CS456 - Systems Programming Spring 2026

Displaying ./code/mar18/fileinfo.c

/*

this program takes a file, and prints some info from the stat structure

*/

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


int main (int argc, char **argv){

	// prints usage statement if no file found
	if(argc < 2){
		fprintf(stderr,"Usage %s file\n", argv[0]);
		exit(1);	
	}

	// calling lstat as we want to get symbolic links
	struct stat st;
	int rt = lstat(argv[1], &st);

	//checking return value for errors
	if (rt < 0){
		perror("Stat Error:");
		exit(-1);
	}

	// calling stat on its own executable
	struct stat self;
	lstat(argv[0], &self);
	

	//get what filetype this file is
	int type = st.st_mode & 0170000;

	//get the overall permissions
	int perms = st.st_mode & 0777;

	//printing info
	printf("Filename : %s\n", argv[1]);
	printf("Device: %ld\n", st.st_dev);
	printf("Inode: %ld\n",  st.st_ino);
	printf("File Type: %o\n", type);
	printf("Permissions: %o\n", perms);
	printf("File Size: %ld\n", st.st_size);

	//checking if we're calling stat on itself

	if(st.st_dev == self.st_dev && st.st_ino == self.st_ino)
		printf("Hey, you called stat on your own stat program!\n");

	return 0;


}