fs/ufs/dir.c

   1 /*
   2  *  linux/fs/ufs/ufs_dir.c
   3  *
   4  * Copyright (C) 1996
   5  * Adrian Rodriguez (adrian@franklins-tower.rutgers.edu)
   6  * Laboratory for Computer Science Research Computing Facility
   7  * Rutgers, The State University of New Jersey
   8  *
   9  * swab support by Francois-Rene Rideau <fare@tunes.org> 19970406
  10  *
  11  * 4.4BSD (FreeBSD) support added on February 1st 1998 by
  12  * Niels Kristian Bech Jensen <nkbj@image.dk> partially based
  13  * on code by Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de>.
  14  */
  15
  16 #include <linux/fs.h>
  17
  18 #include "swab.h"
  19 #include "util.h"
  20
  21 #undef UFS_DIR_DEBUG
  22
  23 #ifdef UFS_DIR_DEBUG
  24 #define UFSD(x) printk("(%s, %d), %s: ", __FILE__, __LINE__, __FUNCTION__); printk x;
  25 #else
  26 #define UFSD(x)
  27 #endif
  28
  29 /*
  30  * This is blatantly stolen from ext2fs
  31  */
  32 static int
  33 ufs_readdir (struct file * filp, void * dirent, filldir_t filldir)
  34 {
  35         struct inode *inode = filp->f_dentry->d_inode;
  36         int error = 0;
  37         unsigned long offset, lblk, blk;
  38         int i, stored;
  39         struct buffer_head * bh;
  40         struct ufs_dir_entry * de;
  41         struct super_block * sb;
  42         int de_reclen;
  43         unsigned flags, swab;
  44
  45
  46         /* Isn't that already done in the upper layer???
  47          * the VFS layer really needs some explicit documentation!
  48          */
  49         if (!inode || !S_ISDIR(inode->i_mode))
  50                 return -EBADF;
  51
  52         sb = inode->i_sb;
  53         swab = sb->u.ufs_sb.s_swab;
  54         flags = sb->u.ufs_sb.s_flags;
  55
  56         UFSD(("ENTER, ino %lu  f_pos %lu\n", inode->i_ino, (unsigned long) filp->f_pos))
  57
  58         stored = 0;
  59         bh = NULL;
  60         offset = filp->f_pos & (sb->s_blocksize - 1);
  61
  62         while (!error && !stored && filp->f_pos < inode->i_size) {
  63                 lblk = (filp->f_pos) >> sb->s_blocksize_bits;
  64                 /* XXX - ufs_bmap() call needs error checking */
  65                 blk = ufs_bmap(inode, lblk);
  66                 bh = bread (sb->s_dev, blk, sb->s_blocksize);
  67                 if (!bh) {
  68                         /* XXX - error - skip to the next block */
  69                         printk("ufs_readdir: "
  70                                "dir inode %lu has a hole at offset %lu\n",
  71                                inode->i_ino, (unsigned long int)filp->f_pos);
  72                         filp->f_pos += sb->s_blocksize - offset;
  73                         continue;
  74                 }
  75
  76 revalidate:
  77                 /* If the dir block has changed since the last call to
  78                  * readdir(2), then we might be pointing to an invalid
  79                  * dirent right now.  Scan from the start of the block
  80                  * to make sure. */
  81                 if (filp->f_version != inode->i_version) {
  82                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
  83                                 de = (struct ufs_dir_entry *)(bh->b_data + i);
  84                                 /* It's too expensive to do a full
  85                                  * dirent test each time round this
  86                                  * loop, but we do have to test at
  87                                  * least that it is non-zero.  A
  88                                  * failure will be detected in the
  89                                  * dirent test below. */
  90                                 de_reclen = SWAB16(de->d_reclen);
  91                                 if (de_reclen < 1)
  92                                         break;
  93                                 i += de_reclen;
  94                         }
  95                         offset = i;
  96                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
  97                                 | offset;
  98                         filp->f_version = inode->i_version;
  99                 }
 100
 101                 while (!error && filp->f_pos < inode->i_size
 102                        && offset < sb->s_blocksize) {
 103                         de = (struct ufs_dir_entry *) (bh->b_data + offset);
 104                         /* XXX - put in a real ufs_check_dir_entry() */
 105                         if ((de->d_reclen == 0) || (ufs_get_de_namlen(de) == 0)) {
 106                         /* SWAB16() was unneeded -- compare to 0 */
 107                                 filp->f_pos = (filp->f_pos &
 108                                               (sb->s_blocksize - 1)) +
 109                                                sb->s_blocksize;
 110                                 brelse(bh);
 111                                 return stored;
 112                         }
 113                         if (!ufs_check_dir_entry ("ufs_readdir", inode, de,
 114                                                    bh, offset)) {
 115                                 /* On error, skip the f_pos to the
 116                                    next block. */
 117                                 filp->f_pos = (filp->f_pos &
 118                                               (sb->s_blocksize - 1)) +
 119                                                sb->s_blocksize;
 120                                 brelse (bh);
 121                                 return stored;
 122                         }
 123                         offset += SWAB16(de->d_reclen);
 124                         if (de->d_ino) {
 125                         /* SWAB16() was unneeded -- compare to 0 */
 126                                 /* We might block in the next section
 127                                  * if the data destination is
 128                                  * currently swapped out.  So, use a
 129                                  * version stamp to detect whether or
 130                                  * not the directory has been modified
 131                                  * during the copy operation. */
 132                                 unsigned long version = inode->i_version;
 133
 134                                 UFSD(("filldir(%s,%u)\n", de->d_name, SWAB32(de->d_ino)))
 135                                 UFSD(("namlen %u\n", ufs_get_de_namlen(de)))
 136                                 error = filldir(dirent, de->d_name, ufs_get_de_namlen(de),
 137                                                 filp->f_pos, SWAB32(de->d_ino));
 138                                 if (error)
 139                                         break;
 140                                 if (version != inode->i_version)
 141                                         goto revalidate;
 142                                 stored ++;
 143                         }
 144                         filp->f_pos += SWAB16(de->d_reclen);
 145                 }
 146                 offset = 0;
 147                 brelse (bh);
 148         }
 149         UPDATE_ATIME(inode);
 150         return 0;
 151 }
 152
 153 int ufs_check_dir_entry (const char * function, struct inode * dir,
 154         struct ufs_dir_entry * de, struct buffer_head * bh,
 155         unsigned long offset)
 156 {
 157         struct super_block * sb;
 158         const char * error_msg;
 159         unsigned flags, swab;
 160
 161         sb = dir->i_sb;
 162         flags = sb->u.ufs_sb.s_flags;
 163         swab = sb->u.ufs_sb.s_swab;
 164         error_msg = NULL;
 165
 166         if (SWAB16(de->d_reclen) < UFS_DIR_REC_LEN(1))
 167                 error_msg = "reclen is smaller than minimal";
 168         else if (SWAB16(de->d_reclen) % 4 != 0)
 169                 error_msg = "reclen % 4 != 0";
 170         else if (SWAB16(de->d_reclen) < UFS_DIR_REC_LEN(ufs_get_de_namlen(de)))
 171                 error_msg = "reclen is too small for namlen";
 172         else if (dir && ((char *) de - bh->b_data) + SWAB16(de->d_reclen) >
 173                  dir->i_sb->s_blocksize)
 174                 error_msg = "directory entry across blocks";
 175         else if (dir && SWAB32(de->d_ino) > (sb->u.ufs_sb.s_uspi->s_ipg * sb->u.ufs_sb.s_uspi->s_ncg))
 176                 error_msg = "inode out of bounds";
 177
 178         if (error_msg != NULL)
 179                 ufs_error (sb, function, "bad entry in directory #%lu, size %lu: %s - "
 180                             "offset=%lu, inode=%lu, reclen=%d, namlen=%d",
 181                             dir->i_ino, dir->i_size, error_msg, offset,
 182                             (unsigned long) SWAB32(de->d_ino),
 183                             SWAB16(de->d_reclen), ufs_get_de_namlen(de));
 184
 185         return (error_msg == NULL ? 1 : 0);
 186 }
 187
 188 static struct file_operations ufs_dir_operations = {
 189         NULL,                   /* lseek */
 190         NULL,                   /* read */
 191         NULL,                   /* write */
 192         ufs_readdir,            /* readdir */
 193         NULL,                   /* select */
 194         NULL,                   /* ioctl */
 195         NULL,                   /* mmap */
 196         NULL,                   /* open */
 197         NULL,                   /* flush */
 198         NULL,                   /* release */
 199         file_fsync,             /* fsync */
 200         NULL,                   /* fasync */
 201         NULL,                   /* check_media_change */
 202         NULL,                   /* revalidate */
 203 };
 204
 205 struct inode_operations ufs_dir_inode_operations = {
 206         &ufs_dir_operations,    /* default directory file operations */
 207         ufs_create,             /* create */
 208         ufs_lookup,             /* lookup */
 209         ufs_link,               /* link */
 210         ufs_unlink,             /* unlink */
 211         ufs_symlink,            /* symlink */
 212         ufs_mkdir,              /* mkdir */
 213         ufs_rmdir,              /* rmdir */
 214         ufs_mknod,              /* mknod */
 215         ufs_rename,             /* rename */
 216         NULL,                   /* readlink */
 217         NULL,                   /* follow_link */
 218         NULL,                   /* readpage */
 219         NULL,                   /* writepage */
 220         NULL,                   /* bmap */
 221         NULL,                   /* truncate */
 222         ufs_permission,         /* permission */
 223         NULL,                   /* smap */
 224 };