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stream.go: Finishing up Sum()

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This commit is contained in:
Vincent Batts 2015-03-30 15:02:53 -04:00
parent 257ed6dfad
commit 1959058d6a
1 changed files with 51 additions and 11 deletions
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58
stream.go
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@ -3,6 +3,7 @@ package merkle
import (
"hash"
"log"
"runtime"
)
// NewHash provides a hash.Hash to generate a merkle.Tree checksum, given a
@ -39,23 +40,62 @@ type merkleHash struct {
//
// if that last block was complete, then no worries. start the next node.
func (mh *merkleHash) Sum(b []byte) []byte {
if b != nil && (len(b)+mh.lastBlockLen) > mh.blockSize {
// write a full node
var (
curBlock = []byte{}
offset int = 0
)
if mh.partialLastNode {
// if this is true, then we need to pop the last node
mh.tree.Nodes = mh.tree.Nodes[:len(mh.tree.Nodes)-1]
mh.partialLastNode = false
}
n, err := NewNodeHashBlock(mh.hm, curBlock)
if mh.lastBlockLen > 0 {
curBlock = append(curBlock[:], mh.lastBlock[:mh.lastBlockLen]...)
mh.lastBlockLen = 0
}
if b != nil && len(b) > 0 {
curBlock = append(curBlock, b...)
}
for i := 0; i < len(curBlock)/mh.blockSize; i++ {
n, err := NewNodeHashBlock(mh.hm, curBlock[offset:(offset+mh.blockSize)])
if err != nil {
// XXX might need to stash again the prior lastBlock and first little chunk
return numWritten, err
// XXX i hate to swallow an error here, but the `Sum() []byte` signature
// :-\
sBuf := make([]byte, 1024)
runtime.Stack(sBuf, false)
log.Printf("[ERROR]: %s %q", err, string(sBuf))
return nil
}
mh.tree.Nodes = append(mh.tree.Nodes, n)
numWritten += offset
offset = offset + mh.blockSize
}
// If there is remainder, we'll need to make a partial node and stash it
if m := (len(curBlock) % mh.blockSize); m != 0 {
mh.lastBlockLen = copy(mh.lastBlock, curBlock[offset:])
n, err := NewNodeHashBlock(mh.hm, curBlock[offset:])
if err != nil {
sBuf := make([]byte, 1024)
runtime.Stack(sBuf, false)
log.Printf("[ERROR]: %s %q", err, string(sBuf))
return nil
}
mh.tree.Nodes = append(mh.tree.Nodes, n)
mh.partialLastNode = true
}
// TODO check if len(mh.lastBlock) < blockSize
sum, err := mh.tree.Root().Checksum()
if err != nil {
// XXX i hate to swallow an error here, but the `Sum() []byte` signature :-\
log.Printf("[ERROR]: %s", err)
// XXX i hate to swallow an error here, but the `Sum() []byte` signature
// :-\
sBuf := make([]byte, 1024)
runtime.Stack(sBuf, false)
log.Printf("[ERROR]: %s %q", err, string(sBuf))
return nil
}
return sum
}