chore: simplify and cleanup

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

internal/archive/workdir.go

@@ -4,85 +4,66 @@ import (
 	"context"
 	"fmt"
 	"os"
-	"sync"
 
 	"github.com/anchore/syft/internal/log"
 	"github.com/anchore/syft/internal/tmpdir"
 )
 
-// workDirName prefixes the directory holding one archive's content and entries, so a scan's leftovers
-// are recognizable. Tests that sample what is on disk match on it.
+// workDirName prefixes the directory holding one archive's overflow files.
 const workDirName = "syft-archive"
 
-// WorkDir is the scratch space one archive writes into, created lazily the first time something needs
-// to write - an archive's own bytes spilling out of memory, or its entries spilling into the overflow
-// blob.
-//
-// Eager creation would put one directory on disk per archive opened, whether or not it ever wrote a
-// byte; most do not, and a scan walks far more archives than it spills. So the path is asked for at
-// the point of writing. A nil *WorkDir has no path and fails the write.
+// WorkDir is the scratch directory one archive writes overflow into. It is created on first use, so
+// an archive that stays in memory never touches the filesystem.
 type WorkDir struct {
-	mu sync.Mutex
+	tempDir *tmpdir.TempDir
 
-	// create makes the directory and returns it with the func that removes it. Called at most once.
-	create func() (string, func(), error)
-
-	path   string
-	remove func()
-	err    error
-	done   bool
+	created bool
+	path    string
+	remove  func()
+	err     error
 }
 
-// NewWorkDir returns the lazily-created work directory for one archive, rooted under the scan's temp
-// root (internal/tmpdir) when the context carries one - so files land where the caller configured and
-// are removed together if an archive's own cleanup is missed - otherwise the system temp dir.
+// NewWorkDir returns a work directory under the scan's temp root when ctx carries one (see
+// internal/tmpdir), otherwise under the system temp directory.
 func NewWorkDir(ctx context.Context) *WorkDir {
-	return &WorkDir{create: func() (string, func(), error) {
-		if td := tmpdir.FromContext(ctx); td != nil {
-			dir, cleanup, err := td.NewChild(workDirName) //nolint:gocritic // cleanup is returned, not deferred here
-			if err != nil {
-				return "", nil, fmt.Errorf("unable to create temp dir for archive extraction: %w", err)
-			}
-			return dir, cleanup, nil
-		}
-
-		dir, err := os.MkdirTemp("", workDirName+"-")
-		if err != nil {
-			return "", nil, fmt.Errorf("unable to create temp dir for archive extraction: %w", err)
-		}
-		return dir, func() {
-			if rmErr := os.RemoveAll(dir); rmErr != nil {
-				log.WithFields("dir", dir, "error", rmErr).Trace("unable to remove archive temp dir")
-			}
-		}, nil
-	}}
+	return &WorkDir{tempDir: tmpdir.FromContext(ctx)}
 }
 
-// Path returns the directory, creating it on the first call. Later calls return the same result,
-// including the same failure.
+// Path returns the directory, creating it on the first call.
 func (w *WorkDir) Path() (string, error) {
 	if w == nil {
 		return "", fmt.Errorf("no work directory for archive content")
 	}
-
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	if !w.done {
+	if !w.created {
+		w.created = true
 		w.path, w.remove, w.err = w.create()
-		w.done = true
 	}
 	return w.path, w.err
 }
 
-// Remove deletes the directory and its contents, and does nothing if it was never created. Safe to
-// call more than once.
-func (w *WorkDir) Remove() {
-	if w == nil {
-		return
+func (w *WorkDir) create() (string, func(), error) {
+	if w.tempDir != nil {
+		dir, remove, err := w.tempDir.NewChild(workDirName) //nolint:gocritic // the cleanup is returned, not deferred
+		if err != nil {
+			return "", nil, fmt.Errorf("unable to create temp dir for archive extraction: %w", err)
+		}
+		return dir, remove, nil
 	}
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	if w.remove == nil {
+
+	dir, err := os.MkdirTemp("", workDirName+"-")
+	if err != nil {
+		return "", nil, fmt.Errorf("unable to create temp dir for archive extraction: %w", err)
+	}
+	return dir, func() {
+		if err := os.RemoveAll(dir); err != nil {
+			log.WithFields("dir", dir, "error", err).Trace("unable to remove archive temp dir")
+		}
+	}, nil
+}
+
+// Remove deletes the directory if it was created. Safe to call more than once.
+func (w *WorkDir) Remove() {
+	if w == nil || w.remove == nil {
 		return
 	}
 	w.remove()