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         loff_t nf_pos, emit_pos = 0;
  43         int flen;
  44         unsigned char *fname = NULL;
  45         int ret = 0;
  46         struct super_block *sb = dir->i_sb;
  47         bool pos_valid = false;
  48         struct udf_fileident_iter iter;
  49
  50         if (ctx->pos == 0) {
  51                 if (!dir_emit_dot(file, ctx))
  52                         return 0;
  53                 ctx->pos = 1;
  54         }
  55         nf_pos = (ctx->pos - 1) << 2;
  56         if (nf_pos >= dir->i_size)
  57                 goto out;
  58
  59         /*
  60          * Something changed since last readdir (either lseek was called or dir
  61          * changed)?  We need to verify the position correctly points at the
  62          * beginning of some dir entry so that the directory parsing code does
  63          * not get confused. Since UDF does not have any reliable way of
  64          * identifying beginning of dir entry (names are under user control),
  65          * we need to scan the directory from the beginning.
  66          */
  67         if (!inode_eq_iversion(dir, file->f_version)) {
  68                 emit_pos = nf_pos;
  69                 nf_pos = 0;
  70         } else {
  71                 pos_valid = true;
  72         }
  73
  74         fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
  75         if (!fname) {
  76                 ret = -ENOMEM;
  77                 goto out;
  78         }
  79
  80         for (ret = udf_fiiter_init(&iter, dir, nf_pos);
  81              !ret && iter.pos < dir->i_size;
  82              ret = udf_fiiter_advance(&iter)) {
  83                 struct kernel_lb_addr tloc;
  84                 udf_pblk_t iblock;
  85
  86                 /* Still not at offset where user asked us to read from? */
  87                 if (iter.pos < emit_pos)
  88                         continue;
  89
  90                 /* Update file position only if we got past the current one */
  91                 pos_valid = true;
  92                 ctx->pos = (iter.pos >> 2) + 1;
  93
  94                 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
  95                         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
  96                                 continue;
  97                 }
  98
  99                 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
 100                         if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
 101                                 continue;
 102                 }
 103
 104                 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
 105                         if (!dir_emit_dotdot(file, ctx))
 106                                 goto out_iter;
 107                         continue;
 108                 }
 109
 110                 flen = udf_get_filename(sb, iter.name,
 111                                 iter.fi.lengthFileIdent, fname, UDF_NAME_LEN);
 112                 if (flen < 0)
 113                         continue;
 114
 115                 tloc = lelb_to_cpu(iter.fi.icb.extLocation);
 116                 iblock = udf_get_lb_pblock(sb, &tloc, 0);
 117                 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
 118                         goto out_iter;
 119         }
 120
 121         if (!ret) {
 122                 ctx->pos = (iter.pos >> 2) + 1;
 123                 pos_valid = true;
 124         }
 125 out_iter:
 126         udf_fiiter_release(&iter);
 127 out:
 128         if (pos_valid)
 129                 file->f_version = inode_query_iversion(dir);
 130         kfree(fname);
 131
 132         return ret;
 133 }
 134
 135 /* readdir and lookup functions */
 136 const struct file_operations udf_dir_operations = {
 137         .llseek                 = generic_file_llseek,
 138         .read                   = generic_read_dir,
 139         .iterate_shared         = udf_readdir,
 140         .unlocked_ioctl         = udf_ioctl,
 141         .fsync                  = generic_file_fsync,
 142 };