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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 "fat_fat.h"
  37. #include <ipc/ipc.h>
  38. #include <libfs.h>
  39. #include <atomic.h>
  40. #include <sys/types.h>
  41. #include <bool.h>
  42. #include "../../vfs/vfs.h"
  43.  
  44. #ifndef dprintf
  45. #define dprintf(...)    printf(__VA_ARGS__)
  46. #endif
  47.  
  48. #define min(a, b)       ((a) < (b) ? (a) : (b))
  49.  
  50. #define BS_BLOCK        0
  51. #define BS_SIZE         512
  52.  
  53. typedef struct fat_bs {
  54.     uint8_t     ji[3];      /**< Jump instruction. */
  55.     uint8_t     oem_name[8];
  56.     /* BIOS Parameter Block */
  57.     uint16_t    bps;        /**< Bytes per sector. */
  58.     uint8_t     spc;        /**< Sectors per cluster. */
  59.     uint16_t    rscnt;      /**< Reserved sector count. */
  60.     uint8_t     fatcnt;     /**< Number of FATs. */
  61.     uint16_t    root_ent_max;   /**< Maximum number of root directory
  62.                          entries. */
  63.     uint16_t    totsec16;   /**< Total sectors. 16-bit version. */
  64.     uint8_t     mdesc;      /**< Media descriptor. */
  65.     uint16_t    sec_per_fat;    /**< Sectors per FAT12/FAT16. */
  66.     uint16_t    sec_per_track;  /**< Sectors per track. */
  67.     uint16_t    headcnt;    /**< Number of heads. */
  68.     uint32_t    hidden_sec; /**< Hidden sectors. */
  69.     uint32_t    totsec32;   /**< Total sectors. 32-bit version. */
  70.  
  71.     union {
  72.         struct {
  73.             /* FAT12/FAT16 only: Extended BIOS Parameter Block */
  74.             /** Physical drive number. */
  75.             uint8_t     pdn;
  76.             uint8_t     reserved;
  77.             /** Extended boot signature. */
  78.             uint8_t     ebs;
  79.             /** Serial number. */
  80.             uint32_t    id;
  81.             /** Volume label. */
  82.             uint8_t     label[11];
  83.             /** FAT type. */
  84.             uint8_t     type[8];
  85.             /** Boot code. */
  86.             uint8_t     boot_code[448];
  87.             /** Boot sector signature. */
  88.             uint16_t    signature;
  89.         } __attribute__ ((packed));
  90.         struct {
  91.             /* FAT32 only */
  92.             /** Sectors per FAT. */
  93.             uint32_t    sectors_per_fat;
  94.             /** FAT flags. */
  95.             uint16_t    flags;
  96.             /** Version. */
  97.             uint16_t    version;
  98.             /** Cluster number of root directory. */
  99.             uint32_t    root_cluster;
  100.             /** Sector number of file system information sector. */
  101.             uint16_t    fsinfo_sec;
  102.             /** Sector number of boot sector copy. */
  103.             uint16_t    bscopy_sec;
  104.             uint8_t     reserved1[12];
  105.             /** Physical drive number. */
  106.             uint8_t     pdn;
  107.             uint8_t     reserved2;
  108.             /** Extended boot signature. */
  109.             uint8_t     ebs;
  110.             /** Serial number. */
  111.             uint32_t    id;
  112.             /** Volume label. */
  113.             uint8_t     label[11];
  114.             /** FAT type. */
  115.             uint8_t     type[8];
  116.             /** Boot code. */
  117.             uint8_t     boot_code[420];
  118.             /** Signature. */
  119.             uint16_t    signature;
  120.         } __attribute__ ((packed));
  121.     };
  122. } __attribute__ ((packed)) fat_bs_t;
  123.  
  124. typedef enum {
  125.     FAT_INVALID,
  126.     FAT_DIRECTORY,
  127.     FAT_FILE
  128. } fat_node_type_t;
  129.  
  130. struct fat_node;
  131.  
  132. /** FAT index structure.
  133.  *
  134.  * This structure exists to help us to overcome certain limitations of the FAT
  135.  * file system design.  The problem with FAT is that it is hard to find
  136.  * an entity which could represent a VFS index.  There are two candidates:
  137.  *
  138.  * a) number of the node's first cluster
  139.  * b) the pair of the parent directory's first cluster and the dentry index
  140.  *    within the parent directory
  141.  *
  142.  * We need VFS indices to be:
  143.  * A) unique
  144.  * B) stable in time, at least until the next mount
  145.  *
  146.  * Unfortunately a) does not meet the A) criterion because zero-length files
  147.  * will have the first cluster field cleared.  And b) does not meet the B)
  148.  * criterion because unlink() and rename() will both free up the original
  149.  * dentry, which contains all the essential info about the file.
  150.  *
  151.  * Therefore, a completely opaque indices are used and the FAT server maintains
  152.  * a mapping between them and otherwise nice b) variant.  On rename(), the VFS
  153.  * index stays unaltered, while the internal FAT "physical tree address"
  154.  * changes.  The unlink case is also handled this way thanks to an in-core node
  155.  * pointer embedded in the index structure.
  156.  */
  157. typedef struct {
  158.     /** Used indices (position) hash table link. */
  159.     link_t      uph_link;
  160.     /** Used indices (index) hash table link. */
  161.     link_t      uih_link;
  162.  
  163.     futex_t     lock;
  164.     dev_handle_t    dev_handle;
  165.     fs_index_t  index;
  166.     /**
  167.      * Parent node's first cluster.
  168.      * Zero is used if this node is not linked, in which case nodep must
  169.      * contain a pointer to the in-core node structure.
  170.      * One is used when the parent is the root directory.
  171.      */
  172.     fat_cluster_t   pfc;
  173.     /** Directory entry index within the parent node. */
  174.     unsigned    pdi;
  175.     /** Pointer to in-core node instance. */
  176.     struct fat_node *nodep;
  177. } fat_idx_t;
  178.  
  179. /** FAT in-core node. */
  180. typedef struct fat_node {
  181.     futex_t         lock;
  182.     fat_node_type_t     type;
  183.     fat_idx_t       *idx;
  184.     /**
  185.      *  Node's first cluster.
  186.      *  Zero is used for zero-length nodes.
  187.      *  One is used to mark root directory.
  188.      */
  189.     fat_cluster_t       firstc;
  190.     /** FAT in-core node free list link. */
  191.     link_t          ffn_link;
  192.     size_t          size;
  193.     unsigned        lnkcnt;
  194.     unsigned        refcnt;
  195.     bool            dirty;
  196. } fat_node_t;
  197.  
  198. extern fs_reg_t fat_reg;
  199.  
  200. extern void fat_mounted(ipc_callid_t, ipc_call_t *);
  201. extern void fat_mount(ipc_callid_t, ipc_call_t *);
  202. extern void fat_lookup(ipc_callid_t, ipc_call_t *);
  203. extern void fat_read(ipc_callid_t, ipc_call_t *);
  204. extern void fat_write(ipc_callid_t, ipc_call_t *);
  205. extern void fat_truncate(ipc_callid_t, ipc_call_t *);
  206. extern void fat_destroy(ipc_callid_t, ipc_call_t *);
  207.  
  208. extern fat_idx_t *fat_idx_get_new(dev_handle_t);
  209. extern fat_idx_t *fat_idx_get_by_pos(dev_handle_t, fat_cluster_t, unsigned);
  210. extern fat_idx_t *fat_idx_get_by_index(dev_handle_t, fs_index_t);
  211. extern void fat_idx_destroy(fat_idx_t *);
  212. extern void fat_idx_hashin(fat_idx_t *);
  213.  
  214. extern int fat_idx_init(void);
  215. extern void fat_idx_fini(void);
  216. extern int fat_idx_init_by_dev_handle(dev_handle_t);
  217. extern void fat_idx_fini_by_dev_handle(dev_handle_t);
  218.  
  219. #endif
  220.  
  221. /**
  222.  * @}
  223.  */
  224.