Catalog archive contents for single-file input (#637)

* add first-level archive processing when input is a file

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* add license exception for github.com/xi2/xz

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* always return cleanup function

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* change source.NewFromFile log entry to warn

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* ensure file source always has cleanup function

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* ensure we are always preferring the unarchive cleanup function for source

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

cmd/packages.go

@@ -251,7 +251,9 @@ func packagesExecWorker(userInput string) <-chan error {
 			errs <- fmt.Errorf("failed to determine image source: %w", err)
 			return
 		}
-		defer cleanup()
+		if cleanup != nil {
+			defer cleanup()
+		}
 
 		catalog, relationships, d, err := syft.CatalogPackages(src, appConfig.Package.Cataloger.ScopeOpt)
 		if err != nil {

cmd/power_user.go

@@ -108,7 +108,9 @@ func powerUserExecWorker(userInput string) <-chan error {
 			errs <- err
 			return
 		}
-		defer cleanup()
+		if cleanup != nil {
+			defer cleanup()
+		}
 
 		s := sbom.SBOM{
 			Source: src.Metadata,