Using Crypto++ with clang

Question

I'm attempting to get the following Crypto++ (C++ Class Library of Cryptographic Schemes) example to work on a iMac using clang++.

Example

SHA256 hash;

byte digest[ SHA256::DIGESTSIZE ];

hash.CalculateDigest( digest, (byte*) &value[ 0 ], value.size( ) );

HexEncoder encoder;

string result = String::empty;

encoder.Attach( new StringSink( result ) );

encoder.Put( digest, sizeof( digest ) );

encoder.MessageEnd( );

Build command

Apple clang version 2.1 (tags/Apple/clang-163.7.1) (based on LLVM 3.0svn)
Target: x86_64-apple-darwin11.4.0
Thread model: posix
 "/usr/bin/clang" -cc1 -triple x86_64-apple-macosx10.7.4 -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -main-file-name checksum_impl.cpp -pic-level 2 -mdisable-fp-elim -relaxed-aliasing -masm-verbose -munwind-tables -target-cpu core2 -target-linker-version 123.2.1 -v -resource-dir /usr/bin/../lib/clang/2.1 -D framework_EXPORTS -I /Users/Ben/Dropbox/appon/build/../source -nostdinc++ -cxx-isystem /usr/include/c++/v1 -Wall -Wextra -Weffc++ -pedantic -std=c++0x -fdeprecated-macro -ferror-limit 19 -fmessage-length 175 -stack-protector 1 -fblocks -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o CMakeFiles/framework.dir/Users/Ben/Dropbox/source/example.cpp.o -x c++ /Users/Ben/Dropbox/source/example.cpp
clang -cc1 version 2.1 based upon llvm 3.0svn hosted on x86_64-apple-darwin11.4.0
#include "..." search starts here:
#include <...> search starts here:
 /Users/Ben/Dropbox/build/../source
 /usr/include/c++/v1
 /usr/local/include
 /usr/bin/../lib/clang/2.1/include
 /usr/include
 /System/Library/Frameworks (framework directory)
 /Library/Frameworks (framework directory)
End of search list.

Linker output

clang: warning: argument unused during compilation: '-std=c++0x'
Undefined symbols for architecture x86_64:
  "CryptoPP::Filter::TransferTo2(CryptoPP::BufferedTransformation&, unsigned long long&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::Filter::CopyRangeTo2(CryptoPP::BufferedTransformation&, unsigned long long&, unsigned long long, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool) const", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::BufferedTransformation::ChannelCreatePutSpace(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, unsigned long&)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::BufferedTransformation::ChannelPut2(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, unsigned char const*, unsigned long, int, bool)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::BufferedTransformation::ChannelPutModifiable2(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, unsigned char*, unsigned long, int, bool)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::BufferedTransformation::ChannelFlush(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool, int, bool)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::BufferedTransformation::ChannelMessageSeriesEnd(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int, bool)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
  "CryptoPP::BufferedTransformation::SetRetrievalChannel(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from:
      vtable for CryptoPP::SimpleProxyFilter in checksum_impl.cpp.o
      vtable for CryptoPP::Bufferless<CryptoPP::Filter> in checksum_impl.cpp.o
      vtable for CryptoPP::Unflushable<CryptoPP::Filter> in checksum_impl.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [all] Error 2

I'm using the latest development version of Crypto++ 5.6.2 as the previous version 5.6.1 fails to build with clang++. However i'm encountering build issues stating that i have missing symbols for x86_64 architecture.

Any hints would be greatly appreciated.

score 3 · Answer 1 · edited May 23 '17 at 12:33

Crypto++ 5.6.2 successfully build on LLVM version 6.1.0 (clang-602.0.53) with make options:

CXXFLAGS="-std=c++11 -stdlib=libstdc++ -DCRYPTOPP_DISABLE_ASM -Wno-c++11-narrowing"

accordingly this script: https://github.com/mapnik/mapnik-packaging/blob/master/osx/scripts/build_cryptopp.sh

-stdlib=libstdc++ need for MacOSX since Mavericks, see: When is it necessary to use use the flag -stdlib=libstdc++?

Jonathan Wakely · Answer 2 · 2012-06-29T08:41:47.910

2

you need to link to the library that provides those symbols, which should be libcryptopp.so, using-lcryptopp in the compiler command

Looking at your "build command" (which is not the command you're running, it's the output of the command you're running, it would be a lot easier to read if you showed the actual command) it seems you are compiling a .cpp file into a .o file, but getting a linker error, which is strange as producing a .o file is usualy the step before linking. What step are you trying to do? Maybe you also need to add -c so it only compiles and doesn't try to link. You will still need -lcryptopp when linking.

edited Jun 29 '12 at 08:41

answered Jun 28 '12 at 20:12

Jonathan Wakely

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Oh :s sorry, Jonathan Wakely I'd forgot I placed this question here. The cause is down to poor support for llvm-clang++. Thank you for your time. – Ben Crowhurst Jul 14 '12 at 15:21

score 1 · Answer 3 · edited May 23 '17 at 11:48

In addition to Jonathon's answer because this is a fairly prevalent problem when -lcryptopp is specified...

Undefined symbols for architecture x86_64. CryptoPP::Filter::TransferTo2(CryptoPP::BufferedTransformation&, unsigned long long&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool)"...

The __1 indicates you are using the LLVM C++ runtime (libc++). Somewhere, you are probably mixing and matching with the GNU C++ runtime (libstdc++). The GNU C++ runtime (libstdc++) lacks the __1 decoration on its symbols.

You should go through the project and all pre-built libraries, and ensure they are using one or the other. For each, you should use CXXFLAGS of either (1) -stdlib=libc++ (LLVM), or (2) -stdlib=libstdc++ (GNU).

Be aware that IDEs like Xcode may use a different -stdlib=... setting than Crypto++. In this case, have Xcode match Crypto++, or rebuild the Crypto++ library to match Xcode.

If Xcode is using LLVM's libc++ and you have to rebuild Crypto++, then open the GNUmakefile and rework this section (around line 90):

ifeq ($(UNAME),Darwin)
  AR = libtool
  ARFLAGS = -static -o
  CXX = c++
  IS_GCC2 = $(shell $(CXX) -v 2>&1 | $(EGREP) -c gcc-932)
ifeq ($(IS_GCC2),1)
    CXXFLAGS += -fno-coalesce-templates -fno-coalesce-static-vtables
    LDLIBS += -lstdc++
    LDFLAGS += -flat_namespace -undefined suppress -m
endif
endif

If you want to use LLVM's libc++, then remove:

# GNU C++ Runtime
LDLIBS += -lstdc++

And add:

# LLVM C++ Runtime
CXXFLAGS += -stdlib=libc++

For completeness, if you want to use GNU's runtime, then remove the LDLIBS += -lstdc++ and add CXXFLAGS += -stdlib=libstdc++.

You can also change CXX = c++ to CXX ?= c++ so the makefile will use c++ if its not specified in the environment or command line.

If interested, the __1 is an inline namespace used for versioning. See What are inline namespaces for? and Where does the __1 symbol come from when using LLVM's libc++?.

score 0 · Accepted Answer · edited Jul 30 '22 at 13:51

0

This issue was relating to Crypto++ not having been ported over to llvm-clang++. The supported compilers are listed on Platforms; supported compilers for previous releases are listed on Compiling.

My solution was to instead use GCrypt.

Sorry I can't supply anymore details on the cause of the failure.

edited Jul 30 '22 at 13:51

apaderno

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answered Jul 14 '12 at 15:22

Ben Crowhurst

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This answer is of no help to anyone else who runs into the same issue. Can you elaborate on what the cause of the problem was, and what the solution is? – Richard Smith Sep 15 '12 at 07:54
The first link takes to a page that says *There is currently no text in this page. You can search for this page title in other pages, or search the related logs, but you do not have permission to create this page.* – apaderno Jul 30 '22 at 13:41

Using Crypto++ with clang

4 Answers4