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32 lines
744 B
C
32 lines
744 B
C
// Replacement for sys/mman.h which factors out platform differences.
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#include <sys/mman.h>
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#if defined(VGO_darwin)
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# define MAP_ANONYMOUS MAP_ANON
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#endif
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#include <assert.h>
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#include <unistd.h>
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// Map a page, then unmap it, then return that address. That
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// guarantees to give an address which will fault when accessed,
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// without making any assumptions about the layout of the address
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// space.
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__attribute__((unused))
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static void* get_unmapped_page(void)
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{
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void* ptr;
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int r;
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long pagesz = sysconf(_SC_PAGE_SIZE);
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assert(pagesz == 4096 || pagesz == 65536);
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ptr = mmap(0, pagesz, PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
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assert(ptr != (void*)-1);
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r = munmap(ptr, pagesz);
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assert(r == 0);
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return ptr;
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}
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