core/commands/unixfs/ls: Set Argument in JSON output

Change the approach to the directory-header control so we can set the
Argument value in the JSON response.

Stripping the trailing newline from the JSON output is annoying, but
looking over [1] I saw no easy way to add a newline to the JSON
output.  And with the general framework that commands/ attempts to be,
it feels a bit funny to customize the JSON output for a command-line
program.  Perhaps a workable solution is to have the command-line
client append newlines to any output that otherwise lacks them?  But
that seems like a change best left to a separate series.

[1]: http://golang.org/pkg/encoding/json/

License: MIT
Signed-off-by: W. Trevor King <wking@tremily.us>

core/commands/unixfs/ls.go

@@ -72,7 +72,7 @@ directories, the child size is the IPFS link size.
 				return
 			}
 
-			output[i] = &LsObject{}
+			output[i] = &LsObject{Argument: fpath}
 
 			t := unixFSNode.GetType()
 			switch t {
@@ -92,7 +92,6 @@ directories, the child size is the IPFS link size.
 					Size: unixFSNode.GetFilesize(),
 				}}
 			case unixfspb.Data_Directory:
-				output[i].Argument = fpath
 				output[i].Links = make([]LsLink, len(merkleNode.Links))
 				for j, link := range merkleNode.Links {
 					getCtx, cancel := context.WithTimeout(context.TODO(), time.Minute)
@@ -132,7 +131,9 @@ directories, the child size is the IPFS link size.
 			w := tabwriter.NewWriter(buf, 1, 2, 1, ' ', 0)
 			lastObjectDirHeader := false
 			for i, object := range output.Objects {
-				if len(output.Objects) > 1 && object.Argument != "" {
+				singleObject := (len(object.Links) == 1 &&
+					object.Links[0].Name == object.Argument)
+				if len(output.Objects) > 1 && !singleObject {
 					if i > 0 {
 						fmt.Fprintln(w)
 					}

test/sharness/t0200-unixfs-ls.sh

@@ -72,6 +72,32 @@ test_ls_cmd() {
 		EOF
 		test_cmp expected_ls_file actual_ls_file
 	'
+
+	test_expect_success "'ipfs --encoding=json file ls <file hashes>' succeeds" '
+		ipfs --encoding=json file ls /ipfs/QmR3jhV4XpxxPjPT3Y8vNnWvWNvakdcT3H6vqpRBsX1MLy/1024 >actual_json_ls_file
+	'
+
+	test_expect_success "'ipfs --encoding=json file ls <file hashes>' output looks good" '
+		cat <<-\EOF >expected_json_ls_file_trailing_newline &&
+			{
+			  "Objects": [
+			    {
+			      "Argument": "/ipfs/QmR3jhV4XpxxPjPT3Y8vNnWvWNvakdcT3H6vqpRBsX1MLy/1024",
+			      "Links": [
+			        {
+			          "Name": "/ipfs/QmR3jhV4XpxxPjPT3Y8vNnWvWNvakdcT3H6vqpRBsX1MLy/1024",
+			          "Hash": "QmbQBUSRL9raZtNXfpTDeaxQapibJEG6qEY8WqAN22aUzd",
+			          "Size": 1024,
+			          "Type": 2
+			        }
+			      ]
+			    }
+			  ]
+			}
+		EOF
+		printf %s "$(cat expected_json_ls_file_trailing_newline)" >expected_json_ls_file &&
+		test_cmp expected_json_ls_file actual_json_ls_file
+	'
 }