1 /* Change the size of a block allocated by `mmalloc'. */
3 /* Copyright (c) 2010-2019. The SimGrid Team.
4 * All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
9 /* Copyright 1990, 1991 Free Software Foundation
10 Written May 1989 by Mike Haertel. */
12 #include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
13 #include <stdlib.h> /* abort */
15 #include "mmprivate.h"
18 #define MIN(a, b) ((a) < (b) ? (a) : (b))
21 /* Resize the given region to the new size, returning a pointer to the (possibly moved) region. This is optimized for
22 * speed; some benchmarks seem to indicate that greater compactness is achieved by unconditionally allocating and
23 * copying to a new region. This module has incestuous knowledge of the internals of both mfree and mmalloc. */
25 void *mrealloc(xbt_mheap_t mdp, void *ptr, size_t size)
30 /* Only keep real realloc, and reroute hidden malloc and free to the relevant functions */
33 return mmalloc(mdp, 0);
34 } else if (ptr == NULL) {
35 return mmalloc(mdp, size);
38 if ((char *) ptr < (char *) mdp->heapbase || BLOCK(ptr) > mdp->heapsize) {
39 printf("FIXME. Ouch, this pointer is not mine, refusing to proceed (another solution would be to malloc "
40 "it instead of reallocing it, see source code)\n");
44 size_t requested_size = size; // The amount of memory requested by user, for real
46 /* Work even if the user was stupid enough to ask a ridiculously small block (even 0-length),
47 * ie return a valid block that can be realloced and freed.
48 * glibc malloc does not use this trick but return a constant pointer, but we need to enlist the free fragments later on.
50 if (size < SMALLEST_POSSIBLE_MALLOC)
51 size = SMALLEST_POSSIBLE_MALLOC;
53 size_t block = BLOCK(ptr);
55 int type = mdp->heapinfo[block].type;
58 case MMALLOC_TYPE_HEAPINFO:
59 fprintf(stderr, "Asked realloc a fragment coming from a heapinfo block. I'm confused.\n");
63 case MMALLOC_TYPE_FREE:
64 fprintf(stderr, "Asked realloc a fragment coming from a *free* block. I'm puzzled.\n");
68 case MMALLOC_TYPE_UNFRAGMENTED:
69 /* Maybe reallocate a large block to a small fragment. */
71 if (size <= BLOCKSIZE / 2) { // Full block -> Fragment; no need to optimize for time
73 result = mmalloc(mdp, size);
74 memcpy(result, ptr, requested_size);
79 /* Full blocks -> Full blocks; see if we can hold it in place. */
80 blocks = BLOCKIFY(size);
81 if (blocks < mdp->heapinfo[block].busy_block.size) {
83 /* The new size is smaller; return excess memory to the free list. */
84 for (it= block+blocks; it< mdp->heapinfo[block].busy_block.size ; it++){
85 mdp->heapinfo[it].type = MMALLOC_TYPE_UNFRAGMENTED; // FIXME that should be useless, type should already be 0 here
86 mdp->heapinfo[it].busy_block.ignore = 0;
87 mdp->heapinfo[it].busy_block.size = 0;
88 mdp->heapinfo[it].busy_block.busy_size = 0;
91 mdp->heapinfo[block + blocks].busy_block.size = mdp->heapinfo[block].busy_block.size - blocks;
92 mfree(mdp, ADDRESS(block + blocks));
94 mdp->heapinfo[block].busy_block.size = blocks;
95 mdp->heapinfo[block].busy_block.busy_size = requested_size;
96 mdp->heapinfo[block].busy_block.ignore = 0;
99 } else if (blocks == mdp->heapinfo[block].busy_block.size) {
101 /* No block size change necessary; only update the requested size */
103 mdp->heapinfo[block].busy_block.busy_size = requested_size;
104 mdp->heapinfo[block].busy_block.ignore = 0;
107 /* Won't fit, so allocate a new region that will.
108 Free the old region first in case there is sufficient adjacent free space to grow without moving.
109 This trick mandates using a specific version of mmalloc that does not memset the memory to 0 after
110 action for obvious reasons. */
111 blocks = mdp->heapinfo[block].busy_block.size;
112 /* Prevent free from actually returning memory to the system. */
113 size_t oldlimit = mdp->heaplimit;
116 mdp->heaplimit = oldlimit;
118 result = mmalloc_no_memset(mdp, requested_size);
121 memmove(result, ptr, blocks * BLOCKSIZE);
122 /* FIXME: we should memset the end of the recently area */
126 default: /* Fragment -> ??; type=logarithm to base two of the fragment size. */
129 fprintf(stderr, "Unkown mmalloc block type.\n");
133 if (size > (size_t) (1 << (type - 1)) && size <= (size_t) (1 << type)) {
134 /* The new size is the same kind of fragment. */
137 int frag_nb = RESIDUAL(result, BLOCKSIZE) >> type;
138 mdp->heapinfo[block].busy_frag.frag_size[frag_nb] = requested_size;
139 mdp->heapinfo[block].busy_frag.ignore[frag_nb] = 0;
141 } else { /* fragment -> Either other fragment, or block */
142 /* The new size is different; allocate a new space,
143 and copy the lesser of the new size and the old. */
145 result = mmalloc(mdp, requested_size);
147 memcpy(result, ptr, MIN(requested_size, (size_t) 1 << type));