#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>

int main(int argc, char* argv[]){
	struct stat sb;
	off_t len;
	char *fp;
	int fd;

	if (argc < 2){
		fprintf(stderr, "usage: %s file1 [file2...]\n", argv[0]);
		exit(1);
	}

	for (int i = 1; i < argc; ++i)
	{
		fd = open (argv[i], O_RDONLY);
		if(fd == -1){
			perror("open");
			exit(2);
		}

		if (fstat (fd, &sb) == -1){
			perror("fstat");
			exit(3);
		}

		if(!S_ISREG (sb.st_mode)){
			fprintf(stderr, "%s is not a file\n", argv[i]);
			exit(4);
		}

		fp = mmap (0, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
		if (fp == MAP_FAILED){
			perror("mmap");
			exit(5);
		}

		if (close(fd) == -1){
			perror("close");
			exit(6);
		}

		write(STDOUT_FILENO, fp, sb.st_size);
		putchar('\n');

		if(munmap (fp, sb.st_size)==-1){
			perror("munmap");
			exit(7);
		}
	}
}