 : 0;
418 return ((memalign_t) cp);
420 if ((res = malloc(nbytes)) == NULL)
421 return ((memalign_t) NULL);
422 if (cp != res) { /* common optimization */
424 * christos: this used to copy nbytes! It should copy the
425 * smaller of the old and new size
427 onb = (1 << (i + 3)) - MEMALIGN(sizeof(union overhead)) - RSLOP;
428 (void) memmove(res, cp, onb < nbytes ? onb : nbytes);
432 return ((memalign_t) res);
435 return ((memalign_t) 0);
437 return ((memalign_t) 0);
445 * Search ``srchlen'' elements of each free list for a block whose
446 * header starts at ``freep''. If srchlen is -1 search the whole list.
447 * Return bucket number, or -1 if not found.
450 findbucket(union overhead *freep, int srchlen)
456 for (i = 0; i < NBUCKETS; i++) {
458 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
470 #else /* SYSMALLOC */
473 ** ``Protected versions'' of malloc, realloc, calloc, and free
477 ** 1. malloc(0) is bad
479 ** 3. realloc(0, n) is bad
480 ** 4. realloc(n, 0) is bad
482 ** Also we call our error routine if we run out of memory.
494 #endif /* HAVE_SBRK */
496 if ((ptr = malloc(n)) == NULL)
499 if (memtop < ((char *) ptr) + n)
500 memtop = ((char *) ptr) + n;
503 #endif /* !HAVE_SBRK */
504 return ((memalign_t) ptr);
508 srealloc(ptr_t p, size_t n)
517 #endif /* HAVE_SBRK */
519 if ((ptr = (p ? realloc(p, n) : malloc(n))) == NULL)
522 if (memtop < ((char *) ptr) + n)
523 memtop = ((char *) ptr) + n;
526 #endif /* !HAVE_SBRK */
527 return ((memalign_t) ptr);
531 scalloc(size_t s, size_t n)
541 #endif /* HAVE_SBRK */
543 if ((ptr = malloc(n)) == NULL)
549 if (memtop < ((char *) ptr) + n)
550 memtop = ((char *) ptr) + n;
553 #endif /* !HAVE_SBRK */
555 return ((memalign_t) ptr);
565 #endif /* SYSMALLOC */
568 * mstats - print out statistics about malloc
570 * Prints two lines of numbers, one showing the length of the free list
571 * for each size category, the second showing the number of mallocs -
572 * frees for each size category.
576 showall(Char **v, struct command *c)
581 int totfree = 0, totused = 0;
583 xprintf(CGETS(19, 8, "%s current memory allocation:\nfree:\t"), progname);
584 for (i = 0; i < NBUCKETS; i++) {
585 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
588 totfree += j * (1 << (i + 3));
590 xprintf(CGETS(19, 9, "\nused:\t"));
591 for (i = 0; i < NBUCKETS; i++) {
592 xprintf(" %4d", nmalloc[i]);
593 totused += nmalloc[i] * (1 << (i + 3));
595 xprintf(CGETS(19, 10, "\n\tTotal in use: %d, total free: %d\n"),
597 xprintf(CGETS(19, 11,
598 "\tAllocated memory from 0x%lx to 0x%lx. Real top at 0x%lx\n"),
599 (unsigned long) membot, (unsigned long) memtop,
600 (unsigned long) sbrk(0));
604 #endif /* HAVE_SBRK */
605 xprintf(CGETS(19, 12, "Allocated memory from 0x%lx to 0x%lx (%ld).\n"),
606 (unsigned long) membot, (unsigned long) memtop,
607 (unsigned long) (memtop - membot));
608 #endif /* SYSMALLOC */