CODEWITHSUNDEEP
c++qtcompiler-errors
mulllhausen
mulllhausen

Reputation: 4435

C++ with Qt compile fail

I'm trying to compile the following short C++ program (not written by me) in Debian:

$ cat checksig.cpp
#include <QByteArray>
#include <QDebug>

#include <openssl/ec.h>
#include <openssl/evp.h>
#include <openssl/ecdsa.h>
#include <openssl/sha.h>

static EC_KEY* EC_KEY_pub_key ( const QByteArray& pub )
{
  static EC_KEY* eckey = EC_KEY_new_by_curve_name ( NID_secp256k1 );
  const quint8* ppub = (const quint8*)pub.constData ( );
  o2i_ECPublicKey ( &eckey, &ppub, pub.size ( ) );
  return eckey;
}
//--------------------------------------------------------------
int main(int argc, char *argv[])
{
  const QByteArray data ( QByteArray::fromHex ( argv [1] ) );
  const QByteArray sign ( QByteArray::fromHex ( argv [2] ) );
  const QByteArray pubk ( QByteArray::fromHex ( argv [3] ) );

  quint8 tmp [32];
  ::SHA256 ( (const quint8*)data.constData ( ), data.size ( ), tmp );
  quint8 digest [32];
  ::SHA256 ( tmp, 32, digest );
  qDebug ( ) << "data=" << QString ( data.toHex ( ) );
  qDebug ( ) << "sign=" << QString ( sign.toHex ( ) );
  qDebug ( ) << "pubk=" << QString ( pubk.toHex ( ) );

  qDebug ( ) << "digest=" << QString ( QByteArray ( (const char*)digest, 32 ).toHex ( ) );

  const bool v ( ::ECDSA_verify ( 0, digest, 32, (const quint8*)sign.constData ( ), sign.size ( ), EC_KEY_pub_key ( pubk ) ) );
  qDebug ( ) << "result=" << v;

  return 0;
}

But I don't think I'm using the right includes, or maybe I need to install more Qt libraries?

$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/QtCore/
In file included from /usr/include/i386-linux-gnu/qt5/QtCore/QByteArray:1:0,
from checksig.cpp:4:/usr/include/i386-linux-gnu/qt5/QtCore/qbytearray.h:45:30: fatal error: QtCore/qrefcount.h: No such file or directory
#include <QtCore/qrefcount.h>
                             ^

and alternatively, using includes and libraries from one directory back:

g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/
checksig.cpp:4:22: fatal error: QByteArray: No such file or directory
#include <QByteArray>
                      ^
compilation terminated.

I'm new to C++. How can I compile this small program in a 1-liner?

As requested in the comments:

$ sudo apt-file search "QtCore/qrefcount.h"
qtbase5-dev: /usr/include/i386-linux-gnu/qt5/QtCore/qrefcount.h

thanks to Michael Popovich's answer i tried the following and got further. but now i have new errors:

$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/ -I /usr/include/i386-linux-gnu/qt5/QtCore/
In file included from /usr/include/i386-linux-gnu/qt5/QtCore/qatomic.h:42:0,
                 from /usr/include/i386-linux-gnu/qt5/QtCore/qrefcount.h:45,
                 from /usr/include/i386-linux-gnu/qt5/QtCore/qbytearray.h:45,
                 from /usr/include/i386-linux-gnu/qt5/QtCore/QByteArray:1,
                 from checksig.cpp:4:
/usr/include/i386-linux-gnu/qt5/QtCore/qglobal.h:1034:4: error: #error "You must build your code with position independent code if Qt was built with -reduce-relocations. " "Compile your code with -fPIC or -fPIE."
 #  error "You must build your code with position independent code if Qt was built with -reduce-relocations. "\
    ^

i have no idea if qt was built with -reduce-relocations i don't think i even installed it myself - it was probably pulled in as a dependency for another install.

anyway, trying with -fPIC and -fPIE:

$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/ -I /usr/include/i386-linux-gnu/qt5/QtCore/ -fPIC
/usr/bin/ld: cannot find -lQtCore
collect2: error: ld returned 1 exit status
$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/ -I /usr/include/i386-linux-gnu/qt5/QtCore/ -fPIE
/usr/bin/ld: cannot find -lQtCore
collect2: error: ld returned 1 exit status

Upvotes: 1

Views: 5467

Answers (2)

m0nhawk
m0nhawk

Reputation: 24138

I'd recommend to build Qt with either CMake or QMake, here is the solution with QMake:

checksig.pro:

QT += core

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = checksig
TEMPLATE = app

SOURCES += checksig.cpp

LIBS += -lssl -lcrypto

And compile like this:

qmake checksig.pro
make

Will compile a correct binary.

And if you really need some 1-liner:

g++ checksig.cpp -o checksig -fPIC -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -lssl -lcrypto -lQt5Core -lpthread

Upvotes: 1

Michael Popovich
Michael Popovich

Reputation: 301

Check #find /usr/include/i386-linux-gnu/qt5/ -name qrefcount.h

Add result path to QtCore/ in your project or your system PATH

Upvotes: 1

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