dir.c

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

#include "fs.h"
// member furnctions for DirEnt, DirBlock class
/*
void DirEntInit(struct DirEnt *de){
   de->ino=-1;
}
*/
static void get_fname_in_dirent(struct DirEnt *dent, char *buf){
   strncpy(buf, dent->fname, dent->name_len);
   buf[dent->name_len]=0;
}
void DirBlk_init(struct DirBlock *db){
//  init db
   int i;
   for(i=0;i<BLKSIZE;i++)
      db->box[i]=0;
}

static struct DirEnt * next_dent(struct DirEnt *dent){
// ret next dir entry of dent
   return  ((struct DirEnt *) ( ((int) dent)+ dent->rec_len));
}

struct DirEnt * DirBlk_get_free_dir_ent(struct DirBlock *db){
// get free entry in directory block d
   struct DirEnt *dent = (struct DirEnt *) db;
   for(;;){ // find dir entry whose reclen=0
      if (dent->rec_len==0)
	     return dent;
      dent = next_dent(dent);
	  if (((int)dent)>=BLKSIZE) break;
   }
   panic("no more entry in dir_ent");
}

void DirBlk_report_new_entry(struct DirBlock *dir, int ino, char *fname){
// fname is a new file with inode num ino. report it in dir
   struct DirEnt *x; int quotient, remain,tot_len;
   printk("DirBlk_report_new_entry for %s\n",fname);
   x=DirBlk_get_free_dir_ent(dir);
   printk("In DirBlk_report_new_entry. %x\n",x);
   x->ino = ino;
   strcpy(x->fname, fname);
   x->name_len = strlen(fname);
   tot_len = 4+ // inode number
                4+ // rec_len & name_len + file_type
                x->name_len; // file name length
   // we need to round up by multiple of 4
   quotient = tot_len / 4;
   remain = tot_len % 4;
   if (remain !=0) quotient++;
   x->rec_len = quotient * 4;
}

void DirBlk_set_empty(struct DirBlock *db,int me, int parent){
// make empty dir block. me is this dir's inode; parent its parent inode
   DirBlk_init(db);
   DirBlk_report_new_entry(db, me, ".");
   DirBlk_report_new_entry(db, parent, "..");
}

int find_ino_for_file_in_dirblk(char *f, char *blk){
   struct DirEnt *dent = (struct DirEnt *) blk;
   char buf[EXT2_NAME_LEN];
   int start = (int) dent;
   printk("finding ino for file %s in dirblk\n",f);
   for(;;){ // find dir entry whose fname is f 
      if (dent->rec_len == 0) break; // end of dir entries
	  get_fname_in_dirent(dent,buf); // get file name as a string in buf
	  printk("the next file name we check is %s\n", buf);
      if (!strcmp(buf, f))
	     return dent->ino;
      dent = next_dent(dent);
	  if ((int)(dent-start) >= BLKSIZE) break; // if at end of blk
   }
   return -1; // no such file name
}
int find_ino_for_file_in_dir(char *f, struct Inode *in){
// return inode num of file "f" which belongs to a directory "in"
   // for all blocks in dir, call find_ino_for_file_in_dirblk
   struct Ext2Inode *inode = in->inode;
   int nblks = inode->i_blocks;
   int i,ino; char *blk;
   printk("finding ino for file %s in dir whose ino is %d\n",f,in->ino);
   for(i=0;i<nblks;i++){
      blk=(char *)FBTable_get_block(inode->i_block[i]);
	  ino=find_ino_for_file_in_dirblk(f, blk);
	  if (ino > 0) break;
   }
   return ino;
}

void dump_directory_file_block(char *blk){
// buf is a block of some dir. dump the contents
   struct DirEnt *dent = (struct DirEnt *) blk;
   char buf[EXT2_NAME_LEN];
   int start=(int)dent;
   for(;;){ // find dir entry whose fname is f 
      if (dent->rec_len == 0) break; // end of dir entries
	  get_fname_in_dirent(dent, buf);
	  printk("ino %d fname %s ", dent->ino, buf);
      dent = next_dent(dent);
	  if ((int)(dent-start)>=BLKSIZE) break;
   }
   printk("dumping ended for this block\n");
}

void dump_directory_file(struct Inode *in){
// in points to a directoy file. dump the contents
   struct Ext2Inode *inode = in->inode;
   int nblks = inode->i_blocks;
   int i; char *blk;
   printk("dumping dir file. nblks is %d\n", nblks);
   for(i=0;i<nblks;i++){
      blk=(char *)FBTable_get_block(inode->i_block[i]);
	  dump_directory_file_block(blk);
   }
}