C++ IO Functions not working

joh

Hello,

the standard io functions of c++, do not seem to be working, while the C ones are working.

Minimum example, gives segmentation fault. Obviously you should not use printf in c++, but std::cout is also not working.

#include <signal.h>

#include <fstream>
#include <iostream>



using namespace std;


bool shutdown_ = false;

void sigint_handler(int s)
{
        shutdown_ = true;
}


int main(const int argc, const char **argv) {
        signal(SIGINT, sigint_handler);

        printf("hello printf\n");


        ofstream outFile ("test.txt");
        outFile << "hello" << std::endl;

        outFile.close();

        return 0;

}

Output:

root@Omega-229D:~# ./main
hello printf
Segmentation fault

So it is compiling, but not working then when running the program.

tjoseph1

@joh :

Just curious..
Are you cross compiling it using "toolchain-mipsel_24kc_gcc-7.3.0_musl" ? Also, would like to know the options passed ..

I use mipsel-linux-muslsf-native.tgz, which is 32-bit, from http://musl.cc (v 9.3.1) for compiling..
Runtime is musl-libc 1.2.1 from http://musl.libc.org, compiled in qemu, then moved to omega2.

The setup is running under qemu-mipsel in Linux x64.Malta 24kec processor can take only 256MB ram.I guess it is by mips design, and no smp.

To complie my 2k loc, that is good.

I have compiled protobuf3 under qemu.

When compiling the entire Omega/OpenWRT..things are different, though.We need lot of ram, smp..

Just sharing.

Thanks..

crispyoz

@joh I compiled your sample and ran it on my device without issue. I would add a statement to your sig handler to determine what signal you may be capturing which I suspect is where you will identify the root cause.

void sigint_handler(int s) {
printf("Caught signal %s", s);
shutdown_ = true;
}

joh

Ok I figured out now that the basic example (https://github.com/OnionIoT/c-cross-compile-example) is working with the file operations.

@tjoseph1 Yes I am using the basic "toolchain-mipsel_24kc_gcc-7.3.0_musl" with the Flags from the xCompile file.

@crispyoz The signal handler did not show anything, I don't think it's the problem.

I have a lot of libraries included, which seem to cause the problem, now I have to find out which one is causing it.

But I still wonder why the library would change the behavior of the file io functions..

joh

Ok I figured out now that the uClibc++ is the problem, I require this library for zmq.

I am using the uClibc++ and zmq just from the make menuconfig, so seems I need to find another version here...