Fix go-to-protobuf wrt gengo/v2
There's some very fishy-smelling logic in here, but this commit is
trying to be as focused as possible.
The *.pb.go diffs are the "name" encoded in the descriptor. The
descriptor blobs can be decoded by this program (thanks StackOverflow!):
```
package main
import (
"bytes"
"compress/gzip"
"encoding/json"
"fmt"
"os"
"io/ioutil"
proto "github.com/golang/protobuf/proto"
dpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
)
func main() {
m := map[string][]byte{
"before": blobv1,
"after": blobv2,
}
arg := os.Args[1]
dump(m[arg])
}
func dump(bytes []byte) {
fd, err := decodeFileDesc(bytes)
if err != nil {
panic(err)
}
b, err := json.MarshalIndent(fd, "", " ")
if err != nil {
panic(err)
}
fmt.Println(string(b))
}
// decompress does gzip decompression.
func decompress(b []byte) ([]byte, error) {
r, err := gzip.NewReader(bytes.NewReader(b))
if err != nil {
return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
}
out, err := ioutil.ReadAll(r)
if err != nil {
return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
}
return out, nil
}
func decodeFileDesc(enc []byte) (*dpb.FileDescriptorProto, error) {
raw, err := decompress(enc)
if err != nil {
return nil, fmt.Errorf("failed to decompress enc: %v", err)
}
fd := new(dpb.FileDescriptorProto)
if err := proto.Unmarshal(raw, fd); err != nil {
return nil, fmt.Errorf("bad descriptor: %v", err)
}
return fd, nil
}
var blobv1 = []byte{
// insert proto "before" blob here
}
var blobv2 = []byte{
// insert proto "after" blob here
}
```
Running this with "before" and "after" args, and diffing the output
yields something like:
```diff
--- /tmp/a 2023-12-23 23:57:04.748090836 -0800
+++ /tmp/b 2023-12-23 23:57:11.000040973 -0800
@@ -1,5 +1,5 @@
{
- "name": "k8s.io/kubernetes/vendor/k8s.io/api/admission/v1/generated.proto",
+ "name": "k8s.io/api/admission/v1/generated.proto",
"package": "k8s.io.api.admission.v1",
"dependency": [
"github.com/gogo/protobuf/gogoproto/gogo.proto",
```
Kubernetes-commit: b0a70dec4ab4cb9f972cf39a81ca5e5555417227
541bc37de9