proc: keep track of nesting depth while reading compile units

Fully read compile units that contain nested entries we don't
understand (such as DW_TAG_namespace) by keeping track of the depth
we're at.

pkg/proc/bininfo.go

@@ -1618,6 +1618,8 @@ func (bi *BinaryInfo) loadDebugInfoMaps(image *Image, debugLineBytes []byte, wg
 func (bi *BinaryInfo) loadDebugInfoMapsCompileUnit(ctxt *loadDebugInfoMapsContext, image *Image, reader *reader.Reader, cu *compileUnit) {
 	hasAttrGoPkgName := goversion.ProducerAfterOrEqual(cu.producer, 1, 13)
 
+	depth := 0
+
 	for entry, err := reader.Next(); entry != nil; entry, err = reader.Next() {
 		if err != nil {
 			image.setLoadError("error reading debug_info: %v", err)
@@ -1625,7 +1627,11 @@ func (bi *BinaryInfo) loadDebugInfoMapsCompileUnit(ctxt *loadDebugInfoMapsContex
 		}
 		switch entry.Tag {
 		case 0:
-			return
+			if depth == 0 {
+				return
+			} else {
+				depth--
+			}
 		case dwarf.TagImportedUnit:
 			bi.loadDebugInfoMapsImportedUnit(entry, ctxt, image, cu)
 			reader.SkipChildren()
@@ -1695,6 +1701,11 @@ func (bi *BinaryInfo) loadDebugInfoMapsCompileUnit(ctxt *loadDebugInfoMapsContex
 					bi.addConcreteSubprogram(entry, ctxt, reader, cu)
 				}
 			}
+
+		default:
+			if entry.Children {
+				depth++
+			}
 		}
 	}
 }

pkg/proc/dwarf_export_test.go

@@ -0,0 +1,6 @@
+package proc
+
+// PackageVars returns bi.packageVars (for tests)
+func (bi *BinaryInfo) PackageVars() []packageVar {
+	return bi.packageVars
+}

pkg/proc/dwarf_expr_test.go

@@ -337,3 +337,19 @@ func TestUnsupportedType(t *testing.T) {
 		t.Errorf("unexpected error reading unsupported type: %#v", err)
 	}
 }
+
+func TestNestedCompileUnts(t *testing.T) {
+	// Tests that a compile unit with a nested entry that we don't care about
+	// (such as a DW_TAG_namespace) is read fully.
+	dwb := dwarfbuilder.New()
+	dwb.AddCompileUnit("main", 0x0)
+	dwb.TagOpen(dwarf.TagNamespace, "namespace")
+	dwb.AddVariable("var1", 0x0, uint64(0x0))
+	dwb.TagClose()
+	dwb.AddVariable("var2", 0x0, uint64(0x0))
+	dwb.TagClose()
+	bi, _ := fakeBinaryInfo(t, dwb)
+	if n := len(bi.PackageVars()); n != 2 {
+		t.Errorf("expected 2 variables, got %d", n)
+	}
+}