dir_f.c

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    1 /*
    2  *  linux/fs/adfs/dir_f.c
    3  *
    4  * Copyright (C) 1997-1999 Russell King
    5  *
    6  * This program is free software; you can redistribute it and/or modify
    7  * it under the terms of the GNU General Public License version 2 as
    8  * published by the Free Software Foundation.
    9  *
   10  *  E and F format directory handling
   11  */
   12 #include <linux/version.h>
   13 #include <linux/errno.h>
   14 #include <linux/fs.h>
   15 #include <linux/adfs_fs.h>
   16 #include <linux/sched.h>
   17 #include <linux/stat.h>
   18 #include <linux/spinlock.h>
   19 
   20 #include "adfs.h"
   21 #include "dir_f.h"
   22 
   23 static void adfs_f_free(struct adfs_dir *dir);
   24 
   25 /*
   26  * Read an (unaligned) value of length 1..4 bytes
   27  */
   28 static inline unsigned int adfs_readval(unsigned char *p, int len)
   29 {
   30         unsigned int val = 0;
   31 
   32         switch (len) {
   33         case 4:         val |= p[3] << 24;
   34         case 3:         val |= p[2] << 16;
   35         case 2:         val |= p[1] << 8;
   36         default:        val |= p[0];
   37         }
   38         return val;
   39 }
   40 
   41 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
   42 {
   43         switch (len) {
   44         case 4:         p[3] = val >> 24;
   45         case 3:         p[2] = val >> 16;
   46         case 2:         p[1] = val >> 8;
   47         default:        p[0] = val;
   48         }
   49 }
   50 
   51 static inline int adfs_readname(char *buf, char *ptr, int maxlen)
   52 {
   53         char *old_buf = buf;
   54 
   55         while (*ptr >= ' ' && maxlen--) {
   56                 if (*ptr == '/')
   57                         *buf++ = '.';
   58                 else
   59                         *buf++ = *ptr;
   60                 ptr++;
   61         }
   62         *buf = '\0';
   63 
   64         return buf - old_buf;
   65 }
   66 
   67 static inline void adfs_writename(char *to, char *from, int maxlen)
   68 {
   69         int i;
   70 
   71         for (i = 0; i < maxlen; i++) {
   72                 if (from[i] == '\0')
   73                         break;
   74                 if (from[i] == '.')
   75                         to[i] = '/';
   76                 else
   77                         to[i] = from[i];
   78         }
   79 
   80         for (; i < maxlen; i++)
   81                 to[i] = '\0';
   82 }
   83 
   84 #define ror13(v) ((v >> 13) | (v << 19))
   85 
   86 #define dir_u8(idx)                             \
   87         ({ int _buf = idx >> blocksize_bits;    \
   88            int _off = idx - (_buf << blocksize_bits);\
   89           *(u8 *)(bh[_buf]->b_data + _off);     \
   90         })
   91 
   92 #define dir_u32(idx)                            \
   93         ({ int _buf = idx >> blocksize_bits;    \
   94            int _off = idx - (_buf << blocksize_bits);\
   95           *(u32 *)(bh[_buf]->b_data + _off);    \
   96         })
   97 
   98 #define bufoff(_bh,_idx)                        \
   99         ({ int _buf = _idx >> blocksize_bits;   \
  100            int _off = _idx - (_buf << blocksize_bits);\
  101           (u8 *)(_bh[_buf]->b_data + _off);     \
  102         })
  103 
  104 /*
  105  * There are some algorithms that are nice in
  106  * assembler, but a bitch in C...  This is one
  107  * of them.
  108  */
  109 static u8
  110 adfs_dir_checkbyte(const struct adfs_dir *dir)
  111 {
  112         struct buffer_head * const *bh = dir->bh;
  113         const int blocksize_bits = dir->sb->s_blocksize_bits;
  114         union { u32 *ptr32; u8 *ptr8; } ptr, end;
  115         u32 dircheck = 0;
  116         int last = 5 - 26;
  117         int i = 0;
  118 
  119         /*
  120          * Accumulate each word up to the last whole
  121          * word of the last directory entry.  This
  122          * can spread across several buffer heads.
  123          */
  124         do {
  125                 last += 26;
  126                 do {
  127                         dircheck = cpu_to_le32(dir_u32(i)) ^ ror13(dircheck);
  128 
  129                         i += sizeof(u32);
  130                 } while (i < (last & ~3));
  131         } while (dir_u8(last) != 0);
  132 
  133         /*
  134          * Accumulate the last few bytes.  These
  135          * bytes will be within the same bh.
  136          */
  137         if (i != last) {
  138                 ptr.ptr8 = bufoff(bh, i);
  139                 end.ptr8 = ptr.ptr8 + last - i;
  140 
  141                 do
  142                         dircheck = *ptr.ptr8++ ^ ror13(dircheck);
  143                 while (ptr.ptr8 < end.ptr8);
  144         }
  145 
  146         /*
  147          * The directory tail is in the final bh
  148          * Note that contary to the RISC OS PRMs,
  149          * the first few bytes are NOT included
  150          * in the check.  All bytes are in the
  151          * same bh.
  152          */
  153         ptr.ptr8 = bufoff(bh, 2008);
  154         end.ptr8 = ptr.ptr8 + 36;
  155 
  156         do {
  157                 unsigned int v = *ptr.ptr32++;
  158                 dircheck = cpu_to_le32(v) ^ ror13(dircheck);
  159         } while (ptr.ptr32 < end.ptr32);
  160 
  161         return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
  162 }
  163 
  164 /*
  165  * Read and check that a directory is valid
  166  */
  167 int
  168 adfs_dir_read(struct super_block *sb, unsigned long object_id,
  169               unsigned int size, struct adfs_dir *dir)
  170 {
  171         const unsigned int blocksize_bits = sb->s_blocksize_bits;
  172         int blk = 0;
  173 
  174         /*
  175          * Directories which are not a multiple of 2048 bytes
  176          * are considered bad v2 [3.6]
  177          */
  178         if (size & 2047)
  179                 goto bad_dir;
  180 
  181         size >>= blocksize_bits;
  182 
  183         dir->nr_buffers = 0;
  184         dir->sb = sb;
  185 
  186         for (blk = 0; blk < size; blk++) {
  187                 int phys;
  188 
  189                 phys = __adfs_block_map(sb, object_id, blk);
  190                 if (!phys) {
  191                         adfs_error(sb, "dir object %lX has a hole at offset %d",
  192                                    object_id, blk);
  193                         goto release_buffers;
  194                 }
  195 
  196                 dir->bh[blk] = sb_bread(sb, phys);
  197                 if (!dir->bh[blk])
  198                         goto release_buffers;
  199         }
  200 
  201         memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
  202         memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
  203 
  204         if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
  205             memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
  206                 goto bad_dir;
  207 
  208         if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
  209             memcmp(&dir->dirhead.startname, "Hugo", 4))
  210                 goto bad_dir;
  211 
  212         if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
  213                 goto bad_dir;
  214 
  215         dir->nr_buffers = blk;
  216 
  217         return 0;
  218 
  219 bad_dir:
  220         adfs_error(sb, "corrupted directory fragment %lX",
  221                    object_id);
  222 release_buffers:
  223         for (blk -= 1; blk >= 0; blk -= 1)
  224                 brelse(dir->bh[blk]);
  225 
  226         dir->sb = NULL;
  227 
  228         return -EIO;
  229 }
  230 
  231 /*
  232  * convert a disk-based directory entry to a Linux ADFS directory entry
  233  */
  234 static inline void
  235 adfs_dir2obj(struct object_info *obj, struct adfs_direntry *de)
  236 {
  237         obj->name_len = adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
  238         obj->file_id  = adfs_readval(de->dirinddiscadd, 3);
  239         obj->loadaddr = adfs_readval(de->dirload, 4);
  240         obj->execaddr = adfs_readval(de->direxec, 4);
  241         obj->size     = adfs_readval(de->dirlen,  4);
  242         obj->attr     = de->newdiratts;
  243 }
  244 
  245 /*
  246  * convert a Linux ADFS directory entry to a disk-based directory entry
  247  */
  248 static inline void
  249 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
  250 {
  251         adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
  252         adfs_writeval(de->dirload, 4, obj->loadaddr);
  253         adfs_writeval(de->direxec, 4, obj->execaddr);
  254         adfs_writeval(de->dirlen,  4, obj->size);
  255         de->newdiratts = obj->attr;
  256 }
  257 
  258 /*
  259  * get a directory entry.  Note that the caller is responsible
  260  * for holding the relevent locks.
  261  */
  262 int
  263 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
  264 {
  265         struct super_block *sb = dir->sb;
  266         struct adfs_direntry de;
  267         int thissize, buffer, offset;
  268 
  269         buffer = pos >> sb->s_blocksize_bits;
  270 
  271         if (buffer > dir->nr_buffers)
  272                 return -EINVAL;
  273 
  274         offset = pos & (sb->s_blocksize - 1);
  275         thissize = sb->s_blocksize - offset;
  276         if (thissize > 26)
  277                 thissize = 26;
  278 
  279         memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
  280         if (thissize != 26)
  281                 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
  282                        26 - thissize);
  283 
  284         if (!de.dirobname[0])
  285                 return -ENOENT;
  286 
  287         adfs_dir2obj(obj, &de);
  288 
  289         return 0;
  290 }
  291 
  292 int
  293 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
  294 {
  295         struct super_block *sb = dir->sb;
  296         struct adfs_direntry de;
  297         int thissize, buffer, offset;
  298 
  299         buffer = pos >> sb->s_blocksize_bits;
  300 
  301         if (buffer > dir->nr_buffers)
  302                 return -EINVAL;
  303 
  304         offset = pos & (sb->s_blocksize - 1);
  305         thissize = sb->s_blocksize - offset;
  306         if (thissize > 26)
  307                 thissize = 26;
  308 
  309         /*
  310          * Get the entry in total
  311          */
  312         memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
  313         if (thissize != 26)
  314                 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
  315                        26 - thissize);
  316 
  317         /*
  318          * update it
  319          */
  320         adfs_obj2dir(&de, obj);
  321 
  322         /*
  323          * Put the new entry back
  324          */
  325         memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
  326         if (thissize != 26)
  327                 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
  328                        26 - thissize);
  329 
  330         return 0;
  331 }
  332 
  333 /*
  334  * the caller is responsible for holding the necessary
  335  * locks.
  336  */
  337 static int
  338 adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
  339 {
  340         int pos, ret;
  341 
  342         ret = -ENOENT;
  343 
  344         for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
  345                 struct object_info obj;
  346 
  347                 if (!__adfs_dir_get(dir, pos, &obj))
  348                         break;
  349 
  350                 if (obj.file_id == object_id) {
  351                         ret = pos;
  352                         break;
  353                 }
  354         }
  355 
  356         return ret;
  357 }
  358 
  359 static int
  360 adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
  361 {
  362         int ret;
  363 
  364         if (sz != ADFS_NEWDIR_SIZE)
  365                 return -EIO;
  366 
  367         ret = adfs_dir_read(sb, id, sz, dir);
  368         if (ret)
  369                 adfs_error(sb, "unable to read directory");
  370         else
  371                 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
  372 
  373         return ret;
  374 }
  375 
  376 static int
  377 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
  378 {
  379         if (fpos >= ADFS_NUM_DIR_ENTRIES)
  380                 return -ENOENT;
  381 
  382         dir->pos = 5 + fpos * 26;
  383         return 0;
  384 }
  385 
  386 static int
  387 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
  388 {
  389         unsigned int ret;
  390 
  391         ret = __adfs_dir_get(dir, dir->pos, obj);
  392         if (ret == 0)
  393                 dir->pos += 26;
  394 
  395         return ret;
  396 }
  397 
  398 static int
  399 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
  400 {
  401         struct super_block *sb = dir->sb;
  402         int ret, i;
  403 
  404         ret = adfs_dir_find_entry(dir, obj->file_id);
  405         if (ret < 0) {
  406                 adfs_error(dir->sb, "unable to locate entry to update");
  407                 goto out;
  408         }
  409 
  410         __adfs_dir_put(dir, ret, obj);
  411  
  412         /*
  413          * Increment directory sequence number
  414          */
  415         dir->bh[0]->b_data[0] += 1;
  416         dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
  417 
  418         ret = adfs_dir_checkbyte(dir);
  419         /*
  420          * Update directory check byte
  421          */
  422         dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
  423 
  424 #if 1
  425         {
  426         const unsigned int blocksize_bits = sb->s_blocksize_bits;
  427 
  428         memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
  429         memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
  430 
  431         if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
  432             memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
  433                 goto bad_dir;
  434 
  435         if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
  436             memcmp(&dir->dirhead.startname, "Hugo", 4))
  437                 goto bad_dir;
  438 
  439         if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
  440                 goto bad_dir;
  441         }
  442 #endif
  443         for (i = dir->nr_buffers - 1; i >= 0; i--)
  444                 mark_buffer_dirty(dir->bh[i]);
  445 
  446         ret = 0;
  447 out:
  448         return ret;
  449 #if 1
  450 bad_dir:
  451         adfs_error(dir->sb, "whoops!  I broke a directory!");
  452         return -EIO;
  453 #endif
  454 }
  455 
  456 static void
  457 adfs_f_free(struct adfs_dir *dir)
  458 {
  459         int i;
  460 
  461         for (i = dir->nr_buffers - 1; i >= 0; i--) {
  462                 brelse(dir->bh[i]);
  463                 dir->bh[i] = NULL;
  464         }
  465 
  466         dir->nr_buffers = 0;
  467         dir->sb = NULL;
  468 }
  469 
  470 struct adfs_dir_ops adfs_f_dir_ops = {
  471         adfs_f_read,
  472         adfs_f_setpos,
  473         adfs_f_getnext,
  474         adfs_f_update,
  475         NULL,
  476         NULL,
  477         adfs_f_free
  478 };
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FreeBSD/Linux Kernel Cross Reference sys/fs/adfs/dir_f.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/adfs/dir_f.c
