root/fs/minix/dir.c

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DEFINITIONS

This source file includes following definitions.
  1. minix_dir_read
  2. minix_readdir

   1 /*
   2  *  linux/fs/minix/dir.c
   3  *
   4  *  Copyright (C) 1991, 1992 Linus Torvalds
   5  *
   6  *  minix directory handling functions
   7  */
   8 
   9 #ifdef MODULE
  10 #include <linux/module.h>
  11 #endif
  12 
  13 #include <asm/segment.h>
  14 
  15 #include <linux/errno.h>
  16 #include <linux/fs.h>
  17 #include <linux/minix_fs.h>
  18 #include <linux/stat.h>
  19 
  20 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
  21 #define ROUND_UP(x) (((x)+3) & ~3)
  22 
  23 static int minix_dir_read(struct inode * inode, struct file * filp, char * buf, int count)
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  24 {
  25         return -EISDIR;
  26 }
  27 
  28 static int minix_readdir(struct inode *, struct file *, struct dirent *, int);
  29 
  30 static struct file_operations minix_dir_operations = {
  31         NULL,                   /* lseek - default */
  32         minix_dir_read,         /* read */
  33         NULL,                   /* write - bad */
  34         minix_readdir,          /* readdir */
  35         NULL,                   /* select - default */
  36         NULL,                   /* ioctl - default */
  37         NULL,                   /* mmap */
  38         NULL,                   /* no special open code */
  39         NULL,                   /* no special release code */
  40         file_fsync              /* default fsync */
  41 };
  42 
  43 /*
  44  * directories can handle most operations...
  45  */
  46 struct inode_operations minix_dir_inode_operations = {
  47         &minix_dir_operations,  /* default directory file-ops */
  48         minix_create,           /* create */
  49         minix_lookup,           /* lookup */
  50         minix_link,             /* link */
  51         minix_unlink,           /* unlink */
  52         minix_symlink,          /* symlink */
  53         minix_mkdir,            /* mkdir */
  54         minix_rmdir,            /* rmdir */
  55         minix_mknod,            /* mknod */
  56         minix_rename,           /* rename */
  57         NULL,                   /* readlink */
  58         NULL,                   /* follow_link */
  59         NULL,                   /* bmap */
  60         minix_truncate,         /* truncate */
  61         NULL                    /* permission */
  62 };
  63 
  64 static int minix_readdir(struct inode * inode, struct file * filp,
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  65         struct dirent * dirent, int count)
  66 {
  67         unsigned int offset,i,ret;
  68         int version;
  69         char c;
  70         struct buffer_head * bh;
  71         struct minix_dir_entry * de;
  72         struct minix_sb_info * info;
  73 
  74         if (!inode || !inode->i_sb || !S_ISDIR(inode->i_mode))
  75                 return -EBADF;
  76         info = &inode->i_sb->u.minix_sb;
  77         if (filp->f_pos & (info->s_dirsize - 1))
  78                 return -EBADF;
  79         ret = 0;
  80         while (!ret && filp->f_pos < inode->i_size) {
  81                 offset = filp->f_pos & 1023;
  82                 bh = minix_bread(inode,(filp->f_pos)>>BLOCK_SIZE_BITS,0);
  83                 if (!bh) {
  84                         filp->f_pos += 1024-offset;
  85                         continue;
  86                 }
  87                 while (!ret && offset < 1024 && filp->f_pos < inode->i_size) {
  88                         de = (struct minix_dir_entry *) (offset + bh->b_data);
  89                         offset += info->s_dirsize;
  90                         filp->f_pos += info->s_dirsize;
  91 retry:
  92                         if (de->inode) {
  93                                 version = inode->i_version;
  94                                 for (i = 0; i < info->s_namelen; i++)
  95                                         if ((c = de->name[i]) != 0)
  96                                                 put_fs_byte(c,i+dirent->d_name);
  97                                         else
  98                                                 break;
  99                                 if (i) {
 100                                         put_fs_long(de->inode,&dirent->d_ino);
 101                                         put_fs_byte(0,i+dirent->d_name);
 102                                         put_fs_word(i,&dirent->d_reclen);
 103                                         if (version != inode->i_version)
 104                                                 goto retry;
 105                                         ret = ROUND_UP(NAME_OFFSET(dirent)+i+1);
 106                                 }
 107                         }
 108                 }
 109                 brelse(bh);
 110         }
 111         return ret;
 112 }

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