ls -latr

Posted 2023-05-29 人，唯一剥夺不了的，只有知识

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实现ls及ls的改进ls的实现

ls的实现及改进ls的实现

参考伪代码实现ls的功能，提交代码的编译，运行结果截图，码云代码链接。

打开目录文件

针对目录文件

读取目录条目

显示文件名

关闭文件目录文件

ls实现代码：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <dirent.h>
#include <string.h>
#include <linux/limits.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>

#define PARAM_NONE 0 //无参数
#define PARAM_A    1 //-a
#define PARAM_L    2 //-l
#define MAXROWLEN  80 //一行最多显示的字符数

int g_leave_len = MAXROWLEN; //一行是剩余长度，用于输出对齐
int g_maxlen;                //存放某目录下最长文件名的长度

void my_error(const char* errstring, int line)
{
    fprintf(stderr,"line:%d",line);
    perror(errstring);
    exit(1);
}

//打印单个文件，且没有-l参数
void display_single(char *name)
{
    int i,len;
    //如果本行不足以打印一个文件名则换行
    if(g_leave_len < g_maxlen)
    {
        printf("
");
        g_leave_len = MAXROWLEN;
    }
    
    len = strlen(name);
    len = g_maxlen - len;
    
    printf("%-s",name);

    for(i=0;i<len;i++)
    {
        printf(" ");
    }
    printf(" ");

    g_leave_len = g_leave_len - g_maxlen - 2;

}

/*获取文件属性并打印*/
void display_attribute(struct stat buf, char *name)
{
    char buf_time[32];
    struct passwd *psd;
    struct group *grp;
    
    //获取文件类型
    if(S_ISLNK(buf.st_mode))
        printf("1");
    else if(S_ISREG(buf.st_mode))
        printf("-");
    else if(S_ISDIR(buf.st_mode))
        printf("d");
    else if(S_ISCHR(buf.st_mode))
        printf("c");
    else if(S_ISBLK(buf.st_mode))
        printf("b");
    else if(S_ISFIFO(buf.st_mode))
        printf("f");
    else if(S_ISSOCK(buf.st_mode))
        printf("s");

    //获取文件权限
    if(buf.st_mode & S_IRUSR)
        printf("r");
    else
        printf("-");
    if(buf.st_mode & S_IWUSR)
        printf("w");
    else
        printf("-");
    if(buf.st_mode & S_IXUSR)
        printf("x");
    else
        printf("-");

    if(buf.st_mode & S_IRGRP)
        printf("r");
    else
        printf("-");
    if(buf.st_mode & S_IWGRP)
        printf("w");
    else
        printf("-");
    if(buf.st_mode & S_IXGRP)
        printf("x");
    else
        printf("-");

    if(buf.st_mode & S_IROTH)
        printf("r");
    else
        printf("-");
    if(buf.st_mode & S_IWOTH)
        printf("w");
    else
        printf("-");
    if(buf.st_mode & S_IXOTH)
        printf("x");
    else
        printf("-");

    printf("  ");
    
    //根据uid和gid获取文件所有者的用户名于组名
    psd = getpwuid(buf.st_uid);
    grp = getgrgid(buf.st_gid);
    printf("%4d",buf.st_nlink);
    printf("%-8s",psd->pw_name);
    printf("%-9s",grp->gr_name);
    
    printf("%6d",buf.st_size);
    strcpy(buf_time, ctime(&buf.st_mtime));//将格林位置时间转化成正常时间格式
    buf_time[strlen(buf_time) - 1] = 0;
    printf(" %s",buf_time);
}

//根据flag参数显示文件内容，调用display_single或者display_attribute
void display(int flag,char *pathname)
{
    int i,j;
    struct stat buf;
    char name[NAME_MAX + 1];

    for(i=0,j=0;i<strlen(pathname);i++)
    {
        if(pathname[i] == '/')
        {
            j = 0;
        }
        else
            name[j++] = pathname[i];
    }
    name[j] = 0;

    if(lstat(pathname,&buf) == -1)
    {
        my_error("stat",__LINE__);
    }
    
    if(flag == PARAM_NONE)
    {
        if(name[0] != '.')//不显示隐藏文件
        {
            display_single(name);
        }
    }
    else if(flag == PARAM_A)
    {
        display_single(name);
    }
    else if(flag == PARAM_L)
    {
        if(name[0] != '.')
        {
            display_attribute(buf,name);
            printf(" %-s
",name);
        }
    }
    else if(flag == (PARAM_A | PARAM_L))
    {
        display_attribute(buf,name);
        printf(" %-s
",name);
    }

}

void display_dir(int flag_param,const char *path)
{
    DIR* dir;
    struct dirent* dirent;
    char filenames[256][PATH_MAX+1],temp[PATH_MAX+1];
    int count = 0;//总共有多少个文件

    if((dir = opendir(path)) == NULL)
    {
        my_error("opendir",__LINE__);
    }
    
    //获取文件总数和最长文件名
    while((dirent = readdir(dir)) != NULL)
    {
        if(g_maxlen < strlen(dirent->d_name))
            g_maxlen = strlen(dirent->d_name);
        count++;
    }
    closedir(dir);
    
    if(count>256)
        my_error("文件太多超过了256个",__LINE__);
    
    int i,j,len = strlen(path);
    //获取目录下所有的文件名
    dir = opendir(path);
    for(i=0;i<count;i++)
    {
        dirent = readdir(dir);
        if(dirent == NULL)
        {
            my_error("readdir",__LINE__);    
        }
        strncpy(filenames[i],path,len);
        filenames[i][len] = 0;
        strcat(filenames[i],dirent->d_name);
        filenames[i][len+strlen(dirent->d_name)] = 0;
    }

    //对文件名进行排序
    for(i=0;i<count-1;i++)
        for(j=i+1;j<count-1;j++)
        {
            if(strcmp(filenames[i],filenames[j]) > 0)
            {
                strcpy(temp,filenames[j]);
                strcpy(filenames[j] , filenames[i]);
                strcpy(filenames[i] , temp);
            }
        }

    for(i=0;i<count;i++)
        display(flag_param,filenames[i]);
    closedir(dir);
    
    //没有-l的话打印一个换行符
    if((flag_param & PARAM_L) == 0)
        printf("
");
}

int main(int argc, char **argv)
{
    int i,j,k;
    int num;//记录-的个数
    char path[PATH_MAX + 1];
    char param[32]; // 保存命令行参数
    int  flag_param = PARAM_NONE;
    struct stat buf;
    
    j = 0;
    num = 0;
    for(i=1;i<argc;i++)
    {
        if(argv[i][0] == '-')
        {
            for(k=1;k<strlen(argv[i]);k++)
            {
                param[j] = argv[i][k];
                j++;
            }
            num++;
        }
    }

    //现在只支持-a和-l参数
    for(i=0;i<j;i++)
    {
        if(param[i] == 'a')
        {
            flag_param |= PARAM_A;
        }
        else if(param[i] == 'l')
        {
            flag_param |= PARAM_L; 
        }
        else
        {
            printf("错误的参数：%c
",param[i]);
            exit(1);
        }
    }

    param[j] = 0;

    //如果没有输入文件名或者目录，就显示当前目录
    if((num + 1) == argc)
    {
        strcpy(path,"./");
        path[2] = 0;
        display_dir(flag_param,path);
        return 0;
    }
    
    i = 1;
    for(i=1;i<argc;i++)
    {
        if(argv[i][0] != '-')
        {
            strcpy(path,argv[i]);
            if(stat(path,&buf) == -1)
                my_error("stat",__LINE__);
            if(S_ISDIR(buf.st_mode))
            {
                //判断目录是否以/结尾
                if(path[strlen(argv[i]) - 1] != '/')
                {
                    path[strlen(argv[i])] = '/';
                    path[strlen(argv[i] + 1)] = 0; 
                }
                else
                    path[strlen(argv[i])] = 0; 
            
                display_dir(flag_param,path);
            }
            else
            {
                display(flag_param,path);
            }
        }
    }

    return 0;     
}

文件可执行建立

测试-l -a

参见附图，改进你的ls的实现。提交代码运行截图和码云链接。

实现代码：

#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 LS_L 101  
#define LS_R 102  
#define LS_D 103  
#define LS_I 104  
#define LS_A 200  
#define LS_AL (LS_A+LS_L)  
#define LS_AI (LS_A+LS_I)  
      
// 展示单个文件的详细信息  
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
", 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 
", dirname);  
    }  
    else  
    {  
        if(mode==LS_D)  
        {  
            printf("%s
", 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 == LS_L||mode == LS_AL)  
                    {  
                        show_file_info(direntp->d_name, &info);  
                    }  
                    else if(mode == LS_A||mode == LS_NONE||mode == LS_I||mode == LS_AI)  
                    {  
                        if(mode == LS_I||mode == LS_AI)  
                        {  
                            printf("%llu ", direntp->d_ino);  
                        }  
      
                        printf("%s
", direntp->d_name);  
                    }  
                    else if(mode == LS_R)  
                    {  
      
                        if(S_ISDIR(info.st_mode))  
                        {  
                            printf("%s
", direntp->d_name);  
                            strcpy (dirs[dir_count],complete_d_name);  
                            dir_count++;  
                        }  
                        else  
                        {  
                            printf("%s
", direntp->d_name);  
                        }  
                    } 
                }  
            }  
            if(mode == LS_R)  
            {  
                int i=0;  
                printf("
");  
                for(;i<dir_count;i++){  
                printf("%s:
", dirs[i]);  
                do_ls(dirs[i],LS_R);  
                printf("
");  
                }  
            }  
        }  
        closedir(dir_ptr);  
    }  
}  
      
// 解析一个单词参数，如-l，-i  
int analyzeParam(char* input){  
    if(strlen(input)==2)  
    {  
        if(input[1]=='l') return LS_L;  
        if(input[1]=='a') return LS_A;  
        if(input[1]=='d') return LS_D;  
        if(input[1]=='R') return LS_R;  
        if(input[1]=='i') return LS_I;  
    }  
    else if(strlen(input)==3)  
    {  
        if(input[1]=='a'&& input[2]=='l') return LS_AL;  
        if(input[1]=='a'&& input[2]=='i') return LS_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; // 是否有输入文件参数  
        while(ac>1)  
        {  
            ac--;  
            av++;  
            int calMode = analyzeParam(*av);  
            if(calMode!=-1)  
            {  
                mode+=calMode;  
            }  
            else  
            {  
                have_file_param = 1;  
                do  
                {  
                    printf("%s:
", *av);  
                    do_ls(*av,mode);  
                    printf("
");  
                    ac--;  
                    av++;  
                }while(ac>=1);  
            }  
        }  
        if (!have_file_param)  
        {  
            do_ls(".",mode);  
        }  
    }       
}

makels改进测试：

码云链接提交图：

码云链接