source: bootcd/isolinux/syslinux-6.03/com32/lib/syslinux/disk.c

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2003-2009 H. Peter Anvin - All Rights Reserved
 *   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
 *   Copyright (C) 2010 Shao Miller
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

/**
 * @file disk.c
 *
 * Deal with disks and partitions
 */

#include <core.h>
#include <dprintf.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslinux/disk.h>

/**
 * Call int 13h, but with retry on failure.  Especially floppies need this.
 *
 * @v inreg                     CPU register settings upon INT call
 * @v outreg                    CPU register settings returned by INT call
 * @ret (int)                   0 upon success, -1 upon failure
 */
int disk_int13_retry(const com32sys_t * inreg, com32sys_t * outreg)
{
    int retry = 6;              /* Number of retries */
    com32sys_t tmpregs;

    if (!outreg)
        outreg = &tmpregs;

    while (retry--) {
        __intcall(0x13, inreg, outreg);
        if (!(outreg->eflags.l & EFLAGS_CF))
            return 0;           /* CF=0, OK */
    }

    return -1;                  /* Error */
}

/**
 * Query disk parameters and EBIOS availability for a particular disk.
 *
 * @v disk                      The INT 0x13 disk drive number to process
 * @v diskinfo                  The structure to save the queried params to
 * @ret (int)                   0 upon success, -1 upon failure
 */
int disk_get_params(int disk, struct disk_info *const diskinfo)
{
    static com32sys_t inreg, outreg;
    struct disk_ebios_eparam *eparam;
    int rv = 0;

    memset(diskinfo, 0, sizeof *diskinfo);
    diskinfo->disk = disk;
    diskinfo->bps = SECTOR;

    /* Get EBIOS support */
    memset(&inreg, 0, sizeof inreg);
    inreg.eax.b[1] = 0x41;
    inreg.ebx.w[0] = 0x55aa;
    inreg.edx.b[0] = disk;
    inreg.eflags.b[0] = 0x3;    /* CF set */

    __intcall(0x13, &inreg, &outreg);

    if (!(outreg.eflags.l & EFLAGS_CF) &&
        outreg.ebx.w[0] == 0xaa55 && (outreg.ecx.b[0] & 1)) {
        diskinfo->ebios = 1;
    }

    eparam = lmalloc(sizeof *eparam);
    if (!eparam)
        return -1;

    /* Get extended disk parameters if ebios == 1 */
    if (diskinfo->ebios) {
        memset(&inreg, 0, sizeof inreg);
        inreg.eax.b[1] = 0x48;
        inreg.edx.b[0] = disk;
        inreg.esi.w[0] = OFFS(eparam);
        inreg.ds = SEG(eparam);

        memset(eparam, 0, sizeof *eparam);
        eparam->len = sizeof *eparam;

        __intcall(0x13, &inreg, &outreg);

        if (!(outreg.eflags.l & EFLAGS_CF)) {
            diskinfo->lbacnt = eparam->lbacnt;
            if (eparam->bps)
                diskinfo->bps = eparam->bps;
            /*
             * don't think about using geometry data returned by
             * 48h, as it can differ from 08h a lot ...
             */
        }
    }
    /*
     * Get disk parameters the old way - really only useful for hard
     * disks, but if we have a partitioned floppy it's actually our best
     * chance...
     */
    memset(&inreg, 0, sizeof inreg);
    inreg.eax.b[1] = 0x08;
    inreg.edx.b[0] = disk;

    __intcall(0x13, &inreg, &outreg);

    if (outreg.eflags.l & EFLAGS_CF) {
        rv = diskinfo->ebios ? 0 : -1;
        goto out;
    }

    diskinfo->spt = 0x3f & outreg.ecx.b[0];
    diskinfo->head = 1 + outreg.edx.b[1];
    diskinfo->cyl = 1 + (outreg.ecx.b[1] | ((outreg.ecx.b[0] & 0xc0u) << 2));

    if (diskinfo->spt)
        diskinfo->cbios = 1;    /* Valid geometry */
    else {
        diskinfo->head = 1;
        diskinfo->spt = 1;
        diskinfo->cyl = 1;
    }

    if (!diskinfo->lbacnt)
        diskinfo->lbacnt = diskinfo->cyl * diskinfo->head * diskinfo->spt;

out:
    lfree(eparam);
    return rv;
}

/**
 * Fill inreg based on EBIOS addressing properties.
 *
 * @v diskinfo                  The disk drive to read from
 * @v inreg                     Register data structure to be filled.
 * @v lba                       The logical block address to begin reading at
 * @v count                     The number of sectors to read
 * @v op_code                   Code to write/read operation
 * @ret                         lmalloc'd buf upon success, NULL upon failure
 */
static void *ebios_setup(const struct disk_info *const diskinfo, com32sys_t *inreg,
                         uint64_t lba, uint8_t count, uint8_t op_code)
{
    static struct disk_ebios_dapa *dapa = NULL;
    void *buf;

    if (!dapa) {
        dapa = lmalloc(sizeof *dapa);
        if (!dapa)
            return NULL;
    }

    buf = lmalloc(count * diskinfo->bps);
    if (!buf)
        return NULL;

    dapa->len = sizeof(*dapa);
    dapa->count = count;
    dapa->off = OFFS(buf);
    dapa->seg = SEG(buf);
    dapa->lba = lba;

    inreg->eax.b[1] = op_code;
    inreg->esi.w[0] = OFFS(dapa);
    inreg->ds = SEG(dapa);
    inreg->edx.b[0] = diskinfo->disk;

    return buf;
}

/**
 * Fill inreg based on CHS addressing properties.
 *
 * @v diskinfo                  The disk drive to read from
 * @v inreg                     Register data structure to be filled.
 * @v lba                       The logical block address to begin reading at
 * @v count                     The number of sectors to read
 * @v op_code                   Code to write/read operation
 * @ret                         lmalloc'd buf upon success, NULL upon failure
 */
static void *chs_setup(const struct disk_info *const diskinfo, com32sys_t *inreg,
                       uint64_t lba, uint8_t count, uint8_t op_code)
{
    unsigned int c, h, s, t;
    void *buf;

    buf = lmalloc(count * diskinfo->bps);
    if (!buf)
        return NULL;

    /*
     * if we passed lba + count check and we get here, that means that
     * lbacnt was calculated from chs geometry (or faked from 1/1/1), thus
     * 32bits are perfectly enough and lbacnt corresponds to cylinder
     * boundary
     */
    s = lba % diskinfo->spt;
    t = lba / diskinfo->spt;
    h = t % diskinfo->head;
    c = t / diskinfo->head;

    memset(inreg, 0, sizeof *inreg);
    inreg->eax.b[0] = count;
    inreg->eax.b[1] = op_code;
    inreg->ecx.b[1] = c;
    inreg->ecx.b[0] = ((c & 0x300) >> 2) | (s+1);
    inreg->edx.b[1] = h;
    inreg->edx.b[0] = diskinfo->disk;
    inreg->ebx.w[0] = OFFS(buf);
    inreg->es = SEG(buf);

    return buf;
}

/**
 * Get disk block(s) and return a malloc'd buffer.
 *
 * @v diskinfo                  The disk drive to read from
 * @v lba                       The logical block address to begin reading at
 * @v count                     The number of sectors to read
 * @ret data                    An allocated buffer with the read data
 *
 * Uses the disk number and information from diskinfo.  Read count sectors
 * from drive, starting at lba.  Return a new buffer, or NULL upon failure.
 */
void *disk_read_sectors(const struct disk_info *const diskinfo, uint64_t lba,
                        uint8_t count)
{
    com32sys_t inreg;
    void *buf;
    void *data = NULL;
    uint32_t maxcnt;
    uint32_t size = 65536;

    maxcnt = (size - diskinfo->bps) / diskinfo->bps;
    if (!count || count > maxcnt || lba + count > diskinfo->lbacnt)
        return NULL;

    memset(&inreg, 0, sizeof inreg);

    if (diskinfo->ebios)
        buf = ebios_setup(diskinfo, &inreg, lba, count, EBIOS_READ_CODE);
    else
        buf = chs_setup(diskinfo, &inreg, lba, count, CHS_READ_CODE);

    if (!buf)
        return NULL;

    if (disk_int13_retry(&inreg, NULL))
        goto out;

    data = malloc(count * diskinfo->bps);
    if (data)
        memcpy(data, buf, count * diskinfo->bps);
out:
    lfree(buf);
    return data;
}

/**
 * Write disk block(s).
 *
 * @v diskinfo                  The disk drive to write to
 * @v lba                       The logical block address to begin writing at
 * @v data                      The data to write
 * @v count                     The number of sectors to write
 * @ret (int)                   0 upon success, -1 upon failure
 *
 * Uses the disk number and information from diskinfo.
 * Write sector(s) to a disk drive, starting at lba.
 */
int disk_write_sectors(const struct disk_info *const diskinfo, uint64_t lba,
                       const void *data, uint8_t count)
{
    com32sys_t inreg;
    void *buf;
    uint32_t maxcnt;
    uint32_t size = 65536;
    int rv = -1;

    maxcnt = (size - diskinfo->bps) / diskinfo->bps;
    if (!count || count > maxcnt || lba + count > diskinfo->lbacnt)
        return -1;

    memset(&inreg, 0, sizeof inreg);

    if (diskinfo->ebios)
        buf = ebios_setup(diskinfo, &inreg, lba, count, EBIOS_WRITE_CODE);
    else
        buf = chs_setup(diskinfo, &inreg, lba, count, CHS_WRITE_CODE);

    if (!buf)
        return -1;

    memcpy(buf, data, count * diskinfo->bps);

    if (disk_int13_retry(&inreg, NULL))
        goto out;

    rv = 0;                     /* ok */
out:
    lfree(buf);
    return rv;
}

/**
 * Write disk blocks and verify they were written.
 *
 * @v diskinfo                  The disk drive to write to
 * @v lba                       The logical block address to begin writing at
 * @v buf                       The data to write
 * @v count                     The number of sectors to write
 * @ret rv                      0 upon success, -1 upon failure
 *
 * Uses the disk number and information from diskinfo.
 * Writes sectors to a disk drive starting at lba, then reads them back
 * to verify they were written correctly.
 */
int disk_write_verify_sectors(const struct disk_info *const diskinfo,
                              uint64_t lba, const void *buf, uint8_t count)
{
    char *rb;
    int rv;

    rv = disk_write_sectors(diskinfo, lba, buf, count);
    if (rv)
        return rv;              /* Write failure */
    rb = disk_read_sectors(diskinfo, lba, count);
    if (!rb)
        return -1;              /* Readback failure */
    rv = memcmp(buf, rb, count * diskinfo->bps);
    free(rb);
    return rv ? -1 : 0;
}

/**
 * Dump info about a DOS partition entry
 *
 * @v part                      The 16-byte partition entry to examine
 */
void disk_dos_part_dump(const struct disk_dos_part_entry *const part)
{
    (void)part;
    dprintf("Partition status _____ : 0x%.2x\n"
            "Partition CHS start\n"
            "  Cylinder ___________ : 0x%.4x (%u)\n"
            "  Head _______________ : 0x%.2x (%u)\n"
            "  Sector _____________ : 0x%.2x (%u)\n"
            "Partition type _______ : 0x%.2x\n"
            "Partition CHS end\n"
            "  Cylinder ___________ : 0x%.4x (%u)\n"
            "  Head _______________ : 0x%.2x (%u)\n"
            "  Sector _____________ : 0x%.2x (%u)\n"
            "Partition LBA start __ : 0x%.8x (%u)\n"
            "Partition LBA count __ : 0x%.8x (%u)\n"
            "-------------------------------\n",
            part->active_flag,
            chs_cylinder(part->start),
            chs_cylinder(part->start),
            chs_head(part->start),
            chs_head(part->start),
            chs_sector(part->start),
            chs_sector(part->start),
            part->ostype,
            chs_cylinder(part->end),
            chs_cylinder(part->end),
            chs_head(part->end),
            chs_head(part->end),
            chs_sector(part->end),
            chs_sector(part->end),
            part->start_lba, part->start_lba, part->length, part->length);
}

/* Trivial error message output */
static inline void error(const char *msg)
{
    fputs(msg, stderr);
}

/**
 * This walk-map effectively reverses the little-endian
 * portions of a GPT disk/partition GUID for a string representation.
 * There might be a better header for this...
 */
static const char guid_le_walk_map[] = {
    3, -1, -1, -1, 0,
    5, -1, 0,
    3, -1, 0,
    2, 1, 0,
    1, 1, 1, 1, 1, 1
};

/**
 * Fill a buffer with a textual GUID representation.
 *
 * @v buf                       Points to a minimum array of 37 chars
 * @v id                        The GUID to represent as text
 *
 * The buffer must be >= char[37] and will be populated
 * with an ASCII NUL C string terminator.
 * Example: 11111111-2222-3333-4444-444444444444
 * Endian:  LLLLLLLL-LLLL-LLLL-BBBB-BBBBBBBBBBBB
 */
void guid_to_str(char *buf, const struct guid *const id)
{
    unsigned int i = 0;
    const char *walker = (const char *)id;

    while (i < sizeof(guid_le_walk_map)) {
        walker += guid_le_walk_map[i];
        if (!guid_le_walk_map[i])
            *buf = '-';
        else {
            *buf = ((*walker & 0xF0) >> 4) + '0';
            if (*buf > '9')
                *buf += 'A' - '9' - 1;
            buf++;
            *buf = (*walker & 0x0F) + '0';
            if (*buf > '9')
                *buf += 'A' - '9' - 1;
        }
        buf++;
        i++;
    }
    *buf = 0;
}

/**
 * Create a GUID structure from a textual GUID representation.
 *
 * @v buf                       Points to a GUID string to parse
 * @v id                        Points to a GUID to be populated
 * @ret (int)                   Returns 0 upon success, -1 upon failure
 *
 * The input buffer must be >= 32 hexadecimal chars and be
 * terminated with an ASCII NUL.  Returns non-zero on failure.
 * Example: 11111111-2222-3333-4444-444444444444
 * Endian:  LLLLLLLL-LLLL-LLLL-BBBB-BBBBBBBBBBBB
 */
int str_to_guid(const char *buf, struct guid *const id)
{
    char guid_seq[sizeof(struct guid) * 2];
    unsigned int i = 0;
    char *walker = (char *)id;

    while (*buf && i < sizeof(guid_seq)) {
        switch (*buf) {
            /* Skip these three characters */
        case '{':
        case '}':
        case '-':
            break;
        default:
            /* Copy something useful to the temp. sequence */
            if ((*buf >= '0') && (*buf <= '9'))
                guid_seq[i] = *buf - '0';
            else if ((*buf >= 'A') && (*buf <= 'F'))
                guid_seq[i] = *buf - 'A' + 10;
            else if ((*buf >= 'a') && (*buf <= 'f'))
                guid_seq[i] = *buf - 'a' + 10;
            else {
                /* Or not */
                error("Illegal character in GUID!\n");
                return -1;
            }
            i++;
        }
        buf++;
    }
    /* Check for insufficient valid characters */
    if (i < sizeof(guid_seq)) {
        error("Too few GUID characters!\n");
        return -1;
    }
    buf = guid_seq;
    i = 0;
    while (i < sizeof(guid_le_walk_map)) {
        if (!guid_le_walk_map[i])
            i++;
        walker += guid_le_walk_map[i];
        *walker = *buf << 4;
        buf++;
        *walker |= *buf;
        buf++;
        i++;
    }
    return 0;
}

/**
 * Display GPT partition details.
 *
 * @v gpt_part                  The GPT partition entry to display
 */
void disk_gpt_part_dump(const struct disk_gpt_part_entry *const gpt_part)
{
    unsigned int i;
    char guid_text[37];

    dprintf("----------------------------------\n"
            "GPT part. LBA first __ : 0x%.16llx\n"
            "GPT part. LBA last ___ : 0x%.16llx\n"
            "GPT part. attribs ____ : 0x%.16llx\n"
            "GPT part. name _______ : '",
            gpt_part->lba_first, gpt_part->lba_last, gpt_part->attribs);
    for (i = 0; i < sizeof(gpt_part->name); i++) {
        if (gpt_part->name[i])
            dprintf("%c", gpt_part->name[i]);
    }
    dprintf("'");
    guid_to_str(guid_text, &gpt_part->type);
    dprintf("GPT part. type GUID __ : {%s}\n", guid_text);
    guid_to_str(guid_text, &gpt_part->uid);
    dprintf("GPT part. unique ID __ : {%s}\n", guid_text);
}

/**
 * Display GPT header details.
 *
 * @v gpt                       The GPT header to display
 */
void disk_gpt_header_dump(const struct disk_gpt_header *const gpt)
{
    char guid_text[37];

    printf("GPT sig ______________ : '%8.8s'\n"
           "GPT major revision ___ : 0x%.4x\n"
           "GPT minor revision ___ : 0x%.4x\n"
           "GPT header size ______ : 0x%.8x\n"
           "GPT header checksum __ : 0x%.8x\n"
           "GPT reserved _________ : '%4.4s'\n"
           "GPT LBA current ______ : 0x%.16llx\n"
           "GPT LBA alternative __ : 0x%.16llx\n"
           "GPT LBA first usable _ : 0x%.16llx\n"
           "GPT LBA last usable __ : 0x%.16llx\n"
           "GPT LBA part. table __ : 0x%.16llx\n"
           "GPT partition count __ : 0x%.8x\n"
           "GPT partition size ___ : 0x%.8x\n"
           "GPT part. table chksum : 0x%.8x\n",
           gpt->sig,
           gpt->rev.fields.major,
           gpt->rev.fields.minor,
           gpt->hdr_size,
           gpt->chksum,
           gpt->reserved1,
           gpt->lba_cur,
           gpt->lba_alt,
           gpt->lba_first_usable,
           gpt->lba_last_usable,
           gpt->lba_table, gpt->part_count, gpt->part_size, gpt->table_chksum);
    guid_to_str(guid_text, &gpt->disk_guid);
    printf("GPT disk GUID ________ : {%s}\n", guid_text);
}