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
  40 static int udf_readdir(struct file *file, struct dir_context *ctx)
  41 {
  42         struct inode *dir = file_inode(file);
  43         struct udf_inode_info *iinfo = UDF_I(dir);
  44         struct udf_fileident_bh fibh = { .sbh = NULL, .ebh = NULL};
  45         struct fileIdentDesc *fi = NULL;
  46         struct fileIdentDesc cfi;
  47         udf_pblk_t block, iblock;
  48         loff_t nf_pos, emit_pos = 0;
  49         int flen;
  50         unsigned char *fname = NULL, *copy_name = NULL;
  51         unsigned char *nameptr;
  52         uint16_t liu;
  53         uint8_t lfi;
  54         loff_t size = udf_ext0_offset(dir) + dir->i_size;
  55         struct buffer_head *tmp, *bha[16];
  56         struct kernel_lb_addr eloc;
  57         uint32_t elen;
  58         sector_t offset;
  59         int i, num, ret = 0;
  60         struct extent_position epos = { NULL, 0, {0, 0} };
  61         struct super_block *sb = dir->i_sb;
  62         bool pos_valid = false;
  63
  64         if (ctx->pos == 0) {
  65                 if (!dir_emit_dot(file, ctx))
  66                         return 0;
  67                 ctx->pos = 1;
  68         }
  69         nf_pos = (ctx->pos - 1) << 2;
  70         if (nf_pos >= size)
  71                 goto out;
  72
  73         /*
  74          * Something changed since last readdir (either lseek was called or dir
  75          * changed)?  We need to verify the position correctly points at the
  76          * beginning of some dir entry so that the directory parsing code does
  77          * not get confused. Since UDF does not have any reliable way of
  78          * identifying beginning of dir entry (names are under user control),
  79          * we need to scan the directory from the beginning.
  80          */
  81         if (!inode_eq_iversion(dir, file->f_version)) {
  82                 emit_pos = nf_pos;
  83                 nf_pos = 0;
  84         } else {
  85                 pos_valid = true;
  86         }
  87
  88         fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
  89         if (!fname) {
  90                 ret = -ENOMEM;
  91                 goto out;
  92         }
  93
  94         if (nf_pos == 0)
  95                 nf_pos = udf_ext0_offset(dir);
  96
  97         fibh.soffset = fibh.eoffset = nf_pos & (sb->s_blocksize - 1);
  98         if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
  99                 if (inode_bmap(dir, nf_pos >> sb->s_blocksize_bits,
 100                     &epos, &eloc, &elen, &offset)
 101                     != (EXT_RECORDED_ALLOCATED >> 30)) {
 102                         ret = -ENOENT;
 103                         goto out;
 104                 }
 105                 block = udf_get_lb_pblock(sb, &eloc, offset);
 106                 if ((++offset << sb->s_blocksize_bits) < elen) {
 107                         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
 108                                 epos.offset -= sizeof(struct short_ad);
 109                         else if (iinfo->i_alloc_type ==
 110                                         ICBTAG_FLAG_AD_LONG)
 111                                 epos.offset -= sizeof(struct long_ad);
 112                 } else {
 113                         offset = 0;
 114                 }
 115
 116                 if (!(fibh.sbh = fibh.ebh = udf_tread(sb, block))) {
 117                         ret = -EIO;
 118                         goto out;
 119                 }
 120
 121                 if (!(offset & ((16 >> (sb->s_blocksize_bits - 9)) - 1))) {
 122                         i = 16 >> (sb->s_blocksize_bits - 9);
 123                         if (i + offset > (elen >> sb->s_blocksize_bits))
 124                                 i = (elen >> sb->s_blocksize_bits) - offset;
 125                         for (num = 0; i > 0; i--) {
 126                                 block = udf_get_lb_pblock(sb, &eloc, offset + i);
 127                                 tmp = udf_tgetblk(sb, block);
 128                                 if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))
 129                                         bha[num++] = tmp;
 130                                 else
 131                                         brelse(tmp);
 132                         }
 133                         if (num) {
 134                                 ll_rw_block(REQ_OP_READ, REQ_RAHEAD, num, bha);
 135                                 for (i = 0; i < num; i++)
 136                                         brelse(bha[i]);
 137                         }
 138                 }
 139         }
 140
 141         while (nf_pos < size) {
 142                 struct kernel_lb_addr tloc;
 143                 loff_t cur_pos = nf_pos;
 144
 145                 /* Update file position only if we got past the current one */
 146                 if (nf_pos >= emit_pos) {
 147                         ctx->pos = (nf_pos >> 2) + 1;
 148                         pos_valid = true;
 149                 }
 150
 151                 fi = udf_fileident_read(dir, &nf_pos, &fibh, &cfi, &epos, &eloc,
 152                                         &elen, &offset);
 153                 if (!fi)
 154                         goto out;
 155                 /* Still not at offset where user asked us to read from? */
 156                 if (cur_pos < emit_pos)
 157                         continue;
 158
 159                 liu = le16_to_cpu(cfi.lengthOfImpUse);
 160                 lfi = cfi.lengthFileIdent;
 161
 162                 if (fibh.sbh == fibh.ebh) {
 163                         nameptr = fi->fileIdent + liu;
 164                 } else {
 165                         int poffset;    /* Unpaded ending offset */
 166
 167                         poffset = fibh.soffset + sizeof(struct fileIdentDesc) + liu + lfi;
 168
 169                         if (poffset >= lfi) {
 170                                 nameptr = (char *)(fibh.ebh->b_data + poffset - lfi);
 171                         } else {
 172                                 if (!copy_name) {
 173                                         copy_name = kmalloc(UDF_NAME_LEN,
 174                                                             GFP_NOFS);
 175                                         if (!copy_name) {
 176                                                 ret = -ENOMEM;
 177                                                 goto out;
 178                                         }
 179                                 }
 180                                 nameptr = copy_name;
 181                                 memcpy(nameptr, fi->fileIdent + liu,
 182                                        lfi - poffset);
 183                                 memcpy(nameptr + lfi - poffset,
 184                                        fibh.ebh->b_data, poffset);
 185                         }
 186                 }
 187
 188                 if ((cfi.fileCharacteristics & FID_FILE_CHAR_DELETED) != 0) {
 189                         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
 190                                 continue;
 191                 }
 192
 193                 if ((cfi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) != 0) {
 194                         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
 195                                 continue;
 196                 }
 197
 198                 if (cfi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
 199                         if (!dir_emit_dotdot(file, ctx))
 200                                 goto out;
 201                         continue;
 202                 }
 203
 204                 flen = udf_get_filename(sb, nameptr, lfi, fname, UDF_NAME_LEN);
 205                 if (flen < 0)
 206                         continue;
 207
 208                 tloc = lelb_to_cpu(cfi.icb.extLocation);
 209                 iblock = udf_get_lb_pblock(sb, &tloc, 0);
 210                 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
 211                         goto out;
 212         } /* end while */
 213
 214         ctx->pos = (nf_pos >> 2) + 1;
 215         pos_valid = true;
 216
 217 out:
 218         if (pos_valid)
 219                 file->f_version = inode_query_iversion(dir);
 220         if (fibh.sbh != fibh.ebh)
 221                 brelse(fibh.ebh);
 222         brelse(fibh.sbh);
 223         brelse(epos.bh);
 224         kfree(fname);
 225         kfree(copy_name);
 226
 227         return ret;
 228 }
 229
 230 /* readdir and lookup functions */
 231 const struct file_operations udf_dir_operations = {
 232         .llseek                 = generic_file_llseek,
 233         .read                   = generic_read_dir,
 234         .iterate_shared         = udf_readdir,
 235         .unlocked_ioctl         = udf_ioctl,
 236         .fsync                  = generic_file_fsync,
 237 };