root/fs/isofs/namei.c

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DEFINITIONS

This source file includes following definitions.
  1. isofs_match
  2. isofs_find_entry
  3. isofs_lookup

   1 /*
   2  *  linux/fs/isofs/namei.c
   3  *
   4  *  (C) 1992  Eric Youngdale Modified for ISO9660 filesystem.
   5  *
   6  *  (C) 1991  Linus Torvalds - minix filesystem
   7  */
   8 
   9 #ifdef MODULE
  10 #include <linux/module.h>
  11 #endif
  12 
  13 #include <linux/sched.h>
  14 #include <linux/iso_fs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/string.h>
  17 #include <linux/stat.h>
  18 #include <linux/fcntl.h>
  19 #include <asm/segment.h>
  20 #include <linux/malloc.h>
  21 
  22 #include <linux/errno.h>
  23 
  24 /*
  25  * ok, we cannot use strncmp, as the name is not in our data space.
  26  * Thus we'll have to use isofs_match. No big problem. Match also makes
  27  * some sanity tests.
  28  *
  29  * NOTE! unlike strncmp, isofs_match returns 1 for success, 0 for failure.
  30  */
  31 static int isofs_match(int len,const char * name, char * compare, int dlen)
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  32 {
  33         if (!compare)
  34                 return 0;
  35 
  36         /* check special "." and ".." files */
  37         if (dlen == 1) {
  38                 /* "." */
  39                 if (compare[0] == 0) {
  40                         if (!len)
  41                                 return 1;
  42                         compare = ".";
  43                 } else if (compare[0] == 1) {
  44                         compare = "..";
  45                         dlen = 2;
  46                 }
  47         }
  48 #if 0
  49         if (len <= 2) printk("Match: %d %d %s %d %d \n",len,dlen,compare,de->name[0], dlen);
  50 #endif
  51         
  52         if (dlen != len)
  53                 return 0;
  54         return !memcmp(name, compare, len);
  55 }
  56 
  57 /*
  58  *      isofs_find_entry()
  59  *
  60  * finds an entry in the specified directory with the wanted name. It
  61  * returns the cache buffer in which the entry was found, and the entry
  62  * itself (as an inode number). It does NOT read the inode of the
  63  * entry - you'll have to do that yourself if you want to.
  64  */
  65 static struct buffer_head * isofs_find_entry(struct inode * dir,
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  66         const char * name, int namelen, unsigned long * ino, unsigned long * ino_back)
  67 {
  68         unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
  69         unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
  70         unsigned int block, i, f_pos, offset, inode_number;
  71         struct buffer_head * bh;
  72         void * cpnt = NULL;
  73         unsigned int old_offset;
  74         unsigned int backlink;
  75         int dlen, rrflag, match;
  76         int high_sierra = 0;
  77         char * dpnt;
  78         struct iso_directory_record * de;
  79         char c;
  80 
  81         *ino = 0;
  82         if (!dir) return NULL;
  83         
  84         if (!(block = dir->u.isofs_i.i_first_extent)) return NULL;
  85   
  86         f_pos = 0;
  87 
  88         offset = f_pos & (bufsize - 1);
  89         block = isofs_bmap(dir,f_pos >> bufbits);
  90 
  91         if (!block || !(bh = bread(dir->i_dev,block,bufsize))) return NULL;
  92   
  93         while (f_pos < dir->i_size) {
  94                 de = (struct iso_directory_record *) (bh->b_data + offset);
  95                 backlink = dir->i_ino;
  96                 inode_number = (block << bufbits) + (offset & (bufsize - 1));
  97 
  98                 /* If byte is zero, this is the end of file, or time to move to
  99                    the next sector. Usually 2048 byte boundaries. */
 100                 
 101                 if (*((unsigned char *) de) == 0) {
 102                         brelse(bh);
 103                         offset = 0;
 104                         f_pos = ((f_pos & ~(ISOFS_BLOCK_SIZE - 1))
 105                                  + ISOFS_BLOCK_SIZE);
 106                         block = isofs_bmap(dir,f_pos>>bufbits);
 107                         if (!block || !(bh = bread(dir->i_dev,block,bufsize)))
 108                                 return 0;
 109                         continue; /* Will kick out if past end of directory */
 110                 }
 111 
 112                 old_offset = offset;
 113                 offset += *((unsigned char *) de);
 114                 f_pos += *((unsigned char *) de);
 115 
 116                 /* Handle case where the directory entry spans two blocks.
 117                    Usually 1024 byte boundaries */
 118                 if (offset >= bufsize) {
 119                         unsigned int frag1;
 120                         frag1 = bufsize - old_offset;
 121                         cpnt = kmalloc(*((unsigned char *) de),GFP_KERNEL);
 122                         if (!cpnt) return 0;
 123                         memcpy(cpnt, bh->b_data + old_offset, frag1);
 124 
 125                         de = (struct iso_directory_record *) cpnt;
 126                         brelse(bh);
 127                         offset = f_pos & (bufsize - 1);
 128                         block = isofs_bmap(dir,f_pos>>bufbits);
 129                         if (!block || !(bh = bread(dir->i_dev,block,bufsize))) {
 130                                 kfree(cpnt);
 131                                 return 0;
 132                         };
 133                         memcpy((char *)cpnt+frag1, bh->b_data, offset);
 134                 }
 135                 
 136                 /* Handle the '.' case */
 137                 
 138                 if (de->name[0]==0 && de->name_len[0]==1) {
 139                         inode_number = dir->i_ino;
 140                         backlink = 0;
 141                 }
 142                 
 143                 /* Handle the '..' case */
 144 
 145                 if (de->name[0]==1 && de->name_len[0]==1) {
 146 #if 0
 147                         printk("Doing .. (%d %d)",
 148                                dir->i_sb->s_firstdatazone,
 149                                dir->i_ino);
 150 #endif
 151                         if((dir->i_sb->u.isofs_sb.s_firstdatazone) != dir->i_ino)
 152                                 inode_number = dir->u.isofs_i.i_backlink;
 153                         else
 154                                 inode_number = dir->i_ino;
 155                         backlink = 0;
 156                 }
 157     
 158                 /* Do not report hidden or associated files */
 159                 high_sierra = dir->i_sb->u.isofs_sb.s_high_sierra;
 160                 if (de->flags[-high_sierra] & 5) {
 161                   if (cpnt) {
 162                     kfree(cpnt);
 163                     cpnt = NULL;
 164                   };
 165                   continue;
 166                 }
 167                 
 168                 dlen = de->name_len[0];
 169                 dpnt = de->name;
 170                 /* Now convert the filename in the buffer to lower case */
 171                 rrflag = get_rock_ridge_filename(de, &dpnt, &dlen, dir);
 172                 if (rrflag) {
 173                   if (rrflag == -1) goto out; /* Relocated deep directory */
 174                 } else {
 175                   if(dir->i_sb->u.isofs_sb.s_mapping == 'n') {
 176                     for (i = 0; i < dlen; i++) {
 177                       c = dpnt[i];
 178                       if (c >= 'A' && c <= 'Z') c |= 0x20;  /* lower case */
 179                       if (c == ';' && i == dlen-2 && dpnt[i+1] == '1') {
 180                         dlen -= 2;
 181                         break;
 182                       }
 183                       if (c == ';') c = '.';
 184                       de->name[i] = c;
 185                     }
 186                     /* This allows us to match with and without a trailing
 187                        period.  */
 188                     if(dpnt[dlen-1] == '.' && namelen == dlen-1)
 189                       dlen--;
 190                   }
 191                 }
 192                 match = isofs_match(namelen,name,dpnt,dlen);
 193                 if (cpnt) {
 194                         kfree(cpnt);
 195                         cpnt = NULL;
 196                 }
 197 
 198                 if(rrflag) kfree(dpnt);
 199                 if (match) {
 200                         if(inode_number == -1) {
 201                                 /* Should only happen for the '..' entry */
 202                                 inode_number = 
 203                                         isofs_lookup_grandparent(dir,
 204                                            find_rock_ridge_relocation(de,dir));
 205                                 if(inode_number == -1){
 206                                         /* Should never happen */
 207                                         printk("Backlink not properly set.\n");
 208                                         goto out;
 209                                 }
 210                         }
 211                         *ino = inode_number;
 212                         *ino_back = backlink;
 213                         return bh;
 214                 }
 215         }
 216  out:
 217         if (cpnt)
 218                 kfree(cpnt);
 219         brelse(bh);
 220         return NULL;
 221 }
 222 
 223 int isofs_lookup(struct inode * dir,const char * name, int len,
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 224         struct inode ** result)
 225 {
 226         unsigned long ino, ino_back;
 227         struct buffer_head * bh;
 228 
 229 #ifdef DEBUG
 230         printk("lookup: %x %d\n",dir->i_ino, len);
 231 #endif
 232         *result = NULL;
 233         if (!dir)
 234                 return -ENOENT;
 235 
 236         if (!S_ISDIR(dir->i_mode)) {
 237                 iput(dir);
 238                 return -ENOENT;
 239         }
 240 
 241         ino = 0;
 242 
 243         if (dcache_lookup(dir, name, len, &ino)) ino_back = dir->i_ino;
 244 
 245         if (!ino) {
 246           if (!(bh = isofs_find_entry(dir,name,len, &ino, &ino_back))) {
 247             iput(dir);
 248             return -ENOENT;
 249           }
 250           if (ino_back == dir->i_ino)
 251                 dcache_add(dir, name, len, ino);
 252           brelse(bh);
 253         };
 254 
 255         if (!(*result = iget(dir->i_sb,ino))) {
 256                 iput(dir);
 257                 return -EACCES;
 258         }
 259 
 260         /* We need this backlink for the ".." entry unless the name that we
 261            are looking up traversed a mount point (in which case the inode
 262            may not even be on an iso9660 filesystem, and writing to
 263            u.isofs_i would only cause memory corruption).
 264         */
 265         
 266         if (ino_back && !(*result)->i_pipe && (*result)->i_sb == dir->i_sb) {
 267           (*result)->u.isofs_i.i_backlink = ino_back; 
 268         }
 269         
 270         iput(dir);
 271         return 0;
 272 }

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