Re: Linker errors while creating a PostgreSQL C extension function.

вс, 19 авг. 2018 г. в 13:56, TalGloz <glozmantal@gmail.com>:
>
> Hello,
>
> *I have this code for my C extension function.
> *
>
> xtern "C" { // C Headers must be inside exter "C" { } block.
> #include <postgres.h>
> #include <fmgr.h>
> #include <utils/builtins.h>
> #include <catalog/pg_type.h>
> #include <utils/rel.h>
> #include <utils/array.h>
> #include <stdlib.h>
> #include <stdint.h>
>
> PG_MODULE_MAGIC;
> }
>
> // CPP Header must be outside extern "C" { } block.
> #include <string>
> #include <vector>
> #include <iostream>
> #include <fstream>
> #include <sstream>
> #include <iterator> // For the ostream_iterator
>
> // External projects c++ libraries compiled and linked on running 'make'.
> #include <seal/seal.h>
> #include <thread>
> #include <cppcodec/base64_rfc4648.hpp>
>
> std::stringstream dec(std::string st){
>
>         // Decode the base64 string into a stringstream
>         auto decodeBase64 = cppcodec::base64_rfc4648::decode(st);
>         std::stringstream decodeBase64SS;
>         std::move(decodeBase64.begin(), decodeBase64.end(),
> std::ostream_iterator<unsigned char>(decodeBase64SS));
>
>         return decodeBase64SS;
> }
>
> std::string enc(std::string st){
>
>         // Create a vector to hold the raw data
>         std::vector<uint8_t> encodeStream;
>
>         // Push all the characters from the raw data string into the vector
>         for (auto &ch : st){
>                 encodeStream.push_back((unsigned char&&)(ch));
>         }
>
>         // Encode the vector as base64 string
>         std::string encodeBase64 =
> cppcodec::base64_rfc4648::encode(encodeStream);
>         encodeStream.clear();
>         return encodeBase64;
>
> }
>
> std::string seal_diff_operation(std::string decodedLocalEncParamTmp,
> std::string decodedLocalTmp1, std::string decodedLocalTmp2){
>
>         std::stringstream decodedLocalEncParam;
>         decodedLocalEncParam.str(decodedLocalEncParamTmp);
>         std::stringstream decodedLocalT1;
>         decodedLocalT1.str(decodedLocalTmp1);
>         std::stringstream decodedLocalT2;
>         decodedLocalT2.str(decodedLocalTmp2);
>
>         // Execute seal library operations
>         // Load the ecryption parameters
>         seal::EncryptionParameters IntegerEncryptorParms;
>         IntegerEncryptorParms.load(decodedLocalEncParam);
>         // Set Context and evaluator objects
>         seal::SEALContext context(IntegerEncryptorParms);
>         seal::Evaluator evaluator(context);
>         // Set the Encoder parameters
>         seal::IntegerEncoder encoder(context.plain_modulus());
>
>         // Create Ciphertexts and load Chipertext information into them
>         seal::Ciphertext number1Encoded;
>         seal::Ciphertext number2Encoded;
>         seal::Ciphertext diffEncodedResult;
>         number1Encoded.load(decodedLocalT1);
>         number2Encoded.load(decodedLocalT2);
>
>         // Do the diff operation on the Ciphertexts and prepare the result
> for output
>         evaluator.sub(number1Encoded, number2Encoded, diffEncodedResult);
>         std::stringstream encResult;
>         diffEncodedResult.save(encResult);
>
>         std::string output = enc(encResult.str());
>         return output;
>
> }
>
> extern "C" { // Usage of CPP functions in the module must be inside extern
> "C" { } block.
> Datum seal_diff_cpp(PG_FUNCTION_ARGS){
>
>         // Get the inputs
>         text *t1 = PG_GETARG_TEXT_PP(0);
>         text *t2 = PG_GETARG_TEXT_PP(1);
>         text *encParam = PG_GETARG_TEXT_PP(2);
>         std::string localT1;
>         std::string localT2;
>         std::string localEncParam;
>         localT1 = text_to_cstring(t1);
>         localT2 = text_to_cstring(t2);
>         localEncParam = text_to_cstring(encParam);
>
>         // Decode the parameters
>         std::stringstream decodedLocalT1 = dec(localT1);
>         std::stringstream decodedLocalT2 = dec(localT2);
>         std::stringstream decodedLocalEncParam = dec(localEncParam);
>
>         // Encode the parameters
>         std::string encodedLocalT1 = enc(decodedLocalT1.str());
>         std::string encodedLocalT2 = enc(decodedLocalT2.str());
>         std::string outputParam =
> seal_diff_operation(decodedLocalEncParam.str(), decodedLocalT1.str(),
> decodedLocalT2.str());
>
>         // Return the result
>         PG_RETURN_TEXT_P(cstring_to_text_with_len(localT1.c_str(),
> localT1.size()));
> };
>
> PG_FUNCTION_INFO_V1(seal_diff_cpp);
> }
>
>
> *And I use this Makefile to create the seal_diff_cpp.so file:
> *
>
> MODULES = seal_diff_cpp
>
> PG_CONFIG = /usr/pgsql-10/bin/pg_config
> PGXS = $(shell $(PG_CONFIG) --pgxs)
> INCLUDEDIR = $(shell $(PG_CONFIG) --includedir-server)
> INCLUDE_SEAL = /usr/local/include/seal
> INCLUDE_SEAL_LIB = /usr/local/lib
> INCLUDE_CPPCODEC = /usr/local/include/cppcodec
> CXX = g++
> CXXFLAGS = -std=c++17 -fPIC -Wall -Iinclude -Werror -g -O0 -pthread \
>            -I$(INCLUDEDIR) -I$(INCLUDE_SEAL) -I$(INCLUDE_CPPCODEC)
> LDFLAGS = -L$(INCLUDE_SEAL_LIB) -llibseal.a -lpthread
> include $(PGXS)
> seal_diff_cpp.so: seal_diff_cpp.o
>         $(CXX) -Wl,--no-undefined -shared -o seal_diff_cpp.so
> seal_diff_cpp.o $(LDFLAGS)
>
> seal_diff_cpp.o: seal_diff_cpp.cpp
>          $(CXX) $(CXXFLAGS) -o seal_diff_cpp.o -c seal_diff_cpp.cpp
>
> *But when I run the make command I get those linker errors
> *
>
> g++ -std=c++17 -fPIC -Wall -Iinclude -Werror -g -O0 -pthread
> -I/usr/pgsql-10/include/server -I"/usr/local/include" -o seal_diff_cpp.o -c
> seal_diff_cpp.cpp
> g++ -Wl,--no-undefined -shared -o seal_diff_cpp.so seal_diff_cpp.o
> -L/usr/pgsql-10/lib   -L/usr/lib64 -Wl,--as-needed
> -Wl,-rpath,'/usr/pgsql-10/lib',--enable-new-dtags
> seal_diff_cpp.o: In function
> `seal_diff_operation(std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >,
> std::__cxx11::basic_string<char, std::char_traits<char>,
> std::allocator<char> >, std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >)':
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:72:
> undefined reference to `seal::EncryptionParameters::EncryptionParameters()'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:73:
> undefined reference to `seal::EncryptionParameters::load(std::istream&)'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:75:
> undefined reference to
> `seal::SEALContext::SEALContext(seal::EncryptionParameters const&)'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:76:
> undefined reference to `seal::Evaluator::Evaluator(seal::SEALContext
> const&)'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:78:
> undefined reference to
> `seal::IntegerEncoder::IntegerEncoder(seal::SmallModulus const&, unsigned
> long)'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:84:
> undefined reference to `seal::Ciphertext::load(std::istream&)'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:85:
> undefined reference to `seal::Ciphertext::load(std::istream&)'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:90:
> undefined reference to `seal::Ciphertext::save(std::ostream&) const'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:78:
> undefined reference to `seal::IntegerEncoder::~IntegerEncoder()'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:78:
> undefined reference to `seal::IntegerEncoder::~IntegerEncoder()'
> seal_diff_cpp.o: In function `seal_diff_cpp':
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:106:
> undefined reference to `pg_detoast_datum_packed'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:107:
> undefined reference to `pg_detoast_datum_packed'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:108:
> undefined reference to `pg_detoast_datum_packed'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:112:
> undefined reference to `text_to_cstring'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:113:
> undefined reference to `text_to_cstring'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:114:
> undefined reference to `text_to_cstring'
> /etc/opt/pgsql_c_functions/CPP/seal_extension/seal_diff_cpp.cpp:130:
> undefined reference to `cstring_to_text_with_len'
> seal_diff_cpp.o: In function
> `seal::EncryptionParameters::~EncryptionParameters()':
> /usr/local/include/seal/encryptionparams.h:48: undefined reference to
> `seal::BigPoly::~BigPoly()'
> seal_diff_cpp.o: In function `seal::Evaluator::sub(seal::Ciphertext const&,
> seal::Ciphertext const&, seal::Ciphertext&)':
> /usr/local/include/seal/evaluator.h:205: undefined reference to
> `seal::Ciphertext::operator=(seal::Ciphertext const&)'
> /usr/local/include/seal/evaluator.h:206: undefined reference to
> `seal::Evaluator::sub(seal::Ciphertext&, seal::Ciphertext const&)'
> seal_diff_cpp.o: In function `seal::SEALContext::~SEALContext()':
> /usr/local/include/seal/context.h:116: undefined reference to
> `seal::BigUInt::~BigUInt()'
> collect2: error: ld returned 1 exit status
> make: *** [Makefile:16: seal_diff_cpp.so] Error 1
>
> I can't figure what am I doing wrong? The SEAL library is an external
> library installed to /usr/local/include/seal and its libseal.a into
> /usr/local/lib/. I was told by the SEAL library creators (Cryptography
> Research Group at Microsoft), that all I need is the installd header files
> in /usr/local/include/seal and the libseal.a in /usr/local/lib/ so I don't
> understand why the linker can't link those functions.
You didn't link against libseal upon building seal_diff_cpp.so, but
you must -- I don't see something like -lseal in the g++ command
string.
Try to replace "-llibseal.a" with "-lseal" in
  LDFLAGS = -L$(INCLUDE_SEAL_LIB) -llibseal.a -lpthread