#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <pwd.h>

#include <sys/types.h>
#include <sys/stat.h>

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

	struct stat    file_stat;
	struct passwd *file_pd;

	int argc_decr;
	mode_t *ft;

	extern int errno;

	argc_decr = argc; /* K&R 117(§5.10) warns against decrementing argc directly */

	if(argc <= 1 || argc >= 5) {

		printf("USAGE: %s <file> [-o, -c]\n", argv[0]);
		return 1;

	} else if(stat(argv[1], &file_stat)) {

		if(errno == ENOENT)
			printf("provided file does not exist.\n");
		else if(errno == EACCES)
			printf("improper permissions to read from file.\n");
		else if(errno == ENAMETOOLONG)
			printf("provided path is too long.\n");
		else if(errno == ENOTDIR)
			printf("provided path contains a non-existant directory.\n");
		else if(errno == EOVERFLOW)
			printf("provided file cannot be properly contained into a stat buf.\n");
		else if(errno == ELOOP)
			printf("provided file points to an irresolvable symlink chain.\n");

		return errno;
	}

	printf("file size in bytes: %llu\n", file_stat.st_size);

	while(argc_decr > 2) {

		if(!strncmp(argv[argc_decr - 1], "-o", 5)) {

			if((file_pd = getpwuid(file_stat.st_uid)) != NULL)
				printf("file owned by user %s.\n", file_pd->pw_name);

			else
				printf("file owned by uid %d.\n", file_stat.st_uid);

		} else if(!strncmp(argv[argc_decr - 1], "-t", 5)) {

			printf("file is a ");
			ft = &(file_stat.st_mode);

			if     (S_ISBLK(*ft))  printf("block device.\n");
			else if(S_ISCHR(*ft))  printf("character device.\n");
			else if(S_ISFIFO(*ft)) printf("fifo pipe.\n");
			else if(S_ISREG(*ft))  printf("regular file.\n");
			else if(S_ISDIR(*ft))  printf("directory.\n");
			else if(S_ISLNK(*ft))  printf("symbolic link.\n");
				
				
		} else {

			printf("provided argument is invalid, must be '-t' or '-o'.\n");
			return 1;
		}

		argc_decr--;
	}

	return 0;
}