Linux下用C语言实现ls -l的功能

今天药忘吃喽~ 2022-07-28 05:07 174阅读 0赞

为了实现ls的全部功能  
现在在逐步完成各项功能

#include <stdio.h>
    #include <sys/types.h>
    #include <dirent.h>
    #include <sys/stat.h>
    #include <pwd.h>
    #include <grp.h>
    #include <unistd.h>
    
    void show_file_info(char* filename, struct stat* info_p)
    {
        char* uid_to_name(), *ctime(), *gid_to_name(), *filemode();
        void mode_to_letters();
        char modestr[11];
    
        mode_to_letters(info_p->st_mode, modestr);
    
        printf("%s", modestr);
        printf(" %4d", (int) info_p->st_nlink);
        printf(" %-8s", uid_to_name(info_p->st_uid));
        printf(" %-8s", gid_to_name(info_p->st_gid));
        printf(" %8ld", (long) info_p->st_size);
        printf(" %.12s", 4 + ctime(&info_p->st_mtime));
        printf(" %s\n", filename);
    }
    
    void mode_to_letters(int mode, char str[])
    {
        strcpy(str, "----------");
    
        if (S_ISDIR(mode))
        {
            str[0] = 'd';
        }
    
        if (S_ISCHR(mode))
        {
            str[0] = 'c';
        }
    
        if (S_ISBLK(mode))
        {
            str[0] = 'b';
        }
    
        if ((mode & S_IRUSR))
        {
            str[1] = 'r';
        }
    
        if ((mode & S_IWUSR))
        {
            str[2] = 'w';
        }
    
        if ((mode & S_IXUSR))
        {
            str[3] = 'x';
        }
    
        if ((mode & S_IRGRP))
        {
            str[4] = 'r';
        }
    
        if ((mode & S_IWGRP))
        {
            str[5] = 'w';
        }
    
        if ((mode & S_IXGRP))
        {
            str[6] = 'x';
        }
    
        if ((mode & S_IROTH))
        {
            str[7] = 'r';
        }
    
        if ((mode & S_IWOTH))
        {
            str[8] = 'w';
        }
    
        if ((mode & S_IXOTH))
        {
            str[9] = 'x';
        }
    }
    
    char* uid_to_name(uid_t uid)
    {
        struct passwd* getpwuid(),* pw_ptr;
        static char numstr[10];
    
        if((pw_ptr = getpwuid(uid)) == NULL)
        {
            sprintf(numstr,"%d",uid);
    
            return numstr;
        }
        else
        {
            return pw_ptr->pw_name;
        }
    }
    
    char* gid_to_name(gid_t gid)
    {
        struct group* getgrgid(),* grp_ptr;
        static char numstr[10];
    
        if(( grp_ptr = getgrgid(gid)) == NULL)
        {
            sprintf(numstr,"%d",gid);
            return numstr;
        }
        else
        {
            return grp_ptr->gr_name;
        }
    }
    void do_ls(char dirname[])
    {
        DIR* dir_ptr;
        struct dirent* direntp;
    
        if ((dir_ptr = opendir(dirname)) == NULL)
        {
            fprintf(stderr, "ls2: cannot open %s \n", dirname);
        }
        else
        {
            while ((direntp = readdir(dir_ptr)) != NULL)
            {
                dostat(direntp->d_name);
            }
    
            close(dir_ptr);
        }
    }
    
    void dostat(char* filename)
    {
        struct stat info;
    
        if (stat(filename, &info) == -1)
        {
            perror(filename);
        }
        else
        {
            show_file_info(filename, &info);
        }
    }
    
    int main(int ac,char* av[])
    {
        if(ac == 1)
        {
            do_ls(".");
        }
        else
        {
            while(--ac)
            {
                printf("%s: \n",++*av);
                do_ls(*av);
            }
        }
    }