ls实现

    #include <stdio.h>  
    #include <sys/types.h>  
    #include <dirent.h>  
    #include <sys/stat.h>  
    #include <pwd.h>  
    #include <grp.h>  
    #include <unistd.h>  
    #include <string.h>  
    #define LS_NONE 0  
    #define L 101  
    #define R 102  
    #define D 103  
    #define I 104  
    #define A 200  
    #define AL (A+L)  
    #define AI (A+I)   
    void show_file(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[],int mode)  
    {  
        DIR* dir_ptr;  
        struct dirent* direntp;  
      
        if ((dir_ptr = opendir(dirname)) == NULL)  
        {  
            fprintf(stderr, "ls2: cannot open %s \n", dirname);  
        }  
        else  
        {  
            if(mode==D)  
            {  
                printf("%s\n", dirname);  
            }  
            else  
            {  
                char dirs[20][100];  
                int dir_count = 0;  
                  
                while ((direntp = readdir(dir_ptr)) != NULL)  
                {  
      
                    if(mode < 200 && direntp->d_name[0]=='.')  
                    {  
                        continue;  
                    }  
      
                    char complete_d_name[200];  // 文件的完整路径  
                    strcpy (complete_d_name,dirname);  
                    strcat (complete_d_name,"/");  
                    strcat (complete_d_name,direntp->d_name);  
                      
                    struct stat info;  
                    if (stat(complete_d_name, &info) == -1)  
                    {  
                        perror(complete_d_name);  
                    }  
                    else  
                    {  
                        if(mode == L||mode == AL)  
                        {  
                            show_file(direntp->d_name, &info);  
                        }  
                        else if(mode == A||mode == LS_NONE||mode == I||mode == AI)  
                        {  
                            if(mode == I||mode == AI)  
                            {  
                                printf("%llu ", direntp->d_ino);  
                            }  
      
                            printf("%s\n", direntp->d_name);  
                        }  
                        else if(mode == R)  
                        {  
      
                            if(S_ISDIR(info.st_mode))  
                            {  
                                printf("%s\n", direntp->d_name);  
      
                                strcpy (dirs[dir_count],complete_d_name);  
                                dir_count++;  
                            }  
                            else  
                            {  
                                printf("%s\n", direntp->d_name);  
                            }  
                        }  
      
                    }  
                }  
      
                if(mode == R)  
                {  
                    int i=0;  
                    printf("\n");  
                    for(;i<dir_count;i++){  
                        printf("%s:\n", dirs[i]);  
                        do_ls(dirs[i],R);  
                        printf("\n");  
                    }  
                }  
      
            }  
      
            closedir(dir_ptr);  
        }  
    }  
    int analyzeParam(char* input){  
        if(strlen(input)==2)  
        {  
            if(input[1]=='l') return L;  
            if(input[1]=='a') return A;  
            if(input[1]=='d') return D;  
            if(input[1]=='R') return R;  
            if(input[1]=='i') return I;  
        }  
        else if(strlen(input)==3)  
        {  
            if(input[1]=='a'&& input[2]=='l') return AL;  
            if(input[1]=='a'&& input[2]=='i') return AI;  
        }  
        return -1;  
    }  
      
    int main(int ac,char* av[])  
    {  
      
        if(ac == 1)  
        {  
            do_ls(".",LS_NONE);  
        }  
        else  
        {  
            int mode = LS_NONE; // 默认为无参数ls  
            int have_file_param = 0; 
      
            while(ac>1)  
            {  
                ac--;  
                av++;  
      
                int calMode = analyzeParam(*av);  
                if(calMode!=-1)  
                {  
                    mode+=calMode;  
                }  
                else  
                {  
                    have_file_param = 1;  
                    do  
                    {  
                        printf("%s:\n", *av);  
                        do_ls(*av,mode);  
                        printf("\n");  
      
                        ac--;  
                        av++;  
                    }while(ac>=1);  
                }  
            }  
      
            if (!have_file_param)  
            {  
                do_ls(".",mode);  
            }  
              
        }       
    }