Use protobuf v34 for macOS Ruby build

Author: tadeja

.github/workflows/ruby.yml

@@ -148,8 +148,6 @@ jobs:
       ARROW_WITH_SNAPPY: ON
       ARROW_WITH_ZLIB: ON
       ARROW_WITH_ZSTD: ON
-      Protobuf_SOURCE: BUNDLED
-      gRPC_SOURCE: BUNDLED
     steps:
       - name: Checkout Arrow
         uses: actions/checkout@v6
@@ -165,16 +163,6 @@ jobs:
           brew bundle --file=cpp/Brewfile
           brew bundle --file=c_glib/Brewfile
 
-          # protobuf@33 workaround: unlink v34 (pulled by grpc) and make
-          # keg-only protobuf@33 visible to CMake and pkg-config.
-          # Remove after gRPC problem is fixed.
-          # See https://github.com/grpc/grpc/issues/41755
-          brew unlink protobuf
-          export PROTOBUF_PREFIX="$(brew --prefix protobuf@33)"
-          echo "PKG_CONFIG_PATH=${PROTOBUF_PREFIX}/lib/pkgconfig:${PKG_CONFIG_PATH}" >> "$GITHUB_ENV"
-          echo "CMAKE_PREFIX_PATH=${PROTOBUF_PREFIX}:${ARROW_HOME}:${CMAKE_PREFIX_PATH}" >> "$GITHUB_ENV"
-          echo "${PROTOBUF_PREFIX}/bin" >> "$GITHUB_PATH"
-
           # For Meson.
           # See also: https://github.com/mesonbuild/meson/issues/7701
           echo "PKG_CONFIG=$(brew --prefix pkgconf)/bin/pkgconf" >> $GITHUB_ENV

cpp/src/arrow/flight/transport/grpc/serialization_internal.cc

@@ -353,7 +353,10 @@ ::grpc::Status FlightDataDeserialize(ByteBuffer* buffer,
         // Can't use ParseFromCodedStream as this reads the entire
         // rest of the stream into the descriptor command field.
         std::string buffer;
-        pb_stream.ReadString(&buffer, length);
+        if (!pb_stream.ReadString(&buffer, length)) {
+          return {::grpc::StatusCode::INTERNAL,
+                  "Unable to read FlightDescriptor from protobuf"};
+        }
         if (!pb_descriptor.ParseFromString(buffer)) {
           return {::grpc::StatusCode::INTERNAL, "Unable to parse FlightDescriptor"};
         }