internal/rosa: stream format for cure report

This is for efficient cure status retrieval by the package website server.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/report_test.go

@@ -0,0 +1,57 @@
+package rosa_test
+
+import (
+	"errors"
+	"os"
+	"path"
+	"syscall"
+	"testing"
+	"unique"
+
+	"hakurei.app/internal/pkg"
+	"hakurei.app/internal/rosa"
+)
+
+func TestReportZeroLength(t *testing.T) {
+	report := path.Join(t.TempDir(), "report")
+	if err := os.WriteFile(report, nil, 0400); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := rosa.OpenReport(report); !errors.Is(err, syscall.EINVAL) {
+		t.Fatalf("OpenReport: error = %v", err)
+	}
+}
+
+func TestReportSIGSEGV(t *testing.T) {
+	report := path.Join(t.TempDir(), "report")
+	if err := os.WriteFile(report, make([]byte, 64), 0400); err != nil {
+		t.Fatal(err)
+	}
+
+	if r, err := rosa.OpenReport(report); err != nil {
+		t.Fatalf("OpenReport: error = %v", err)
+	} else {
+		status, n := r.ArtifactOf(unique.Make(pkg.ID{}))
+		if len(status) != 0 {
+			t.Errorf("ArtifactsOf: status = %#v", status)
+		}
+		if n != 0 {
+			t.Errorf("ArtifactsOf: n = %d", n)
+		}
+
+		if err = r.Close(); err != nil {
+			t.Fatalf("Close: error = %v", err)
+		}
+
+		defer func() {
+			ioErr := err.(*rosa.ReportIOError)
+			if ioErr.Offset != 48 {
+				panic(ioErr)
+			}
+		}()
+		defer r.HandleAccess(&err)()
+		r.ArtifactOf(unique.Make(pkg.ID{}))
+	}
+
+}