fix wrong IndexFile truncate (#2346)

Author: alessio-perugini

Diff for: arduino/resources/index.go

@@ -42,11 +42,16 @@ type IndexResource struct {
 // IndexFileName returns the index file name as it is saved in data dir (package_xxx_index.json).
 func (res *IndexResource) IndexFileName() (string, error) {
 	filename := path.Base(res.URL.Path) // == package_index.json[.gz] || packacge_index.tar.bz2
-	if filename == "." || filename == "" {
+	if filename == "." || filename == "" || filename == "/" {
 		return "", &arduino.InvalidURLError{}
 	}
-	if i := strings.Index(filename, "."); i != -1 {
-		filename = filename[:i]
+	switch {
+	case strings.HasSuffix(filename, ".json"):
+		return filename, nil
+	case strings.HasSuffix(filename, ".gz"):
+		return strings.TrimSuffix(filename, ".gz"), nil
+	case strings.HasSuffix(filename, ".tar.bz2"):
+		return strings.TrimSuffix(filename, ".tar.bz2") + ".json", nil
 	}
 	return filename + ".json", nil
 }

Diff for: arduino/resources/resources_test.go

@@ -18,6 +18,7 @@ package resources
 import (
 	"crypto"
 	"encoding/hex"
+	"fmt"
 	"net"
 	"net/http"
 	"net/url"
@@ -148,3 +149,25 @@ func TestIndexDownloadAndSignatureWithinArchive(t *testing.T) {
 	require.False(t, invDestDir.Join("package_index.json").Exist())
 	require.False(t, invDestDir.Join("package_index.json.sig").Exist())
 }
+
+func TestIndexFileName(t *testing.T) {
+	tests := []struct {
+		url      string
+		expected string
+	}{
+		{url: "package_index.json", expected: "package_index.json"},
+		{url: "package_index.json.gz", expected: "package_index.json"},
+		{url: "package_index.tar.bz2", expected: "package_index.json"},
+		// https://github.com/arduino/arduino-cli/issues/2345
+		{url: "package_arduino.cc_index.json", expected: "package_arduino.cc_index.json"},
+		{url: "package_arduino.cc_index.json.gz", expected: "package_arduino.cc_index.json"},
+		{url: "package_arduino.cc_index.tar.bz2", expected: "package_arduino.cc_index.json"},
+		{url: "http://drazzy.com/package_drazzy.com_index.json", expected: "package_drazzy.com_index.json"},
+	}
+	for _, tc := range tests {
+		ir := IndexResource{URL: &url.URL{Path: tc.url}}
+		name, err := ir.IndexFileName()
+		require.NoError(t, err, fmt.Sprintf("error trying url: %v", tc))
+		require.Equal(t, tc.expected, name)
+	}
+}