fs/udf/dir.c

   1 /*
   2  * dir.c
   3  *
   4  * PURPOSE
   5  *  Directory handling routines for the OSTA-UDF(tm) filesystem.
   6  *
   7  * COPYRIGHT
   8  *      This file is distributed under the terms of the GNU General Public
   9  *      License (GPL). Copies of the GPL can be obtained from:
  10  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
  11  *      Each contributing author retains all rights to their own work.
  12  *
  13  *  (C) 1998-2004 Ben Fennema
  14  *
  15  * HISTORY
  16  *
  17  *  10/05/98 dgb  Split directory operations into its own file
  18  *                Implemented directory reads via do_udf_readdir
  19  *  10/06/98      Made directory operations work!
  20  *  11/17/98      Rewrote directory to support ICBTAG_FLAG_AD_LONG
  21  *  11/25/98 blf  Rewrote directory handling (readdir+lookup) to support reading
  22  *                across blocks.
  23  *  12/12/98      Split out the lookup code to namei.c. bulk of directory
  24  *                code now in directory.c:udf_fileident_read.
  25  */
  26
  27 #include "udfdecl.h"
  28
  29 #include <linux/string.h>
  30 #include <linux/errno.h>
  31 #include <linux/mm.h>
  32 #include <linux/slab.h>
  33 #include <linux/bio.h>
  34 #include <linux/iversion.h>
  35
  36 #include "udf_i.h"
  37 #include "udf_sb.h"
  38
  39 static int udf_readdir(struct file *file, struct dir_context *ctx)
  40 {
  41         struct inode *dir = file_inode(file);
  42         struct udf_inode_info *iinfo = UDF_I(dir);
  43         struct udf_fileident_bh fibh = { .sbh = NULL, .ebh = NULL};
  44         struct fileIdentDesc *fi = NULL;
  45         struct fileIdentDesc cfi;
  46         udf_pblk_t block, iblock;
  47         loff_t nf_pos, emit_pos = 0;
  48         int flen;
  49         unsigned char *fname = NULL, *copy_name = NULL;
  50         unsigned char *nameptr;
  51         uint16_t liu;
  52         uint8_t lfi;
  53         loff_t size = udf_ext0_offset(dir) + dir->i_size;
  54         struct buffer_head *tmp, *bha[16];
  55         struct kernel_lb_addr eloc;
  56         uint32_t elen;
  57         sector_t offset;
  58         int i, num, ret = 0;
  59         struct extent_position epos = { NULL, 0, {0, 0} };
  60         struct super_block *sb = dir->i_sb;
  61         bool pos_valid = false;
  62
  63         if (ctx->pos == 0) {
  64                 if (!dir_emit_dot(file, ctx))
  65                         return 0;
  66                 ctx->pos = 1;
  67         }
  68         nf_pos = (ctx->pos - 1) << 2;
  69         if (nf_pos >= size)
  70                 goto out;
  71
  72         /*
  73          * Something changed since last readdir (either lseek was called or dir
  74          * changed)?  We need to verify the position correctly points at the
  75          * beginning of some dir entry so that the directory parsing code does
  76          * not get confused. Since UDF does not have any reliable way of
  77          * identifying beginning of dir entry (names are under user control),
  78          * we need to scan the directory from the beginning.
  79          */
  80         if (!inode_eq_iversion(dir, file->f_version)) {
  81                 emit_pos = nf_pos;
  82                 nf_pos = 0;
  83         } else {
  84                 pos_valid = true;
  85         }
  86
  87         fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
  88         if (!fname) {
  89                 ret = -ENOMEM;
  90                 goto out;
  91         }
  92
  93         if (nf_pos == 0)
  94                 nf_pos = udf_ext0_offset(dir);
  95
  96         fibh.soffset = fibh.eoffset = nf_pos & (sb->s_blocksize - 1);
  97         if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
  98                 if (inode_bmap(dir, nf_pos >> sb->s_blocksize_bits,
  99                     &epos, &eloc, &elen, &offset)
 100                     != (EXT_RECORDED_ALLOCATED >> 30)) {
 101                         ret = -ENOENT;
 102                         goto out;
 103                 }
 104                 block = udf_get_lb_pblock(sb, &eloc, offset);
 105                 if ((++offset << sb->s_blocksize_bits) < elen) {
 106                         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
 107                                 epos.offset -= sizeof(struct short_ad);
 108                         else if (iinfo->i_alloc_type ==
 109                                         ICBTAG_FLAG_AD_LONG)
 110                                 epos.offset -= sizeof(struct long_ad);
 111                 } else {
 112                         offset = 0;
 113                 }
 114
 115                 if (!(fibh.sbh = fibh.ebh = udf_tread(sb, block))) {
 116                         ret = -EIO;
 117                         goto out;
 118                 }
 119
 120                 if (!(offset & ((16 >> (sb->s_blocksize_bits - 9)) - 1))) {
 121                         i = 16 >> (sb->s_blocksize_bits - 9);
 122                         if (i + offset > (elen >> sb->s_blocksize_bits))
 123                                 i = (elen >> sb->s_blocksize_bits) - offset;
 124                         for (num = 0; i > 0; i--) {
 125                                 block = udf_get_lb_pblock(sb, &eloc, offset + i);
 126                                 tmp = udf_tgetblk(sb, block);
 127                                 if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))
 128                                         bha[num++] = tmp;
 129                                 else
 130                                         brelse(tmp);
 131                         }
 132                         if (num) {
 133                                 ll_rw_block(REQ_OP_READ | REQ_RAHEAD, num, bha);
 134                                 for (i = 0; i < num; i++)
 135                                         brelse(bha[i]);
 136                         }
 137                 }
 138         }
 139
 140         while (nf_pos < size) {
 141                 struct kernel_lb_addr tloc;
 142                 loff_t cur_pos = nf_pos;
 143
 144                 /* Update file position only if we got past the current one */
 145                 if (nf_pos >= emit_pos) {
 146                         ctx->pos = (nf_pos >> 2) + 1;
 147                         pos_valid = true;
 148                 }
 149
 150                 fi = udf_fileident_read(dir, &nf_pos, &fibh, &cfi, &epos, &eloc,
 151                                         &elen, &offset);
 152                 if (!fi)
 153                         goto out;
 154                 /* Still not at offset where user asked us to read from? */
 155                 if (cur_pos < emit_pos)
 156                         continue;
 157
 158                 liu = le16_to_cpu(cfi.lengthOfImpUse);
 159                 lfi = cfi.lengthFileIdent;
 160
 161                 if (fibh.sbh == fibh.ebh) {
 162                         nameptr = udf_get_fi_ident(fi);
 163                 } else {
 164                         int poffset;    /* Unpaded ending offset */
 165
 166                         poffset = fibh.soffset + sizeof(struct fileIdentDesc) + liu + lfi;
 167
 168                         if (poffset >= lfi) {
 169                                 nameptr = (char *)(fibh.ebh->b_data + poffset - lfi);
 170                         } else {
 171                                 if (!copy_name) {
 172                                         copy_name = kmalloc(UDF_NAME_LEN,
 173                                                             GFP_NOFS);
 174                                         if (!copy_name) {
 175                                                 ret = -ENOMEM;
 176                                                 goto out;
 177                                         }
 178                                 }
 179                                 nameptr = copy_name;
 180                                 memcpy(nameptr, udf_get_fi_ident(fi),
 181                                        lfi - poffset);
 182                                 memcpy(nameptr + lfi - poffset,
 183                                        fibh.ebh->b_data, poffset);
 184                         }
 185                 }
 186
 187                 if ((cfi.fileCharacteristics & FID_FILE_CHAR_DELETED) != 0) {
 188                         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
 189                                 continue;
 190                 }
 191
 192                 if ((cfi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) != 0) {
 193                         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
 194                                 continue;
 195                 }
 196
 197                 if (cfi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
 198                         if (!dir_emit_dotdot(file, ctx))
 199                                 goto out;
 200                         continue;
 201                 }
 202
 203                 flen = udf_get_filename(sb, nameptr, lfi, fname, UDF_NAME_LEN);
 204                 if (flen < 0)
 205                         continue;
 206
 207                 tloc = lelb_to_cpu(cfi.icb.extLocation);
 208                 iblock = udf_get_lb_pblock(sb, &tloc, 0);
 209                 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
 210                         goto out;
 211         } /* end while */
 212
 213         ctx->pos = (nf_pos >> 2) + 1;
 214         pos_valid = true;
 215
 216 out:
 217         if (pos_valid)
 218                 file->f_version = inode_query_iversion(dir);
 219         if (fibh.sbh != fibh.ebh)
 220                 brelse(fibh.ebh);
 221         brelse(fibh.sbh);
 222         brelse(epos.bh);
 223         kfree(fname);
 224         kfree(copy_name);
 225
 226         return ret;
 227 }
 228
 229 /* readdir and lookup functions */
 230 const struct file_operations udf_dir_operations = {
 231         .llseek                 = generic_file_llseek,
 232         .read                   = generic_read_dir,
 233         .iterate_shared         = udf_readdir,
 234         .unlocked_ioctl         = udf_ioctl,
 235         .fsync                  = generic_file_fsync,
 236 };