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  1. /*
  2.  * Copyright (c) 2008 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup fs
  30.  * @{
  31.  */
  32.  
  33. #ifndef FAT_FAT_H_
  34. #define FAT_FAT_H_
  35.  
  36. #include <ipc/ipc.h>
  37. #include <libfs.h>
  38. #include <atomic.h>
  39. #include <sys/types.h>
  40. #include <bool.h>
  41. #include "../../vfs/vfs.h"
  42.  
  43. #define dprintf(...)    printf(__VA_ARGS__)
  44.  
  45. typedef struct {
  46.     uint8_t     ji[3];      /**< Jump instruction. */
  47.     uint8_t     oem_name[8];
  48.     /* BIOS Parameter Block */
  49.     uint16_t    bps;        /**< Bytes per sector. */
  50.     uint8_t     spc;        /**< Sectors per cluster. */
  51.     uint16_t    rscnt;      /**< Reserved sector count. */
  52.     uint8_t     fatcnt;     /**< Number of FATs. */
  53.     uint16_t    root_ent_max;   /**< Maximum number of root directory
  54.                          entries. */
  55.     uint16_t    totsec16;   /**< Total sectors. 16-bit version. */
  56.     uint8_t     mdesc;      /**< Media descriptor. */
  57.     uint16_t    sec_per_fat;    /**< Sectors per FAT12/FAT16. */
  58.     uint16_t    sec_per_track;  /**< Sectors per track. */
  59.     uint16_t    headcnt;    /**< Number of heads. */
  60.     uint32_t    hidden_sec; /**< Hidden sectors. */
  61.     uint32_t    totsec32;   /**< Total sectors. 32-bit version. */
  62.  
  63.     union {
  64.         struct {
  65.             /* FAT12/FAT16 only: Extended BIOS Parameter Block */
  66.             /** Physical drive number. */
  67.             uint8_t     pdn;
  68.             uint8_t     reserved;
  69.             /** Extended boot signature. */
  70.             uint8_t     ebs;
  71.             /** Serial number. */
  72.             uint32_t    id;
  73.             /** Volume label. */
  74.             uint8_t     label[11];
  75.             /** FAT type. */
  76.             uint8_t     type[8];
  77.             /** Boot code. */
  78.             uint8_t     boot_code[448];
  79.             /** Boot sector signature. */
  80.             uint16_t    signature;
  81.         } __attribute__ ((packed));
  82.         struct {
  83.             /* FAT32 only */
  84.             /** Sectors per FAT. */
  85.             uint32_t    sectors_per_fat;
  86.             /** FAT flags. */
  87.             uint16_t    flags;
  88.             /** Version. */
  89.             uint16_t    version;
  90.             /** Cluster number of root directory. */
  91.             uint32_t    root_cluster;
  92.             /** Sector number of file system information sector. */
  93.             uint16_t    fsinfo_sec;
  94.             /** Sector number of boot sector copy. */
  95.             uint16_t    bscopy_sec;
  96.             uint8_t     reserved1[12];
  97.             /** Physical drive number. */
  98.             uint8_t     pdn;
  99.             uint8_t     reserved2;
  100.             /** Extended boot signature. */
  101.             uint8_t     ebs;
  102.             /** Serial number. */
  103.             uint32_t    id;
  104.             /** Volume label. */
  105.             uint8_t     label[11];
  106.             /** FAT type. */
  107.             uint8_t     type[8];
  108.             /** Boot code. */
  109.             uint8_t     boot_code[420];
  110.             /** Signature. */
  111.             uint16_t    signature;
  112.         } __attribute__ ((packed));
  113.     };
  114. } __attribute__ ((packed)) fat_bs_t;
  115.  
  116. #define FAT_ATTR_RDONLY     (1 << 0)
  117. #define FAT_ATTR_VOLLABEL   (1 << 3)
  118. #define FAT_ATTR_SUBDIR     (1 << 4)
  119.  
  120. typedef struct {
  121.     uint8_t     name[8];
  122.     uint8_t     ext[3];
  123.     uint8_t     attr;
  124.     uint8_t     reserved;
  125.     uint8_t     ctime_fine;
  126.     uint16_t    ctime;
  127.     uint16_t    cdate;
  128.     uint16_t    adate;
  129.     union {
  130.         uint16_t    eaidx;      /* FAT12/FAT16 */
  131.         uint16_t    firstc_hi;  /* FAT32 */
  132.     };
  133.     uint16_t    mtime;
  134.     uint16_t    mdate;
  135.     union {
  136.         uint16_t    firstc;     /* FAT12/FAT16 */
  137.         uint16_t    firstc_lo;  /* FAT32 */
  138.     };
  139.     uint32_t    size;
  140. } __attribute__ ((packed)) fat_dentry_t;
  141.  
  142. typedef uint16_t fat_cluster_t;
  143.  
  144. typedef enum {
  145.     FAT_INVALID,
  146.     FAT_DIRECTORY,
  147.     FAT_FILE
  148. } fat_node_type_t;
  149.  
  150. struct fat_node;
  151.  
  152. /** FAT index structure.
  153.  *
  154.  * This structure exists to help us to overcome certain limitations of the FAT
  155.  * file system design.  The problem with FAT is that it is hard to find
  156.  * an entity which could represent a VFS index.  There are two candidates:
  157.  *
  158.  * a) number of the node's first cluster
  159.  * b) the pair of the parent directory's first cluster and the dentry index
  160.  *    within the parent directory
  161.  *
  162.  * We need VFS indices to be:
  163.  * A) unique
  164.  * B) stable in time, at least until the next mount
  165.  *
  166.  * Unfortunately a) does not meet the A) criterion because zero-length files
  167.  * will have the first cluster field cleared.  And b) does not meet the B)
  168.  * criterion because unlink() and rename() will both free up the original
  169.  * dentry, which contains all the essential info about the file.
  170.  *
  171.  * Therefore, a completely opaque indices are used and the FAT server maintains
  172.  * a mapping between them and otherwise nice b) variant.  On rename(), the VFS
  173.  * index stays unaltered, while the internal FAT "physical tree address"
  174.  * changes.  The unlink case is also handled this way thanks to an in-core node
  175.  * pointer embedded in the index structure.
  176.  */
  177. typedef struct {
  178.     /** Used indices (position) hash table link. */
  179.     link_t      uph_link;
  180.     /** Used indices (index) hash table link. */
  181.     link_t      uih_link;
  182.  
  183.     futex_t     lock;
  184.     dev_handle_t    dev_handle;
  185.     fs_index_t  index;
  186.     /**
  187.      * Parent node's first cluster.
  188.      * Zero is used if this node is not linked, in which case nodep must
  189.      * contain a pointer to the in-core node structure.
  190.      * One is used when the parent is the root directory.
  191.      */
  192.     fat_cluster_t   pfc;
  193.     /** Directory entry index within the parent node. */
  194.     unsigned    pdi;
  195.     /** Pointer to in-core node instance. */
  196.     struct fat_node *nodep;
  197. } fat_idx_t;
  198.  
  199. /** FAT in-core node. */
  200. typedef struct fat_node {
  201.     futex_t         lock;
  202.     fat_node_type_t     type;
  203.     fat_idx_t       *idx;
  204.     /**
  205.      *  Node's first cluster.
  206.      *  Zero is used for zero-length nodes.
  207.      *  One is used to mark root directory.
  208.      */
  209.     fat_cluster_t       firstc;
  210.     /** FAT in-core node free list link. */
  211.     link_t          ffn_link;
  212.     size_t          size;
  213.     unsigned        lnkcnt;
  214.     unsigned        refcnt;
  215.     bool            dirty;
  216. } fat_node_t;
  217.  
  218. extern fs_reg_t fat_reg;
  219.  
  220. extern void fat_lookup(ipc_callid_t, ipc_call_t *);
  221.  
  222. extern fat_idx_t *fat_idx_get_by_pos(dev_handle_t, fat_cluster_t, unsigned);
  223. extern fat_idx_t *fat_idx_get_by_index(dev_handle_t, fs_index_t);
  224.  
  225. #endif
  226.  
  227. /**
  228.  * @}
  229.  */
  230.