linux下用c语言实现ls -l 对文件或者目录的属性遍历

#include <head.h>

void display_file(const char *filename)//单个的显示一个文件的属性  ls  -l file
{
struct stat f_info;

if(stat(filename,&f_info) < 0)
{
fprintf(stderr,"@@File to stat %s:%s",filename,strerror(errno));
return ;
}

switch(f_info.st_mode & S_IFMT)  //文件的类型 b c d - l s p
{
case S_IFSOCK:
putchar('s');
break;
case S_IFLNK:
putchar('l');
break;
case S_IFDIR:
putchar('d');
break;
case S_IFCHR:
putchar('c');
break;
case S_IFBLK:
putchar('b');
break;
case S_IFREG:
putchar('-');
break;
case S_IFIFO:
putchar('p');
break;
default:
break;
}

#if 0/*{{{*/
//怎么优化 if  else ???
//主用户的权限
if(f_info.st_mode & S_IRUSR)
putchar('r');
else
putchar('-');
if(f_info.st_mode & S_IWUSR)
putchar('w');
else
putchar('-');
if(f_info.st_mode & S_IXUSR)
putchar('x');
else
putchar('-');
//用户组的权限
if(f_info.st_mode & S_IRGRP)
putchar('r');
else
putchar('-');
if(f_info.st_mode & S_IWGRP)
putchar('w');
else
putchar('-');
if(f_info.st_mode & S_IXGRP)
putchar('x');
else
putchar('-');
//其他人的权限
if(f_info.st_mode & S_IROTH)
putchar('r');
else
putchar('-');
if(f_info.st_mode & S_IWOTH)
putchar('w');
else
putchar('-');
if(f_info.st_mode & S_IXOTH)
putchar('x');
else
putchar('-');
#endif/*}}}*/

/************   if else   语句的优化   *****************/
int i;
int mov_n;
unsigned int mode;
for(mov_n = 6;mov_n >= 0;mov_n -=3)
{
mode = f_info.st_mode >> mov_n;
for(i = 2;i >= 0;i--)
{
switch(mode & ( 1 << i))
{
case 0:putchar('-');break;
case 1:putchar('x');break;
case 2:putchar('w');break;
case 4:putchar('r');break;
default:
break;
}
}
i = i-3;
}

/************   *******    *********      ***************/

//打印硬连接数
printf("%4d",f_info.st_nlink);

//打印用户名
printf("  %s",getpwuid(f_info.st_uid)->pw_name);

//打印组名
printf("  %s",getgrgid(f_info.st_gid)->gr_name);

//打印大小
printf(" %5ld",f_info.st_size);

//打印最后一次次改时间

time_t t;
struct tm  *ptm;   //利用到了time  与 localtime
t = f_info.st_atime;
ptm = localtime(&t);

printf("  %d %d %d  ",1+ptm->tm_mon,ptm->tm_mday,1900+ptm->tm_year);
printf("%d:%d ",ptm->tm_hour,ptm->tm_min);

printf("%s \n",filename);

return ;
}

<pre name="code" class="cpp">//显示目录中所有的文件
#if 1
void display_dir(const char *pathname)
{
DIR *dirp;
dirp = opendir(pathname); //打开一个目录的操作
if(dirp == NULL)
{
fprintf(stderr,"##File to opendir %s:%s\n",pathname,strerror(errno));
return ;
}

struct dirent *pdirent;
chdir(pathname);

while((pdirent = readdir(dirp)) != NULL)
{
if(pdirent->d_name[0] == '.')
continue;
//printf("%s \n",pdirent->d_name);//可以实现对任何目录名字的遍历
display_file(pdirent->d_name);  //可以实现对当前目录下文件的属性遍历
}
closedir(dirp);//关闭打开的目录
return ;
}
#endif

int main(int argc, const char *argv[])
{
if(argc < 2)
{
fprintf(stderr,"Uaage :%s argv[1]\n",argv[0]);
return -1;
}

//	display_file(argv[1]);//显示单个文件的属性

struct stat f_infor;

if(stat(argv[1],&f_infor) < 0)
{
fprintf(stderr,"$$File to stat %s:%s",argv[1],strerror(errno));
return -1;
}

#if 1
if( (f_infor.st_mode & S_IFMT) == S_IFDIR )
display_dir(argv[1]);
else
display_file(argv[1]);
#endif
return 0;
}