ssize_t (*read_f)(int fd, void *buffer, size_t n);
void *(*mmap_f)(void *start, size_t length, int prot, int flags, int fd, int64_t offset);
int (*munmap_f)(void *_start, size_t length);
ssize_t (*read_f)(int fd, void *buffer, size_t n);
void *(*mmap_f)(void *start, size_t length, int prot, int flags, int fd, int64_t offset);
int (*munmap_f)(void *_start, size_t length);