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2627 jermar 1
/*
2793 jermar 2
 * Copyright (c) 2008 Jakub Jermar
2627 jermar 3
 * 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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/**
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 * @file    fat_ops.c
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 * @brief   Implementation of VFS operations for the FAT file system server.
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 */
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#include "fat.h"
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#include "../../vfs/vfs.h"
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#include <libfs.h>
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#include <ipc/ipc.h>
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#include <async.h>
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#include <errno.h>
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#include <string.h>
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#include <byteorder.h>
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#define FAT_NAME_LEN        8
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#define FAT_EXT_LEN     3
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#define FAT_PAD         ' ' 
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#define FAT_DENTRY_UNUSED   0x00
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#define FAT_DENTRY_E5_ESC   0x05
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#define FAT_DENTRY_DOT      0x2e
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#define FAT_DENTRY_ERASED   0xe5
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static void dentry_name_canonify(fat_dentry_t *d, char *buf)
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{
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    int i;
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    for (i = 0; i < FAT_NAME_LEN; i++) {
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        if (d->name[i] == FAT_PAD) {
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            buf++;
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            break;
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        }
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        if (d->name[i] == FAT_DENTRY_E5_ESC)
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            *buf++ = 0xe5;
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        else
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            *buf++ = d->name[i];
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    }
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    if (d->ext[0] != FAT_PAD)
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        *buf++ = '.';
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    for (i = 0; i < FAT_EXT_LEN; i++) {
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        if (d->ext[i] == FAT_PAD) {
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            *buf = '\0';
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            return;
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        }
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        if (d->ext[i] == FAT_DENTRY_E5_ESC)
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            *buf++ = 0xe5;
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        else
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            *buf++ = d->ext[i];
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    }
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}
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2822 jermar 85
/* TODO and also move somewhere else */
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typedef struct {
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    void *data;
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} block_t;
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static block_t *block_get(dev_handle_t dev_handle, off_t offset)
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{
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    return NULL;    /* TODO */
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}
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static block_t *fat_block_get(fat_node_t *node, off_t offset) {
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    return NULL;    /* TODO */
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}
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static void block_put(block_t *block)
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{
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    /* TODO */
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}
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static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)
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{
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    return NULL;    /* TODO */
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}
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#define BS_BLOCK    0
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static void *fat_match(void *prnt, const char *component)
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{
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    fat_node_t *parentp = (fat_node_t *)prnt;
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    char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
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    unsigned i, j;
2828 jermar 116
    unsigned bps;       /* bytes per sector */
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    unsigned dps;       /* dentries per sector */
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    unsigned blocks;
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    fat_dentry_t *d;
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    block_t *bb;
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    block_t *b;
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    bb = block_get(parentp->dev_handle, BS_BLOCK);
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    if (!bb)
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        return NULL;
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    bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps);
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    block_put(bb);
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    dps = bps / sizeof(fat_dentry_t);
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    blocks = parentp->size / bps + (parentp->size % bps != 0);
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    for (i = 0; i < blocks; i++) {
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        unsigned dentries;
2793 jermar 132
 
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        b = fat_block_get(parentp, i);
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        if (!b)
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            return NULL;
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        dentries = (i == blocks - 1) ?
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            parentp->size % sizeof(fat_dentry_t) :
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            dps;
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        for (j = 0; j < dentries; j++) {
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            d = ((fat_dentry_t *)b->data) + j;
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            if (d->attr & FAT_ATTR_VOLLABEL) {
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                /* volume label entry */
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                continue;
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            }
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            if (d->name[0] == FAT_DENTRY_ERASED) {
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                /* not-currently-used entry */
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                continue;
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            }
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            if (d->name[0] == FAT_DENTRY_UNUSED) {
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                /* never used entry */
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                block_put(b);
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                return NULL;
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            }
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            if (d->name[0] == FAT_DENTRY_DOT) {
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                /*
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                 * Most likely '.' or '..'.
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                 * It cannot occur in a regular file name.
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                 */
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                continue;
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            }
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            dentry_name_canonify(d, name);
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            if (strcmp(name, component) == 0) {
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                /* hit */
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                void *node = fat_node_get(parentp->dev_handle,
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                    (fs_index_t)uint16_t_le2host(d->firstc));
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                block_put(b);
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                return node;
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            }
2793 jermar 171
        }
2822 jermar 172
        block_put(b);
2639 jermar 173
    }
2793 jermar 174
 
175
    return NULL;
2638 jermar 176
}
177
 
2793 jermar 178
/** libfs operations */
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libfs_ops_t fat_libfs_ops = {
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    .match = fat_match,
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    .node_get = fat_node_get,
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    .create = NULL,
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    .destroy = NULL,
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    .link = NULL,
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    .unlink = NULL,
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    .index_get = NULL,
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    .size_get = NULL,
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    .lnkcnt_get = NULL,
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    .has_children = NULL,
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    .root_get = NULL,
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    .plb_get_char = NULL,
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    .is_directory = NULL,
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    .is_file = NULL
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};
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2627 jermar 196
void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
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{
2793 jermar 198
    libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
2627 jermar 199
}
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/**
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 * @}
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 */