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#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
/* This function should work with most dlmalloc-like chunk bookkeeping
* systems, but it's only guaranteed to work with the native implementation
* used in this library. */
void *aligned_alloc(size_t align, size_t len)
{
unsigned char *mem, *new, *end;
size_t header, footer;
if ((align & -align) != align) {
errno = EINVAL;
return NULL;
}
if (len > SIZE_MAX - align) {
errno = ENOMEM;
return NULL;
}
if (align <= 4*sizeof(size_t)) {
if (!(mem = malloc(len)))
return NULL;
return mem;
}
if (!(mem = malloc(len + align-1)))
return NULL;
header = ((size_t *)mem)[-1];
new = (void *)((uintptr_t)mem + align-1 & -align);
if (!(header & 7)) {
((size_t *)new)[-2] = ((size_t *)mem)[-2] + (new-mem);
((size_t *)new)[-1] = ((size_t *)mem)[-1] - (new-mem);
return new;
}
end = mem + (header & -8);
footer = ((size_t *)end)[-2];
((size_t *)mem)[-1] = header&7 | new-mem;
((size_t *)new)[-2] = footer&7 | new-mem;
((size_t *)new)[-1] = header&7 | end-new;
((size_t *)end)[-2] = footer&7 | end-new;
if (new != mem) free(mem);
return new;
}
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