1 /* $Header: /p/tcsh/cvsroot/tcsh/tc.alloc.c,v 3.50 2011/12/30 20:55:24 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
46 RCSID("$tcsh: tc.alloc.c,v 3.50 2011/12/30 20:55:24 christos Exp $")
51 static char *memtop = NULL; /* PWP: top of current memory */
52 static char *membot = NULL; /* PWP: bottom of allocatable memory */
57 # define malloc fmalloc
59 # define calloc fcalloc
60 # define realloc frealloc
61 #endif /* WINNT_NATIVE */
63 #if !defined(DEBUG) || defined(SYSMALLOC)
67 static const char msg[] = "Out of memory\n";
69 write(didfds ? 2 : SHDIAG, msg, strlen(msg));
80 * Lots of os routines are busted and try to free invalid pointers.
81 * Although our free routine is smart enough and it will pick bad
82 * pointers most of the time, in cases where we know we are going to get
83 * a bad pointer, we'd rather leak.
90 typedef unsigned char U_char; /* we don't really have signed chars */
91 typedef unsigned int U_int;
92 typedef unsigned short U_short;
93 typedef unsigned long U_long;
97 * The overhead on a block is at least 4 bytes. When free, this space
98 * contains a pointer to the next free block, and the bottom two bits must
99 * be zero. When in use, the first byte is set to MAGIC, and the second
100 * byte is the size index. The remaining bytes are for alignment.
101 * If range checking is enabled and the size of the block fits
102 * in two bytes, then the top two bytes hold the size of the requested block
103 * plus the range checking words, and the header word MINUS ONE.
107 #define MEMALIGN(a) (((a) + ROUNDUP) & ~ROUNDUP)
110 union overhead *ov_next; /* when free */
112 U_char ovu_magic; /* magic number */
113 U_char ovu_index; /* bucket # */
115 U_short ovu_size; /* actual block size */
116 U_int ovu_rmagic; /* range magic number */
119 #define ov_magic ovu.ovu_magic
120 #define ov_index ovu.ovu_index
121 #define ov_size ovu.ovu_size
122 #define ov_rmagic ovu.ovu_rmagic
125 #define MAGIC 0xfd /* magic # on accounting info */
126 #define RMAGIC 0x55555555 /* magic # on range info */
128 #define RSLOP sizeof (U_int)
137 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
138 * smallest allocatable block is 8 bytes. The overhead information
139 * precedes the data area returned to the user.
141 #define NBUCKETS ((sizeof(long) << 3) - 3)
142 static union overhead *nextf[NBUCKETS] IZERO_STRUCT;
145 * nmalloc[i] is the difference between the number of mallocs and frees
146 * for a given block size.
148 static U_int nmalloc[NBUCKETS] IZERO_STRUCT;
151 static int findbucket (union overhead *, int);
152 static void morecore (int);
157 # define CHECK(a, str, p) \
160 xprintf(" (memtop = %p membot = %p)\n", memtop, membot); \
164 # define CHECK(a, str, p) \
167 xprintf(" (memtop = %p membot = %p)\n", memtop, membot); \
173 malloc(size_t nbytes)
181 * Convert amount of memory requested into closest block size stored in
182 * hash buckets which satisfies request. Account for space used per block
187 * SunOS localtime() overwrites the 9th byte on an 8 byte malloc()....
188 * so we get one more...
189 * From Michael Schroeder: This is not true. It depends on the
190 * timezone string. In Europe it can overwrite the 13th byte on a
192 * So we punt and we always allocate an extra byte.
197 nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead)) + nbytes + RSLOP);
198 shiftr = (nbytes - 1) >> 2;
200 /* apart from this loop, this is O(1) */
201 while ((shiftr >>= 1) != 0)
204 * If nothing in hash bucket right now, request more memory from the
207 if (nextf[bucket] == NULL)
209 if ((p = nextf[bucket]) == NULL) {
215 xprintf(CGETS(19, 1, "nbytes=%zu: Out of memory\n"), nbytes);
219 return ((memalign_t) 0);
221 /* remove from linked list */
222 nextf[bucket] = nextf[bucket]->ov_next;
224 p->ov_index = bucket;
228 * Record allocated size of block and bound space with magic numbers.
230 p->ov_size = (p->ov_index <= 13) ? nbytes - 1 : 0;
231 p->ov_rmagic = RMAGIC;
232 *((U_int *) (((caddr_t) p) + nbytes - RSLOP)) = RMAGIC;
234 return ((memalign_t) (((caddr_t) p) + MEMALIGN(sizeof(union overhead))));
237 return ((memalign_t) 0);
239 return ((memalign_t) 0);
245 * Allocate more memory to the indicated bucket.
251 int rnu; /* 2^rnu bytes will be requested */
252 int nblks; /* become nblks blocks of the desired size */
258 * Insure memory is allocated on a page boundary. Should make getpageize
261 op = (union overhead *) sbrk(0);
262 memtop = (char *) op;
265 if ((long) op & 0x3ff) {
266 memtop = sbrk((int) (1024 - ((long) op & 0x3ff)));
267 memtop += (long) (1024 - ((long) op & 0x3ff));
270 /* take 2k unless the block is bigger than that */
271 rnu = (bucket <= 8) ? 11 : bucket + 3;
272 nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
273 memtop = sbrk(1 << rnu); /* PWP */
274 op = (union overhead *) memtop;
278 memtop += (long) (1 << rnu);
280 * Round up to minimum allocation size boundary and deduct from block count
283 if (((U_long) op) & ROUNDUP) {
284 op = (union overhead *) (((U_long) op + (ROUNDUP + 1)) & ~ROUNDUP);
288 * Add new memory allocated to that on free list for this hash bucket.
291 siz = 1 << (bucket + 3);
292 while (--nblks > 0) {
293 op->ov_next = (union overhead *) (((caddr_t) op) + siz);
294 op = (union overhead *) (((caddr_t) op) + siz);
309 * the don't free flag is there so that we avoid os bugs in routines
310 * that free invalid pointers!
312 if (cp == NULL || dont_free)
314 CHECK(!memtop || !membot,
315 CGETS(19, 2, "free(%p) called before any allocations."), cp);
316 CHECK(cp > (ptr_t) memtop,
317 CGETS(19, 3, "free(%p) above top of memory."), cp);
318 CHECK(cp < (ptr_t) membot,
319 CGETS(19, 4, "free(%p) below bottom of memory."), cp);
320 op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
321 CHECK(op->ov_magic != MAGIC,
322 CGETS(19, 5, "free(%p) bad block."), cp);
325 if (op->ov_index <= 13)
326 CHECK(*(U_int *) ((caddr_t) op + op->ov_size + 1 - RSLOP) != RMAGIC,
327 CGETS(19, 6, "free(%p) bad range check."), cp);
329 CHECK(op->ov_index >= NBUCKETS,
330 CGETS(19, 7, "free(%p) bad block index."), cp);
332 op->ov_next = nextf[size];
344 calloc(size_t i, size_t j)
353 return ((memalign_t) cp);
356 return ((memalign_t) 0);
358 return ((memalign_t) 0);
363 * When a program attempts "storage compaction" as mentioned in the
364 * old malloc man page, it realloc's an already freed block. Usually
365 * this is the last block it freed; occasionally it might be farther
366 * back. We have to search all the free lists for the block in order
367 * to determine its bucket: 1st we make one pass thru the lists
368 * checking only the first block in each; if that fails we search
369 * ``realloc_srchlen'' blocks in each list for a match (the variable
370 * is extern so the caller can modify it). If that fails we just copy
371 * however many bytes was given to realloc() and hope it's not huge.
374 /* 4 should be plenty, -1 =>'s whole list */
375 static int realloc_srchlen = 4;
379 realloc(ptr_t cp, size_t nbytes)
389 return (malloc(nbytes));
390 op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
391 if (op->ov_magic == MAGIC) {
397 * Already free, doing "compaction".
399 * Search for the old block of memory on the free list. First, check the
400 * most common case (last element free'd), then (this failing) the last
401 * ``realloc_srchlen'' items free'd. If all lookups fail, then assume
402 * the size of the memory block being realloc'd is the smallest
405 if ((i = findbucket(op, 1)) < 0 &&
406 (i = findbucket(op, realloc_srchlen)) < 0)
409 onb = MEMALIGN(nbytes + MEMALIGN(sizeof(union overhead)) + RSLOP);
411 /* avoid the copy if same size block */
412 if (was_alloced && (onb <= (U_int) (1 << (i + 3))) &&
413 (onb > (U_int) (1 << (i + 2)))) {
415 /* JMR: formerly this wasn't updated ! */
416 nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead))+nbytes+RSLOP);
417 *((U_int *) (((caddr_t) op) + nbytes - RSLOP)) = RMAGIC;
418 op->ov_rmagic = RMAGIC;
419 op->ov_size = (op->ov_index <= 13) ? nbytes - 1 : 0;
421 return ((memalign_t) cp);
423 if ((res = malloc(nbytes)) == NULL)
424 return ((memalign_t) NULL);
425 if (cp != res) { /* common optimization */
427 * christos: this used to copy nbytes! It should copy the
428 * smaller of the old and new size
430 onb = (1 << (i + 3)) - MEMALIGN(sizeof(union overhead)) - RSLOP;
431 (void) memmove(res, cp, onb < nbytes ? onb : nbytes);
435 return ((memalign_t) res);
438 return ((memalign_t) 0);
440 return ((memalign_t) 0);
445 * On linux, _nss_nis_setnetgrent() calls this function to determine
446 * the usable size of the pointer passed, but this is not a portable
447 * API, so we cannot use our malloc replacement without providing one.
448 * Thanks a lot glibc!
455 size_t malloc_usable_size(M_U_S_CONST void *);
457 malloc_usable_size(M_U_S_CONST void *ptr)
459 const union overhead *op = (const union overhead *)
460 (((const char *) ptr) - MEMALIGN(sizeof(*op)));
461 if (op->ov_magic == MAGIC)
462 return 1 << (op->ov_index + 2);
470 * Search ``srchlen'' elements of each free list for a block whose
471 * header starts at ``freep''. If srchlen is -1 search the whole list.
472 * Return bucket number, or -1 if not found.
475 findbucket(union overhead *freep, int srchlen)
481 for (i = 0; i < NBUCKETS; i++) {
483 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
495 #else /* SYSMALLOC */
498 ** ``Protected versions'' of malloc, realloc, calloc, and free
502 ** 1. malloc(0) is bad
504 ** 3. realloc(0, n) is bad
505 ** 4. realloc(n, 0) is bad
507 ** Also we call our error routine if we run out of memory.
519 #endif /* HAVE_SBRK */
521 if ((ptr = malloc(n)) == NULL)
524 if (memtop < ((char *) ptr) + n)
525 memtop = ((char *) ptr) + n;
528 #endif /* !HAVE_SBRK */
529 return ((memalign_t) ptr);
533 srealloc(ptr_t p, size_t n)
542 #endif /* HAVE_SBRK */
544 if ((ptr = (p ? realloc(p, n) : malloc(n))) == NULL)
547 if (memtop < ((char *) ptr) + n)
548 memtop = ((char *) ptr) + n;
551 #endif /* !HAVE_SBRK */
552 return ((memalign_t) ptr);
556 scalloc(size_t s, size_t n)
566 #endif /* HAVE_SBRK */
568 if ((ptr = malloc(n)) == NULL)
574 if (memtop < ((char *) ptr) + n)
575 memtop = ((char *) ptr) + n;
578 #endif /* !HAVE_SBRK */
580 return ((memalign_t) ptr);
590 #endif /* SYSMALLOC */
593 * mstats - print out statistics about malloc
595 * Prints two lines of numbers, one showing the length of the free list
596 * for each size category, the second showing the number of mallocs -
597 * frees for each size category.
601 showall(Char **v, struct command *c)
606 int totfree = 0, totused = 0;
608 xprintf(CGETS(19, 8, "%s current memory allocation:\nfree:\t"), progname);
609 for (i = 0; i < NBUCKETS; i++) {
610 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
613 totfree += j * (1 << (i + 3));
615 xprintf("\n%s:\t", CGETS(19, 9, "used"));
616 for (i = 0; i < NBUCKETS; i++) {
617 xprintf(" %4d", nmalloc[i]);
618 totused += nmalloc[i] * (1 << (i + 3));
620 xprintf(CGETS(19, 10, "\n\tTotal in use: %d, total free: %d\n"),
622 xprintf(CGETS(19, 11,
623 "\tAllocated memory from 0x%lx to 0x%lx. Real top at 0x%lx\n"),
624 (unsigned long) membot, (unsigned long) memtop,
625 (unsigned long) sbrk(0));
626 #else /* SYSMALLOC */
627 #ifndef HAVE_MALLINFO
630 #endif /* HAVE_SBRK */
631 xprintf(CGETS(19, 12, "Allocated memory from 0x%lx to 0x%lx (%ld).\n"),
632 (unsigned long) membot, (unsigned long) memtop,
633 (unsigned long) (memtop - membot));
634 #else /* HAVE_MALLINFO */
638 xprintf(CGETS(19, 13, "%s current memory allocation:\n"), progname);
639 xprintf(CGETS(19, 14, "Total space allocated from system: %d\n"), mi.arena);
640 xprintf(CGETS(19, 15, "Number of non-inuse chunks: %d\n"), mi.ordblks);
641 xprintf(CGETS(19, 16, "Number of mmapped regions: %d\n"), mi.hblks);
642 xprintf(CGETS(19, 17, "Total space in mmapped regions: %d\n"), mi.hblkhd);
643 xprintf(CGETS(19, 18, "Total allocated space: %d\n"), mi.uordblks);
644 xprintf(CGETS(19, 19, "Total non-inuse space: %d\n"), mi.fordblks);
645 xprintf(CGETS(19, 20, "Top-most, releasable space: %d\n"), mi.keepcost);
646 #endif /* HAVE_MALLINFO */
647 #endif /* SYSMALLOC */