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TOMOYO Linux Cross Reference
Linux/fs/efs/dir.c

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  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 
102 

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