ls的实现

1.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("\n");
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\n",name);
}
}
else if(flag == (PARAM_A | PARAM_L))
{
display_attribute(buf,name);
printf(" %-s\n",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("\n");
}
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\n",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;
}
2.运行截图