Ruby: Allow to get a file descriptor by a file name (#20287)

In Python, users can get a file descriptor by a file name. https://googleapis.dev/python/protobuf/latest/google/protobuf/descriptor_pool.html#google.protobuf.descriptor_pool.DescriptorPool.FindFileByName

This would be useful for sometimes. For example, GRPC Reflection allows to get a proto by file name.
https://github.com/grpc/grpc-proto/blob/483f11e91a30de9c11d65d872c09bc529e94e2ee/grpc/reflection/v1/reflection.proto#L45-L46

This feature would be useful to implement such a case.

Closes #20287

PiperOrigin-RevId: 729274388

Author: y-yagi

php/ext/google/protobuf/php-upb.h

@@ -13130,7 +13130,7 @@ UPB_API const upb_EnumDef* upb_DefPool_FindEnumByName(const upb_DefPool* s,
 const upb_EnumValueDef* upb_DefPool_FindEnumByNameval(const upb_DefPool* s,
                                                       const char* sym);
 
-const upb_FileDef* upb_DefPool_FindFileByName(const upb_DefPool* s,
+UPB_API const upb_FileDef* upb_DefPool_FindFileByName(const upb_DefPool* s,
                                               const char* name);
 
 const upb_FileDef* upb_DefPool_FindFileByNameWithSize(const upb_DefPool* s,

ruby/ext/google/protobuf_c/defs.c

@@ -156,6 +156,7 @@ static VALUE DescriptorPool_lookup(VALUE _self, VALUE name) {
   const upb_EnumDef* enumdef;
   const upb_FieldDef* fielddef;
   const upb_ServiceDef* servicedef;
+  const upb_FileDef* filedef;
 
   msgdef = upb_DefPool_FindMessageByName(self->symtab, name_str);
   if (msgdef) {
@@ -177,6 +178,11 @@ static VALUE DescriptorPool_lookup(VALUE _self, VALUE name) {
     return get_servicedef_obj(_self, servicedef);
   }
 
+  filedef = upb_DefPool_FindFileByName(self->symtab, name_str);
+  if (filedef) {
+    return get_filedef_obj(_self, filedef);
+  }
+
   return Qnil;
 }
 

ruby/ext/google/protobuf_c/ruby-upb.h

@@ -13132,7 +13132,7 @@ UPB_API const upb_EnumDef* upb_DefPool_FindEnumByName(const upb_DefPool* s,
 const upb_EnumValueDef* upb_DefPool_FindEnumByNameval(const upb_DefPool* s,
                                                       const char* sym);
 
-const upb_FileDef* upb_DefPool_FindFileByName(const upb_DefPool* s,
+UPB_API const upb_FileDef* upb_DefPool_FindFileByName(const upb_DefPool* s,
                                               const char* name);
 
 const upb_FileDef* upb_DefPool_FindFileByNameWithSize(const upb_DefPool* s,

ruby/lib/google/protobuf/ffi/descriptor_pool.rb

@@ -17,6 +17,7 @@ class FFI
       attach_function :lookup_extension,      :upb_DefPool_FindExtensionByName,[:DefPool, :string], FieldDescriptor
       attach_function :lookup_msg,            :upb_DefPool_FindMessageByName,  [:DefPool, :string], Descriptor
       attach_function :lookup_service,        :upb_DefPool_FindServiceByName,  [:DefPool, :string], ServiceDescriptor
+      attach_function :lookup_file,           :upb_DefPool_FindFileByName,     [:DefPool, :string], FileDescriptor
 
         # FileDescriptorProto
       attach_function :parse,                 :FileDescriptorProto_parse,      [:binary_string, :size_t, Internal::Arena], :FileDescriptorProto
@@ -56,7 +57,8 @@ def lookup name
         Google::Protobuf::FFI.lookup_msg(@descriptor_pool, name) ||
           Google::Protobuf::FFI.lookup_enum(@descriptor_pool, name) ||
           Google::Protobuf::FFI.lookup_extension(@descriptor_pool, name) ||
-          Google::Protobuf::FFI.lookup_service(@descriptor_pool, name)
+          Google::Protobuf::FFI.lookup_service(@descriptor_pool, name) ||
+          Google::Protobuf::FFI.lookup_file(@descriptor_pool, name)
       end
 
       def self.generated_pool

ruby/lib/google/protobuf/ffi/file_descriptor.rb

@@ -18,6 +18,32 @@ class FFI
     class FileDescriptor
       attr :descriptor_pool, :file_def
 
+      # FFI Interface methods and setup
+      extend ::FFI::DataConverter
+      native_type ::FFI::Type::POINTER
+
+      class << self
+        prepend Google::Protobuf::Internal::TypeSafety
+        include Google::Protobuf::Internal::PointerHelper
+
+        # @param value [FileDescriptor] FileDescriptor to convert to an FFI native type
+        # @param _ [Object] Unused
+        def to_native(value, _)
+          file_def_ptr = value.nil? ? nil : value.instance_variable_get(:@file_def)
+          return ::FFI::Pointer::NULL if file_def_ptr.nil?
+          raise "Underlying file_def was null!" if file_def_ptr.null?
+          file_def_ptr
+        end
+
+        ##
+        # @param file_def [::FFI::Pointer] FileDef pointer to be wrapped
+        # @param _ [Object] Unused
+        def from_native(file_def, _ = nil)
+          return nil if file_def.nil? or file_def.null?
+          descriptor_from_file_def(file_def)
+        end
+      end
+
       def initialize(file_def, descriptor_pool)
         @descriptor_pool = descriptor_pool
         @file_def = file_def

ruby/lib/google/protobuf/ffi/internal/pointer_helper.rb

@@ -13,7 +13,8 @@ module PointerHelper
         # the pool, and either retrieve the wrapper object for the given pointer
         # or create one. Assumes that the caller is the wrapper class for the
         # given pointer and that it implements `private_constructor`.
-        def descriptor_from_file_def(file_def, pointer)
+        def descriptor_from_file_def(file_def, pointer = nil)
+          pointer = file_def if pointer.nil?
           raise RuntimeError.new "FileDef is nil" if file_def.nil?
           raise RuntimeError.new "FileDef is null" if file_def.null?
           pool_def = Google::Protobuf::FFI.file_def_pool file_def

ruby/lib/google/protobuf_ffi.rb

@@ -17,8 +17,8 @@
 require 'google/protobuf/ffi/oneof_descriptor'
 require 'google/protobuf/ffi/method_descriptor'
 require 'google/protobuf/ffi/service_descriptor'
-require 'google/protobuf/ffi/descriptor_pool'
 require 'google/protobuf/ffi/file_descriptor'
+require 'google/protobuf/ffi/descriptor_pool'
 require 'google/protobuf/ffi/map'
 require 'google/protobuf/ffi/object_cache'
 require 'google/protobuf/ffi/repeated_field'

ruby/src/main/java/com/google/protobuf/jruby/RubyDescriptorPool.java

@@ -39,7 +39,6 @@
 import com.google.protobuf.Descriptors.FieldDescriptor;
 import com.google.protobuf.Descriptors.FileDescriptor;
 import com.google.protobuf.Descriptors.ServiceDescriptor;
-import com.google.protobuf.Descriptors.MethodDescriptor;
 import com.google.protobuf.ExtensionRegistry;
 import com.google.protobuf.InvalidProtocolBufferException;
 import java.util.ArrayList;
@@ -164,6 +163,11 @@ protected void registerFileDescriptor(
     for (ServiceDescriptor serviceDescriptor : fd.getServices())
       registerService(context, serviceDescriptor, packageName);
 
+    RubyFileDescriptor rfd =
+        (RubyFileDescriptor) RubyFileDescriptor.getRubyFileDescriptor(context, fd);
+    RubyString name = context.runtime.newString(fd.getName());
+    symtab.put(name, rfd);
+
     // Mark this as a loaded file
     fileDescriptors.add(fd);
   }

ruby/tests/basic.rb

@@ -560,6 +560,13 @@ def test_file_descriptor
       assert_equal "basic_test.proto", file_descriptor.name
     end
 
+    def test_lookup_filename
+      file_descriptor = Google::Protobuf::DescriptorPool.generated_pool.lookup 'basic_test.proto'
+      refute_nil file_descriptor
+      assert_kind_of Google::Protobuf::FileDescriptor, file_descriptor
+      assert_equal "basic_test.proto", file_descriptor.name
+    end
+
     def test_map_freeze
       m = proto_module::MapMessage.new
       m.map_string_int32['a'] = 5

upb/reflection/def_pool.h

@@ -46,8 +46,8 @@ UPB_API const upb_EnumDef* upb_DefPool_FindEnumByName(const upb_DefPool* s,
 const upb_EnumValueDef* upb_DefPool_FindEnumByNameval(const upb_DefPool* s,
                                                       const char* sym);
 
-const upb_FileDef* upb_DefPool_FindFileByName(const upb_DefPool* s,
-                                              const char* name);
+UPB_API const upb_FileDef* upb_DefPool_FindFileByName(const upb_DefPool* s,
+                                                      const char* name);
 
 const upb_FileDef* upb_DefPool_FindFileByNameWithSize(const upb_DefPool* s,
                                                       const char* name,