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-rw-r--r--pkg/merkletree/merkletree.go135
1 files changed, 0 insertions, 135 deletions
diff --git a/pkg/merkletree/merkletree.go b/pkg/merkletree/merkletree.go
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index 906f67943..000000000
--- a/pkg/merkletree/merkletree.go
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@@ -1,135 +0,0 @@
-// Copyright 2020 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package merkletree implements Merkle tree generating and verification.
-package merkletree
-
-import (
- "crypto/sha256"
- "io"
-
- "gvisor.dev/gvisor/pkg/usermem"
-)
-
-const (
- // sha256DigestSize specifies the digest size of a SHA256 hash.
- sha256DigestSize = 32
-)
-
-// Size defines the scale of a Merkle tree.
-type Size struct {
- // blockSize is the size of a data block to be hashed.
- blockSize int64
- // digestSize is the size of a generated hash.
- digestSize int64
- // hashesPerBlock is the number of hashes in a block. For example, if
- // blockSize is 4096 bytes, and digestSize is 32 bytes, there will be 128
- // hashesPerBlock. Therefore 128 hashes in a lower level will be put into a
- // block and generate a single hash in an upper level.
- hashesPerBlock int64
- // levelStart is the start block index of each level. The number of levels in
- // the tree is the length of the slice. The leafs (level 0) are hashes of
- // blocks in the input data. The levels above are hashes of lower level
- // hashes. The highest level is the root hash.
- levelStart []int64
-}
-
-// MakeSize initializes and returns a new Size object describing the structure
-// of a tree. dataSize specifies the number of the file system size in bytes.
-func MakeSize(dataSize int64) Size {
- size := Size{
- blockSize: usermem.PageSize,
- // TODO(b/156980949): Allow config other hash methods (SHA384/SHA512).
- digestSize: sha256DigestSize,
- hashesPerBlock: usermem.PageSize / sha256DigestSize,
- }
- numBlocks := (dataSize + size.blockSize - 1) / size.blockSize
- level := int64(0)
- offset := int64(0)
-
- // Calcuate the number of levels in the Merkle tree and the beginning offset
- // of each level. Level 0 is the level directly above the data blocks, while
- // level NumLevels - 1 is the root.
- for numBlocks > 1 {
- size.levelStart = append(size.levelStart, offset)
- // Round numBlocks up to fill up a block.
- numBlocks += (size.hashesPerBlock - numBlocks%size.hashesPerBlock) % size.hashesPerBlock
- offset += numBlocks / size.hashesPerBlock
- numBlocks = numBlocks / size.hashesPerBlock
- level++
- }
- size.levelStart = append(size.levelStart, offset)
- return size
-}
-
-// Generate constructs a Merkle tree for the contents of data. The output is
-// written to treeWriter. The treeReader should be able to read the tree after
-// it has been written. That is, treeWriter and treeReader should point to the
-// same underlying data but have separate cursors.
-func Generate(data io.Reader, dataSize int64, treeReader io.Reader, treeWriter io.Writer) ([]byte, error) {
- size := MakeSize(dataSize)
-
- numBlocks := (dataSize + size.blockSize - 1) / size.blockSize
-
- var root []byte
- for level := 0; level < len(size.levelStart); level++ {
- for i := int64(0); i < numBlocks; i++ {
- buf := make([]byte, size.blockSize)
- var (
- n int
- err error
- )
- if level == 0 {
- // Read data block from the target file since level 0 is directly above
- // the raw data block.
- n, err = data.Read(buf)
- } else {
- // Read data block from the tree file since levels higher than 0 are
- // hashing the lower level hashes.
- n, err = treeReader.Read(buf)
- }
-
- // err is populated as long as the bytes read is smaller than the buffer
- // size. This could be the case if we are reading the last block, and
- // break in that case. If this is the last block, the end of the block
- // will be zero-padded.
- if n == 0 && err == io.EOF {
- break
- } else if err != nil && err != io.EOF {
- return nil, err
- }
- // Hash the bytes in buf.
- digest := sha256.Sum256(buf)
-
- if level == len(size.levelStart)-1 {
- root = digest[:]
- }
-
- // Write the generated hash to the end of the tree file.
- if _, err = treeWriter.Write(digest[:]); err != nil {
- return nil, err
- }
- }
- // If the genereated digests do not round up to a block, zero-padding the
- // remaining of the last block. But no need to do so for root.
- if level != len(size.levelStart)-1 && numBlocks%size.hashesPerBlock != 0 {
- zeroBuf := make([]byte, size.blockSize-(numBlocks%size.hashesPerBlock)*size.digestSize)
- if _, err := treeWriter.Write(zeroBuf[:]); err != nil {
- return nil, err
- }
- }
- numBlocks = (numBlocks + size.hashesPerBlock - 1) / size.hashesPerBlock
- }
- return root, nil
-}