LinuxC模拟ls -ls

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LinuxC——ls -l实现

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

void mode_to_letters(int mode, char str[]) //mode转为rwx格式字符串
{
	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)  //uid转为用户名
{
	struct passwd *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) //gid转为用户组
{
	struct group *str;
	static char name_gid[10];
	if((str=getgrgid(gid))==NULL)
	{
		sprintf(name_gid,"%d",gid);
		return name_gid;
	}
	else
	{
		return str->gr_name;
	}
}
int main(int argc,char *argv[])
{
	if(2!=argc)  //没加参数直接报错
	{
		perror("error input");
	}
	chdir(argv[1]);  //切换目录
	DIR *dp=opendir(argv[1]);  //打开目录文件
	char name[11];
	if(NULL==dp)   //目录不存在报错
	{
		perror("cannot open the dir\n");
	}
	struct dirent *entry;
	struct stat statbuf;
	while((entry=readdir(dp))!=NULL)
	{
		if(strcmp(entry->d_name,".")==0||strcmp(entry->d_name,"..")==0)
		{
			continue;
		}
		stat(entry->d_name,&statbuf);
		mode_to_letters(statbuf.st_mode,name);
		printf("%s",name);
		printf("%4d ",(int) statbuf.st_nlink);
		printf("%-13s",uid_to_name(statbuf.st_uid));
		printf("%-13s",gid_to_name(statbuf.st_gid));
		printf("%8ld  ",(long) statbuf.st_size);
		printf("%.12s  ",4+ctime(&statbuf.st_mtime));
		printf("%s\n",entry->d_name);
	}
}