tools: Move Protoc plugins into top-level `tools/` directory

The Protoc plugins we use are hidden away deep into the `proto/`
directory, which makes it very hard to discover them when one doesn't
already know about their existence. Let's move them into a new top-level
`tools/` directory.

1 files changed, 139 insertions, 0 deletions

diff --git a/tools/protoc-gen-gitaly-protolist/main.go b/tools/protoc-gen-gitaly-protolist/main.go
new file mode 100644
index 000000000..7e775360e
--- /dev/null
+++ b/tools/protoc-gen-gitaly-protolist/main.go
@@ -0,0 +1,139 @@
+// Command protoc-gen-gitaly-protolist is designed to be used as a protobuf compiler to generate a
+// list of protobuf files via a publicly accessible variable.
+//
+// This plugin can be accessed by invoking the protoc compiler with the following arguments:
+//
+//    protoc --plugin=protoc-gen-gitaly-protolist --gitaly_protolist_out=.
+//
+// The plugin accepts a protobuf message in STDIN that describes the parsed protobuf files. A
+// response is sent back on STDOUT that contains any errors.
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/pluginpb"
+)
+
+const (
+	gitalyProtoDirArg = "proto_dir"
+	gitalypbDirArg    = "gitalypb_dir"
+)
+
+func main() {
+	data, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		log.Fatalf("reading input: %s", err)
+	}
+
+	req := &pluginpb.CodeGeneratorRequest{}
+
+	if err := proto.Unmarshal(data, req); err != nil {
+		log.Fatalf("parsing input proto: %s", err)
+	}
+
+	if err := generateProtolistGo(req); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func parseArgs(argString string) (gitalyProtoDir string, gitalypbDir string) {
+	for _, arg := range strings.Split(argString, ",") {
+		argKeyValue := strings.Split(arg, "=")
+		if len(argKeyValue) != 2 {
+			continue
+		}
+		switch argKeyValue[0] {
+		case gitalyProtoDirArg:
+			gitalyProtoDir = argKeyValue[1]
+		case gitalypbDirArg:
+			gitalypbDir = argKeyValue[1]
+		}
+	}
+
+	return gitalyProtoDir, gitalypbDir
+}
+
+func generateProtolistGo(req *pluginpb.CodeGeneratorRequest) error {
+	var err error
+	gitalyProtoDir, gitalypbDir := parseArgs(req.GetParameter())
+
+	if gitalyProtoDir == "" {
+		return fmt.Errorf("%s not provided", gitalyProtoDirArg)
+	}
+	if gitalypbDir == "" {
+		return fmt.Errorf("%s not provided", gitalypbDirArg)
+	}
+
+	var protoNames []string
+
+	if gitalyProtoDir, err = filepath.Abs(gitalyProtoDir); err != nil {
+		return fmt.Errorf("failed to get absolute path for %s: %v", gitalyProtoDir, err)
+	}
+
+	files, err := os.ReadDir(gitalyProtoDir)
+	if err != nil {
+		return fmt.Errorf("failed to read %s: %v", gitalyProtoDir, err)
+	}
+
+	for _, fi := range files {
+		if !fi.IsDir() && strings.HasSuffix(fi.Name(), ".proto") {
+			protoNames = append(protoNames, fmt.Sprintf(`"%s"`, fi.Name()))
+		}
+	}
+
+	f, err := os.Create(filepath.Join(gitalypbDir, "protolist.go"))
+	if err != nil {
+		return fmt.Errorf("could not create protolist.go: %v", err)
+	}
+	defer f.Close()
+
+	if err = renderProtoList(f, protoNames); err != nil {
+		return fmt.Errorf("could not render go code: %v", err)
+	}
+
+	return nil
+}
+
+// renderProtoList generate a go file with a list of gitaly protos
+func renderProtoList(dest io.WriteCloser, protoNames []string) error {
+	joinFunc := template.FuncMap{"join": strings.Join}
+	protoList := `package gitalypb
+	// Code generated by protoc-gen-gitaly. DO NOT EDIT
+
+	// GitalyProtos is a list of gitaly protobuf files
+	var GitalyProtos = []string{
+		{{join . ",\n"}},
+	}
+	`
+	protoListTempl, err := template.New("protoList").Funcs(joinFunc).Parse(protoList)
+	if err != nil {
+		return fmt.Errorf("could not create go code template: %v", err)
+	}
+
+	var rawGo bytes.Buffer
+
+	if err := protoListTempl.Execute(&rawGo, protoNames); err != nil {
+		return fmt.Errorf("could not execute go code template: %v", err)
+	}
+
+	formattedGo, err := format.Source(rawGo.Bytes())
+	if err != nil {
+		return fmt.Errorf("could not format go code: %v", err)
+	}
+
+	if _, err = io.Copy(dest, bytes.NewBuffer(formattedGo)); err != nil {
+		return fmt.Errorf("failed to write protolist.go file: %v", err)
+	}
+
+	return nil
+}