Subversion Repositories freemyipod

#include <stdio.h> 

#include <stdint.h>

#include <stdbool.h>

#include <fcntl.h>

static void mark_bad(uint32_t* bitmap, int sector)

{

    bitmap[sector >> 5] &= ~(1 << (sector & 31));

}

static bool is_good(uint32_t* bitmap, int sector)

{

    return bitmap[sector >> 5] & (1 << (sector & 31));

}

int main(int argc, char** argv)

{

    int sectors;

    sscanf(argv[3], "%i", &sectors);

    size_t bitmapsize = ((sectors + 65535) & ~0xffff) >> 3;

    uint32_t* bitmap = malloc(bitmapsize);

    memset(bitmap, 0xff, bitmapsize);

    FILE* in = fopen(argv[1], "r");

    if (!in)

    {

        perror("Failed to open input file");

        return 2;

    }

    char line[256];

    while (fgets(line, sizeof(line), in))

    {

        int sector;

        if (sscanf(line, "%i", &sector) == 1 && sector) mark_bad(bitmap, sector);

    }

    fclose(in);

    int l0count = (sectors + 0xfffff) >> 19;

    int bbtpages = 64 + ((l0count + 0x3f) & ~0x3f);

    int bbtsize;

    uint16_t (*bbt)[0x20];

    bool success = false;

    while (bbtpages <= 32832)

    {

        bbtsize = bbtpages << 6;

        bbt = malloc(bbtsize);

        memset(bbt, 0, bbtsize);

        int logical = 0;

        int physical = 1;

        int remapbase;

        int bbtgood;

        for (bbtgood = 0; bbtgood < (bbtpages >> 6) - 1; physical++)

            if (is_good(bitmap, physical))

            {

                ((uint32_t*)bbt)[0x200 + bbtgood] = physical;

                bbtgood++;

            }

        int bbtused = 64 + l0count;

        int level;

        uint16_t *l1, *l2, *l3;

        int l1count = 0, l2count = 0, l3count = 0;

        while (!success)

        {

            if (!(logical & 0x7fff)) level = 0;

            else if (!(logical & 0x3ff)) level = 1;

            else if (!(logical & 0x1f)) level = 2;

            else level = 3;

            if (!level) remapbase = ((physical - logical) >> 12) << 12;

            if (physical - logical - remapbase > 0x7fff || remapbase > 0xffff)

            {

                printf("Need to remap across too high distance!\n");

                return 5;

            }

            int clean;

            for (clean = 0; clean < (1 << ((3 - level) * 5)) && physical + clean < sectors; clean++)

                if (!is_good(bitmap, physical + clean))

                    break;

            if (clean >= 32768)

            {

                bbt[64][(logical >> 15) << 1] = physical - logical - remapbase;

                bbt[64][((logical >> 15) << 1) | 1] = remapbase >> 12;

                physical += 32768;

                logical += 32768;

            }

            else if (clean >= 1024)

            {

                if (level == 0)

                {

                    if (bbtused == bbtpages) break;

                    level = 1;

                    l1 = bbt[bbtused];

                    bbt[64][(logical >> 15) << 1] = 0x8000 | (bbtused - 64);

                    bbt[64][((logical >> 15) << 1) | 1] = remapbase >> 12;

                    bbtused++;

                    l1count++;

                }

                l1[(logical >> 10) & 0x1f] = physical - logical - remapbase;

                physical += 1024;

                logical += 1024;

            }

            else if (clean >= 32)

            {

                if (level == 0)

                {

                    if (bbtused == bbtpages) break;

                    level = 1;

                    l1 = bbt[bbtused];

                    bbt[64][(logical >> 15) << 1] = 0x8000 | (bbtused - 64);

                    bbt[64][((logical >> 15) << 1) | 1] = remapbase >> 12;

                    bbtused++;

                    l1count++;

                }

                if (level == 1)

                {

                    if (bbtused == bbtpages) break;

                    level = 2;

                    l2 = bbt[bbtused];

                    l1[(logical >> 10) & 0x1f] = 0x8000 | (bbtused - 64);

                    bbtused++;

                    l2count++;

                }

                l2[(logical >> 5) & 0x1f] = physical - logical - remapbase;

                physical += 32;

                logical += 32;

            }

            else if (clean >= 1)

            {

                if (level == 0)

                {

                    if (bbtused == bbtpages) break;

                    level = 1;

                    l1 = bbt[bbtused];

                    bbt[64][(logical >> 15) << 1] = 0x8000 | (bbtused - 64);

                    bbt[64][((logical >> 15) << 1) | 1] = remapbase >> 12;

                    bbtused++;

                    l1count++;

                }

                if (level == 1)

                {

                    if (bbtused == bbtpages) break;

                    level = 2;

                    l2 = bbt[bbtused];

                    l1[(logical >> 10) & 0x1f] = 0x8000 | (bbtused - 64);

                    bbtused++;

                    l2count++;

                }

                if (level == 2)

                {

                    if (bbtused == bbtpages) break;

                    level = 3;

                    l3 = bbt[bbtused];

                    l2[(logical >> 5) & 0x1f] = 0x8000 | (bbtused - 64);

                    bbtused++;

                    l3count++;

                }

                l3[logical & 0x1f] = physical - logical - remapbase;

                physical++;

                logical++;

            }

            else physical++;

            if (physical >= sectors) success = true;

        }

        if (success)

        {        

            printf("BBT using %d sectors (%d KiB)\n", bbtgood + 1, bbtsize >> 10);

            printf("Level 0: %d pages, Level 1: %d pages, Level 2: %d pages, Level 3: %d pages\n",

                   l0count, l1count, l2count, l3count);

            printf("User data sectors: %d (%d KiB)\n", logical, logical << 2);

            memcpy(bbt, "emBIbbth", 8);

            ((uint32_t*)bbt)[0x1fc] = logical;

            ((uint32_t*)bbt)[0x1ff] = (bbtpages >> 6) - 1;

            break;

        }

        free(bbt);

        bbtpages += 64;

    }

    if (success)

    {

        int out = open(argv[2], O_CREAT | O_TRUNC | O_WRONLY | O_BINARY, 0644);

        if (out < 0)

        {

            perror("Failed to open output file");

            return 3;

        }

        int rc;

        while (bbtsize && (rc = write(out, bbt, bbtsize)) >= 0) bbtsize -= rc;

        if (rc < 0)

        {

            perror("Failed to open output file");

            return 4;

        }

        close(out);

        return 0;

    }

    printf("Can't fit BBT into 2052 KiB!\n");

    return 1;

}