ls -l 实现

#include
#include
#include
#include
#include
#include
#include
const int N_BITS=3;

typedef struct dir_lnk{
 char d_name[256];
 struct dir_lnk * next;
}dirlnk;

typedef struct item_info{
 unsigned long inode;
  char permission[11];
 int owner;
 int group;
 off_t size;
 time_t mod_time;
 char name[256];
}info;

//将目录中所有的文件信息放到一个链表中
dirlnk* get_dir_detail(char* dirname)
{
   DIR* dir;
   struct dirent* drt;
   dir=opendir(dirname);
       
   if(dir==NULL){
  perror("Cannot open the desired directory");
  return NULL;
  }

          dirlnk* dir_head=NULL;
          dirlnk* cur_item=NULL;

   while((drt=readdir(dir))!=NULL){
  if((strcmp(drt->d_name,".")==0)||(strcmp(drt->d_name,"..")==0))
   continue;
 
  dirlnk *next_item=(dirlnk*)malloc(sizeof(dirlnk));
 
  if(cur_item==NULL)
   cur_item=next_item;
  else
   cur_item->next=next_item;

  cur_item=next_item;

  if(dir_head==NULL)
   dir_head=cur_item;
 
   strcpy(cur_item->d_name,drt->d_name);
   }

  cur_item->next=NULL;
  closedir(dir);
  
  return dir_head;
}

void print_file_info(dirlnk* dir_head)
{
 static char* perm[]={"---","--x","-w-","-wx",
  "r--","r-x","rw-","rwx"};
  unsigned int mask=0700;
 struct stat file_stat;
        dirlnk* cur_dir=dir_head;

 while(cur_dir!=NULL){
  mask=0700;
  info file_info;
  if(stat(cur_dir->d_name,&file_stat)==-1){
   perror("Cannot get the information of the file!");
   cur_dir=cur_dir->next;
   continue;
  }
   
  if(S_ISREG(file_stat.st_mode))
   file_info.permission[0]='-';
   
  if(S_ISDIR(file_stat.st_mode))
   file_info.permission[0]='d';
 
       int i=3;
        int j=0;
      while(i>0)
  {
   file_info.permission[1+j*3]=perm[(file_stat.st_mode & mask)>>(i-1)*N_BITS][0];
   file_info.permission[2+j*3]=perm[(file_stat.st_mode & mask)>>(i-1)*N_BITS][1];
          file_info.permission[3+j*3]=perm[(file_stat.st_mode & mask)>>(i-1)*N_BITS][2];
   
   j++;
   i--;
          mask>>=N_BITS;
         }
              
                file_info.permission[10]='\0';
  file_info.owner=file_stat.st_uid;
  file_info.group=file_stat.st_gid;
         file_info.mod_time=file_stat.st_atime;
  file_info.size=file_stat.st_size;
  strcpy(file_info.name,cur_dir->d_name);
  file_info.inode=file_stat.st_ino;
 
         printf("%u  ",file_info.inode);
  printf("%s  ",file_info.permission);
  printf("%d  ",file_info.owner);
  printf("%d  ",file_info.group);
  printf("%u  ",file_info.size);
  printf("%s  ",ctime(&file_info.mod_time));
  printf("%s  \n",file_info.name);
               
   cur_dir=cur_dir->next;
 }
}

int main(int argc, char* argv[]){
 
 dirlnk* head=get_dir_detail(".");
 print_file_info(head);

   
}