go/nix/nar: move narinfo to go/nix/nar/narinfo

go/nix/nar/default.nix

@@ -2,13 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-{ depot, ... }:
-depot.third_party.buildGo.package {
-  name = "nar";
-  srcs = [
-    ./narinfo.go
-  ];
-  deps = with depot; [
-    third_party.gopkgs."github.com".numtide.go-nix.nixbase32
-  ];
+args:
+{
+  narinfo = import ./narinfo args;
 }

go/nix/nar/narinfo/default.nix

@@ -0,0 +1,14 @@
+# SPDX-FileCopyrightText: 2020 Luke Granger-Brown <depot@lukegb.com>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+{ depot, ... }:
+depot.third_party.buildGo.package {
+  name = "narinfo";
+  srcs = [
+    ./narinfo.go
+  ];
+  deps = with depot; [
+    third_party.gopkgs."github.com".numtide.go-nix.nixbase32
+  ];
+}

go/nix/nar/narinfo/narinfo.go

@@ -2,8 +2,8 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 
-// Package nar implements a simple NAR read/writer.
-package nar
+// Package narinfo implements a simple narinfo read/writer.
+package narinfo
 
 import (
 	"bufio"
@@ -207,6 +207,7 @@ type NarInfo struct {
 	Deriver     string
 	System      string
 	Sig         map[string][]byte
+	CA          string
 }
 
 func (ni NarInfo) WriteTo(w io.Writer) error {
@@ -273,6 +274,11 @@ func (ni NarInfo) WriteTo(w io.Writer) error {
 			}
 		}
 	}
+	if ni.CA != "" {
+		if _, err := fmt.Fprintf(w, "CA: %s\n", ni.CA); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
@@ -335,6 +341,9 @@ func ParseNarInfo(r io.Reader) (*NarInfo, error) {
 			}
 		case "References":
 			ni.References = strings.Split(value, " ")
+			if len(ni.References) == 1 && ni.References[0] == "" {
+				ni.References = nil
+			}
 		case "Deriver":
 			if value != "unknown-deriver" {
 				ni.Deriver = value
@@ -355,7 +364,7 @@ func ParseNarInfo(r io.Reader) (*NarInfo, error) {
 			}
 			ni.Sig[bits[0]] = rawVal
 		case "CA":
-			return nil, fmt.Errorf("content-addressed NARs not supported yet")
+			ni.CA = value
 		}
 	}
 	if err := s.Err(); err != nil {

go/nix/nar/narinfo/narinfo_test.go

@@ -1,4 +1,4 @@
-package nar
+package narinfo
 
 import (
 	"strings"