[Normal] ls -l 긴 형식으로 출력

#include <stdio.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/stat.h>
#include <pwd.h>
#include <grp.h>

#define ON      1
#define OFF     0
#define SIZE    512

main(int argc, char *argv[])
{
        void    fatal(char *);
        DIR     *dir;
        int     i, j;
        char    permission[10];
        char    list[SIZE];
        char    buff[SIZE];
        char    file[SIZE + 1];
        struct  dirent  *directory;
        struct  stat    file_stat;
        struct  passwd  *user_information;
        struct  group   *group_information;


        if(argc != 2)
                {
                puts("사용법 : a.out directory_name");
                exit(0);
                }

        for(i = 0;i < 10;i++)
                permission[i] = '\0';

        if((dir = opendir(argv[1])) == NULL)
                fatal("opendir");

        while(directory = readdir(dir))
                {
                if(strcmp(directory->d_name, ".") == 0 ||
                        strcmp(directory->d_name, "..") == 0 ||
                        strncmp(directory->d_name, ".", 1) == 0)
                        continue;
                if(directory->d_ino == 0)
                        continue;

                sprintf(file, "%s/%s", argv[1], directory->d_name);//절대경로를 얻음
                if(lstat(file, &file_stat) < 0)
                        fatal("stat");

                switch(file_stat.st_mode & S_IFMT)
                        {
                        case    S_IFREG : list[0] = '-'; break;
                        case    S_IFDIR : list[0] = 'd'; break;
                        case    S_IFIFO : list[0] = 'p'; break;
                        case    S_IFLNK : list[0] = 'l'; break;
                        }
                list[1] = '\0';

                for(i = 0, j = 0;i < 3;i++, j += 3)//파일의 권한 알아내기
                        {
                        if(file_stat.st_mode & (S_IREAD >> (i * 3)))
                                permission[j] = 'r';
                        else    permission[j] = '-';
                        if(file_stat.st_mode & (S_IWRITE >> (i * 3)))
                                permission[j+1] = 'w';
                        else    permission[j+1] = '-';
                        if(file_stat.st_mode & (S_IEXEC >> (i * 3)))
                                permission[j+2] = 'x';
                        else    permission[j+2] = '-';
                        }

                permission[9] = '\0';

                /* 권한 출력 */
                strcat(list, permission);
                sprintf(buff, "%5d ", file_stat.st_nlink);
                strcat(list, buff);

                /* 사용자 이름 출력 */
                user_information = getpwuid(file_stat.st_uid);
                strcat(list, user_information->pw_name);

                /* 그룹 이름 출력 */
                group_information = getgrgid(file_stat.st_gid);
                sprintf(buff, " %s", group_information->gr_name);
                strcat(list, buff);

                /* 파일 크기 출력 */
                sprintf(buff, " %10d", file_stat.st_size);
                strcat(list, buff);

                /* 파일 접근 시간 출력 */
                sprintf(buff, " %s", ctime(&file_stat.st_mtime));
                buff[strlen(buff) - 1] = '\0';
                strcat(list, buff);

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

        putchar('\n');
        closedir(dir);
}
void
fatal(char *error_name)
{
        perror(error_name);
        exit(1);
}