fs/efs/dir.c

   1 /*
   2  * dir.c
   3  *
   4  * Copyright (c) 1999 Al Smith
   5  */
   6
   7 #include <linux/efs_fs.h>
   8
   9 static int efs_readdir(struct file *, void *, filldir_t);
  10
  11 struct file_operations efs_dir_operations = {
  12         read:           generic_read_dir,
  13         readdir:        efs_readdir,
  14 };
  15
  16 struct inode_operations efs_dir_inode_operations = {
  17         lookup:         efs_lookup,
  18 };
  19
  20 static int efs_readdir(struct file *filp, void *dirent, filldir_t filldir) {
  21         struct inode *inode = filp->f_dentry->d_inode;
  22         struct buffer_head *bh;
  23
  24         struct efs_dir          *dirblock;
  25         struct efs_dentry       *dirslot;
  26         efs_ino_t               inodenum;
  27         efs_block_t             block;
  28         int                     slot, namelen;
  29         char                    *nameptr;
  30
  31         if (inode->i_size & (EFS_DIRBSIZE-1))
  32                 printk(KERN_WARNING "EFS: WARNING: readdir(): directory size not a multiple of EFS_DIRBSIZE\n");
  33
  34         /* work out where this entry can be found */
  35         block = filp->f_pos >> EFS_DIRBSIZE_BITS;
  36
  37         /* each block contains at most 256 slots */
  38         slot  = filp->f_pos & 0xff;
  39
  40         /* look at all blocks */
  41         while (block < inode->i_blocks) {
  42                 /* read the dir block */
  43                 bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
  44
  45                 if (!bh) {
  46                         printk(KERN_ERR "EFS: readdir(): failed to read dir block %d\n", block);
  47                         break;
  48                 }
  49
  50                 dirblock = (struct efs_dir *) bh->b_data;
  51
  52                 if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
  53                         printk(KERN_ERR "EFS: readdir(): invalid directory block\n");
  54                         brelse(bh);
  55                         break;
  56                 }
  57
  58                 while (slot < dirblock->slots) {
  59                         if (dirblock->space[slot] == 0) {
  60                                 slot++;
  61                                 continue;
  62                         }
  63
  64                         dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  65
  66                         inodenum = be32_to_cpu(dirslot->inode);
  67                         namelen  = dirslot->namelen;
  68                         nameptr  = dirslot->name;
  69
  70 #ifdef DEBUG
  71                         printk(KERN_DEBUG "EFS: readdir(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n", block, slot, dirblock->slots-1, inodenum, nameptr, namelen);
  72 #endif
  73                         if (namelen > 0) {
  74                                 /* found the next entry */
  75                                 filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
  76
  77                                 /* copy filename and data in dirslot */
  78                                 filldir(dirent, nameptr, namelen, filp->f_pos, inodenum, DT_UNKNOWN);
  79
  80                                 /* sanity check */
  81                                 if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
  82                                         printk(KERN_WARNING "EFS: directory entry %d exceeds directory block\n", slot);
  83                                         slot++;
  84                                         continue;
  85                                 }
  86
  87                                 /* store position of next slot */
  88                                 if (++slot == dirblock->slots) {
  89                                         slot = 0;
  90                                         block++;
  91                                 }
  92                                 brelse(bh);
  93                                 filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
  94                                 return 0;
  95                         }
  96                         slot++;
  97                 }
  98                 brelse(bh);
  99
 100                 slot = 0;
 101                 block++;
 102         }
 103
 104         filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
 105         return 0;
 106 }
 107