Subversion Repositories HelenOS

/*

 * Copyright (c) 1987,1997, Prentice Hall

 * All rights reserved.

 *

 * Redistribution and use of the MINIX operating system 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.

 * - Neither the name of Prentice Hall nor the names of the software

 *   authors or contributors may be used to endorse or promote

 *   products derived from this software without specific prior

 *   written permission.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS, AUTHORS, AND

 * CONTRIBUTORS ``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 PRENTICE HALL OR ANY AUTHORS OR CONTRIBUTORS 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 FileSystemImpl

* @{

*/

/**

 * @file    utility.c

 * @brief   Superblock support.

 */

#include <string.h>

#include "fs.h"

#include "block.h"

#include "inode.h"

#include "super.h"

#include <stdio.h>

super_block_t* super_block;

static int v1(int magic, int *version, int *extend);

static int v2(int magic ,int*version, int *extend);

static int get_native(int magic, int *version, int *extend);

/**

 * File system versions

 */

int (*versions[TOTAL_VERSIONS])(int , int*, int*)  = {

        v1, /* 0 = V1 version */

        v2  /* 1 = V2 version */

    };

/**

 * Initializes the superblock structure for later use

 */

int init_super_block()

{

    super_block = (super_block_t*)malloc(sizeof(super_block_t));

    if (super_block != NULL)

        return TRUE;

        return FALSE;  

}

/**

 * Return pointer at the superblock

 */

super_block_t *get_super()

{  

    return super_block;

}

/**

 * Read a superblock

 */

int read_super(register super_block_t *sp)

{

    /* Read a superblock. */

    register block_t *bp;

    int magic, version, extend, native;

    bp = get_block(SUPER_BLOCK);

    memcpy((void *)sp, (void *)(bp->b.b__data), (size_t)SUPER_SIZE);

    magic = sp->s_magic;        /* determines file system type */

    /* Get file system version and type. */

    native = get_native(magic, &version, &extend);

    if (native == FS_EINVAL) {

        print_console("Unknown version of file system\n");

        print_console("Magic is bad\n");

        return FS_EINVAL;  

    }

    /* In V1, the device size was kept in a short, s_nzones, which limited

       * devices to 32K zones.  For V2, it was decided to keep the size as a

       * long.  However, just changing s_nzones to a long would not work, since

       * then the position of s_magic in the super block would not be the same

       * in V1 and V2 file systems, and there would be no way to tell whether

       * a newly mounted file system was V1 or V2.  The solution was to introduce

       * a new variable, s_zones, and copy the size there.

       *

       * Calculate some other numbers that depend on the version here too, to

       * hide some of the differences.

       */

    if (version == V1) {

        sp->s_zones = sp->s_nzones;     /* only V1 needs this copy */

        sp->s_inodes_per_block = V1_INODES_PER_BLOCK;

        sp->s_ndzones = V1_NR_DZONES;

        sp->s_nindirs = V1_INDIRECTS;

    }

    else {

        sp->s_inodes_per_block = V2_INODES_PER_BLOCK;

        sp->s_ndzones = V2_NR_DZONES;

        sp->s_nindirs = V2_INDIRECTS;

    }

    sp->s_isearch = 0;  /* inode searches initially start at 0 */

    sp->s_zsearch = 0;  /* zone searches initially start at 0 */

    sp->s_version = version;

    sp->s_native  = native;    

    sp->s_extend = extend;

    /* Make a few basic checks to see if super block looks reasonable. */

    if (sp->s_imap_blocks < 1 || sp->s_zmap_blocks < 1

        || sp->s_ninodes < 1 || sp->s_zones < 1

        || (unsigned) sp->s_log_zone_size > 4) {

        return FS_EINVAL;

    }  

    return OK;

}

/**

 * Test the superblock against MINIX FS v1

 */

int v1(int magic, int* version, int *extend)

{

    if (magic == SUPER_MAGIC || magic == conv2(BYTE_SWAP,SUPER_MAGIC)) {

        *version = V1; *extend = FALSE;

        return TRUE;

    }

    if (magic == SUPER_MAGIC2 || magic == conv2(BYTE_SWAP,SUPER_MAGIC2)) {

        *version = V1; *extend = TRUE;

        return TRUE;

    }

    return FALSE;

}

/**

 * Test the superblock against MINIX FS v2

 */

int v2(int magic, int *version, int *extend)

{

    if (magic == SUPER_V2 || magic == conv2(BYTE_SWAP,SUPER_V2)) {

        *version = V2; *extend = FALSE;

        return TRUE;

    }

    if (magic == SUPER_V2E || magic == conv2(BYTE_SWAP,SUPER_V2E)) {

        *version = V2; *extend = TRUE;

        return TRUE;

    }

    return FALSE;

}

/**

 * Check the file system version and type

 */

int get_native(int magic, int *version, int *extend)

{  

    int i, result;

    /* Get file system version and type */

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

        result = versions[i](magic, version, extend);

        if (result) {

            return result;

        }

    }

    return FS_EINVAL;

}

/**

 * }

 */