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#ifndef INIT_MMAP
#define depends_alloca(N) alloca(N)
#define read_alloca(N) alloca(N)
#define INIT_FREE_MEMBLOCKS(X) X
#define free_execve(...) execve(__VA_ARGS__)
#else
#include <sys/mman.h>
#include <sys/shm.h> /* for PAGE_SIZE */
#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
#endif
#define depends_alloca(N) mmap_alloca(N)
#define read_alloca(N) \
((read_buf) ? read_buf : (read_buf=mmap_alloca(N)))
#define INIT_FREE_MEMBLOCKS(X) read_buf=0; mmap_free(); X
#define free_execve(...) mmap_free(); execve(__VA_ARGS__)
#define mem_x_size ((sizeof(struct memalloc) + 16) & ~15)
static struct memalloc *mroot;
static void *read_buf;
static void *mmap_alloca(uint32t n) {
n = (n + 16) & ~15;
if (mroot == 0 || n + mem_x_size >= mroot->r) {
struct memalloc *m;
uint32t len = (n + (PAGE_SIZE + mem_x_size)) & ~(PAGE_SIZE-1);
m = mmap(0,len,PROT_READ|PROT_WRITE,MAP_ANONYMOUS|MAP_PRIVATE,-1,0);
if (m == (struct memalloc *)-1) return 0;
m->x = mroot; /* previous block */
m->a = len;
m->r = len;
mroot = m;
}
mroot->r -= n;
return (void *)mroot + mroot->r;
}
#undef mem_x_size
static void mmap_free() {
while (mroot) {
void *x = mroot->x;
munmap(mroot,mroot->a);
mroot = x;
}
}
#endif
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