chore: revert custom index in favor of key_Split

Signed-off-by: Keith Zantow <keith.zantow@anchore.com>

internal/archive/helpers_test.go

@@ -0,0 +1,59 @@
+package archive
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// Seams the package itself does not need, kept here so no production file carries a function only
+// tests call.
+
+// WorkDirAt returns a WorkDir over a directory that already exists. Production always creates its own
+// (NewWorkDir); a test lends one it can inspect afterwards, so Remove leaves it alone.
+func WorkDirAt(dir string) *WorkDir {
+	return &WorkDir{path: dir, done: true}
+}
+
+// heldInMemory reports the entry content this store is still holding in memory. Production never asks:
+// the limiter is what bounds it, and the store charges as it goes rather than tracking a total.
+func (s *EntryStore) heldInMemory() int64 {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	var total int64
+	for _, entry := range s.entries {
+		if entry.ref.mem != nil {
+			total += entry.ref.length
+		}
+	}
+	return total
+}
+
+// created reports whether anything ever asked for the directory, and so whether there is anything to
+// remove.
+func (w *WorkDir) created() bool {
+	if w == nil {
+		return false
+	}
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	return w.remove != nil
+}
+
+// held reports what this charge is currently holding, in memory and on disk.
+func (c *Charge) held() (memory, disk int64) {
+	if c == nil || c.limiter == nil {
+		return 0, 0
+	}
+	c.limiter.mu.Lock()
+	defer c.limiter.mu.Unlock()
+	return c.memory, c.disk
+}
+
+// openFileContent opens an archive already on disk as Content. The caller closes it.
+func openFileContent(path string) (Content, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return Content{}, err
+	}
+	return Content{Name: filepath.Base(path), Reader: f, closer: f}, nil
+}