fs/sysv/dir.c

   1 /*
   2  *  linux/fs/sysv/dir.c
   3  *
   4  *  minix/dir.c
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  *
   7  *  coh/dir.c
   8  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
   9  *
  10  *  sysv/dir.c
  11  *  Copyright (C) 1993  Bruno Haible
  12  *
  13  *  SystemV/Coherent directory handling functions
  14  */
  15
  16 #include <linux/errno.h>
  17 #include <linux/fs.h>
  18 #include <linux/sysv_fs.h>
  19 #include <linux/stat.h>
  20 #include <linux/string.h>
  21
  22 #include <asm/uaccess.h>
  23
  24 static ssize_t sysv_dir_read(struct file * filp, char * buf,
  25                              size_t count, loff_t *ppos)
  26 {
  27         return -EISDIR;
  28 }
  29
  30 static int sysv_readdir(struct file *, void *, filldir_t);
  31
  32 static struct file_operations sysv_dir_operations = {
  33         NULL,                   /* lseek - default */
  34         sysv_dir_read,          /* read */
  35         NULL,                   /* write - bad */
  36         sysv_readdir,           /* readdir */
  37         NULL,                   /* poll - default */
  38         NULL,                   /* ioctl - default */
  39         NULL,                   /* mmap */
  40         NULL,                   /* no special open code */
  41         NULL,                   /* flush */
  42         NULL,                   /* no special release code */
  43         file_fsync              /* default fsync */
  44 };
  45
  46 /*
  47  * directories can handle most operations...
  48  */
  49 struct inode_operations sysv_dir_inode_operations = {
  50         &sysv_dir_operations,   /* default directory file-ops */
  51         sysv_create,            /* create */
  52         sysv_lookup,            /* lookup */
  53         sysv_link,              /* link */
  54         sysv_unlink,            /* unlink */
  55         sysv_symlink,           /* symlink */
  56         sysv_mkdir,             /* mkdir */
  57         sysv_rmdir,             /* rmdir */
  58         sysv_mknod,             /* mknod */
  59         sysv_rename,            /* rename */
  60         NULL,                   /* readlink */
  61         NULL,                   /* follow_link */
  62         NULL,                   /* readpage */
  63         NULL,                   /* writepage */
  64         NULL,                   /* bmap */
  65         sysv_truncate,          /* truncate */
  66         NULL                    /* permission */
  67 };
  68
  69 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
  70 {
  71         struct inode *inode = filp->f_dentry->d_inode;
  72         struct super_block * sb;
  73         unsigned int offset,i;
  74         struct buffer_head * bh;
  75         char* bh_data;
  76         struct sysv_dir_entry * de, sde;
  77
  78         if (!inode || !(sb = inode->i_sb) || !S_ISDIR(inode->i_mode))
  79                 return -EBADF;
  80         if ((unsigned long)(filp->f_pos) % SYSV_DIRSIZE)
  81                 return -EBADF;
  82         while (filp->f_pos < inode->i_size) {
  83                 offset = filp->f_pos & sb->sv_block_size_1;
  84                 bh = sysv_file_bread(inode, filp->f_pos >> sb->sv_block_size_bits, 0);
  85                 if (!bh) {
  86                         filp->f_pos += sb->sv_block_size - offset;
  87                         continue;
  88                 }
  89                 bh_data = bh->b_data;
  90                 while (offset < sb->sv_block_size && filp->f_pos < inode->i_size) {
  91                         de = (struct sysv_dir_entry *) (offset + bh_data);
  92                         if (de->inode) {
  93                                 /* Copy the directory entry first, because the directory
  94                                  * might be modified while we sleep in filldir()...
  95                                  */
  96                                 memcpy(&sde, de, sizeof(struct sysv_dir_entry));
  97
  98                                 if (sde.inode > inode->i_sb->sv_ninodes)
  99                                         printk("sysv_readdir: Bad inode number on dev "
 100                                                "%s, ino %ld, offset 0x%04lx: %d is out of range\n",
 101                                                kdevname(inode->i_dev),
 102                                                inode->i_ino, (off_t) filp->f_pos, sde.inode);
 103
 104                                 i = strnlen(sde.name, SYSV_NAMELEN);
 105                                 if (filldir(dirent, sde.name, i, filp->f_pos, sde.inode) < 0) {
 106                                         brelse(bh);
 107                                         return 0;
 108                                 }
 109                         }
 110                         offset += SYSV_DIRSIZE;
 111                         filp->f_pos += SYSV_DIRSIZE;
 112                 }
 113                 brelse(bh);
 114         }
 115         return 0;
 116 }