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Diffstat (limited to 'fs/ntfs/mst.c')
-rw-r--r-- | fs/ntfs/mst.c | 189 |
1 files changed, 0 insertions, 189 deletions
diff --git a/fs/ntfs/mst.c b/fs/ntfs/mst.c deleted file mode 100644 index 16b3c884ab..0000000000 --- a/fs/ntfs/mst.c +++ /dev/null @@ -1,189 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-or-later -/* - * mst.c - NTFS multi sector transfer protection handling code. Part of the - * Linux-NTFS project. - * - * Copyright (c) 2001-2004 Anton Altaparmakov - */ - -#include "ntfs.h" - -/** - * post_read_mst_fixup - deprotect multi sector transfer protected data - * @b: pointer to the data to deprotect - * @size: size in bytes of @b - * - * Perform the necessary post read multi sector transfer fixup and detect the - * presence of incomplete multi sector transfers. - In that case, overwrite the - * magic of the ntfs record header being processed with "BAAD" (in memory only!) - * and abort processing. - * - * Return 0 on success and -EINVAL on error ("BAAD" magic will be present). - * - * NOTE: We consider the absence / invalidity of an update sequence array to - * mean that the structure is not protected at all and hence doesn't need to - * be fixed up. Thus, we return success and not failure in this case. This is - * in contrast to pre_write_mst_fixup(), see below. - */ -int post_read_mst_fixup(NTFS_RECORD *b, const u32 size) -{ - u16 usa_ofs, usa_count, usn; - u16 *usa_pos, *data_pos; - - /* Setup the variables. */ - usa_ofs = le16_to_cpu(b->usa_ofs); - /* Decrement usa_count to get number of fixups. */ - usa_count = le16_to_cpu(b->usa_count) - 1; - /* Size and alignment checks. */ - if ( size & (NTFS_BLOCK_SIZE - 1) || - usa_ofs & 1 || - usa_ofs + (usa_count * 2) > size || - (size >> NTFS_BLOCK_SIZE_BITS) != usa_count) - return 0; - /* Position of usn in update sequence array. */ - usa_pos = (u16*)b + usa_ofs/sizeof(u16); - /* - * The update sequence number which has to be equal to each of the - * u16 values before they are fixed up. Note no need to care for - * endianness since we are comparing and moving data for on disk - * structures which means the data is consistent. - If it is - * consistenty the wrong endianness it doesn't make any difference. - */ - usn = *usa_pos; - /* - * Position in protected data of first u16 that needs fixing up. - */ - data_pos = (u16*)b + NTFS_BLOCK_SIZE/sizeof(u16) - 1; - /* - * Check for incomplete multi sector transfer(s). - */ - while (usa_count--) { - if (*data_pos != usn) { - /* - * Incomplete multi sector transfer detected! )-: - * Set the magic to "BAAD" and return failure. - * Note that magic_BAAD is already converted to le32. - */ - b->magic = magic_BAAD; - return -EINVAL; - } - data_pos += NTFS_BLOCK_SIZE/sizeof(u16); - } - /* Re-setup the variables. */ - usa_count = le16_to_cpu(b->usa_count) - 1; - data_pos = (u16*)b + NTFS_BLOCK_SIZE/sizeof(u16) - 1; - /* Fixup all sectors. */ - while (usa_count--) { - /* - * Increment position in usa and restore original data from - * the usa into the data buffer. - */ - *data_pos = *(++usa_pos); - /* Increment position in data as well. */ - data_pos += NTFS_BLOCK_SIZE/sizeof(u16); - } - return 0; -} - -/** - * pre_write_mst_fixup - apply multi sector transfer protection - * @b: pointer to the data to protect - * @size: size in bytes of @b - * - * Perform the necessary pre write multi sector transfer fixup on the data - * pointer to by @b of @size. - * - * Return 0 if fixup applied (success) or -EINVAL if no fixup was performed - * (assumed not needed). This is in contrast to post_read_mst_fixup() above. - * - * NOTE: We consider the absence / invalidity of an update sequence array to - * mean that the structure is not subject to protection and hence doesn't need - * to be fixed up. This means that you have to create a valid update sequence - * array header in the ntfs record before calling this function, otherwise it - * will fail (the header needs to contain the position of the update sequence - * array together with the number of elements in the array). You also need to - * initialise the update sequence number before calling this function - * otherwise a random word will be used (whatever was in the record at that - * position at that time). - */ -int pre_write_mst_fixup(NTFS_RECORD *b, const u32 size) -{ - le16 *usa_pos, *data_pos; - u16 usa_ofs, usa_count, usn; - le16 le_usn; - - /* Sanity check + only fixup if it makes sense. */ - if (!b || ntfs_is_baad_record(b->magic) || - ntfs_is_hole_record(b->magic)) - return -EINVAL; - /* Setup the variables. */ - usa_ofs = le16_to_cpu(b->usa_ofs); - /* Decrement usa_count to get number of fixups. */ - usa_count = le16_to_cpu(b->usa_count) - 1; - /* Size and alignment checks. */ - if ( size & (NTFS_BLOCK_SIZE - 1) || - usa_ofs & 1 || - usa_ofs + (usa_count * 2) > size || - (size >> NTFS_BLOCK_SIZE_BITS) != usa_count) - return -EINVAL; - /* Position of usn in update sequence array. */ - usa_pos = (le16*)((u8*)b + usa_ofs); - /* - * Cyclically increment the update sequence number - * (skipping 0 and -1, i.e. 0xffff). - */ - usn = le16_to_cpup(usa_pos) + 1; - if (usn == 0xffff || !usn) - usn = 1; - le_usn = cpu_to_le16(usn); - *usa_pos = le_usn; - /* Position in data of first u16 that needs fixing up. */ - data_pos = (le16*)b + NTFS_BLOCK_SIZE/sizeof(le16) - 1; - /* Fixup all sectors. */ - while (usa_count--) { - /* - * Increment the position in the usa and save the - * original data from the data buffer into the usa. - */ - *(++usa_pos) = *data_pos; - /* Apply fixup to data. */ - *data_pos = le_usn; - /* Increment position in data as well. */ - data_pos += NTFS_BLOCK_SIZE/sizeof(le16); - } - return 0; -} - -/** - * post_write_mst_fixup - fast deprotect multi sector transfer protected data - * @b: pointer to the data to deprotect - * - * Perform the necessary post write multi sector transfer fixup, not checking - * for any errors, because we assume we have just used pre_write_mst_fixup(), - * thus the data will be fine or we would never have gotten here. - */ -void post_write_mst_fixup(NTFS_RECORD *b) -{ - le16 *usa_pos, *data_pos; - - u16 usa_ofs = le16_to_cpu(b->usa_ofs); - u16 usa_count = le16_to_cpu(b->usa_count) - 1; - - /* Position of usn in update sequence array. */ - usa_pos = (le16*)b + usa_ofs/sizeof(le16); - - /* Position in protected data of first u16 that needs fixing up. */ - data_pos = (le16*)b + NTFS_BLOCK_SIZE/sizeof(le16) - 1; - - /* Fixup all sectors. */ - while (usa_count--) { - /* - * Increment position in usa and restore original data from - * the usa into the data buffer. - */ - *data_pos = *(++usa_pos); - - /* Increment position in data as well. */ - data_pos += NTFS_BLOCK_SIZE/sizeof(le16); - } -} |