i386/linux/linux-0.99/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 <asm/segment.h>
  10
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/minix_fs.h>
  14 #include <linux/stat.h>
  15
  16 static int minix_dir_read(struct inode * inode, struct file * filp, char * buf, int count)
  17 {
  18         return -EISDIR;
  19 }
  20
  21 static int minix_readdir(struct inode *, struct file *, struct dirent *, int);
  22
  23 static struct file_operations minix_dir_operations = {
  24         NULL,                   /* lseek - default */
  25         minix_dir_read,         /* read */
  26         NULL,                   /* write - bad */
  27         minix_readdir,          /* readdir */
  28         NULL,                   /* select - default */
  29         NULL,                   /* ioctl - default */
  30         NULL,                   /* mmap */
  31         NULL,                   /* no special open code */
  32         NULL,                   /* no special release code */
  33         file_fsync              /* default fsync */
  34 };
  35
  36 /*
  37  * directories can handle most operations...
  38  */
  39 struct inode_operations minix_dir_inode_operations = {
  40         &minix_dir_operations,  /* default directory file-ops */
  41         minix_create,           /* create */
  42         minix_lookup,           /* lookup */
  43         minix_link,             /* link */
  44         minix_unlink,           /* unlink */
  45         minix_symlink,          /* symlink */
  46         minix_mkdir,            /* mkdir */
  47         minix_rmdir,            /* rmdir */
  48         minix_mknod,            /* mknod */
  49         minix_rename,           /* rename */
  50         NULL,                   /* readlink */
  51         NULL,                   /* follow_link */
  52         NULL,                   /* bmap */
  53         minix_truncate,         /* truncate */
  54         NULL                    /* permission */
  55 };
  56
  57 static int minix_readdir(struct inode * inode, struct file * filp,
  58         struct dirent * dirent, int count)
  59 {
  60         unsigned int offset,i;
  61         char c;
  62         struct buffer_head * bh;
  63         struct minix_dir_entry * de;
  64         struct minix_sb_info * info;
  65
  66         if (!inode || !inode->i_sb || !S_ISDIR(inode->i_mode))
  67                 return -EBADF;
  68         info = &inode->i_sb->u.minix_sb;
  69         if (filp->f_pos & (info->s_dirsize - 1))
  70                 return -EBADF;
  71         while (filp->f_pos < inode->i_size) {
  72                 offset = filp->f_pos & 1023;
  73                 bh = minix_bread(inode,(filp->f_pos)>>BLOCK_SIZE_BITS,0);
  74                 if (!bh) {
  75                         filp->f_pos += 1024-offset;
  76                         continue;
  77                 }
  78                 while (offset < 1024 && filp->f_pos < inode->i_size) {
  79                         de = (struct minix_dir_entry *) (offset + bh->b_data);
  80                         offset += info->s_dirsize;
  81                         filp->f_pos += info->s_dirsize;
  82                         if (de->inode) {
  83                                 for (i = 0; i < info->s_namelen; i++)
  84                                         if ((c = de->name[i]) != 0)
  85                                                 put_fs_byte(c,i+dirent->d_name);
  86                                         else
  87                                                 break;
  88                                 if (i) {
  89                                         put_fs_long(de->inode,&dirent->d_ino);
  90                                         put_fs_byte(0,i+dirent->d_name);
  91                                         put_fs_word(i,&dirent->d_reclen);
  92                                         brelse(bh);
  93                                         return i;
  94                                 }
  95                         }
  96                 }
  97                 brelse(bh);
  98         }
  99         return 0;
 100 }