52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
#define _GNU_SOURCE
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <string.h>
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#include "meta.h"
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void *realloc(void *p, size_t n)
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{
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if (!p) return malloc(n);
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if (size_overflows(n)) return 0;
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struct meta *g = get_meta(p);
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int idx = get_slot_index(p);
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size_t stride = get_stride(g);
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unsigned char *start = g->mem->storage + stride*idx;
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unsigned char *end = start + stride - IB;
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size_t old_size = get_nominal_size(p, end);
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size_t avail_size = end-(unsigned char *)p;
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void *new;
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// only resize in-place if size class matches
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if (n <= avail_size && n<MMAP_THRESHOLD
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&& size_to_class(n)+1 >= g->sizeclass) {
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set_size(p, end, n);
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return p;
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}
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// use mremap if old and new size are both mmap-worthy
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if (g->sizeclass>=48 && n>=MMAP_THRESHOLD) {
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assert(g->sizeclass==63);
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size_t base = (unsigned char *)p-start;
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size_t needed = (n + base + UNIT + IB + 4095) & -4096;
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new = g->maplen*4096UL == needed ? g->mem :
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mremap(g->mem, g->maplen*4096UL, needed, MREMAP_MAYMOVE);
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if (new!=MAP_FAILED) {
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g->mem = new;
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g->maplen = needed/4096;
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p = g->mem->storage + base;
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end = g->mem->storage + (needed - UNIT) - IB;
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*end = 0;
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set_size(p, end, n);
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return p;
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}
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}
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new = malloc(n);
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if (!new) return 0;
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memcpy(new, p, n < old_size ? n : old_size);
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free(p);
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return new;
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}
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