source: mainline/uspace/srv/bd/part/mbr_part/mbr_part.c@ 135486d

/*
 * Copyright (c) 2009 Jiri Svoboda
 * 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 bd
 * @{
 */

/**
 * @file
 * @brief PC MBR partition driver
 *
 * Handles the PC MBR partitioning scheme. Uses a block device
 * and provides one for each partition.
 *
 * Limitations:
 * 
 * Only works with boot records using LBA. CHS-only records are not
 * supported.
 *
 * Referemces:
 *
 * The source of MBR structures for this driver have been the following
 * Wikipedia articles:
 *      - http://en.wikipedia.org/wiki/Master_Boot_Record
 *      - http://en.wikipedia.org/wiki/Extended_boot_record
 *
 * The fact that the extended partition has type 0x05 is pure observation.
 * (TODO: can it have any other type number?)
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <async.h>
#include <as.h>
#include <bd_srv.h>
#include <fibril_synch.h>
#include <loc.h>
#include <sys/types.h>
#include <sys/typefmt.h>
#include <inttypes.h>
#include <libblock.h>
#include <errno.h>
#include <bool.h>
#include <byteorder.h>
#include <assert.h>
#include <macros.h>
#include <task.h>

#define NAME "mbr_part"

enum {
        /** Number of primary partition records */
        N_PRIMARY       = 4,

        /** Boot record signature */
        BR_SIGNATURE    = 0xAA55
};

enum ptype {
        /** Unused partition entry */
        PT_UNUSED       = 0x00,
        /** Extended partition */
        PT_EXTENDED     = 0x05,
};

/** Partition */
typedef struct part {
        /** Primary partition entry is in use */
        bool present;
        /** Address of first block */
        aoff64_t start_addr;
        /** Number of blocks */
        aoff64_t length;
        /** Device representing the partition (outbound device) */
        service_id_t dsid;
        /** Block device service sturcture */
        bd_srvs_t bds;
        /** Points to next partition structure. */
        struct part *next;
} part_t;

/** Structure of a partition table entry */
typedef struct {
        uint8_t status;
        /** CHS of fist block in partition */
        uint8_t first_chs[3];
        /** Partition type */
        uint8_t ptype;
        /** CHS of last block in partition */
        uint8_t last_chs[3];
        /** LBA of first block in partition */
        uint32_t first_lba;
        /** Number of blocks in partition */
        uint32_t length;
} __attribute__((packed)) pt_entry_t;

/** Structure of a boot-record block */
typedef struct {
        /* Area for boot code */
        uint8_t code_area[440];

        /* Optional media ID */
        uint32_t media_id;

        uint16_t pad0;

        /** Partition table entries */
        pt_entry_t pte[N_PRIMARY];

        /** Boot record block signature (@c BR_SIGNATURE) */
        uint16_t signature;
} __attribute__((packed)) br_block_t;


static size_t block_size;

/** Partitioned device (inbound device) */
static service_id_t indev_sid;

/** List of partitions. This structure is an empty head. */
static part_t plist_head;

static int mbr_init(const char *dev_name);
static int mbr_part_read(void);
static part_t *mbr_part_new(void);
static void mbr_pte_to_part(uint32_t base, const pt_entry_t *pte, part_t *part);
static void mbr_connection(ipc_callid_t iid, ipc_call_t *icall, void *arg);
static int mbr_bsa_translate(part_t *p, uint64_t ba, size_t cnt, uint64_t *gba);

static int mbr_bd_open(bd_srvs_t *, bd_srv_t *);
static int mbr_bd_close(bd_srv_t *);
static int mbr_bd_read_blocks(bd_srv_t *, aoff64_t, size_t, void *, size_t);
static int mbr_bd_write_blocks(bd_srv_t *, aoff64_t, size_t, const void *, size_t);
static int mbr_bd_get_block_size(bd_srv_t *, size_t *);
static int mbr_bd_get_num_blocks(bd_srv_t *, aoff64_t *);

static bd_ops_t mbr_bd_ops = {
        .open = mbr_bd_open,
        .close = mbr_bd_close,
        .read_blocks = mbr_bd_read_blocks,
        .write_blocks = mbr_bd_write_blocks,
        .get_block_size = mbr_bd_get_block_size,
        .get_num_blocks = mbr_bd_get_num_blocks
};

static part_t *bd_srv_part(bd_srv_t *bd)
{
        return (part_t *)bd->srvs->sarg;
}

int main(int argc, char **argv)
{
        printf(NAME ": PC MBR partition driver\n");

        if (argc != 2) {
                printf("Expected one argument (device name).\n");
                return -1;
        }

        if (mbr_init(argv[1]) != EOK)
                return -1;

        printf(NAME ": Accepting connections\n");
        task_retval(0);
        async_manager();

        /* Not reached */
        return 0;
}

static int mbr_init(const char *dev_name)
{
        int rc;
        int i;
        char *name;
        service_id_t dsid;
        uint64_t size_mb;
        part_t *part;

        rc = loc_service_get_id(dev_name, &indev_sid, 0);
        if (rc != EOK) {
                printf(NAME ": could not resolve device `%s'.\n", dev_name);
                return rc;
        }

        rc = block_init(EXCHANGE_SERIALIZE, indev_sid, 2048);
        if (rc != EOK)  {
                printf(NAME ": could not init libblock.\n");
                return rc;
        }

        /* Determine and verify block size. */

        rc = block_get_bsize(indev_sid, &block_size);
        if (rc != EOK) {
                printf(NAME ": error getting block size.\n");
                return rc;
        }

        if (block_size < 512 || (block_size % 512) != 0) {
                printf(NAME ": invalid block size %zu.\n", block_size);
                return ENOTSUP;
        }

        /* Read in partition records. */
        rc = mbr_part_read();
        if (rc != EOK)
                return rc;

        /* Register server with location service. */
        async_set_client_connection(mbr_connection);
        rc = loc_server_register(NAME);
        if (rc != EOK) {
                printf(NAME ": Unable to register server.\n");
                return rc;
        }

        /*
         * Create partition devices.
         */
        i = 0;
        part = plist_head.next;

        while (part != NULL) {
                /* Skip absent partitions. */
                if (!part->present) {
                        part = part->next;
                        ++i;
                        continue;
                }

                asprintf(&name, "%sp%d", dev_name, i);
                if (name == NULL)
                        return ENOMEM;

                rc = loc_service_register(name, &dsid);
                if (rc != EOK) {
                        printf(NAME ": Unable to register service %s.\n", name);
                        return rc;
                }

                size_mb = (part->length * block_size + 1024 * 1024 - 1)
                    / (1024 * 1024);
                printf(NAME ": Registered device %s: %" PRIuOFF64 " blocks "
                    "%" PRIu64 " MB.\n", name, part->length, size_mb);

                part->dsid = dsid;
                free(name);

                part = part->next;
                ++i;
        }

        return EOK;
}

/** Read in partition records. */
static int mbr_part_read(void)
{
        int i, rc;
        br_block_t *brb;
        uint16_t sgn;
        uint32_t ba;
        part_t *ext_part, cp;
        uint32_t base;
        part_t *prev, *p;

        brb = malloc(sizeof(br_block_t));
        if (brb == NULL) {
                printf(NAME ": Failed allocating memory.\n");
                return ENOMEM;
        }

        /*
         * Read primary partition entries.
         */

        rc = block_read_direct(indev_sid, 0, 1, brb);
        if (rc != EOK) {
                printf(NAME ": Failed reading MBR block.\n");
                return rc;
        }

        sgn = uint16_t_le2host(brb->signature);
        if (sgn != BR_SIGNATURE) {
                printf(NAME ": Invalid boot record signature 0x%04" PRIX16
                    ".\n", sgn);
                return EINVAL;
        }

        ext_part = NULL;
        plist_head.next = NULL;
        prev = &plist_head;

        for (i = 0; i < N_PRIMARY; ++i) {
                p = mbr_part_new();
                if (p == NULL)
                        return ENOMEM;

                mbr_pte_to_part(0, &brb->pte[i], p);
                prev->next = p;
                prev = p;

                if (brb->pte[i].ptype == PT_EXTENDED) {
                        p->present = false;
                        ext_part = p;
                }
        }

        if (ext_part == NULL)
                return EOK;

        printf("Extended partition found.\n");

        /*
         * Read extended partition entries.
         */

        cp.start_addr = ext_part->start_addr;
        cp.length = ext_part->length;
        base = ext_part->start_addr;

        do {
                /*
                 * Addressing in the EBR chain is relative to the beginning
                 * of the extended partition.
                 */
                ba = cp.start_addr;
                rc = block_read_direct(indev_sid, ba, 1, brb);
                if (rc != EOK) {
                        printf(NAME ": Failed reading EBR block at %"
                            PRIu32 ".\n", ba);
                        return rc;
                }

                sgn = uint16_t_le2host(brb->signature);
                if (sgn != BR_SIGNATURE) {
                        printf(NAME ": Invalid boot record signature 0x%04"
                            PRIX16 " in EBR at %" PRIu32 ".\n", sgn, ba);
                        return EINVAL;
                }

                p = mbr_part_new();
                if (p == NULL)
                        return ENOMEM;

                /* First PTE is the logical partition itself. */
                mbr_pte_to_part(base, &brb->pte[0], p);
                prev->next = p;
                prev = p;

                /* Second PTE describes next chain element. */
                mbr_pte_to_part(base, &brb->pte[1], &cp);
        } while (cp.present);

        return EOK;
}

/** Allocate a new @c part_t structure. */
static part_t *mbr_part_new(void)
{
        return malloc(sizeof(part_t));
}

/** Parse partition table entry. */
static void mbr_pte_to_part(uint32_t base, const pt_entry_t *pte, part_t *part)
{
        uint32_t sa, len;

        sa = uint32_t_le2host(pte->first_lba);
        len = uint32_t_le2host(pte->length);

        part->start_addr = base + sa;
        part->length     = len;

        part->present = (pte->ptype != PT_UNUSED) ? true : false;

        bd_srvs_init(&part->bds);
        part->bds.ops = &mbr_bd_ops;
        part->bds.sarg = part;

        part->dsid = 0;
        part->next = NULL;
}

static void mbr_connection(ipc_callid_t iid, ipc_call_t *icall, void *arg)
{
        service_id_t dh;
        part_t *part;

        /* Get the device handle. */
        dh = IPC_GET_ARG1(*icall);

        /* 
         * Determine which partition device is the client connecting to.
         * A linear search is not terribly fast, but we only do this
         * once for each connection.
         */
        part = plist_head.next;
        while (part != NULL && part->dsid != dh)
                part = part->next;

        if (part == NULL) {
                async_answer_0(iid, EINVAL);
                return;
        }

        assert(part->present == true);
        bd_conn(iid, icall, &part->bds);
}

/** Open device. */
static int mbr_bd_open(bd_srvs_t *bds, bd_srv_t *bd)
{
        return EOK;
}

/** Close device. */
static int mbr_bd_close(bd_srv_t *bd)
{
        return EOK;
}

/** Read blocks from partition. */
static int mbr_bd_read_blocks(bd_srv_t *bd, aoff64_t ba, size_t cnt, void *buf,
    size_t size)
{
        part_t *p = bd_srv_part(bd);
        aoff64_t gba;

        if (cnt * block_size < size)
                return EINVAL;

        if (mbr_bsa_translate(p, ba, cnt, &gba) != EOK)
                return ELIMIT;

        return block_read_direct(indev_sid, gba, cnt, buf);
}

/** Write blocks to partition. */
static int mbr_bd_write_blocks(bd_srv_t *bd, aoff64_t ba, size_t cnt,
    const void *buf, size_t size)
{
        part_t *p = bd_srv_part(bd);
        aoff64_t gba;

        if (cnt * block_size < size)
                return EINVAL;

        if (mbr_bsa_translate(p, ba, cnt, &gba) != EOK)
                return ELIMIT;

        return block_write_direct(indev_sid, gba, cnt, buf);
}

/** Get device block size. */
static int mbr_bd_get_block_size(bd_srv_t *bd, size_t *rsize)
{
        *rsize = block_size;
        return EOK;
}

/** Get number of blocks on device. */
static int mbr_bd_get_num_blocks(bd_srv_t *bd, aoff64_t *rnb)
{
        part_t *part = bd_srv_part(bd);

        *rnb = part->length;
        return EOK;
}

/** Translate block segment address with range checking. */
static int mbr_bsa_translate(part_t *p, uint64_t ba, size_t cnt, uint64_t *gba)
{
        if (ba + cnt > p->length)
                return ELIMIT;

        *gba = p->start_addr + ba;
        return EOK;
}

/**
 * @}
 */