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- /* raid6_recover.c - module to recover from faulty RAID6 arrays. */
- /*
- * GRUB -- GRand Unified Bootloader
- * Copyright (C) 2006,2007,2008,2009 Free Software Foundation, Inc.
- *
- * GRUB is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * GRUB is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
- */
- #include <grub/dl.h>
- #include <grub/disk.h>
- #include <grub/mm.h>
- #include <grub/err.h>
- #include <grub/misc.h>
- #include <grub/raid.h>
- static grub_uint8_t raid6_table1[256][256];
- static grub_uint8_t raid6_table2[256][256];
- static void
- grub_raid_block_mul (grub_uint8_t mul, char *buf, int size)
- {
- int i;
- grub_uint8_t *p;
- p = (grub_uint8_t *) buf;
- for (i = 0; i < size; i++, p++)
- *p = raid6_table1[mul][*p];
- }
- static void
- grub_raid6_init_table (void)
- {
- int i, j;
- for (i = 0; i < 256; i++)
- raid6_table1[i][1] = raid6_table1[1][i] = i;
- for (i = 2; i < 256; i++)
- for (j = i; j < 256; j++)
- {
- int n;
- grub_uint8_t c;
- n = i >> 1;
- c = raid6_table1[n][j];
- c = (c << 1) ^ ((c & 0x80) ? 0x1d : 0);
- if (i & 1)
- c ^= j;
- raid6_table1[j][i] = raid6_table1[i][j] = c;
- }
- raid6_table2[0][0] = 1;
- for (i = 1; i < 256; i++)
- raid6_table2[i][i] = raid6_table1[raid6_table2[i - 1][i - 1]][2];
- for (i = 0; i < 254; i++)
- for (j = 0; j < 254; j++)
- {
- grub_uint8_t c, n;
- int k;
- if (i == j)
- continue;
- k = i - j;
- if (k < 0)
- k += 255;
- c = n = raid6_table2[k][k] ^ 1;
- for (k = 0; k < 253; k++)
- c = raid6_table1[c][n];
- raid6_table2[i][j] = raid6_table1[raid6_table2[255 - j][255 - j]][c];
- }
- }
- static grub_err_t
- grub_raid6_recover (struct grub_raid_array *array, int disknr, int p,
- char *buf, grub_disk_addr_t sector, int size)
- {
- int i, q, pos;
- int bad1 = -1, bad2 = -1;
- char *pbuf = 0, *qbuf = 0;
- size <<= GRUB_DISK_SECTOR_BITS;
- pbuf = grub_zalloc (size);
- if (!pbuf)
- goto quit;
- qbuf = grub_zalloc (size);
- if (!qbuf)
- goto quit;
- q = p + 1;
- if (q == (int) array->total_devs)
- q = 0;
- pos = q + 1;
- if (pos == (int) array->total_devs)
- pos = 0;
- for (i = 0; i < (int) array->total_devs - 2; i++)
- {
- if (pos == disknr)
- bad1 = i;
- else
- {
- if ((array->device[pos]) &&
- (! grub_disk_read (array->device[pos], sector, 0, size, buf)))
- {
- grub_raid_block_xor (pbuf, buf, size);
- grub_raid_block_mul (raid6_table2[i][i], buf, size);
- grub_raid_block_xor (qbuf, buf, size);
- }
- else
- {
- /* Too many bad devices */
- if (bad2 >= 0)
- goto quit;
- bad2 = i;
- grub_errno = GRUB_ERR_NONE;
- }
- }
- pos++;
- if (pos == (int) array->total_devs)
- pos = 0;
- }
- /* Invalid disknr or p */
- if (bad1 < 0)
- goto quit;
- if (bad2 < 0)
- {
- /* One bad device */
- if ((array->device[p]) &&
- (! grub_disk_read (array->device[p], sector, 0, size, buf)))
- {
- grub_raid_block_xor (buf, pbuf, size);
- goto quit;
- }
- if (! array->device[q])
- {
- grub_error (GRUB_ERR_READ_ERROR, "not enough disk to restore");
- goto quit;
- }
- grub_errno = GRUB_ERR_NONE;
- if (grub_disk_read (array->device[q], sector, 0, size, buf))
- goto quit;
- grub_raid_block_xor (buf, qbuf, size);
- grub_raid_block_mul (raid6_table2[255 - bad1][255 - bad1], buf,
- size);
- }
- else
- {
- /* Two bad devices */
- grub_uint8_t c;
- if ((! array->device[p]) || (! array->device[q]))
- {
- grub_error (GRUB_ERR_READ_ERROR, "not enough disk to restore");
- goto quit;
- }
- if (grub_disk_read (array->device[p], sector, 0, size, buf))
- goto quit;
- grub_raid_block_xor (pbuf, buf, size);
- if (grub_disk_read (array->device[q], sector, 0, size, buf))
- goto quit;
- grub_raid_block_xor (qbuf, buf, size);
- c = raid6_table2[bad2][bad1];
- grub_raid_block_mul (c, qbuf, size);
- c = raid6_table1[raid6_table2[bad2][bad2]][c];
- grub_raid_block_mul (c, pbuf, size);
- grub_raid_block_xor (pbuf, qbuf, size);
- grub_memcpy (buf, pbuf, size);
- }
- quit:
- grub_free (pbuf);
- grub_free (qbuf);
- return grub_errno;
- }
- GRUB_MOD_INIT(raid6rec)
- {
- grub_raid6_init_table ();
- grub_raid6_recover_func = grub_raid6_recover;
- }
- GRUB_MOD_FINI(raid6rec)
- {
- grub_raid6_recover_func = 0;
- }
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