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/*
* LIB/XMAP.C
*
* Some machines fail if mmap() is passed with odd arguments. The xmap() calls
* page-align everything, allowing non-aligned offsets and sizes to be
* requested.
*/
#include "defs.h"
Prototype void *xmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset);
Prototype void xunmap(void *addr, size_t len);
static int XPageMask;
void *
xmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset)
{
int n;
void *ptr;
struct stat st;
if (XPageMask == 0)
XPageMask = getpagesize() - 1;
n = offset & XPageMask;
offset -= n;
len += n;
len = (len + XPageMask) & ~XPageMask;
st.st_size = 0;
fstat(fd, &st);
if (offset + len > ((st.st_size + XPageMask) & ~XPageMask)) {
ptr = NULL;
} else {
ptr = (void *)mmap((caddr_t)addr, len, prot, flags, fd, offset);
}
if (ptr == (void *)-1)
ptr = NULL;
if (ptr)
return((char *)ptr + n);
return(NULL);
}
void
xunmap(void *ptr, size_t len)
{
long n; /* assume sizeof(long) == sizeof(ptr)*/
if (XPageMask == 0)
XPageMask = getpagesize() - 1;
n = (long)ptr & XPageMask;
ptr = (char *)ptr - n;
len += n;
len = (len + XPageMask) & ~XPageMask;
munmap((caddr_t)ptr, len);
}
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