fs/minix/dir.c

   1 /*
   2  *  linux/fs/minix/dir.c
   3  *
   4  *  Copyright (C) 1991, 1992 Linus Torvalds
   5  *
   6  *  minix directory handling functions
   7  */
   8
   9 #include <linux/string.h>
  10 #include <linux/errno.h>
  11 #include <linux/fs.h>
  12 #include <linux/minix_fs.h>
  13 #include <linux/stat.h>
  14
  15 #include <asm/uaccess.h>
  16
  17 static ssize_t minix_dir_read(struct file * filp, char * buf,
  18                               size_t count, loff_t *ppos)
  19 {
  20         return -EISDIR;
  21 }
  22
  23 static int minix_readdir(struct file *, void *, filldir_t);
  24
  25 static struct file_operations minix_dir_operations = {
  26         NULL,                   /* lseek - default */
  27         minix_dir_read,         /* read */
  28         NULL,                   /* write - bad */
  29         minix_readdir,          /* readdir */
  30         NULL,                   /* poll - default */
  31         NULL,                   /* ioctl - default */
  32         NULL,                   /* mmap */
  33         NULL,                   /* no special open code */
  34         NULL,                   /* flush */
  35         NULL,                   /* no special release code */
  36         file_fsync              /* default fsync */
  37 };
  38
  39 /*
  40  * directories can handle most operations...
  41  */
  42 struct inode_operations minix_dir_inode_operations = {
  43         &minix_dir_operations,  /* default directory file-ops */
  44         minix_create,           /* create */
  45         minix_lookup,           /* lookup */
  46         minix_link,             /* link */
  47         minix_unlink,           /* unlink */
  48         minix_symlink,          /* symlink */
  49         minix_mkdir,            /* mkdir */
  50         minix_rmdir,            /* rmdir */
  51         minix_mknod,            /* mknod */
  52         minix_rename,           /* rename */
  53         NULL,                   /* readlink */
  54         NULL,                   /* follow_link */
  55         NULL,                   /* readpage */
  56         NULL,                   /* writepage */
  57         NULL,                   /* bmap */
  58         minix_truncate,         /* truncate */
  59         NULL                    /* permission */
  60 };
  61
  62 static int minix_readdir(struct file * filp,
  63         void * dirent, filldir_t filldir)
  64 {
  65         unsigned int offset;
  66         struct buffer_head * bh;
  67         struct minix_dir_entry * de;
  68         struct minix_sb_info * info;
  69         struct inode *inode = filp->f_dentry->d_inode;
  70
  71         if (!inode || !inode->i_sb || !S_ISDIR(inode->i_mode))
  72                 return -EBADF;
  73         info = &inode->i_sb->u.minix_sb;
  74         if (filp->f_pos & (info->s_dirsize - 1))
  75                 return -EBADF;
  76         while (filp->f_pos < inode->i_size) {
  77                 offset = filp->f_pos & 1023;
  78                 bh = minix_bread(inode,(filp->f_pos)>>BLOCK_SIZE_BITS,0);
  79                 if (!bh) {
  80                         filp->f_pos += 1024-offset;
  81                         continue;
  82                 }
  83                 do {
  84                         de = (struct minix_dir_entry *) (offset + bh->b_data);
  85                         if (de->inode) {
  86                                 int size = strnlen(de->name, info->s_namelen);
  87                                 if (filldir(dirent, de->name, size, filp->f_pos, de->inode) < 0) {
  88                                         brelse(bh);
  89                                         return 0;
  90                                 }
  91                         }
  92                         offset += info->s_dirsize;
  93                         filp->f_pos += info->s_dirsize;
  94                 } while (offset < 1024 && filp->f_pos < inode->i_size);
  95                 brelse(bh);
  96         }
  97         UPDATE_ATIME(inode);
  98         return 0;
  99 }