mmap cat implementation

mmapcat.c

#include <stdio.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/mman.h>

int main(int argc,char **argv)
{
	assert(argc==2);
	int file=open(argv[1],O_RDONLY);
	assert(file>0);
	
	struct stat st;
	fstat(file,&st);
	
	void *addr=mmap((void *)0xffffffff00000000,st.st_size,PROT_READ,MAP_PRIVATE,file,0);
	assert(addr);
	
	fwrite(addr,st.st_size,1,stdout);
	
	munmap(addr,st.st_size);
	close(file);
	return 0; 
}