From 68abb41a9b6fcbd6b61ee1066580b7719b988b42 Mon Sep 17 00:00:00 2001
From: Kevin Atkinson <k@kevina.org>
Date: Tue, 15 Aug 2017 14:47:23 -0400
Subject: [PATCH] Add ability to change CID version.

---
 cid-fmt/main.go      | 66 ++++++++++++++++++++++++++++++++++++--------
 cid-fmt/main_test.go | 37 +++++++++++++++++++++++++
 2 files changed, 91 insertions(+), 12 deletions(-)

diff --git a/cid-fmt/main.go b/cid-fmt/main.go
index b09d28a..cc870dd 100644
--- a/cid-fmt/main.go
+++ b/cid-fmt/main.go
@@ -13,7 +13,7 @@ import (
 )
 
 func usage() {
-	fmt.Fprintf(os.Stderr, "usage: %s [-b multibase-code] <fmt-str> <cid> ...\n\n", os.Args[0])
+	fmt.Fprintf(os.Stderr, "usage: %s [-b multibase-code] [-v cid-version] <fmt-str> <cid> ...\n\n", os.Args[0])
 	fmt.Fprintf(os.Stderr, "<fmt-str> is either 'prefix' or a printf style format string:\n%s", fmtRef)
 	os.Exit(1)
 }
@@ -46,16 +46,38 @@ func main() {
 		usage()
 	}
 	newBase := mb.Encoding(-1)
+	var verConv func(cid *c.Cid) (*c.Cid, error)
 	args := os.Args[1:]
-	if args[0] == "-b" {
-		if len(args) < 2 {
-			usage()
+outer:
+	for {
+		switch args[0] {
+		case "-b":
+			if len(args) < 2 {
+				usage()
+			}
+			if len(args[1]) != 1 {
+				fmt.Fprintf(os.Stderr, "Error: Invalid multibase code: %s\n", args[1])
+				os.Exit(1)
+			}
+			newBase = mb.Encoding(args[1][0])
+			args = args[2:]
+		case "-v":
+			if len(args) < 2 {
+				usage()
+			}
+			switch args[1] {
+			case "0":
+				verConv = toCidV0
+			case "1":
+				verConv = toCidV1
+			default:
+				fmt.Fprintf(os.Stderr, "Error: Invalid cid version: %s\n", args[1])
+				os.Exit(1)
+			}
+			args = args[2:]
+		default:
+			break outer
 		}
-		if len(args[1]) != 1 {
-			fmt.Fprintf(os.Stderr, "Error: Invalid multibase code: %s\n", args[1])
-		}
-		newBase = mb.Encoding(args[1][0])
-		args = args[2:]
 	}
 	if len(args) < 2 {
 		usage()
@@ -71,15 +93,24 @@ func main() {
 	}
 	for _, cidStr := range args[1:] {
 		base, cid, err := decode(cidStr)
-		if newBase != -1 {
-			base = newBase
-		}
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Error: %s: %v\n", cidStr, err)
 			fmt.Fprintf(os.Stdout, "!INVALID_CID!\n")
 			// Don't abort on a bad cid
 			continue
 		}
+		if newBase != -1 {
+			base = newBase
+		}
+		if verConv != nil {
+			cid, err = verConv(cid)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Error: %s: %v\n", cidStr, err)
+				fmt.Fprintf(os.Stdout, "!CONVERSION_ERROR!\n")
+				// Don't abort on a bad conversion
+				continue
+			}
+		}
 		str, err := fmtCid(fmtStr, base, cid)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
@@ -221,3 +252,14 @@ func encode(base mb.Encoding, data []byte, strip bool) string {
 	}
 	return str
 }
+
+func toCidV0(cid *c.Cid) (*c.Cid, error) {
+	if cid.Type() != c.DagProtobuf {
+		return nil, fmt.Errorf("can't convert non-protobuf nodes to cidv0")
+	}
+	return c.NewCidV0(cid.Hash()), nil
+}
+
+func toCidV1(cid *c.Cid) (*c.Cid, error) {
+	return c.NewCidV1(cid.Type(), cid.Hash()), nil
+}
diff --git a/cid-fmt/main_test.go b/cid-fmt/main_test.go
index 2d69eb1..4d4713c 100644
--- a/cid-fmt/main_test.go
+++ b/cid-fmt/main_test.go
@@ -71,3 +71,40 @@ func testFmt(t *testing.T, cidStr string, newBase mb.Encoding, fmtStr string, re
 		t.Error(fmt.Sprintf("expected: %s; but got: %s", result, str))
 	}
 }
+
+func TestCidConv(t *testing.T) {
+	cidv0 := "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn"
+	cidv1 := "zdj7WbTaiJT1fgatdet9Ei9iDB5hdCxkbVyhyh8YTUnXMiwYi"
+	_, cid, err := decode(cidv0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cid, err = toCidV1(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if cid.String() !=  cidv1 {
+		t.Fatal("conversion failure")
+	}
+	cid, err = toCidV0(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cidStr := cid.String()
+	if cidStr != cidv0 {
+		t.Error(fmt.Sprintf("conversion failure, expected: %s; but got: %s", cidv0, cidStr))
+	}
+}
+
+func TestBadCidConv(t *testing.T) {
+	// this cid is a raw leaf and should not be able to convert to cidv0
+	cidv1 := "zb2rhhzX7uSKrtQ2ZZXFAabKiKFYZrJqKY2KE1cJ8yre2GSWZ"
+	_, cid, err := decode(cidv1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cid, err = toCidV0(cid)
+	if err == nil {
+		t.Fatal("expected failure")
+	}
+}