From e58a32ab1e18d8a9562d1908a08c5a84863593ef Mon Sep 17 00:00:00 2001
From: Steven Allen <steven@stebalien.com>
Date: Tue, 7 Jan 2020 19:32:16 -0600
Subject: [PATCH] feat(commands/cid): add a flag for setting the codec

This will be useful when testing `refs local, `repo gc`, and `repo verify`
commands once we store blocks by multihash instead of by CID. At that point,
these commands will return raw v1 CIDs as the blockstore won't actually remember
the codec used to store the block.

Flags choice:

* Ideally, we'd use the `-f, --format` flags like every other command but we're
  already using `-f` (format) for the format string.
* Alternatively, I'd like to use `-c`. However, we're using _that_ for a global
  `--config` flag (bit of a waste given that it doesn't work...).

`--codec` will have to do for now.
---
 core/commands/cid.go       | 25 ++++++++++++++++++++++---
 test/sharness/t0290-cid.sh | 17 +++++++++++++++++
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/core/commands/cid.go b/core/commands/cid.go
index f65aaef31..30304f737 100644
--- a/core/commands/cid.go
+++ b/core/commands/cid.go
@@ -31,6 +31,7 @@ var CidCmd = &cmds.Command{
 const (
 	cidFormatOptionName    = "f"
 	cidVerisonOptionName   = "v"
+	cidCodecOptionName     = "codec"
 	cidMultibaseOptionName = "b"
 )
 
@@ -49,11 +50,13 @@ The optional format string is a printf style format string:
 	Options: []cmds.Option{
 		cmds.StringOption(cidFormatOptionName, "Printf style format string.").WithDefault("%s"),
 		cmds.StringOption(cidVerisonOptionName, "CID version to convert to."),
+		cmds.StringOption(cidCodecOptionName, "CID codec to convert to."),
 		cmds.StringOption(cidMultibaseOptionName, "Multibase to display CID in."),
 	},
 	Run: func(req *cmds.Request, resp cmds.ResponseEmitter, env cmds.Environment) error {
 		fmtStr, _ := req.Options[cidFormatOptionName].(string)
 		verStr, _ := req.Options[cidVerisonOptionName].(string)
+		codecStr, _ := req.Options[cidCodecOptionName].(string)
 		baseStr, _ := req.Options[cidMultibaseOptionName].(string)
 
 		opts := cidFormatOpts{}
@@ -63,10 +66,21 @@ The optional format string is a printf style format string:
 		}
 		opts.fmtStr = fmtStr
 
+		if codecStr != "" {
+			codec, ok := cid.Codecs[codecStr]
+			if !ok {
+				return fmt.Errorf("unknown IPLD codec: %s", codecStr)
+			}
+			opts.newCodec = codec
+		} // otherwise, leave it as 0 (not a valid IPLD codec)
+
 		switch verStr {
 		case "":
 			// noop
 		case "0":
+			if opts.newCodec != 0 && opts.newCodec != cid.DagProtobuf {
+				return fmt.Errorf("cannot convert to CIDv0 with any codec other than DagPB")
+			}
 			opts.verConv = toCidV0
 		case "1":
 			opts.verConv = toCidV1
@@ -125,9 +139,10 @@ var base32Cmd = &cmds.Command{
 }
 
 type cidFormatOpts struct {
-	fmtStr  string
-	newBase mbase.Encoding
-	verConv func(cid cid.Cid) (cid.Cid, error)
+	fmtStr   string
+	newBase  mbase.Encoding
+	verConv  func(cid cid.Cid) (cid.Cid, error)
+	newCodec uint64
 }
 
 type argumentIterator struct {
@@ -170,6 +185,10 @@ func emitCids(req *cmds.Request, resp cmds.ResponseEmitter, opts cidFormatOpts)
 			continue
 		}
 
+		if opts.newCodec != 0 && opts.newCodec != c.Type() {
+			c = cid.NewCidV1(opts.newCodec, c.Hash())
+		}
+
 		if opts.verConv != nil {
 			c, err = opts.verConv(c)
 			if err != nil {
diff --git a/test/sharness/t0290-cid.sh b/test/sharness/t0290-cid.sh
index b7f6e8e53..0659df2a2 100755
--- a/test/sharness/t0290-cid.sh
+++ b/test/sharness/t0290-cid.sh
@@ -10,6 +10,10 @@ CIDv0="QmS4ustL54uo8FzR9455qaxZwuMiUhyvMcX9Ba8nUH4uVv"
 CIDv1="zdj7WZAAFKPvYPPzyJLso2hhxo8a7ZACFQ4DvvfrNXTHidofr"
 CIDb32="bafybeibxm2nsadl3fnxv2sxcxmxaco2jl53wpeorjdzidjwf5aqdg7wa6u"
 
+CIDbase="QmYNmQKp6SuaVrpgWRsPTgCQCnpxUYGq76YEKBXuj2N4H6"
+CIDb32pb="bafybeievd6mwe6vcwnkwo3eizs3h7w3a34opszbyfxziqdxguhjw7imdve"
+CIDb32raw="bafkreievd6mwe6vcwnkwo3eizs3h7w3a34opszbyfxziqdxguhjw7imdve"
+
 test_expect_success "cid base32 works" '
   echo $CIDb32 > expected &&
   ipfs cid base32 $CIDv0 > actual1 &&
@@ -234,4 +238,17 @@ test_expect_success "cid hashes --numeric" '
   test_cmp hashes_expect actual
 '
 
+test_expect_success "cid format -c raw" '
+  echo $CIDb32raw > expected &&
+  ipfs cid format --codec raw -b base32 $CIDb32pb > actual &&
+  test_cmp actual expected
+'
+
+test_expect_success "cid format -c protobuf -v 0" '
+  echo $CIDbase > expected &&
+  ipfs cid format --codec protobuf -v 0 $CIDb32raw > actual &&
+  test_cmp actual expected
+'
+
+
 test_done