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/*

 * 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

 * @{

 */

/**

 * @file    fat_ops.c

 * @brief   Implementation of VFS operations for the FAT file system server.

 */

#include "fat.h"

#include "../../vfs/vfs.h"

#include <libfs.h>

#include <ipc/ipc.h>

#include <async.h>

#include <errno.h>

#include <string.h>

#include <byteorder.h>

#define FAT_NAME_LEN        8

#define FAT_EXT_LEN     3

#define FAT_PAD         ' ' 

#define FAT_DENTRY_UNUSED   0x00

#define FAT_DENTRY_E5_ESC   0x05

#define FAT_DENTRY_DOT      0x2e

#define FAT_DENTRY_ERASED   0xe5

static void dentry_name_canonify(fat_dentry_t *d, char *buf)

{

    int i;

    for (i = 0; i < FAT_NAME_LEN; i++) {

        if (d->name[i] == FAT_PAD) {

            buf++;

            break;

        }

        if (d->name[i] == FAT_DENTRY_E5_ESC)

            *buf++ = 0xe5;

        else

            *buf++ = d->name[i];

    }

    if (d->ext[0] != FAT_PAD)

        *buf++ = '.';

    for (i = 0; i < FAT_EXT_LEN; i++) {

        if (d->ext[i] == FAT_PAD) {

            *buf = '\0';

            return;

        }

        if (d->ext[i] == FAT_DENTRY_E5_ESC)

            *buf++ = 0xe5;

        else

            *buf++ = d->ext[i];

    }

}

/* TODO and also move somewhere else */

typedef struct {

    void *data;

} block_t;

static block_t *block_get(dev_handle_t dev_handle, off_t offset)

{

    return NULL;    /* TODO */

}

static block_t *fat_block_get(fat_node_t *node, off_t offset) {

    return NULL;    /* TODO */

}

static void block_put(block_t *block)

{

    /* TODO */

}

static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)

{

    return NULL;    /* TODO */

}

#define BS_BLOCK    0

static void *fat_match(void *prnt, const char *component)

{

    fat_node_t *parentp = (fat_node_t *)prnt;

    char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];

    unsigned i, j;

    unsigned bps;       /* bytes per sector */

    unsigned dps;       /* dentries per sector */

    unsigned blocks;

    fat_dentry_t *d;

    block_t *bb;

    block_t *b;

    bb = block_get(parentp->dev_handle, BS_BLOCK);

    if (!bb)

        return NULL;

    bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps);

    block_put(bb);

    dps = bps / sizeof(fat_dentry_t);

    blocks = parentp->size / bps + (parentp->size % bps != 0);

    for (i = 0; i < blocks; i++) {

        unsigned dentries;

        b = fat_block_get(parentp, i);

        if (!b)

            return NULL;

        dentries = (i == blocks - 1) ?

            parentp->size % sizeof(fat_dentry_t) :

            dps;

        for (j = 0; j < dentries; j++) {

            d = ((fat_dentry_t *)b->data) + j;

            if (d->attr & FAT_ATTR_VOLLABEL) {

                /* volume label entry */

                continue;

            }

            if (d->name[0] == FAT_DENTRY_ERASED) {

                /* not-currently-used entry */

                continue;

            }

            if (d->name[0] == FAT_DENTRY_UNUSED) {

                /* never used entry */

                block_put(b);

                return NULL;

            }

            if (d->name[0] == FAT_DENTRY_DOT) {

                /*

                 * Most likely '.' or '..'.

                 * It cannot occur in a regular file name.

                 */

                continue;

            }

            dentry_name_canonify(d, name);

            if (strcmp(name, component) == 0) {

                /* hit */

                void *node = fat_node_get(parentp->dev_handle,

                    (fs_index_t)uint16_t_le2host(d->firstc));

                block_put(b);

                return node;

            }

        }

        block_put(b);

    }

    return NULL;

}

/** libfs operations */

libfs_ops_t fat_libfs_ops = {

    .match = fat_match,

    .node_get = fat_node_get,

    .create = NULL,

    .destroy = NULL,

    .link = NULL,

    .unlink = NULL,

    .index_get = NULL,

    .size_get = NULL,

    .lnkcnt_get = NULL,

    .has_children = NULL,

    .root_get = NULL,

    .plb_get_char = NULL,

    .is_directory = NULL,

    .is_file = NULL

};

void fat_lookup(ipc_callid_t rid, ipc_call_t *request)

{

    libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);

}

/**

 * @}

 */