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#include <stdlib.h>
#include <stdint.h>
#include <limits.h>
#include <errno.h>
#include "libc.h"
uintptr_t __brk(uintptr_t);
#define ALIGN 16
void *__simple_malloc(size_t n)
{
static uintptr_t cur, brk;
uintptr_t base, new;
static int lock[2];
size_t align=1;
if (!n) n++;
if (n > SIZE_MAX/2) goto toobig;
while (align<n && align<ALIGN)
align += align;
n = n + align - 1 & -align;
LOCK(lock);
if (!cur) cur = brk = __brk(0)+16;
base = cur + align-1 & -align;
if (n > SIZE_MAX - PAGE_SIZE - base) goto fail;
if (base+n > brk) {
new = base+n + PAGE_SIZE-1 & -PAGE_SIZE;
if (__brk(new) != new) goto fail;
brk = new;
}
cur = base+n;
UNLOCK(lock);
return (void *)base;
fail:
UNLOCK(lock);
toobig:
errno = ENOMEM;
return 0;
}
weak_alias(__simple_malloc, malloc);
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