Unescape characters in inspect JSON format output

This patch changes the way the inspect command output is displayed
on the screen when the format is set to JSON.

Note: if the output is redirected to a file the output is *not*
escaped.

For example, before this commit if you run:
$ sudo podman inspect --format "json" daveimg
[
   {
   ...
      "Author": "Dave \u003cdave@corp.io\u003e",
   }
   ...
]

with this patch the output will be:
[
   {
   ...
      "Author": "Dave <dave@corp.io>",
   }
   ...
]

Signed-off-by: Boaz Shuster <ripcurld.github@gmail.com>

Closes: #602
Approved by: mheon

1 files changed, 14 insertions, 2 deletions

diff --git a/cmd/podman/formats/formats.go b/cmd/podman/formats/formats.go
index bfd773c45..3da0ea385 100644
--- a/cmd/podman/formats/formats.go
+++ b/cmd/podman/formats/formats.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"strings"
 	"text/tabwriter"
@@ -55,12 +56,23 @@ type YAMLStruct struct {
 	Output interface{}
 }
 
+func setJSONFormatEncoder(isTerminal bool, w io.Writer) *json.Encoder {
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "    ")
+	if isTerminal {
+		enc.SetEscapeHTML(false)
+	}
+	return enc
+}
+
 // Out method for JSON Arrays
 func (j JSONStructArray) Out() error {
-	data, err := json.MarshalIndent(j.Output, "", "    ")
-	if err != nil {
+	buf := bytes.NewBuffer(nil)
+	enc := setJSONFormatEncoder(terminal.IsTerminal(int(os.Stdout.Fd())), buf)
+	if err := enc.Encode(j.Output); err != nil {
 		return err
 	}
+	data := buf.Bytes()
 
 	// JSON returns a byte array with a literal null [110 117 108 108] in it
 	// if it is passed empty data.  We used bytes.Compare to see if that is