CS456 - Systems Programming Spring 2026

Displaying ./code/h3/filetype.c

/*

This takes a file, and depending on it's attributes, something happens

We get a file, and were going to do the following:

If it is a regular file:
	- print the following
	- name
	- device_id
	- inode
	- permissions (in octal) 
	- size		
If it is a directory:
	- open the directory, print the contents that aren't hidden files 
	- print the count of the total number of files as well as the number of files that are hidden

If it is anything else:
	- print the name of the file along with it's type (in octal).
	- you can get the numerical value for that pretty easy

Do as well as you can here, we may be revisiting this program later

*/

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <dirent.h>

// what other header files wil i need?

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

	//prints usage statement if file not provided
	if(argc < 2){
		fprintf(stderr, "Usage %s file\n", argv[0]);
		exit(1);
	}

	// call stat on the file we're passing in (YOU DO THIS)
	// make sure you use the correct variant of stat (Hint: we want to detect links)
	//don't forget to check the return value
	struct stat st;
	int rt = lstat(argv[1], &st);

	if(rt < 0){
		perror("stat failed");
		exit(-1);
	}


	//check what type of file we have here
	// also get the permissions here too 



	// for the if statements you can use a macro from man 7 inode
	// or AND the mode with the mask value like in fileinfo.c
	// which you need to do for the 'other' case anyway
	// macro is probably easier

	//if it's a regular file, print specified values
	if(S_ISREG(st.st_mode)){
		int perms = st.st_mode & 0777;

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

	} else if(S_ISDIR(st.st_mode)){
		DIR *mydir;
		struct dirent *file;

		mydir = opendir(argv[1]);

		//check return value of opendir
		if(mydir == NULL){
			perror("opendir failed");
			exit(-2);
		}

		//keep counts of files
		int count = 0;
		int hidden = 0;

		//reading through directory
		while((file = readdir(mydir)) != NULL){
			count++;

			// checking if this is a hidden file , 
			// denoted by a '.' period character in the first chaacter of filename
			if(file->d_name[0] == '.'){
				hidden++;
				continue;
			}

			printf("%s\n", file->d_name);
		}

		printf("The directory %s has %d files, of which %d are hidden\n", argv[1], count, hidden);
		closedir(mydir);

	} else {
		//get what filetype this file is
		int type = st.st_mode & 0170000;
		printf("Name: %s Type: %o\n", argv[1], type);


	}



	//if it's a directory, 
		// print the contents but not hidden files
		// print the count of total files as well as hidden files
	
		
    
    //anything else, just print the name along with it's file type in octal


	return 0;

}