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2627 jermar 1
/*
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 * Copyright (c) 2008 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup fs
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 * @{
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 */
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#ifndef FAT_FAT_H_
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#define FAT_FAT_H_
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#include "fat_fat.h"
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#include <ipc/ipc.h>
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#include <libfs.h>
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#include <atomic.h>
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#include <sys/types.h>
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#include <bool.h>
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#include "../../vfs/vfs.h"
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#ifndef dprintf
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#define dprintf(...)    printf(__VA_ARGS__)
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#endif
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#define min(a, b)       ((a) < (b) ? (a) : (b))
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#define BS_BLOCK        0
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#define BS_SIZE         512
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typedef struct fat_bs {
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    uint8_t     ji[3];      /**< Jump instruction. */
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    uint8_t     oem_name[8];
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    /* BIOS Parameter Block */
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    uint16_t    bps;        /**< Bytes per sector. */
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    uint8_t     spc;        /**< Sectors per cluster. */
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    uint16_t    rscnt;      /**< Reserved sector count. */
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    uint8_t     fatcnt;     /**< Number of FATs. */
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    uint16_t    root_ent_max;   /**< Maximum number of root directory
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                         entries. */
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    uint16_t    totsec16;   /**< Total sectors. 16-bit version. */
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    uint8_t     mdesc;      /**< Media descriptor. */
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    uint16_t    sec_per_fat;    /**< Sectors per FAT12/FAT16. */
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    uint16_t    sec_per_track;  /**< Sectors per track. */
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    uint16_t    headcnt;    /**< Number of heads. */
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    uint32_t    hidden_sec; /**< Hidden sectors. */
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    uint32_t    totsec32;   /**< Total sectors. 32-bit version. */
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    union {
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        struct {
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            /* FAT12/FAT16 only: Extended BIOS Parameter Block */
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            /** Physical drive number. */
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            uint8_t     pdn;
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            uint8_t     reserved;
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            /** Extended boot signature. */
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            uint8_t     ebs;
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            /** Serial number. */
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            uint32_t    id;
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            /** Volume label. */
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            uint8_t     label[11];
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            /** FAT type. */
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            uint8_t     type[8];
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            /** Boot code. */
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            uint8_t     boot_code[448];
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            /** Boot sector signature. */
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            uint16_t    signature;
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        } __attribute__ ((packed));
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        struct {
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            /* FAT32 only */
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            /** Sectors per FAT. */
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            uint32_t    sectors_per_fat;
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            /** FAT flags. */
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            uint16_t    flags;
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            /** Version. */
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            uint16_t    version;
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            /** Cluster number of root directory. */
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            uint32_t    root_cluster;
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            /** Sector number of file system information sector. */
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            uint16_t    fsinfo_sec;
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            /** Sector number of boot sector copy. */
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            uint16_t    bscopy_sec;
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            uint8_t     reserved1[12];
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            /** Physical drive number. */
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            uint8_t     pdn;
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            uint8_t     reserved2;
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            /** Extended boot signature. */
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            uint8_t     ebs;
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            /** Serial number. */
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            uint32_t    id;
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            /** Volume label. */
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            uint8_t     label[11];
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            /** FAT type. */
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            uint8_t     type[8];
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            /** Boot code. */
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            uint8_t     boot_code[420];
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            /** Signature. */
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            uint16_t    signature;
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        } __attribute__ ((packed));
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    };
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} __attribute__ ((packed)) fat_bs_t;
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typedef enum {
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    FAT_INVALID,
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    FAT_DIRECTORY,
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    FAT_FILE
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} fat_node_type_t;
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struct fat_node;
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/** FAT index structure.
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 *
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 * This structure exists to help us to overcome certain limitations of the FAT
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 * file system design.  The problem with FAT is that it is hard to find
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 * an entity which could represent a VFS index.  There are two candidates:
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 *
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 * a) number of the node's first cluster
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 * b) the pair of the parent directory's first cluster and the dentry index
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 *    within the parent directory
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 *
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 * We need VFS indices to be:
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 * A) unique
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 * B) stable in time, at least until the next mount
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 *
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 * Unfortunately a) does not meet the A) criterion because zero-length files
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 * will have the first cluster field cleared.  And b) does not meet the B)
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 * criterion because unlink() and rename() will both free up the original
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 * dentry, which contains all the essential info about the file.
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 *
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 * Therefore, a completely opaque indices are used and the FAT server maintains
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 * a mapping between them and otherwise nice b) variant.  On rename(), the VFS
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 * index stays unaltered, while the internal FAT "physical tree address"
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 * changes.  The unlink case is also handled this way thanks to an in-core node
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 * pointer embedded in the index structure.
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 */
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typedef struct {
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    /** Used indices (position) hash table link. */
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    link_t      uph_link;
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    /** Used indices (index) hash table link. */
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    link_t      uih_link;
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    futex_t     lock;
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    dev_handle_t    dev_handle;
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    fs_index_t  index;
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    /**
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     * Parent node's first cluster.
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     * Zero is used if this node is not linked, in which case nodep must
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     * contain a pointer to the in-core node structure.
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     * One is used when the parent is the root directory.
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     */
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    fat_cluster_t   pfc;
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    /** Directory entry index within the parent node. */
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    unsigned    pdi;
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    /** Pointer to in-core node instance. */
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    struct fat_node *nodep;
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} fat_idx_t;
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/** FAT in-core node. */
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typedef struct fat_node {
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    futex_t         lock;
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    fat_node_type_t     type;
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    fat_idx_t       *idx;
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    /**
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     *  Node's first cluster.
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     *  Zero is used for zero-length nodes.
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     *  One is used to mark root directory.
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     */
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    fat_cluster_t       firstc;
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    /** FAT in-core node free list link. */
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    link_t          ffn_link;
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    size_t          size;
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    unsigned        lnkcnt;
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    unsigned        refcnt;
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    bool            dirty;
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} fat_node_t;
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extern fs_reg_t fat_reg;
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extern void fat_mounted(ipc_callid_t, ipc_call_t *);
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extern void fat_mount(ipc_callid_t, ipc_call_t *);
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extern void fat_lookup(ipc_callid_t, ipc_call_t *);
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extern void fat_read(ipc_callid_t, ipc_call_t *);
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extern void fat_write(ipc_callid_t, ipc_call_t *);
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extern void fat_truncate(ipc_callid_t, ipc_call_t *);
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extern void fat_destroy(ipc_callid_t, ipc_call_t *);
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extern fat_idx_t *fat_idx_get_new(dev_handle_t);
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extern fat_idx_t *fat_idx_get_by_pos(dev_handle_t, fat_cluster_t, unsigned);
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extern fat_idx_t *fat_idx_get_by_index(dev_handle_t, fs_index_t);
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extern void fat_idx_destroy(fat_idx_t *);
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extern void fat_idx_hashin(fat_idx_t *);
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extern int fat_idx_init(void);
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extern void fat_idx_fini(void);
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extern int fat_idx_init_by_dev_handle(dev_handle_t);
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extern void fat_idx_fini_by_dev_handle(dev_handle_t);
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#endif
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/**
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 * @}
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 */