From e21c9cf7e243ca30868c2dfdd232168d7c4f744e Mon Sep 17 00:00:00 2001
From: Hidde Beydals <hidde@hhh.computer>
Date: Thu, 20 Jul 2023 23:23:35 +0200
Subject: [PATCH] repo: detect JSON and unmarshal efficiently

When an index is in a JSON format, the `sigs.k8s.io/yaml` package uses
an inefficient approach to unmarshaling the data, as it does an
unnecessary roundtrip on the data to transform the YAML to valid JSON.

To prevent this from happening, detect if the bytes which we attempt
to load contain valid JSON, and unmarshal them directly using
`json.Unmarshal` instead.

Signed-off-by: Hidde Beydals <hidde@hhh.computer>
---
 pkg/repo/index.go                  | 17 +++++++++-
 pkg/repo/index_test.go             |  5 +++
 pkg/repo/testdata/local-index.json | 53 ++++++++++++++++++++++++++++++
 3 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 pkg/repo/testdata/local-index.json

diff --git a/pkg/repo/index.go b/pkg/repo/index.go
index ba2e365c8fc..0618fe70ae7 100644
--- a/pkg/repo/index.go
+++ b/pkg/repo/index.go
@@ -18,6 +18,7 @@ package repo
 
 import (
 	"bytes"
+	"encoding/json"
 	"log"
 	"os"
 	"path"
@@ -336,7 +337,7 @@ func loadIndex(data []byte, source string) (*IndexFile, error) {
 		return i, ErrEmptyIndexYaml
 	}
 
-	if err := yaml.UnmarshalStrict(data, i); err != nil {
+	if err := jsonOrYamlUnmarshal(data, i); err != nil {
 		return i, err
 	}
 
@@ -361,3 +362,17 @@ func loadIndex(data []byte, source string) (*IndexFile, error) {
 	}
 	return i, nil
 }
+
+// jsonOrYamlUnmarshal unmarshals the given byte slice containing JSON or YAML
+// into the provided interface.
+//
+// It automatically detects whether the data is in JSON or YAML format by
+// checking its validity as JSON. If the data is valid JSON, it will use the
+// `encoding/json` package to unmarshal it. Otherwise, it will use the
+// `sigs.k8s.io/yaml` package to unmarshal the YAML data.
+func jsonOrYamlUnmarshal(b []byte, i interface{}) error {
+	if json.Valid(b) {
+		return json.Unmarshal(b, i)
+	}
+	return yaml.UnmarshalStrict(b, i)
+}
diff --git a/pkg/repo/index_test.go b/pkg/repo/index_test.go
index bbc48c97e98..5528bd9435b 100644
--- a/pkg/repo/index_test.go
+++ b/pkg/repo/index_test.go
@@ -37,6 +37,7 @@ const (
 	annotationstestfile = "testdata/local-index-annotations.yaml"
 	chartmuseumtestfile = "testdata/chartmuseum-index.yaml"
 	unorderedTestfile   = "testdata/local-index-unordered.yaml"
+	jsonTestfile        = "testdata/local-index.json"
 	testRepo            = "test-repo"
 	indexWithDuplicates = `
 apiVersion: v1
@@ -145,6 +146,10 @@ func TestLoadIndex(t *testing.T) {
 			Name:     "chartmuseum index file",
 			Filename: chartmuseumtestfile,
 		},
+		{
+			Name:     "JSON index file",
+			Filename: jsonTestfile,
+		},
 	}
 
 	for _, tc := range tests {
diff --git a/pkg/repo/testdata/local-index.json b/pkg/repo/testdata/local-index.json
new file mode 100644
index 00000000000..25296d5ca24
--- /dev/null
+++ b/pkg/repo/testdata/local-index.json
@@ -0,0 +1,53 @@
+{
+  "apiVersion": "v1",
+  "entries": {
+    "nginx": [
+      {
+        "urls": ["https://charts.helm.sh/stable/nginx-0.2.0.tgz"],
+        "name": "nginx",
+        "description": "string",
+        "version": "0.2.0",
+        "home": "https://github.com/something/else",
+        "digest": "sha256:1234567890abcdef",
+        "keywords": ["popular", "web server", "proxy"],
+        "apiVersion": "v2"
+      },
+      {
+        "urls": ["https://charts.helm.sh/stable/nginx-0.1.0.tgz"],
+        "name": "nginx",
+        "description": "string",
+        "version": "0.1.0",
+        "home": "https://github.com/something",
+        "digest": "sha256:1234567890abcdef",
+        "keywords": ["popular", "web server", "proxy"],
+        "apiVersion": "v2"
+      }
+    ],
+    "alpine": [
+      {
+        "urls": [
+          "https://charts.helm.sh/stable/alpine-1.0.0.tgz",
+          "http://storage2.googleapis.com/kubernetes-charts/alpine-1.0.0.tgz"
+        ],
+        "name": "alpine",
+        "description": "string",
+        "version": "1.0.0",
+        "home": "https://github.com/something",
+        "keywords": ["linux", "alpine", "small", "sumtin"],
+        "digest": "sha256:1234567890abcdef",
+        "apiVersion": "v2"
+      }
+    ],
+    "chartWithNoURL": [
+      {
+        "name": "chartWithNoURL",
+        "description": "string",
+        "version": "1.0.0",
+        "home": "https://github.com/something",
+        "keywords": ["small", "sumtin"],
+        "digest": "sha256:1234567890abcdef",
+        "apiVersion": "v2"
+      }
+    ]
+  }
+}