source: mainline/uspace/srv/fs/fat/fat.h@ efcebe1

/*
 * Copyright (c) 2008 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup fs
 * @{
 */ 

#ifndef FAT_FAT_H_
#define FAT_FAT_H_

#include "fat_fat.h"
#include <fibril_synch.h>
#include <libfs.h>
#include <atomic.h>
#include <sys/types.h>
#include <bool.h>
#include "../../vfs/vfs.h"

#ifndef dprintf
#define dprintf(...)    printf(__VA_ARGS__)
#endif

#define min(a, b)               ((a) < (b) ? (a) : (b))

/*
 * Convenience macros for accessing some frequently used boot sector members.
 */
#define BPS(bs)         uint16_t_le2host((bs)->bps)
#define SPC(bs)         (bs)->spc
#define RSCNT(bs)       uint16_t_le2host((bs)->rscnt)
#define FATCNT(bs)      (bs)->fatcnt
#define SF(bs)          uint16_t_le2host((bs)->sec_per_fat)
#define RDE(bs)         uint16_t_le2host((bs)->root_ent_max)
#define TS(bs)          (uint16_t_le2host((bs)->totsec16) != 0 ? \
                        uint16_t_le2host((bs)->totsec16) : \
                        uint32_t_le2host(bs->totsec32))

#define BS_BLOCK                0
#define BS_SIZE                 512

typedef struct fat_bs {
        uint8_t         ji[3];          /**< Jump instruction. */
        uint8_t         oem_name[8];
        /* BIOS Parameter Block */
        uint16_t        bps;            /**< Bytes per sector. */
        uint8_t         spc;            /**< Sectors per cluster. */
        uint16_t        rscnt;          /**< Reserved sector count. */
        uint8_t         fatcnt;         /**< Number of FATs. */
        uint16_t        root_ent_max;   /**< Maximum number of root directory
                                             entries. */
        uint16_t        totsec16;       /**< Total sectors. 16-bit version. */
        uint8_t         mdesc;          /**< Media descriptor. */
        uint16_t        sec_per_fat;    /**< Sectors per FAT12/FAT16. */
        uint16_t        sec_per_track;  /**< Sectors per track. */
        uint16_t        headcnt;        /**< Number of heads. */
        uint32_t        hidden_sec;     /**< Hidden sectors. */
        uint32_t        totsec32;       /**< Total sectors. 32-bit version. */

        union {
                struct {
                        /* FAT12/FAT16 only: Extended BIOS Parameter Block */
                        /** Physical drive number. */
                        uint8_t         pdn;
                        uint8_t         reserved;
                        /** Extended boot signature. */
                        uint8_t         ebs;
                        /** Serial number. */
                        uint32_t        id;
                        /** Volume label. */
                        uint8_t         label[11];
                        /** FAT type. */
                        uint8_t         type[8];
                        /** Boot code. */
                        uint8_t         boot_code[448];
                        /** Boot sector signature. */
                        uint16_t        signature;
                } __attribute__ ((packed));
                struct {
                        /* FAT32 only */
                        /** Sectors per FAT. */
                        uint32_t        sectors_per_fat;
                        /** FAT flags. */
                        uint16_t        flags;
                        /** Version. */
                        uint16_t        version;
                        /** Cluster number of root directory. */
                        uint32_t        root_cluster;
                        /** Sector number of file system information sector. */
                        uint16_t        fsinfo_sec;
                        /** Sector number of boot sector copy. */
                        uint16_t        bscopy_sec;
                        uint8_t         reserved1[12];
                        /** Physical drive number. */
                        uint8_t         pdn;
                        uint8_t         reserved2;
                        /** Extended boot signature. */
                        uint8_t         ebs;
                        /** Serial number. */
                        uint32_t        id;
                        /** Volume label. */
                        uint8_t         label[11];
                        /** FAT type. */
                        uint8_t         type[8];
                        /** Boot code. */
                        uint8_t         boot_code[420];
                        /** Signature. */
                        uint16_t        signature;
                } fat32 __attribute__ ((packed));
        };
} __attribute__ ((packed)) fat_bs_t;

typedef enum {
        FAT_INVALID,
        FAT_DIRECTORY,
        FAT_FILE
} fat_node_type_t;

struct fat_node;

/** FAT index structure.
 *
 * This structure exists to help us to overcome certain limitations of the FAT
 * file system design.  The problem with FAT is that it is hard to find
 * an entity which could represent a VFS index.  There are two candidates:
 *
 * a) number of the node's first cluster
 * b) the pair of the parent directory's first cluster and the dentry index
 *    within the parent directory
 *
 * We need VFS indices to be:
 * A) unique
 * B) stable in time, at least until the next mount
 *
 * Unfortunately a) does not meet the A) criterion because zero-length files
 * will have the first cluster field cleared.  And b) does not meet the B)
 * criterion because unlink() and rename() will both free up the original
 * dentry, which contains all the essential info about the file.
 *
 * Therefore, a completely opaque indices are used and the FAT server maintains
 * a mapping between them and otherwise nice b) variant.  On rename(), the VFS
 * index stays unaltered, while the internal FAT "physical tree address"
 * changes.  The unlink case is also handled this way thanks to an in-core node
 * pointer embedded in the index structure.
 */
typedef struct {
        /** Used indices (position) hash table link. */
        link_t          uph_link;
        /** Used indices (index) hash table link. */
        link_t          uih_link;

        fibril_mutex_t  lock;
        devmap_handle_t devmap_handle;
        fs_index_t      index;
        /**
         * Parent node's first cluster.
         * Zero is used if this node is not linked, in which case nodep must
         * contain a pointer to the in-core node structure.
         * One is used when the parent is the root directory.
         */
        fat_cluster_t   pfc;
        /** Directory entry index within the parent node. */
        unsigned        pdi;
        /** Pointer to in-core node instance. */
        struct fat_node *nodep;
} fat_idx_t;

/** FAT in-core node. */
typedef struct fat_node {
        /** Back pointer to the FS node. */
        fs_node_t               *bp;
        
        fibril_mutex_t          lock;
        fat_node_type_t         type;
        fat_idx_t               *idx;
        /**
         *  Node's first cluster.
         *  Zero is used for zero-length nodes.
         *  One is used to mark root directory.
         */
        fat_cluster_t           firstc;
        /** FAT in-core node free list link. */
        link_t                  ffn_link;
        aoff64_t                size;
        unsigned                lnkcnt;
        unsigned                refcnt;
        bool                    dirty;

        /*
         * Cache of the node's last and "current" cluster to avoid some
         * unnecessary FAT walks.
         */
        /* Node's last cluster in FAT. */
        bool            lastc_cached_valid;
        fat_cluster_t   lastc_cached_value;
        /* Node's "current" cluster, i.e. where the last I/O took place. */
        bool            currc_cached_valid;
        aoff64_t        currc_cached_bn;
        fat_cluster_t   currc_cached_value;
} fat_node_t;

extern vfs_out_ops_t fat_ops;
extern libfs_ops_t fat_libfs_ops;

extern int fat_idx_get_new(fat_idx_t **, devmap_handle_t);
extern fat_idx_t *fat_idx_get_by_pos(devmap_handle_t, fat_cluster_t, unsigned);
extern fat_idx_t *fat_idx_get_by_index(devmap_handle_t, fs_index_t);
extern void fat_idx_destroy(fat_idx_t *);
extern void fat_idx_hashin(fat_idx_t *);
extern void fat_idx_hashout(fat_idx_t *);

extern int fat_idx_init(void);
extern void fat_idx_fini(void);
extern int fat_idx_init_by_devmap_handle(devmap_handle_t);
extern void fat_idx_fini_by_devmap_handle(devmap_handle_t);

#endif

/**
 * @}
 */