I have been struggling with Google protobufs lately. I have written a proto file called Button.proto.
Here are its contents:
syntax = "proto3";
package robotjoystick;
message Button {
string name = 1;
int32 id = 2;
uint32 state = 3;
}
I successfully compiled it with this command (with the $USER replaced with the acctual computer user):
protoc -I=/home/$USER/robotjoystickserver --cpp_out=/home/$USER/robotjoystickserver/proto_classes Button.proto
I am using protobuf version 3.7.1.
My *.cpp file is calleddumbprrotos.cpp and it is not compiling for some reason.
Here is my *.cpp file:
// Client side C/C++ program to demonstrate Socket programming
#include <stdio.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
// This line was forgotten apparently - https://stackoverflow.com/questions/15660203/inet-pton-identifier-not-found
#include <arpa/inet.h>
// This one was also forgotten - https://www.reddit.com/r/learnprogramming/comments/3tlii5/clinux_why_is_write_or_close_not_declared_in_this/
#include <unistd.h>
// This is SDL 2.0, the joystick control library
#include <SDL2/SDL.h>
// For Ctrl+C quitting
#include <signal.h>
// for std::end
//#include <iostream>
// Now we import the header files the protobuf compiler generated.
#include "proto_classes/Button.pb.h"
// This is a standard port
#define PORT 8080
//#include<iostream>
using namespace std;
// For the protobuf generated class.
using namespace robotjoystick;
int main(int argc, char const *argv[])
{
// https://developers.google.com/protocol-buffers/docs/cpptutorial
// Verify that the version of the library that we linked against is
// compatible with the version of the headers we compiled against.
GOOGLE_PROTOBUF_VERIFY_VERSION;
// Broken method 1
/*
const string thename = "blah";
robotjoystick::Button * thebutton;
thebutton = new Button();
thebutton->set_name("john");
thebutton->set_id(12);
*/
// Broken method 2
const string thename = "blah";
robotjoystick::Button thebutton;
thebutton.set_name("john");
thebutton.set_id(12);
return 0;
}
The 2 sections of code I have labeled are 2 versions of the same thing that I am trying to accomplish, but both are throwing the same type of error and I have no idea how to interpret it. What do I need to do to make this code compile?
I should also mention that I installed protobuf 3.7.1 right off of my home directory (meaning that the zip file for protobuf was extracted there and then installed there).
The error I get when I currently run the code, the exact way it is, I get this error:
Compiling dumbprotos.cpp
/tmp/cc7HHVQf.o: In function `google::protobuf::internal::GetEmptyStringAlreadyInited[abi:cxx11]()':
dumbprotos.cpp:(.text._ZN6google8protobuf8internal27GetEmptyStringAlreadyInitedB5cxx11Ev[_ZN6google8protobuf8internal27GetEmptyStringAlreadyInitedB5cxx11Ev]+0x5): undefined reference to `google::protobuf::internal::fixed_address_empty_string[abi:cxx11]'
/tmp/ccMdby3z.o: In function `AddDescriptors_Button_2eproto()':
Button.pb.cc:(.text+0xa6): undefined reference to `google::protobuf::internal::AddDescriptors(google::protobuf::internal::DescriptorTable*, void (* const*)(), int)'
/tmp/ccMdby3z.o: In function `robotjoystick::Button::MergePartialFromCodedStream(google::protobuf::io::CodedInputStream*)':
Button.pb.cc:(.text+0x660): undefined reference to `google::protobuf::io::CodedInputStream::ReadTagFallback(unsigned int)'
Button.pb.cc:(.text+0x73f): undefined reference to `google::protobuf::internal::WireFormatLite::VerifyUtf8String(char const*, int, google::protobuf::internal::WireFormatLite::Operation, char const*)'
/tmp/ccMdby3z.o: In function `robotjoystick::Button::SerializeWithCachedSizes(google::protobuf::io::CodedOutputStream*) const':
Button.pb.cc:(.text+0x904): undefined reference to `google::protobuf::internal::WireFormatLite::VerifyUtf8String(char const*, int, google::protobuf::internal::WireFormatLite::Operation, char const*)'
/tmp/ccMdby3z.o: In function `robotjoystick::Button::InternalSerializeWithCachedSizesToArray(unsigned char*) const':
Button.pb.cc:(.text+0xa98): undefined reference to `google::protobuf::internal::WireFormatLite::VerifyUtf8String(char const*, int, google::protobuf::internal::WireFormatLite::Operation, char const*)'
/tmp/ccMdby3z.o: In function `robotjoystick::Button::GetMetadata() const':
Button.pb.cc:(.text+0x1386): undefined reference to `google::protobuf::internal::AssignDescriptors(google::protobuf::internal::AssignDescriptorsTable*)'
/tmp/ccMdby3z.o: In function `robotjoystick::Button* google::protobuf::Arena::CreateMaybeMessage<robotjoystick::Button>(google::protobuf::Arena*)':
Button.pb.cc:(.text+0x142e): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAligned(unsigned long)'
Button.pb.cc:(.text+0x144b): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAlignedAndAddCleanup(unsigned long, void (*)(void*))'
/tmp/ccMdby3z.o: In function `google::protobuf::io::CodedInputStream::ReadVarint32(unsigned int*)':
Button.pb.cc:(.text._ZN6google8protobuf2io16CodedInputStream12ReadVarint32EPj[_ZN6google8protobuf2io16CodedInputStream12ReadVarint32EPj]+0x78): undefined reference to `google::protobuf::io::CodedInputStream::ReadVarint32Fallback(unsigned int)'
/tmp/ccMdby3z.o: In function `google::protobuf::Arena::AllocHook(std::type_info const*, unsigned long) const':
Button.pb.cc:(.text._ZNK6google8protobuf5Arena9AllocHookEPKSt9type_infom[_ZNK6google8protobuf5Arena9AllocHookEPKSt9type_infom]+0x3d): undefined reference to `google::protobuf::Arena::OnArenaAllocation(std::type_info const*, unsigned long) const'
/tmp/ccMdby3z.o: In function `google::protobuf::internal::ArenaStringPtr::CreateInstance(google::protobuf::Arena*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const*)':
Button.pb.cc:(.text._ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x23e): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAligned(unsigned long)'
Button.pb.cc:(.text._ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x25b): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAlignedAndAddCleanup(unsigned long, void (*)(void*))'
/tmp/ccMdby3z.o: In function `google::protobuf::internal::InitSCC(google::protobuf::internal::SCCInfoBase*)':
Button.pb.cc:(.text._ZN6google8protobuf8internal7InitSCCEPNS1_11SCCInfoBaseE[_ZN6google8protobuf8internal7InitSCCEPNS1_11SCCInfoBaseE]+0x4d): undefined reference to `google::protobuf::internal::InitSCCImpl(google::protobuf::internal::SCCInfoBase*)'
/tmp/ccMdby3z.o: In function `google::protobuf::internal::OnShutdownDestroyMessage(void const*)':
Button.pb.cc:(.text._ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv[_ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv]+0x14): undefined reference to `google::protobuf::internal::DestroyMessage(void const*)'
Button.pb.cc:(.text._ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv[_ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv]+0x19): undefined reference to `google::protobuf::internal::OnShutdownRun(void (*)(void const*), void const*)'
/tmp/ccMdby3z.o: In function `google::protobuf::internal::InternalMetadataWithArena::default_instance()':
Button.pb.cc:(.text._ZN6google8protobuf8internal25InternalMetadataWithArena16default_instanceEv[_ZN6google8protobuf8internal25InternalMetadataWithArena16default_instanceEv]+0x5): undefined reference to `google::protobuf::UnknownFieldSet::default_instance()'
/tmp/ccMdby3z.o: In function `google::protobuf::internal::InternalMetadataWithArenaBase<google::protobuf::UnknownFieldSet, google::protobuf::internal::InternalMetadataWithArena>::mutable_unknown_fields_slow()':
Button.pb.cc:(.text._ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv[_ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv]+0x15c): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAligned(unsigned long)'
Button.pb.cc:(.text._ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv[_ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv]+0x176): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAlignedAndAddCleanup(unsigned long, void (*)(void*))'
/tmp/ccMdby3z.o:(.rodata._ZTVN13robotjoystick6ButtonE[_ZTVN13robotjoystick6ButtonE]+0xb8): undefined reference to `google::protobuf::Message::SpaceUsedLong() const'
collect2: error: ld returned 1 exit status
When I compile the code wth the other broken scenario,
const string thename = "blah";
robotjoystick::Button * thebutton;
thebutton = new Button();
thebutton->set_name("john");
thebutton->set_id(12);
I get this error instead:
Compiling dumbprotos.cpp
/tmp/ccaCT7Iy.o: In function `google::protobuf::internal::GetEmptyStringAlreadyInited[abi:cxx11]()':
dumbprotos.cpp:(.text._ZN6google8protobuf8internal27GetEmptyStringAlreadyInitedB5cxx11Ev[_ZN6google8protobuf8internal27GetEmptyStringAlreadyInitedB5cxx11Ev]+0x5): undefined reference to `google::protobuf::internal::fixed_address_empty_string[abi:cxx11]'
/tmp/ccfmvBXP.o: In function `AddDescriptors_Button_2eproto()':
Button.pb.cc:(.text+0xa6): undefined reference to `google::protobuf::internal::AddDescriptors(google::protobuf::internal::DescriptorTable*, void (* const*)(), int)'
/tmp/ccfmvBXP.o: In function `robotjoystick::Button::MergePartialFromCodedStream(google::protobuf::io::CodedInputStream*)':
Button.pb.cc:(.text+0x660): undefined reference to `google::protobuf::io::CodedInputStream::ReadTagFallback(unsigned int)'
Button.pb.cc:(.text+0x73f): undefined reference to `google::protobuf::internal::WireFormatLite::VerifyUtf8String(char const*, int, google::protobuf::internal::WireFormatLite::Operation, char const*)'
/tmp/ccfmvBXP.o: In function `robotjoystick::Button::SerializeWithCachedSizes(google::protobuf::io::CodedOutputStream*) const':
Button.pb.cc:(.text+0x904): undefined reference to `google::protobuf::internal::WireFormatLite::VerifyUtf8String(char const*, int, google::protobuf::internal::WireFormatLite::Operation, char const*)'
/tmp/ccfmvBXP.o: In function `robotjoystick::Button::InternalSerializeWithCachedSizesToArray(unsigned char*) const':
Button.pb.cc:(.text+0xa98): undefined reference to `google::protobuf::internal::WireFormatLite::VerifyUtf8String(char const*, int, google::protobuf::internal::WireFormatLite::Operation, char const*)'
/tmp/ccfmvBXP.o: In function `robotjoystick::Button::GetMetadata() const':
Button.pb.cc:(.text+0x1386): undefined reference to `google::protobuf::internal::AssignDescriptors(google::protobuf::internal::AssignDescriptorsTable*)'
/tmp/ccfmvBXP.o: In function `robotjoystick::Button* google::protobuf::Arena::CreateMaybeMessage<robotjoystick::Button>(google::protobuf::Arena*)':
Button.pb.cc:(.text+0x142e): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAligned(unsigned long)'
Button.pb.cc:(.text+0x144b): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAlignedAndAddCleanup(unsigned long, void (*)(void*))'
/tmp/ccfmvBXP.o: In function `google::protobuf::io::CodedInputStream::ReadVarint32(unsigned int*)':
Button.pb.cc:(.text._ZN6google8protobuf2io16CodedInputStream12ReadVarint32EPj[_ZN6google8protobuf2io16CodedInputStream12ReadVarint32EPj]+0x78): undefined reference to `google::protobuf::io::CodedInputStream::ReadVarint32Fallback(unsigned int)'
/tmp/ccfmvBXP.o: In function `google::protobuf::Arena::AllocHook(std::type_info const*, unsigned long) const':
Button.pb.cc:(.text._ZNK6google8protobuf5Arena9AllocHookEPKSt9type_infom[_ZNK6google8protobuf5Arena9AllocHookEPKSt9type_infom]+0x3d): undefined reference to `google::protobuf::Arena::OnArenaAllocation(std::type_info const*, unsigned long) const'
/tmp/ccfmvBXP.o: In function `google::protobuf::internal::ArenaStringPtr::CreateInstance(google::protobuf::Arena*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const*)':
Button.pb.cc:(.text._ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x23e): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAligned(unsigned long)'
Button.pb.cc:(.text._ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN6google8protobuf8internal14ArenaStringPtr14CreateInstanceEPNS0_5ArenaEPKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x25b): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAlignedAndAddCleanup(unsigned long, void (*)(void*))'
/tmp/ccfmvBXP.o: In function `google::protobuf::internal::InitSCC(google::protobuf::internal::SCCInfoBase*)':
Button.pb.cc:(.text._ZN6google8protobuf8internal7InitSCCEPNS1_11SCCInfoBaseE[_ZN6google8protobuf8internal7InitSCCEPNS1_11SCCInfoBaseE]+0x4d): undefined reference to `google::protobuf::internal::InitSCCImpl(google::protobuf::internal::SCCInfoBase*)'
/tmp/ccfmvBXP.o: In function `google::protobuf::internal::OnShutdownDestroyMessage(void const*)':
Button.pb.cc:(.text._ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv[_ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv]+0x14): undefined reference to `google::protobuf::internal::DestroyMessage(void const*)'
Button.pb.cc:(.text._ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv[_ZN6google8protobuf8internal24OnShutdownDestroyMessageEPKv]+0x19): undefined reference to `google::protobuf::internal::OnShutdownRun(void (*)(void const*), void const*)'
/tmp/ccfmvBXP.o: In function `google::protobuf::internal::InternalMetadataWithArena::default_instance()':
Button.pb.cc:(.text._ZN6google8protobuf8internal25InternalMetadataWithArena16default_instanceEv[_ZN6google8protobuf8internal25InternalMetadataWithArena16default_instanceEv]+0x5): undefined reference to `google::protobuf::UnknownFieldSet::default_instance()'
/tmp/ccfmvBXP.o: In function `google::protobuf::internal::InternalMetadataWithArenaBase<google::protobuf::UnknownFieldSet, google::protobuf::internal::InternalMetadataWithArena>::mutable_unknown_fields_slow()':
Button.pb.cc:(.text._ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv[_ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv]+0x15c): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAligned(unsigned long)'
Button.pb.cc:(.text._ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv[_ZN6google8protobuf8internal29InternalMetadataWithArenaBaseINS0_15UnknownFieldSetENS1_25InternalMetadataWithArenaEE27mutable_unknown_fields_slowEv]+0x176): undefined reference to `google::protobuf::internal::ArenaImpl::AllocateAlignedAndAddCleanup(unsigned long, void (*)(void*))'
/tmp/ccfmvBXP.o:(.rodata._ZTVN13robotjoystick6ButtonE[_ZTVN13robotjoystick6ButtonE]+0xb8): undefined reference to `google::protobuf::Message::SpaceUsedLong() const'
collect2: error: ld returned 1 exit status
This is the script I am using to compile the code:
#!/bin/sh
echo "Compiling dumbprotos.cpp"
echo ""
g++ dumbprotos.cpp proto_classes/Button.pb.cc -o ./pleasework -std=c++11 -lSDL2 -lprotobuf
I think that is everything I need to show you guys. Did I miss anything? What do I need to do to make my *.cpp code compile?
I am on Ubuntu 16.04.
After thinking about the comment provided by @goduk, I thought I should look further into the linking library issue and find the files I need to source. It turns out that I was not linking to any specific location.
I decided to look through the docs under protobuf-3.7.1/src/README.md to explore further to find the .../lib/ directory. After re-reading those docs, a specific section caught my eye.
To compile a package that uses Protocol Buffers, you need to pass
various flags to your compiler and linker. As of version 2.2.0,
Protocol Buffers integrates with pkg-config to manage this. If you
have pkg-config installed, then you can invoke it to get a list of
flags like so:
pkg-config --cflags protobuf # print compiler flags
pkg-config --libs protobuf # print linker flags
pkg-config --cflags --libs protobuf # print both
For example:
c++ my_program.cc my_proto.pb.cc `pkg-config --cflags --libs protobuf`
On my laptop, the command pkg-config --cflags --libs protobuf returns -pthread -I/usr/local/include -L/usr/local/lib -lprotobuf -pthread.
Instead of trying to determine the correct compiling flags, I simply needed to call the required flags using pkg-config --cflags --libs protobuf at the end.
I had never heard of pkg-config before, but this solved all of my problems.
The final bash script line is now this:
g++ dumbprotos.cpp proto_classes/Button.pb.cc -o ./pleasework -std=c++11 -lSDL2 `pkg-config --cflags --libs protobuf`
Thanks for the help. (This is a linker type issue.)
I should also mention that, if the protobuf object contains other protobuf objects, you have to include those in the command line call:
g++ my_program.cc my_proto_imported.pb.cc my_proto_containing.pb.cc `pkg-config --cflags --libs protobuf`
Meaning that my_proto_imported.pb.cc is a protobuf imported and used in my_proto_contained.pb.cc.