#include <sys/mman.h>
#include <sys/fcntl.h>
#include <unistd.h>
#include <stddef.h>
#include <sys/stat.h>
#define round_up(x, y) (((x) + (y) - 1) & ~((y) - 1))
static int pagesize;
static void __attribute__((constructor)) init_ps(void)
{
pagesize = sysconf(_SC_PAGESIZE);
}
void *mapfile(char *fn, size_t *size)
{
int fd = open(fn, O_RDWR);
if (fd < 0)
return NULL;
struct stat st;
void *map = (void *)-1L;
if (fstat(fd, &st) >= 0) {
*size = st.st_size;
map = mmap(NULL, round_up(st.st_size, pagesize),
PROT_READ|PROT_WRITE,
MAP_PRIVATE, fd, 0);
}
close(fd);
return map != (void *)-1L ? map : NULL;
}
void unmapfile(void *map, size_t size)
{
munmap(map, round_up(size, pagesize));
}