mkexfat: Fix FAT initialization

[helenos.git] / uspace / app / mkexfat / mkexfat.c

/*
 * Copyright (c) 2012 Maurizio Lombardi
 * 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        mkexfat.c
 * @brief       Tool for creating new exFAT file systems.
 *
 */

#include <stdio.h>
#include <libblock.h>
#include <assert.h>
#include <errno.h>
#include <malloc.h>
#include <byteorder.h>
#include <align.h>
#include <sys/types.h>
#include <sys/typefmt.h>
#include "exfat.h"

#define NAME    "mkexfat"

/** First sector of the FAT */
#define FAT_SECTOR_START 128

/** First sector of the Main Extended Boot Region */
#define EBS_SECTOR_START 1

/** First sector of the Main Extended Boot Region Backup */
#define EBS_BACKUP_SECTOR_START 13

/** First sector of the Main Boot Sector */
#define MBS_SECTOR 0

/** First sector of the Main Boot Sector Backup */
#define MBS_BACKUP_SECTOR 12

/** Size of the Main Extended Boot Region */
#define EBS_SIZE 8

/** Divide and round up. */
#define div_round_up(a, b) (((a) + (b) - 1) / (b))

/** The default size of each cluster is 4096 byte */
#define DEFAULT_CLUSTER_SIZE 4096

typedef struct exfat_cfg {
        aoff64_t volume_start;
        aoff64_t volume_count;
        unsigned long fat_sector_count;
        unsigned long data_start_sector;
        unsigned long rootdir_cluster;
        unsigned long total_clusters;
        size_t   sector_size;
        size_t   cluster_size;
} exfat_cfg_t;


static unsigned log2(unsigned n);

static uint32_t
vbr_checksum_start(void const *octets, size_t nbytes);

static void
vbr_checksum_update(void const *octets, size_t nbytes, uint32_t *checksum);

static int
ebs_write(service_id_t service_id, exfat_cfg_t *cfg,
    int base, uint32_t *chksum);

static void usage(void)
{
        printf("Usage: mkexfat <device>\n");
}

/** Initialize the exFAT params structure.
 *
 * @param cfg Pointer to the exFAT params structure to initialize.
 */
static void
cfg_params_initialize(exfat_cfg_t *cfg)
{
        unsigned long fat_bytes;
        aoff64_t const volume_bytes = (cfg->volume_count - FAT_SECTOR_START) *
            cfg->sector_size;

        aoff64_t n_req_clusters = volume_bytes / DEFAULT_CLUSTER_SIZE;
        cfg->cluster_size = DEFAULT_CLUSTER_SIZE;

        /* Compute the required cluster size to index
         * the entire storage device and to keep the FAT
         * size less or equal to 64 Mb.
         */
        while (n_req_clusters > 16000000ULL &&
            (cfg->cluster_size < 32 * 1024 * 1024)) {

                cfg->cluster_size <<= 1;
                n_req_clusters = volume_bytes / cfg->cluster_size;
        }

        /* The first two clusters are reserved */
        cfg->total_clusters = n_req_clusters + 2;

        /* Compute the FAT size in sectors */
        fat_bytes = (cfg->total_clusters + 1) * 4;
        cfg->fat_sector_count = div_round_up(fat_bytes, cfg->sector_size);

        /* Compute the number of the first data sector */
        cfg->data_start_sector = ROUND_UP(FAT_SECTOR_START +
            cfg->fat_sector_count, cfg->cluster_size / cfg->sector_size);

        cfg->rootdir_cluster = 0;

        /* The first sector of the partition is zero */
        cfg->volume_start = 0;
}

/** Prints the exFAT structure values
 *
 * @param cfg Pointer to the exfat_cfg_t structure.
 */
static void
cfg_print_info(exfat_cfg_t *cfg)
{
        printf(NAME ": Sector size:           %lu\n", cfg->sector_size);
        printf(NAME ": Cluster size:          %lu\n", cfg->cluster_size);
        printf(NAME ": FAT size in sectors:   %lu\n", cfg->fat_sector_count);
        printf(NAME ": Data start sector:     %lu\n", cfg->data_start_sector);
        printf(NAME ": Total num of clusters: %lu\n", cfg->total_clusters);
}

/** Initialize the Main Boot Sector fields.
 *
 * @param mbs Pointer to the Main Boot Sector structure.
 * @param cfg Pointer to the exFAT configuration structure.
 * @return    Initial checksum value.
 */
static uint32_t
vbr_initialize(exfat_bs_t *mbs, exfat_cfg_t *cfg)
{
        /* Fill the structure with zeroes */
        memset(mbs, 0, sizeof(exfat_bs_t));

        /* Init Jump Boot section */
        mbs->jump[0] = 0xEB;
        mbs->jump[1] = 0x76;
        mbs->jump[2] = 0x90;

        /* Set the filesystem name */
        memcpy(mbs->oem_name, "EXFAT   ", sizeof(mbs->oem_name));

        mbs->volume_start = host2uint64_t_le(cfg->volume_start);
        mbs->volume_count = host2uint64_t_le(cfg->volume_count);
        mbs->fat_sector_start = host2uint32_t_le(FAT_SECTOR_START);
        mbs->fat_sector_count = host2uint32_t_le(cfg->fat_sector_count);
        mbs->data_start_sector = host2uint32_t_le(cfg->data_start_sector);

        mbs->data_clusters = host2uint32_t_le(cfg->total_clusters - 
            div_round_up(cfg->data_start_sector, cfg->cluster_size));

        mbs->rootdir_cluster = 0;
        mbs->volume_serial = 0;
        mbs->version.major = 1;
        mbs->version.minor = 0;
        mbs->volume_flags = host2uint16_t_le(0);
        mbs->bytes_per_sector = log2(cfg->sector_size);
        mbs->sec_per_cluster = log2(cfg->cluster_size / cfg->sector_size);

        /* Maximum cluster size is 32 Mb */
        assert((mbs->bytes_per_sector + mbs->sec_per_cluster) <= 25);

        mbs->fat_count = 1;
        mbs->drive_no = 0x80;
        mbs->allocated_percent = 0;
        mbs->signature = host2uint16_t_le(0xAA55);

        return vbr_checksum_start(mbs, sizeof(exfat_bs_t));
}

static int
bootsec_write(service_id_t service_id, exfat_cfg_t *cfg)
{
        exfat_bs_t mbs;
        uint32_t vbr_checksum;
        uint32_t initial_checksum;
        int rc;

        vbr_checksum = vbr_initialize(&mbs, cfg);
        initial_checksum = vbr_checksum;

        /* Write the Main Boot Sector to disk */
        rc = block_write_direct(service_id, MBS_SECTOR, 1, &mbs);
        if (rc != EOK)
                return rc;

        /* Write the Main extended boot sectors to disk */
        rc = ebs_write(service_id, cfg, EBS_SECTOR_START, &vbr_checksum);
        if (rc != EOK)
                return rc;

        /* Write the Main Boot Sector backup to disk */
        rc = block_write_direct(service_id, MBS_BACKUP_SECTOR, 1, &mbs);
        if (rc != EOK)
                return rc;

        /* Restore the checksum to its initial value */
        vbr_checksum = initial_checksum;

        /* Write the Main extended boot sectors backup to disk */ 
        return ebs_write(service_id, cfg,
            EBS_BACKUP_SECTOR_START, &vbr_checksum);
}

/** Write the Main Extended Boot Sector to disk
 *
 * @param service_id  The service id.
 * @param cfg  Pointer to the exFAT configuration structure.
 * @param base Base sector of the EBS.
 * @return  EOK on success or a negative error code.
 */
static int
ebs_write(service_id_t service_id, exfat_cfg_t *cfg, int base, uint32_t *chksum)
{
        uint32_t *ebs = calloc(cfg->sector_size, sizeof(uint8_t));
        int i, rc;
        unsigned idx;

        if (!ebs)
                return ENOMEM;

        ebs[cfg->sector_size / 4 - 1] = host2uint32_t_le(0xAA550000);

        for (i = 0; i < EBS_SIZE; ++i) {
                vbr_checksum_update(ebs, cfg->sector_size, chksum);

                rc = block_write_direct(service_id,
                    i + EBS_SECTOR_START + base, 1, ebs);

                if (rc != EOK)
                        goto exit;
        }

        /* The OEM record is not yet used
         * by the official exFAT implementation, we'll fill
         * it with zeroes.
         */

        memset(ebs, 0, cfg->sector_size);
        vbr_checksum_update(ebs, cfg->sector_size, chksum);

        rc = block_write_direct(service_id, i++ + base, 1, ebs);
        if (rc != EOK)
                goto exit;

        /* The next sector is reserved, fill it with zeroes too */
        vbr_checksum_update(ebs, cfg->sector_size, chksum);
        rc = block_write_direct(service_id, i++ + base, 1, ebs);
        if (rc != EOK)
                goto exit;

        /* Write the checksum sector */
        for (idx = 0; idx < cfg->sector_size / sizeof(uint32_t); ++idx)
                ebs[idx] = host2uint32_t_le(*chksum);

        rc = block_write_direct(service_id, i + base, 1, ebs);

exit:
        free(ebs);
        return rc;
}

/** Writes the FAT on disk.
 *
 * @param service_id  The service id.
 * @param cfg Pointer to the exfat_cfg structure.
 * @return EOK on success or a negative error code.
 */
static int
fat_write(service_id_t service_id, exfat_cfg_t *cfg)
{
        unsigned long i;
        uint32_t *pfat;
        int rc;

        pfat = calloc(cfg->fat_sector_count, cfg->sector_size);
        if (!pfat)
                return ENOMEM;

        pfat[0] = host2uint32_t_le(0xFFFFFFF8);
        pfat[1] = host2uint32_t_le(0xFFFFFFFF);

        /* Allocate clusters for the bitmap, upcase table
         * and the root directory.
         */
        pfat[2] = host2uint32_t_le(0xFFFFFFFF);
        pfat[3] = host2uint32_t_le(0xFFFFFFFF);
        pfat[4] = host2uint32_t_le(0xFFFFFFFF);

        rc = block_write_direct(service_id, FAT_SECTOR_START, 1, pfat);
        if (rc != EOK)
                goto error;

        memset(pfat, 0, 5 * sizeof(uint32_t));

        for (i = 1; i < cfg->fat_sector_count + 1; ++i) {
                rc = block_write_direct(service_id,
                    FAT_SECTOR_START + i, 1, pfat);
                if (rc != EOK)
                        goto error;
        }

error:
        free(pfat);
        return rc;
}

/** Given a number (n), returns the result of log2(n).
 *
 * It works only if n is a power of two.
 */
static unsigned
log2(unsigned n)
{
        unsigned r;

        for (r = 0;n >> r != 1; ++r);

        return r;
}

/** Initialize the VBR checksum calculation */
static uint32_t
vbr_checksum_start(void const *data, size_t nbytes)
{
        uint32_t checksum = 0;
        size_t index;
        uint8_t const *octets = (uint8_t *) data;

        for (index = 0; index < nbytes; ++index) {
                if (index == 106 || index == 107 || index == 112) {
                        /* Skip volume_flags and allocated_percent fields */
                        continue;
                }

                checksum = ((checksum << 31) | (checksum >> 1)) + octets[index];
        }

        return checksum;
}

/** Update the VBR checksum */
static void
vbr_checksum_update(void const *data, size_t nbytes, uint32_t *checksum)
{
        size_t index;
        uint8_t const *octets = (uint8_t *) data;

        for (index = 0; index < nbytes; ++index)
                *checksum = ((*checksum << 31) | (*checksum >> 1)) + octets[index];
}

int main (int argc, char **argv)
{
        exfat_cfg_t cfg;
        char *dev_path;
        service_id_t service_id;
        int rc;

        if (argc < 2) {
                printf(NAME ": Error, argument missing\n");
                usage();
                return 1;
        }

        /* TODO: Add parameters */

        ++argv;
        dev_path = *argv;

        printf(NAME ": Device = %s\n", dev_path);

        rc = loc_service_get_id(dev_path, &service_id, 0);
        if (rc != EOK) {
                printf(NAME ": Error resolving device `%s'.\n", dev_path);
                return 2;
        }

        rc = block_init(EXCHANGE_SERIALIZE, service_id, 2048);
        if (rc != EOK) {
                printf(NAME ": Error initializing libblock.\n");
                return 2;
        }

        rc = block_get_bsize(service_id, &cfg.sector_size);
        if (rc != EOK) {
                printf(NAME ": Error determining device block size.\n");
                return 2;
        }

        if (cfg.sector_size > 4096) {
                printf(NAME ": Error, sector size can't be greater" \
                    " than 4096 bytes.\n");
                return 2;
        }

        rc = block_get_nblocks(service_id, &cfg.volume_count);
        if (rc != EOK) {
                printf(NAME ": Warning, failed to obtain" \
                    " device block size.\n");
                /* FIXME: the user should be able to specify the filesystem size */
                return 1;
        } else {
                printf(NAME ": Block device has %" PRIuOFF64 " blocks.\n",
                    cfg.volume_count);
        }

        cfg_params_initialize(&cfg);
        cfg_print_info(&cfg);

        rc = bootsec_write(service_id, &cfg);
        if (rc != EOK) {
                printf(NAME ": Error, failed to write the VBR to disk\n");
                return 2;
        }

        rc = fat_write(service_id, &cfg);
        if (rc != EOK) {
                printf(NAME ": Error, failed to write the FAT to disk\n");
                return 2;
        }

        return 0;
}