undefined reference to `ERR_load_crypto_strings' - linux

I am trying to get OpenSSL to work, but it seems to have a problem with linking. Here is what I did:
I downloaded OpenSSL for Linux from https://www.openssl.org/source/ I tried versions 0.9.8zc, 1.0.0o and 1.0.1j, all with the same result.
I installed each OpenSSL version using ./config, make and sudo make install.
For debugging purposes, I went to /usr/lib/ssl and used sudo chmod -R 777 * to remove any restrictions that could have caused the error.
I created the following program:
main.c:
#include <errno.h>
#include <malloc.h>
#include <resolv.h>
#include <openssl/bio.h>
#include <openssl/ssl.h>
int main(void) {
SSL_load_error_strings();
return EXIT_SUCCESS;
}
I created the following makefile in the same directory as my .c file:
makefile:
all: main.o
cc -o main main.o -L/usr/local/ssl/lib/ -lcrypto -lssl
main.o: main.c
cc -c -Wall main.c -I/usr/local/ssl/include/ -o main.o
When I run the makefile, I get the following error:
cc -o main main.o -L/usr/local/ssl/lib/ -lcrypto -lssl
/usr/local/ssl/lib//libssl.a(ssl_err2.o): In function SSL_load_error_strings':
ssl_err2.c:(.text+0x4): undefined reference toERR_load_crypto_strings'
/usr/local/ssl/lib//libssl.a(ssl_err.o): In function ERR_load_SSL_strings':
ssl_err.c:(.text+0xc): undefined reference toERR_func_error_string'
ssl_err.c:(.text+0x28): undefined reference to ERR_load_strings'
ssl_err.c:(.text+0x3c): undefined reference toERR_load_strings'
collect2: ld returned 1 exit status
make: *** [all] Error 1
What am I doing wrong?
Cheers
Alex

As answered on the maillist by scott_n but for the record here, swap the order to -lssl -lcrypto.
Explanation: for static C libraries in general on nearly all systems, members of library files like libxxx.a are only pulled in by the linker if they define things referenced from translation units already linked i.e. to the left in the command line. OpenSSL libssl has (numerous) references to libcrypto. If you link -lcrypto first, those references haven't been seen, so the libcrypto files aren't linked; then you link -lssl and create the unsatisfied references. In cases of mutual dependency also called recursive dependency you may need to repeat a library like -lcrypto -lssl -lcrypto but OpenSSL has no such "backward" references.

Related

Question about compiling sources code with HDF5 and mpi

When I am trying to compile the source code by 'make', the first steps that creating the '.o' files are running fine, and all '.o' files could be compiled normally. However, when compiling the executable file:
mpifort -fopenmp -O3 -o MyEXE sth.o main.o -L/usr/local/share/fftw-3.3.8/lib -lfftw3_mpi -lfftw3 -lm -L/usr/local/share/mpich-3.2/lib -lmpi -lz -L/usr/local/share/hdf5-1.8.18/lib -lhdf5_fortran -lhdf5hl_fortran -lhdf5_hl -lhdf5 -fPIC
it gots the following error:
/usr/bin/ld: /usr/local/share/hdf5-1.8.18/lib/libhdf5.a(H5PL.o): undefined reference to symbol 'dlclose##GLIBC_2.2.5'
//lib/x86_64-linux-gnu/libdl.so.2: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
How could I solve this problem? Some pages suggest that it is due to the '-ldl- flag when calling c++ compiler, but I couldn't find a way to make it suitable for my cases.
The pages were right. Your HDF5 library libhdf5.a uses the function dlclose, which is defined in the library libdl. To use it, you need to simply add -ldl at the end of your mpifort command line.

Error while linking a custom dynamic library Rust

In a directory I have a C file and its header
/home/test/c_pro
f.c
f.h
libf.so
I have compiled the f.c into a dll called libf.so using the following command
gcc -c -fPIC f.c -o f.o
gcc f.o -shared -o f.so
I want to use this in my Rust project.
So in Rust project I have a build.rs
println!("cargo:rustc-link-search=/home/test/c_pro");
println!("cargo:rustc-link-lib=dylib=f")
When I run a cargo build the build fails with the following errors
/home/test/c_pro/f.so: undefined reference to `EC_KEY_new_by_curve_name'
collect2: error: ld returned 1 exit status
In my f.c I do some imports from openssl
#include <openssl/bio.h>
#include <openssl/bn.h>
#include <openssl/ecdsa.h>
#include <openssl/obj_mac.h>
and use symbols from these libraries.
Any ideas as to why the build fails? I am following the official doc and am relying on 2 build parameters
cargo:rustc-link-search so that cargo can know that he has to do a look up in this directory as well.
cargo:rustc-link-lib=dylib to tell what dynamic library to link to.
What am I missing here folks?
Thanks in advance.
EDIT+UPDATE:
I did as pointed out by #Uli Schlachter and it compiles but I get a runtime error stating that libf.so is not found.
ldd ./target/debug/test_f
libf.so => not found.
Any ideas?
Compile your shared object with
gcc -c -fPIC f.c -o f.o
gcc f.o -shared -o f.so -lssl

Cross-compiling Snap7 for MIPS with OpenWrt as OS

Currently i'm working on a project to log data out of a Siemens PLC. To achieve this i'm using Snap7. Snap7 (http://snap7.sourceforge.net/) is a communication library.
I've managed to get it work on my linux desktop but when i try to cross-compile the snap7 library i get some errors
The error is generated when linking all of the object files.
g++ -shared -fPIC -o ../bin/mips-openwrt-linux-g++/libsnap7.so #"filelist.txt" -L. -lpthread -lrt -O3
/usr/bin/ld: ../temp/mips-openwrt-linux/sys_snap_msgsock.o: Relocations in generic ELF (EM: 8)
./temp/mips-openwrt-linux/sys_snap_msgsock.o: could not read symbols: File in wrong format
collect2: error: ld returned 1 exit status
make: *** [../bin/mips-openwrt-linux-g++/libsnap7.so] Error 1
If i'm correct i think it's using the wrong linker, it should use the linker of the toolchain located at: openwrt/staging_dir/toolchain-mips_34kc_gcc-4.8-linaro_uClibc-0.9.33.2/bin/
I've also tried to compile the software with mips-openwrt-linux-g++.
Now another error is given:
mips-openwrt-linux-g++ -shared -fPIC -o ../bin/mips-openwrt-linux-g++/libsnap7.so #"filelist.txt" -L. -lpthread -lrt -O3
openwrt/staging_dir/toolchain-mips_34kc_gcc-4.8-linaro_uClibc-0.9.33.2/lib/gcc/mips-openwrt-linux-uclibc/4.8.3/../../../../mips-openwrt-linux-uclibc/bin/ld: ../temp/mips-openwrt-linux/sys_snap_msgsock.o: relocation R_MIPS_26 against `close' can not be used when making a shared object; recompile with -fPIC
../temp/mips-openwrt-linux/sys_snap_msgsock.o: could not read symbols: Bad value
collect2: error: ld returned 1 exit status
make: *** [../bin/mips-openwrt-linux-g++/libsnap7.so] Error 1
I hope someone is familiar with this error and can help me out.
Thanks in advance.
edit1:
There are some pre-compiled binaries. In the makefiles i changed the CC to my g++ directory. There is no LD flag so i cannot set my linker over there.
Can you cross compile and run a "hello world" program?
What is the output of file ../temp/mips-openwrt-linux/sys_snap_msgsock.o?

Can't link application with mudflap

My application uses my shared library. Application and library must be mudflapped to check out of bounds reads and writes both on stack and heap. Shared library was successfully build, but while linking application I had a lot of errors.
I made a simple example that reproduces this issue. Here are steps to reproduce:
create C++ dynamic shared library project with 2 files: h and cpp files with some class, and in h or cpp file use #include <iostream>
create C++ application that uses this library (uses class from inside shared library)
build library
build application (here you will catch an linking error)
Here are my files:
SharedLibTest.h
#ifndef SHAREDLIBTEST_H_
#define SHAREDLIBTEST_H_
#include <iostream>
class SharedLibTest {
public:
void func();
};
#endif /* SHAREDLIBTEST_H_ */
SharedLibTest.cpp
#include "SharedLibTest.h"
void SharedLibTest::func()
{}
main.cpp
#include <SharedLibTest.h>
int main(int argc, char *argv[])
{
SharedLibTest obj;
obj.func();
return 0;
}
Building the library:
g++ -O0 -g3 -Wall -c -fmessage-length=0 -fmudflap -funwind-tables -fPIC -MMD -MP -MF"SharedLibTest.d" -MT"SharedLibTest.d" -o "SharedLibTest.o" "../SharedLibTest.cpp"
g++ -rdynamic -shared -o "libshared_lib.so" ./SharedLibTest.o -lmudflap
Building the application:
g++ -I"/home/msviridov/work/prj/workspace/shared_lib" -O0 -g3 -Wall -c -fmessage-length=0 -fmudflap -funwind-tables -MMD -MP -MF"main.d" -MT"main.d" -o "main.o" "../main.cpp"
g++ -L"/home/msviridov/work/prj/workspace/shared_lib/Debug" -rdynamic -v -o "executable" ./main.o -lshared_lib -lmudflap
Linker error output is:
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<unsigned long>::__digits'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<long>::__min'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<short>::__min'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<char>::__max'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<short>::__max'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<long>::__max'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<int>::__max'
/home/msviridov/work/prj/workspace/shared_lib/Debug/libshared_lib.so: undefined reference to `__gnu_cxx::__numeric_traits_integer<int>::__min'
collect2: ld returned 1 exit status
make: *** [executable] Error 1
Though, if I remove mudflap compiler and linker flags for library the build of application will finish successfully.
But it's not true for vice versa.
I don't understand what does lead to such result.
My platform is Linux Mint 13 Maya 64 bit. I'll appreciate any help. Thanks.
Remove #include <iostream> from your header file. If you want to include iostream do that in your source (SharedLibTest.cpp) file.
Including it in header file also includes lots of garbage for you and also may cause some reference errors like this. Create SharedLibTest.o without that include and compare the sizes of object files.
You are probably hitting bug 53359 but you'd need recent 4.8 code to check. Furthermore, be advised that mudflap is for C and very simple C++ programs so you may find false possitives (ala bug 19319) and it doesn't work with DSOs yet.

Undefined Reference to `pthread_init' When Using -lpthread Flag:

I'm compiling using:
gcc -o outfile infile.c -lpthread
and the only undefined reference is pthread_init.
I have tried using -pthread instead of -lpthread, as per some suggestions online.
I am including <pthread.h>
Any ideas?
Don't call pthread_init(). It's not necessary on Linux.

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