I am trying to use v8 in a Dart native extension.
The v8 getting started guide says to compile the hello world example like this.
g++ -I. -Iinclude samples/hello-world.cc -o hello-world -Wl,--start-group \
out.gn/x64.release/obj/{libv8_{base,libbase,external_snapshot,libplatform,libsampler},\
third_party/icu/libicu{uc,i18n},src/inspector/libinspector}.a \
-Wl,--end-group -lrt -ldl -pthread -std=c++0x
Dart says to compile native extensions like so:
g++ -fPIC -I{path to SDK include directory} -DDART_SHARED_LIB -c sample_extension.cc
gcc -shared -m32 -Wl,-soname,libsample_extension.so -o libsample_extension.so sample_extension.o
This is the hybrid I came up with
g++ -fPIC -I{path to SDK include directory} -Iinclude -DDART_SHARED_LIB -c sample_extension.cc -std=c++0x
gcc -shared -Wl,-soname,libsample_extension.so -Wl,--start-group out.gn/x64.release/obj/{libv8_{base,libbase,external_snapshot,libplatform,libsampler},third_party/icu/libicu{uc,i18n},src/inspector/libinspector}.a -Wl,--end-group -o libsample_extension.so sample_extension.o -lrt -ldl -pthread -std=c++0x
However, while trying to run my application, I get an error stating that v8 is not linked properly.
dart: symbol lookup error: /mnt/c/Users/zvacu/Documents/Code/Dart/require/libsample_extension.so: undefined symbol: _ZN2v82V828InitializeICUDefaultLocationEPKcS2_
I can manage to link it properly when using the hello world example provided.
Doing a little research it seems like the problem it is on the -shared property on the second command. You need to pay attention with C++ and shared libraries, so check if your library get's all its dependencies by:
ldd /mnt/c/Users/zvacu/Documents/Code/Dart/require/libsample_extension.so
After this you will get a list of all dependencies, then you will need to search if there is anyone missing.
If this does not answer your question, see this related answer:
Undefined symbol when loading a shared library
Related
I am new to C++ and learning RTI DDS at the moment by compiling their examples. I am currently using their make files but I want to learn how to compile individual files using gcc directly. The make files first compiles objects and links them together as per below.
g++ -DRTI_UNIX -DRTI_LINUX -DRTI_64BIT -m64 -O2 -o objs/x64Linux3gcc4.8.2/HelloPublisher.o -Isrc -Isrc/idl -I/opt/rti_connext_dds-5.2.3/include -I/opt/rti_connext_dds-5.2.3/include/ndds -c src/HelloPublisher.cpp
g++ -m64 -static-libgcc -Wl,--no-as-needed objs/x64Linux3gcc4.8.2/HelloPublisher.o -o objs/x64Linux3gcc4.8.2/HelloPublisher -L/opt/rti_connext_dds-5.2.3/lib/x64Linux3gcc4.8.2 -lnddscppz -lnddscz -lnddscorez -ldl -lnsl -lm -lpthread -lrt
How can I write a single command using g++/gcc to do both?
The usual way is
g++ -o $prog -DRTI_UNIX $moreflags $file1.cpp $file2.cpp $prog.cpp $libs
You'll have to try a bit with the myriad of arguments you got since order matters.
I have a makefile project in which I include a few different libraries. One of them is the boost library which I statically link in order to make my program portable. This is how my makefile command looks like:
g++ -O0 -g test.cpp testObject.o -pthread -I/home/user/devel/lmx-sdk-4.7.1/include/ -L/home/user/devel/lmx-sdk-4.7.1/linux_x64 -llmxclient -lrt -ldl -lboost_filesystem -lboost_system -static -static-libgcc -o $#
I have also linked lmx-sdk library to my project in order to use the licensing functionality; however, it seems to be that lmx-sdk doesn't seem to like static link as it gives an error "Using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking".
How can I make it possible to link some libraries statically and the other ones dynamically ?
Thanks in advance
P.S. I have checked some of similar topics and tried a few methods which didn't work out for me.
Using -Wl,-Bdynamic and -Wl,-Bstatic instead of just using -Bdynamic and -Bstatic solved the problem.
The full link line looks like this now:
g++ -O0 -g test.cpp testObject.o -pthread -Bdynamic -I/home/user/devel/lmx-sdk-4.7.1/include/ -L/home/user/devel/lmx-sdk-4.7.1/linux_x64 -llmxclient -lrt -ldl -Wl,-Bstatic -lboost_filesystem -lboost_system -o $#
You can use -Bstatic to statically link what comes after it, then -Bdynamic to do the opposite. As many times as you need on the command line.
I am trying to add multithreading into my library, so I am working on creating a thread executor for my library. For this I am using boost threads.
This is the error I am getting when running a test case that links to the library:
symbol lookup error: libmylibexample.so.0: undefined symbol: _ZTVN5boost6detail16thread_data_baseE
This is the line of code in my shared library that is causing the error:
MyNameSpace::Producer producer = MyNameSpace::Producer();
threads.create_thread(boost::bind(&MyNameSpace::Producer::run, &producer));
I am compiling the library using autotools and libtool. The code compiles fine. I then create a test case that I am trying to reference the library. Here is the compilation order for compiling the test case:
g++ -I. -I../include -g -O2 -MT runTest-runTest.o -MD -MP -MF .deps/runTest-runTest.Tpo -c -o runTest-runTest.o `test -f 'runTest.cc' || echo './'`runTest.cc
and this is my linking stage:
mv -f .deps/runTest-runTest.Tpo .deps/runTest-runTest.Po
/bin/bash ../libtool --tag=CXX --mode=link g++ -g -O2 ../libmylibexample/libmylibexample.la -o runTest runTest-runTest.o -lboost_system -lboost_filesystem -lboost_regex -lboost_thread-mt -lfftw3 -ltiff
libtool: link: g++ -g -O2 -o .libs/runTest runTest-runTest.o ../libmylibexample/.libs/libmylibexample.so -lboost_system -lboost_filesystem -lboost_regex -lboost_thread-mt -lfftw3 /usr/lib/x86_64-linux-gnu/libtiff.so
One of my colleagues suggested initializing some boost templates relating to threading to help the shared library to load the symbol from the boost_thread library. I am not entirely certain the best method to do this and if this it the right way of making things get loaded.
So to wrap things up: The error appears to involve not being able to load a symbol defined in libboost_thread from my shared library.
As the error indicates, you need to link libmylibexample with libboost_thread.
This is my first time trying to make a simple library. I worked in Ubuntu 12.04 with g++ 4.6.3. Here is the problem:
[[mylib.cpp]]
#include<sqlite3.h>
void Mylib::blahblah() {...}
void Mylib::evenmoreblah() {...}
...
[[mylib.h]]
#include <...>
class Mylib {
...
};
Then I made the lib by:
gcc -c -Wall -fpic mylib.cpp
gcc -shared -o libmylib.so mylib.o
I used the library in a single test.cpp which contains only the main(). I put libmylib.so in ./libdir, and compiled by using:
g++ -g test.cpp -o test -lpthread -L/usr/local/lib -lsqlite3 -L./libdir -lmylib
The error I got:
./libdir/libmylib.so: undefined reference to `sqlite3_close'
./libdir/libmylib.so: undefined reference to `sqlite3_exec'
./libdir/libmylib.so: undefined reference to `sqlite3_free'
./libdir/libmylib.so: undefined reference to `sqlite3_open'
You could link -lsqlite3 into your shared library with
gcc -shared mylib.o -o libmylib.so -lsqlite3
If you do that, you don't need to explicitly link -lsqlite3 to your program, but that won't harm.
and the order of linking arguments for your program is important:
g++ -Wall -g test.cpp -o mytest \
-L./libdir -lmylib -L/usr/local/lib -lsqlite3 -lpthread
it should go from higher-level libraries to lower-level (i.e. system) ones. And don't forget -Wall to get almost all warnings from the compiler, which is very useful.
Read the Program Library HowTo.
PS. Don't call your program test which is a shell builtin (and the standard /usr/bin/test). Use some other name.
If your library make references to sqlite3, you should link sqlite after linking your library :
g++ -g test.cpp -o test -lpthread -L/usr/local/lib -L./libdir -lmylib -lsqlite3
Otherwise ld won't find anything useful in libsqlite3 before linking your library and won't be able to find the requested symbols after that.
Since your library uses sqlite3, you need to add that AFTER your own library in the linker command. I think you could add it to the linking of your shared library too, but not certain.
The linker resolves libraries and their references in the order you list them, so the order is important.
I compiled LD_PRELOAD which uses boost (locks.hpp). Compile was successfull. I copied this LD_PRELOAD to other linux server, and when i run, error:
/usr/bin/java: symbol lookup error: /test/test.so: undefined symbol:
_ZN5boost11this_thread20disable_interruptionC1Ev
How can i fix this? Can i avoid this problem without installing boost on this server?
How i compile LD_PRELOAD:
g++ -fPIC -m32 -shared -Wl,-soname,test.so -ldl -o test.so test.cpp
Thanks!
It seems you have to get libboost_thread into your test.so file. Something along the lines of:
g++ -fPIC -m32 -shared -Wl,-soname,test.so -ldl -o test.so test.cpp \
/usr/lib/libboost_thread.a -lpthread
Since I wouldn't know the specifics for your system, the boost library might be in a different place than from mine.