protobuf/lib: pread failed: is a directory, cross-compilation, deploy client application to Android phone

[jsulm]

@a_so Can you please execute

file /media/qt5-qwt6/android_sdk/protobuf_android/lib/libprotobuf.so

and post its output here?

[a_so]

output is:

/media/qt5-qwt6/android_sdk/protobuf_android/lib/libprotobuf.so: symbolic link to `libprotobuf.so.8.0.0'

[jsulm]

@a_so OK, then do:

file /media/qt5-qwt6/android_sdk/protobuf_android/lib/libprotobuf.so.8.0.0

and post the output here...

[a_so]

/media/qt5-qwt6/android_sdk/protobuf_android/lib/libprotobuf.so.8.0.0: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=ebd5a270582d8e3188c77f4027be7df7058f5f1d, not stripped

for qwt I get the following output:

/media/qt5-qwt6/qwt_android/qwt-6.1.3/lib/libqwt.so: ELF 32-bit LSB shared object, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped

[jsulm]

@a_so As you can see it is x86_64 binary, not ARM...

[a_so]

@jsulm yes, I see. My cross compilation for arm did not work obviously. I will try to compile it again.

[a_so]

I have managed to cross compile protobuf 2.5.0 for arm-linux-androideabi with this script:

#!/bin/bash
export NDK=/media/qt5-qwt6/ndk10/android-ndk-r10e
export SYSROOT=$NDK/platforms/android-21/arch-arm

export TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64

export PATH=$PATH:$TOOLCHAIN/bin

export CC="$TOOLCHAIN/bin/arm-linux-androideabi-gcc --sysroot $SYSROOT"
export CXX="$TOOLCHAIN/bin/arm-linux-androideabi-g++ --sysroot $SYSROOT"
export CXXSTL=$NDK/sources/cxx-stl/gnu-libstdc++/4.9

function build_one
{
mkdir build

./configure --prefix=$(pwd)/build \
--host=arm-linux-androideabi \
--with-sysroot=$SYSROOT \
--enable-static \
--disable-shared \
--enable-cross-compile \
--with-protoc=protoc \
CFLAGS="-march=armv7-a" \
CXXFLAGS="-march=armv7-a -I$CXXSTL/include -I$CXXSTL/libs/armeabi-v7a/include -L$CXXSTL/libs/armeabi-v7a/ -lgnustl_static"

make clean
make
make install
}

# pwd is current directory
CPU=arm
PREFIX=$(pwd)/android/$CPU
ADDI_CFLAGS="-marm"
build_one

# Inspect the library architecture specific information
# arm-linux-androideabi-readelf -A build/lib/libprotobuf-lite.a

find for protoc delivers:

/home/staff/Desktop/protobuf/protobuf-2.5.0/build/bin/protoc: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped

next step, I linked to the libraries in my Qt project in .pri file:

#Protobuf support (arm compiled)
LIBS += -L/home/staff/Desktop/protobuf/protobuf-2.5.0/build/lib -lprotobuf
INCLUDEPATH += /home/staff/Desktop/protobuf/protobuf-2.5.0/build/include

#qwt support (armv7)
LIBS += -L/media/qt5-qwt6/lib -lqwt
INCLUDEPATH += /media/qt5-qwt6/include

#Bonjour/Avahi support
LIBS += -L/usr/lib64/libdns_sd.so.1.0.0

#Protobuf support (arm compiled)
LIBS += -L/home/staff/Desktop/protobuf/protobuf-2.5.0/build/lib -lprotobuf
INCLUDEPATH += /home/staff/Desktop/protobuf/protobuf-2.5.0/build/include

When I try to run the project on my phone, protobuf is found but I get the following errors:

/media/qt5-qwt6/ndk10/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9/../../../../arm-linux-androideabi/bin/ld: warning: skipping incompatible /home/staff/Qt5.8.0/5.8/android_armv7/lib/libqwt.so while searching for qwt
/media/qt5-qwt6/ndk10/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9/../../../../arm-linux-androideabi/bin/ld: warning: skipping incompatible /media/qt5-qwt6/lib/libqwt.so while searching for qwt
/media/qt5-qwt6/ndk10/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9/../../../../arm-linux-androideabi/bin/ld: error: cannot find -lqwt
/media/qt5-qwt6/ndk10/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9/../../../../arm-linux-androideabi/bin/ld: error: cannot find -ldns_sd
../sozius-client/so_bonjourservicebrowser.cpp:57: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourservicebrowser.cpp:92: error: undefined reference to 'DNSServiceBrowse'
../sozius-client/so_bonjourservicebrowser.cpp:103: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourservicebrowser.cpp:138: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourserviceresolver.cpp:79: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourserviceresolver.cpp:121: error: undefined reference to 'DNSServiceResolve'
../sozius-client/so_bonjourserviceresolver.cpp:132: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourserviceresolver.cpp:169: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourservicereconfirmer.cpp:46: error: undefined reference to 'DNSServiceQueryRecord'
../sozius-client/so_bonjourservicereconfirmer.cpp:57: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourservicereconfirmer.cpp:104: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourservicereconfirmer.cpp:122: error: undefined reference to 'DNSServiceConstructFullName'
../sozius-client/so_bonjourservicereconfirmer.cpp:140: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourservicereconfirmer.cpp:161: error: undefined reference to 'DNSServiceReconfirmRecord'
../sozius-client/so_bonjourservicequeryrecord.cpp:84: error: undefined reference to 'DNSServiceQueryRecord'
../sozius-client/so_bonjourservicequeryrecord.cpp:99: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourservicequeryrecord.cpp:133: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourservicequeryrecord.cpp:145: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourservice.cpp:43: error: undefined reference to 'TXTRecordGetCount'
../sozius-client/so_bonjourservice.cpp:47: error: undefined reference to 'TXTRecordGetItemAtIndex'
../sozius-client/so_bonjourservice.cpp:229: error: undefined reference to 'DNSServiceConstructFullName'
../sozius-client/so_infograph_p.cpp:61: error: undefined reference to 'QwtPlot::setAxisTitle(int, QString const&)'
../sozius-client/so_infograph_p.cpp:99: error: undefined reference to 'QwtPlot::setFooter(QString const&)'
../sozius-client/so_infograph_p.cpp:135: error: undefined reference to 'QwtPlot::setAxisScale(int, double, double, double)'
../sozius-client/so_infograph_p.cpp:152: error: undefined reference to 'QwtPlot::setAxisAutoScale(int, bool)'
../sozius-client/so_infograph_p.cpp:157: error: undefined reference to 'QwtPlot::setAxisAutoScale(int, bool)'
../sozius-client/so_infograph_p.cpp:158: error: undefined reference to 'QwtPlot::setAxisScale(int, double, double, double)'
../sozius-client/so_infograph_p.cpp:177: error: undefined reference to 'QwtPlot::setFooter(QString const&)'
../sozius-client/so_infograph_p.cpp:178: error: undefined reference to 'QwtPlot::setCanvasBackground(QBrush const&)'
../sozius-client/so_infograph_p.cpp:179: error: undefined reference to 'QwtPlot::setAxisTitle(int, QString const&)'
../sozius-client/so_infograph_p.cpp:182: error: undefined reference to 'QwtPlot::setAxisScale(int, double, double, double)'
../sozius-client/so_infograph_p.cpp:183: error: undefined reference to 'QwtPlot::setAxisAutoScale(int, bool)'
../sozius-client/so_infograph_p.cpp:186: error: undefined reference to 'QwtPlot::setAxisScale(int, double, double, double)'
../sozius-client/so_infograph_p.cpp:201: error: undefined reference to 'QwtPlotCurve::QwtPlotCurve(QString const&)'
../sozius-client/so_infograph_p.cpp:203: error: undefined reference to 'QwtPlotCurve::setPen(QColor const&, double, Qt::PenStyle)'
../sozius-client/so_infograph_p.cpp:204: error: undefined reference to 'QwtPlotItem::setRenderHint(QwtPlotItem::RenderHint, bool)'
../sozius-client/so_infograph_p.cpp:248: error: undefined reference to 'QwtPlotCurve::setSamples(QVector<QPointF> const&)'
../sozius-client/so_infograph_p.cpp:249: error: undefined reference to 'QwtPlotItem::attach(QwtPlot*)'
../sozius-client/so_qwtplot.cpp:3: error: undefined reference to 'QwtPlot::QwtPlot(QWidget*)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::metaObject() const'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::qt_metacast(char const*)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::qt_metacall(QMetaObject::Call, int, void**)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::event(QEvent*)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::eventFilter(QObject*, QEvent*)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::resizeEvent(QResizeEvent*)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::canvasMap(int) const'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::updateLayout()'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::drawCanvas(QPainter*)'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::getCanvasMarginsHint(QwtScaleMap const*, QRectF const&, double&, double&, double&, double&) const'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::drawItems(QPainter*, QRectF const&, QwtScaleMap const*) const'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::itemToInfo(QwtPlotItem*) const'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::infoToItem(QVariant const&) const'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:vtable for so_QwtPlot: error: undefined reference to 'QwtPlot::replot()'
../build/Linux/debug/.obj/so_qwtplot.o:so_qwtplot.cpp:typeinfo for so_QwtPlot: error: undefined reference to 'typeinfo for QwtPlot'
../sozius-client/so_qwtplot.h:9: error: undefined reference to 'QwtPlot::~QwtPlot()'
/home/staff/Desktop/protobuf/protobuf-2.5.0/build/lib/libprotobuf.a(strutil.o):strutil.cc:function google::protobuf::safe_strtof(char const*, float*): error: undefined reference to 'strtof'
collect2: error: ld returned 1 exit status
make: *** [../build/Linux/debug/libsozius-client.so] Error 1
12:13:04: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project sozius-client (kit: Android for armeabi-v7a (GCC 4.9, Qt 5.8.0))
When executing step "Make"
12:13:04: Elapsed time: 02:52.

My questions are:

1. what architecture/configuration does qwt need? I have several of them on my machine

/home/staff/Qt5.8.0/5.8/android_armv7/lib/libqwt.so.6.1.2: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, BuildID[sha1]=131bd147d36585511f96ccd14ba1ccdd88c327cc, stripped

/media/qt5-qwt6/lib/libqwt.so.6.1.2: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, BuildID[sha1]=131bd147d36585511f96ccd14ba1ccdd88c327cc, stripped

/media/qt5-qwt6/qwt_android/qwt-6.1.3/lib/libqwt.so: ELF 32-bit LSB shared object, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped

2. why is -ldns_sd not found? The dynamic libraries are definitely installed. Is it because they are not static libraries like the ones for protobuf?

/usr/lib64/libdns_sd.so
/usr/lib64/libdns_sd.so.1
/usr/lib64/libdns_sd.so.1.0.0

Thank you for your patience with me

[jsulm]

@a_so You need ARM build of libqwt (same as protobuf) as you're going to use it on an ARM processor, right?
Fix your pro file:

LIBS += -L/media/qt5-qwt6/qwt_android/qwt-6.1.3/lib -lqwt
INCLUDEPATH += /media/qt5-qwt6/qwt_android/qwt-6.1.3/include

Are those directories on your host machine?

/usr/lib64/libdns_sd.so
/usr/lib64/libdns_sd.so.1
/usr/lib64/libdns_sd.so.1.0.0

If so, then please keep in mind that you cannot use them on your target (again: your target is ARM). You need libdns_sd.so in your sysroot. Is it there?

[a_so]

I edited the .pro file as you suggested, but I get the warning

:-1: warning: skipping incompatible /home/staff/Qt5.8.0/5.8/android_armv7/lib/libqwt.so while searching for qwt

The warning appears, yet I do not see any associated errors with qwt. I guess, this warning is implemented somewhere in the project and appears. But of course I used the paths you suggested. I should not worry too much about this warning, right?

The directories are on my host machine on which I run my qt. What do you mean by sysroot?

[jsulm]

@a_so Do you build for Android when this warning occurs?

Your sysroot seems to be --with-sysroot=/media/qt5-qwt6/android_sdk/Sdk/ndk-bundle/sysroot

[a_so]

Yes. I found the problem for this. I copied the library files in there once and as the content in this path is loaded when I try to build the project, this warning gets displayed. My errors now are all linked to libdns from avahi.

/media/qt5-qwt6/ndk10/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9/../../../../arm-linux-androideabi/bin/ld: error: cannot find -ldns_sd
../sozius-client/so_bonjourservicebrowser.cpp:57: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourservicebrowser.cpp:92: error: undefined reference to 'DNSServiceBrowse'
../sozius-client/so_bonjourservicebrowser.cpp:103: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourservicebrowser.cpp:138: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourserviceresolver.cpp:79: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourserviceresolver.cpp:121: error: undefined reference to 'DNSServiceResolve'
../sozius-client/so_bonjourserviceresolver.cpp:132: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourserviceresolver.cpp:169: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourservicereconfirmer.cpp:46: error: undefined reference to 'DNSServiceQueryRecord'
../sozius-client/so_bonjourservicereconfirmer.cpp:57: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourservicereconfirmer.cpp:104: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourservicereconfirmer.cpp:122: error: undefined reference to 'DNSServiceConstructFullName'
../sozius-client/so_bonjourservicereconfirmer.cpp:140: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourservicereconfirmer.cpp:161: error: undefined reference to 'DNSServiceReconfirmRecord'
../sozius-client/so_bonjourservicequeryrecord.cpp:84: error: undefined reference to 'DNSServiceQueryRecord'
../sozius-client/so_bonjourservicequeryrecord.cpp:99: error: undefined reference to 'DNSServiceRefSockFD'
../sozius-client/so_bonjourservicequeryrecord.cpp:133: error: undefined reference to 'DNSServiceProcessResult'
../sozius-client/so_bonjourservicequeryrecord.cpp:145: error: undefined reference to 'DNSServiceRefDeallocate'
../sozius-client/so_bonjourservice.cpp:43: error: undefined reference to 'TXTRecordGetCount'
../sozius-client/so_bonjourservice.cpp:47: error: undefined reference to 'TXTRecordGetItemAtIndex'
../sozius-client/so_bonjourservice.cpp:229: error: undefined reference to 'DNSServiceConstructFullName'
collect2: error: ld returned 1 exit status
make: *** [../build/Linux/debug/libsozius-client.so] Error 1
10:40:03: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project sozius-client (kit: Android for armeabi-v7a (GCC 4.9, Qt 5.8.0))
When executing step "Make"
10:40:03: Elapsed time: 00:01.

My sysroot for ndk is

export NDK=/media/qt5-qwt6/ndk10/android-ndk-r10e
export SYSROOT=$NDK/platforms/android-21/arch-arm

[jsulm]

@a_so Where is libdns_sd.so ?

[a_so]

it is in:

/usr/lib64

But this is a x86_64 version for my linux host system. I want to build my shared library libdns_sd.so for arm architecture, but was not successful as a file is missing according to the link:

http://gaiger-programming.blogspot.co.at/2015/12/utilize-avahi-libraries-in-android-for.html

I have already contacted avahi but have not received a reply yet.

[jsulm]

@a_so Do you mean 0002-Add-uninstalled.pc.in-files.patch ?
I just downloaded it clicking on it on that web site.

[a_so]

Yes. Your are right. It works. When I tried to download it some days ago I got directed to a shutdown avahi page. So I will try to generate the library files for arm. Hopefully it works. Thank you for your help!