From 2a16e048433a70e2cc5b9df59570195e591226e6 Mon Sep 17 00:00:00 2001
From: Paul Holzinger <pholzing@redhat.com>
Date: Tue, 3 Jan 2023 18:06:04 +0100
Subject: [PATCH] system df: improve json output code

The current code modifies a global variable which works but is bad
design since it could be uses elsewhere. Since we just exit after the df
command this is not an issue right now but it could become one in the
future.

A better fix is to implement a custom `MarshalJSON()` method on the
struct which will be called if this struct will be marshaled.

[NO NEW TESTS NEEDED]
Fixes some changes from 24b1e81c5d76, the test should from there should
still pass.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>
---
 cmd/podman/system/df.go | 60 +++++++++++------------------------------
 1 file changed, 16 insertions(+), 44 deletions(-)

diff --git a/cmd/podman/system/df.go b/cmd/podman/system/df.go
index 099bbb0948..a69abeec91 100644
--- a/cmd/podman/system/df.go
+++ b/cmd/podman/system/df.go
@@ -1,7 +1,6 @@
 package system
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 	"math"
@@ -146,7 +145,6 @@ func printSummary(cmd *cobra.Command, reports *entities.SystemDfReport) error {
 
 	rpt := report.New(os.Stdout, cmd.Name())
 	defer rpt.Flush()
-	report.DefaultFuncs["json"] = rptJSON
 
 	var err error
 	if cmd.Flags().Changed("format") {
@@ -164,46 +162,7 @@ func printSummary(cmd *cobra.Command, reports *entities.SystemDfReport) error {
 	return writeTemplate(rpt, hdrs, dfSummaries)
 }
 
-type jsonSummary struct {
-	Type           string
-	Total          int
-	Active         int
-	RawSize        int64
-	RawReclaimable int64
-
-	TotalCount  int
-	Size        string
-	Reclaimable string
-}
-
-func jsonConvert(df *dfSummary) *jsonSummary {
-	return &jsonSummary{
-		Type:           df.Type,
-		Total:          df.Total,
-		TotalCount:     df.Total,
-		Active:         df.Active,
-		RawSize:        df.RawSize,
-		RawReclaimable: df.RawReclaimable,
-		Size:           df.Size(),
-		Reclaimable:    df.Reclaimable(),
-	}
-}
-
-func rptJSON(df *dfSummary) string {
-	buf := new(bytes.Buffer)
-	enc := json.NewEncoder(buf)
-	enc.SetEscapeHTML(false)
-	_ = enc.Encode(jsonConvert(df))
-	// Remove the trailing new line added by the encoder
-	return strings.TrimSpace(buf.String())
-}
-
-func printJSON(dfSummaries []*dfSummary) error {
-	data := make([]jsonSummary, len(dfSummaries))
-	for i, df := range dfSummaries {
-		data[i] = *jsonConvert(df)
-	}
-
+func printJSON(data []*dfSummary) error {
 	bytes, err := json.MarshalIndent(data, "", "    ")
 	if err != nil {
 		return err
@@ -343,8 +302,8 @@ type dfSummary struct {
 	Type           string
 	Total          int
 	Active         int
-	RawSize        int64 `json:"Size"`
-	RawReclaimable int64 `json:"Reclaimable"`
+	RawSize        int64
+	RawReclaimable int64
 }
 
 func (d *dfSummary) Size() string {
@@ -359,3 +318,16 @@ func (d *dfSummary) Reclaimable() string {
 	}
 	return fmt.Sprintf("%s (%d%%)", units.HumanSize(float64(d.RawReclaimable)), percent)
 }
+
+func (d dfSummary) MarshalJSON() ([]byte, error) {
+	// need to create a new type here to prevent infinite recursion in MarshalJSON() call
+	type rawDf dfSummary
+
+	return json.Marshal(struct {
+		rawDf
+		// fields for docker compat https://github.com/containers/podman/issues/16902
+		TotalCount  int
+		Size        string
+		Reclaimable string
+	}{rawDf(d), d.Total, d.Size(), d.Reclaimable()})
+}