Question

I’m having trouble building Protocol Buffers for Android using a standalone NDK toolchain created with the $NDK/build/tools/make-standalone-toolchain.sh script. The problem I’m having is this:

libtool: link: g++ -Wall -Wwrite-strings -Woverloaded-virtual -Wno-sign-compare -O2 -g -DNDEBUG -o protoc main.o  ./.libs/libprotobuf.a ./.libs/libprotoc.a /home/sizeak/AudioFingerprinting/ProtoBuf/jni/src/.libs/libprotobuf.a -lz -lc
./.libs/libprotoc.a(plugin.pb.o): In function `GoogleOnceInit':
/home/sizeak/AudioFingerprinting/ProtoBuf/jni/src/./google/protobuf/stubs/once.h:115: undefined reference to `pthread_once'

Which seems to imply that the pthreads library is missing, however the sysroot was created by the ndk script so should contain everything, right? I read somewhere that it is unnecessary to explicitly link pthreads when using the standalone toolchain. The configure command I used was:

./configure --host=arm-eabi --with-sysroot=$SYSROOT CC=$CC --enable-cross-compile --with-protoc=protoc LIBS="-lc"

Where the environment variables are set up to point at the sysroot created by the script.

I’ve seen this problem on a number of pages on the net, but no one seems to have posted an answer. Can anyone help?

Answer 1

I managed to build it using the ndk-build method, using information found here: How to build protocol buffer by Android NDK

To setup the configure script, I ran these commands:

export CFLAGS="-march=armv7-a -mfloat-abi=softfp -DGOOGLE_PROTOBUF_NO_RTTI"
export CC=arm-linux-androideabi-gcc
export SYSROOT=$NDK/platforms/android-9/arch-arm
./configure --host=arm-eabi --with-sysroot=$SYSROOT CC=$CC --enable-cross-compile --with-protoc=protoc LIBS="-lc"

This is the Application.mk I used:

APP_STL := gnustl_static
APP_ABI := armeabi-v7a armeabi
APP_PROJECT_PATH := ./
APP_BUILD_SCRIPT := ./Android.mk

And the Android.mk used:

# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
CC_LITE_SRC_FILES := \
src/google/protobuf/stubs/common.cc                              \
src/google/protobuf/stubs/once.cc                                \
src/google/protobuf/extension_set.cc                             \
src/google/protobuf/generated_message_util.cc                    \
src/google/protobuf/message_lite.cc                              \
src/google/protobuf/repeated_field.cc                            \
src/google/protobuf/wire_format_lite.cc                          \
src/google/protobuf/io/coded_stream.cc                           \
src/google/protobuf/io/zero_copy_stream.cc                       \
src/google/protobuf/io/zero_copy_stream_impl_lite.cc


COMPILER_SRC_FILES :=  \
src/google/protobuf/descriptor.cc \
src/google/protobuf/descriptor.pb.cc \
src/google/protobuf/descriptor_database.cc \
src/google/protobuf/dynamic_message.cc \
src/google/protobuf/extension_set.cc \
src/google/protobuf/extension_set_heavy.cc \
src/google/protobuf/generated_message_reflection.cc \
src/google/protobuf/generated_message_util.cc \
src/google/protobuf/message.cc \
src/google/protobuf/message_lite.cc \
src/google/protobuf/reflection_ops.cc \
src/google/protobuf/repeated_field.cc \
src/google/protobuf/service.cc \
src/google/protobuf/text_format.cc \
src/google/protobuf/unknown_field_set.cc \
src/google/protobuf/wire_format.cc \
src/google/protobuf/wire_format_lite.cc \
src/google/protobuf/compiler/code_generator.cc \
src/google/protobuf/compiler/command_line_interface.cc \
src/google/protobuf/compiler/importer.cc \
src/google/protobuf/compiler/main.cc \
src/google/protobuf/compiler/parser.cc \
src/google/protobuf/compiler/plugin.cc \
src/google/protobuf/compiler/plugin.pb.cc \
src/google/protobuf/compiler/subprocess.cc \
src/google/protobuf/compiler/zip_writer.cc \
src/google/protobuf/compiler/cpp/cpp_enum.cc \
src/google/protobuf/compiler/cpp/cpp_enum_field.cc \
src/google/protobuf/compiler/cpp/cpp_extension.cc \
src/google/protobuf/compiler/cpp/cpp_field.cc \
src/google/protobuf/compiler/cpp/cpp_file.cc \
src/google/protobuf/compiler/cpp/cpp_generator.cc \
src/google/protobuf/compiler/cpp/cpp_helpers.cc \
src/google/protobuf/compiler/cpp/cpp_message.cc \
src/google/protobuf/compiler/cpp/cpp_message_field.cc \
src/google/protobuf/compiler/cpp/cpp_primitive_field.cc \
src/google/protobuf/compiler/cpp/cpp_service.cc \
src/google/protobuf/compiler/cpp/cpp_string_field.cc \
src/google/protobuf/compiler/java/java_enum.cc \
src/google/protobuf/compiler/java/java_enum_field.cc \
src/google/protobuf/compiler/java/java_extension.cc \
src/google/protobuf/compiler/java/java_field.cc \
src/google/protobuf/compiler/java/java_file.cc \
src/google/protobuf/compiler/java/java_generator.cc \
src/google/protobuf/compiler/java/java_helpers.cc \
src/google/protobuf/compiler/java/java_message.cc \
src/google/protobuf/compiler/java/java_message_field.cc \
src/google/protobuf/compiler/java/java_primitive_field.cc \
src/google/protobuf/compiler/java/java_service.cc \
src/google/protobuf/compiler/javamicro/javamicro_enum.cc \
src/google/protobuf/compiler/javamicro/javamicro_enum_field.cc \
src/google/protobuf/compiler/javamicro/javamicro_field.cc \
src/google/protobuf/compiler/javamicro/javamicro_file.cc \
src/google/protobuf/compiler/javamicro/javamicro_generator.cc \
src/google/protobuf/compiler/javamicro/javamicro_helpers.cc \
src/google/protobuf/compiler/javamicro/javamicro_message.cc \
src/google/protobuf/compiler/javamicro/javamicro_message_field.cc \
src/google/protobuf/compiler/javamicro/javamicro_primitive_field.cc \
src/google/protobuf/compiler/python/python_generator.cc \
src/google/protobuf/io/coded_stream.cc \
src/google/protobuf/io/gzip_stream.cc \
src/google/protobuf/io/printer.cc \
src/google/protobuf/io/tokenizer.cc \
src/google/protobuf/io/zero_copy_stream.cc \
src/google/protobuf/io/zero_copy_stream_impl.cc \
src/google/protobuf/io/zero_copy_stream_impl_lite.cc \
src/google/protobuf/stubs/common.cc \
src/google/protobuf/stubs/once.cc \
src/google/protobuf/stubs/structurally_valid.cc \
src/google/protobuf/stubs/strutil.cc \
src/google/protobuf/stubs/substitute.cc

# C++ full library
# =======================================================
#include $(CLEAR_VARS)

LOCAL_MODULE := libprotobuf-lite
LOCAL_MODULE_TAGS := optional

LOCAL_CPP_EXTENSION := .cc

LOCAL_SRC_FILES := \
$(CC_LITE_SRC_FILES)                                             #\
#src/google/protobuf/stubs/strutil.cc                             \
#src/google/protobuf/stubs/substitute.cc                          \
#src/google/protobuf/stubs/structurally_valid.cc                  \
#src/google/protobuf/descriptor.cc                                \
#src/google/protobuf/descriptor.pb.cc                             \
#src/google/protobuf/descriptor_database.cc                       \
#src/google/protobuf/dynamic_message.cc                           \
#src/google/protobuf/extension_set_heavy.cc                       \
#src/google/protobuf/generated_message_reflection.cc              \
#src/google/protobuf/message.cc                                   \
#src/google/protobuf/reflection_ops.cc                            \
#src/google/protobuf/service.cc                                   \
#src/google/protobuf/text_format.cc                               \
#src/google/protobuf/unknown_field_set.cc                         \
#src/google/protobuf/wire_format.cc                               \
#src/google/protobuf/io/gzip_stream.cc                            \
#src/google/protobuf/io/printer.cc                                \
#src/google/protobuf/io/tokenizer.cc                              \
#src/google/protobuf/io/zero_copy_stream_impl.cc                  \
#src/google/protobuf/compiler/importer.cc                         \
#src/google/protobuf/compiler/parser.cc

LOCAL_C_INCLUDES := \
$(LOCAL_PATH)/src

LOCAL_C_INCLUDES := \
$(LOCAL_PATH)/android \
bionic \
$(LOCAL_PATH)/src \
$(JNI_H_INCLUDE)

LOCAL_SHARED_LIBRARIES := \
libz libcutils libutils
LOCAL_LDLIBS := -lz
# stlport conflicts with the host stl library
#ifneq ($(TARGET_SIMULATOR),true)
#LOCAL_C_INCLUDES += external/stlport/stlport
#LOCAL_SHARED_LIBRARIES += libstlport
#endif

# Define the header files to be copied
#LOCAL_COPY_HEADERS := \
#    src/google/protobuf/stubs/once.h \
#    src/google/protobuf/stubs/common.h \
#    src/google/protobuf/io/coded_stream.h \
#    src/google/protobuf/generated_message_util.h \
#    src/google/protobuf/repeated_field.h \
#    src/google/protobuf/extension_set.h \
#    src/google/protobuf/wire_format_lite_inl.h
#
#LOCAL_COPY_HEADERS_TO := $(LOCAL_MODULE)

LOCAL_CFLAGS := -DGOOGLE_PROTOBUF_NO_RTTI

include $(BUILD_SHARED_LIBRARY)

To include the built library in my other NDK project that I’m using Protocol Buffers in, I had to copy the library into the jni folder of the project using the library and modify its Android.mk to add a reference to it:

...
...
LOCAL_LDLIBS := -llog -lOpenSLES -lGLESv2 jni/libprotobuf-lite.so   
include $(BUILD_SHARED_LIBRARY)

include $(CLEAR_VARS)

LOCAL_MODULE := protobuf-lite
LOCAL_SRC_FILES := libprotobuf-lite.so 

include $(PREBUILT_SHARED_LIBRARY)

I think that’s it, hope someone finds it useful.