diff options
Diffstat (limited to 'cryptfs/address_translation.go')
-rw-r--r-- | cryptfs/address_translation.go | 89 |
1 files changed, 0 insertions, 89 deletions
diff --git a/cryptfs/address_translation.go b/cryptfs/address_translation.go deleted file mode 100644 index b21cfc7..0000000 --- a/cryptfs/address_translation.go +++ /dev/null @@ -1,89 +0,0 @@ -package cryptfs - -// CryptFS methods that translate offsets between ciphertext and plaintext - -// get the block number at plain-text offset -func (be *CryptFS) PlainOffToBlockNo(plainOffset uint64) uint64 { - return plainOffset / be.plainBS -} - -// get the block number at ciphter-text offset -func (be *CryptFS) CipherOffToBlockNo(cipherOffset uint64) uint64 { - return (cipherOffset - HEADER_LEN) / be.cipherBS -} - -// get ciphertext offset of block "blockNo" -func (be *CryptFS) BlockNoToCipherOff(blockNo uint64) uint64 { - return HEADER_LEN + blockNo*be.cipherBS -} - -// get plaintext offset of block "blockNo" -func (be *CryptFS) BlockNoToPlainOff(blockNo uint64) uint64 { - return blockNo * be.plainBS -} - -// PlainSize - calculate plaintext size from ciphertext size -func (be *CryptFS) CipherSizeToPlainSize(cipherSize uint64) uint64 { - - // Zero sized files stay zero-sized - if cipherSize == 0 { - return 0 - } - - if cipherSize == HEADER_LEN { - Warn.Printf("cipherSize %d == header size: interrupted write?\n", cipherSize) - return 0 - } - - if cipherSize < HEADER_LEN { - Warn.Printf("cipherSize %d < header size: corrupt file\n", cipherSize) - return 0 - } - - // Block number at last byte - blockNo := be.CipherOffToBlockNo(cipherSize - 1) - blockCount := blockNo + 1 - - overhead := be.BlockOverhead()*blockCount + HEADER_LEN - - return cipherSize - overhead -} - -// CipherSize - calculate ciphertext size from plaintext size -func (be *CryptFS) PlainSizeToCipherSize(plainSize uint64) uint64 { - - // Block number at last byte - blockNo := be.PlainOffToBlockNo(plainSize - 1) - blockCount := blockNo + 1 - - overhead := be.BlockOverhead()*blockCount + HEADER_LEN - - return plainSize + overhead -} - -// Split a plaintext byte range into (possibly partial) blocks -func (be *CryptFS) ExplodePlainRange(offset uint64, length uint64) []intraBlock { - var blocks []intraBlock - var nextBlock intraBlock - nextBlock.fs = be - - for length > 0 { - nextBlock.BlockNo = be.PlainOffToBlockNo(offset) - nextBlock.Skip = offset - be.BlockNoToPlainOff(nextBlock.BlockNo) - - // Minimum of remaining data and remaining space in the block - nextBlock.Length = MinUint64(length, be.plainBS-nextBlock.Skip) - - blocks = append(blocks, nextBlock) - offset += nextBlock.Length - length -= nextBlock.Length - } - return blocks -} - -func MinUint64(x uint64, y uint64) uint64 { - if x < y { - return x - } - return y -} |