fs/efs/dir.c

   1 /*
   2  * dir.c
   3  *
   4  * Copyright (c) 1999 Al Smith
   5  */
   6
   7 #include <linux/buffer_head.h>
   8 #include "efs.h"
   9
  10 static int efs_readdir(struct file *, struct dir_context *);
  11
  12 const struct file_operations efs_dir_operations = {
  13         .llseek         = generic_file_llseek,
  14         .read           = generic_read_dir,
  15         .iterate        = efs_readdir,
  16 };
  17
  18 const struct inode_operations efs_dir_inode_operations = {
  19         .lookup         = efs_lookup,
  20 };
  21
  22 static int efs_readdir(struct file *file, struct dir_context *ctx)
  23 {
  24         struct inode *inode = file_inode(file);
  25         efs_block_t             block;
  26         int                     slot;
  27
  28         if (inode->i_size & (EFS_DIRBSIZE-1))
  29                 printk(KERN_WARNING "EFS: WARNING: readdir(): directory size not a multiple of EFS_DIRBSIZE\n");
  30
  31         /* work out where this entry can be found */
  32         block = ctx->pos >> EFS_DIRBSIZE_BITS;
  33
  34         /* each block contains at most 256 slots */
  35         slot  = ctx->pos & 0xff;
  36
  37         /* look at all blocks */
  38         while (block < inode->i_blocks) {
  39                 struct efs_dir          *dirblock;
  40                 struct buffer_head *bh;
  41
  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                 for (; slot < dirblock->slots; slot++) {
  59                         struct efs_dentry *dirslot;
  60                         efs_ino_t inodenum;
  61                         const char *nameptr;
  62                         int namelen;
  63
  64                         if (dirblock->space[slot] == 0)
  65                                 continue;
  66
  67                         dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  68
  69                         inodenum = be32_to_cpu(dirslot->inode);
  70                         namelen  = dirslot->namelen;
  71                         nameptr  = dirslot->name;
  72
  73 #ifdef DEBUG
  74                         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);
  75 #endif
  76                         if (!namelen)
  77                                 continue;
  78                         /* found the next entry */
  79                         ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
  80
  81                         /* sanity check */
  82                         if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
  83                                 printk(KERN_WARNING "EFS: directory entry %d exceeds directory block\n", slot);
  84                                 continue;
  85                         }
  86
  87                         /* copy filename and data in dirslot */
  88                         if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {
  89                                 brelse(bh);
  90                                 return 0;
  91                         }
  92                 }
  93                 brelse(bh);
  94
  95                 slot = 0;
  96                 block++;
  97         }
  98         ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
  99         return 0;
 100 }
 101