>GNU Cat actually performs better than Busybox Cat because it does actual buffering and mmap trickery so it can handle large files better.
Or they could just
```
for(int i = 1; i < argc; i++) {
struct stat st;
stat(argv[i], &st);
int fd = open(argv[i], O_RDONLY);
sendfile(stdout, fd, NULL, st.st_size);
close(fd);
}
```
Here. That's the entire cat for you, give or take error handling.
