.

wcfs/zblk.go

@@ -25,6 +25,7 @@ import (
 	"context"
 	"fmt"
 	"reflect"
+	"sort"
 	"sync"
 
 	"golang.org/x/sync/errgroup"
@@ -147,6 +148,14 @@ func (zb *ZBlk1) LoadBlkData(ctx context.Context) ([]byte, error) {
 	var mu sync.Mutex
 	chunktab := make(map[int64]*ZData)
 
+	// on return deactivate all loaded ZData objects in chunktab
+	defer func() {
+		for _, zd := range chunktab {
+			zd.PDeactivate()
+		}
+	}()
+
+
 	wg, ctx := errgroup.WithContext(ctx)
 
 	// loadZData loads 1 ZData object into chunktab and leaves it activated.
@@ -226,17 +235,46 @@ func (zb *ZBlk1) LoadBlkData(ctx context.Context) ([]byte, error) {
 	})
 
 	err = wg.Wait()
+	if err != nil {
+		return nil, err // XXX err ctx
+	}
 
-	// deactivate all loaded ZData objects in chunktab
-	for _, zd := range chunktab {
-		zd.PDeactivate()
+	// empty .chunktab -> ø
+	if len(chunktab) == 0 {
+		return nil, nil
 	}
 
-	if err != nil {
-		panic(err) // XXX
+	// glue all chunks from chunktab
+	offv := make([]int64, 0, len(chunktab)) // ↑
+	for off := range(chunktab) {
+		offv = append(offv, off)
+	}
+	sort.Slice(offv, func(i, j int) bool {
+		return offv[i] < offv[j]
+	})
+
+
+        // find out whole blk len via inspecting tail chunk
+	tailStart := offv[len(offv)-1]
+	tailChunk := chunktab[tailStart]
+	blklen    := tailStart + int64(len(tailChunk.data))
+
+        // whole buffer initialized as 0 + tail_chunk
+	blkdata := make([]byte, blklen)
+	copy(blkdata[tailStart:], tailChunk.data)
+
+        // go through all chunks besides tail and extract them
+	stop := int64(0)
+	_ = stop	// XXX
+	for _, start := range offv[:len(offv)-1] {
+		chunk := chunktab[start]
+		// XXX assert start >= stop	// verify chunks don't overlap
+		// XXX assert start + len(chunk.data) <= len(blkdata)
+		stop = start + int64(len(chunk.data))
+		copy(blkdata[start:], chunk.data)
 	}
 
-	panic("TODO")
+	return blkdata, nil
 }