chore: revert custom index in favor of key_Split

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

internal/archive/entry_header.go

@@ -0,0 +1,47 @@
+package archive
+
+import (
+	"archive/tar"
+	"io/fs"
+	"strings"
+	"time"
+
+	"github.com/mholt/archives"
+
+	"github.com/anchore/syft/internal/log"
+)
+
+// entryHeader builds the tar header for one archive entry's metadata, or reports false when the entry
+// is not worth carrying. The entry's bytes are held separately.
+//
+// Symlinks are recorded as headers, not real links; the target is resolved later inside the archive's
+// own filetree, so one naming the host filesystem resolves to nothing. Device nodes, fifos and
+// sockets are skipped - no cataloger reads them.
+func entryHeader(f archives.FileInfo) (*tar.Header, bool) {
+	mode := f.Mode()
+	if !mode.IsRegular() && !mode.IsDir() && mode.Type()&fs.ModeSymlink == 0 {
+		log.WithFields("entry", f.NameInArchive, "mode", mode).Debug("skipping non-regular archive entry")
+		return nil, false
+	}
+
+	hdr, err := tar.FileInfoHeader(f.FileInfo, f.LinkTarget)
+	if err != nil {
+		log.WithFields("entry", f.NameInArchive, "error", err).Debug("skipping archive entry with an unusable header")
+		return nil, false
+	}
+
+	// carried through as-is: nothing is written through this name, and the filetree sanitizes it
+	hdr.Name = f.NameInArchive
+	if f.IsDir() && !strings.HasSuffix(hdr.Name, "/") {
+		hdr.Name += "/"
+	}
+	hdr.Linkname = f.LinkTarget
+
+	// dropped: no cataloger reads them, and the header is charged against the memory budget
+	hdr.PAXRecords = nil
+	hdr.Uname, hdr.Gname = "", ""
+	hdr.AccessTime, hdr.ChangeTime = time.Time{}, time.Time{}
+	hdr.ModTime = hdr.ModTime.Truncate(time.Second)
+
+	return hdr, true
+}