Qt library dependecy under Ubuntu - qt

I have a Qt app with OpenMesh dependency. I built the OpenMesh library from source:
cmake ...
make
make install
It installed to the /usr/local/lib/OpenMesh folder:
libOpenMeshCored.a
libOpenMeshCored.so.3.2
libOpenMeshToolsd.so
libOpenMeshCored.so
libOpenMeshToolsd.a
libOpenMeshToolsd.so.3.2
The libs are included into the Qt project.
LIBS += -L/usr/local/lib/OpenMesh/ \
-lOpenMeshCored \
-lOpenMeshToolsd
When I start the application from Qt Creator, it works fine. But if I start the built executable from command line, it gives back the following error:
error while loading shared libraries: libOpenMeshCored.so.3.2: cannot open shared object file: No such file or directory
So why does it know about, where to find the shared objects, when I start it from Qt, and why not, when I start without it?
And how can I fix this problem?

Related

Conan-based Qt installation uses wrong home dir for linking

I'm trying to build our application using Qt 5.13.0 installed via Conan/Artifactory. We run our own Artifactory server and the Qt version there is self-build (and statically linked) in our CI solution. We use the Conan recipe for Qt written by the bincrafters, slightly modified to apply some patches for known Qt bugs and set some flags for building properly on Android and WebAssembly.
When trying to build the application, the linker fails to find the necessary dependencies for Qt itself because it tries to look them up in the home folder of the user who build the Qt package, not the user who's running the build.
Here's an excerpt from the build log, showing the attempt at linking all previously compiled object files together:
application folder-------v subproject of the application----v-------v dependency of the application, correct user home dir---------v Qt library installed via Conan, correct user home dir-------v dependency of Qt, WRONG user home dir------------v
g++ -Wl,--gc-sections -o ../../fah [--> all the .o files <--] -L../lib -lmodel -lcore [--> more linked libraries and application parts <--] -L/home/kaupes/.conan/data/libsodium/1.0.18/bje/stable/package/d1efe3774eed76670888f919621e7c4e1b52efa9/lib /home/kaupes/.conan/data/qt/5.13.0/bje/stable/package/d6b3f512e1a5607061462f94e3271dc8af3dd516/lib/libQt5Gui.a /home/dev/.conan/data/harfbuzz/2.4.0/bje/stable/package/c68551ae35bf5d62e66263379d58a38416eb84a9/lib/libharfbuzz.a [--> many, many more libraries <--]
g++: error: /home/dev/.conan/data/harfbuzz/2.4.0/bje/stable/package/c68551ae35bf5d62e66263379d58a38416eb84a9/lib/libharfbuzz.a: No such file or directory
many, many more errors...
As you can see, the user running the build is kaupes, but the g++ invocation attempts to look for the dependencies in /home/dev/, the home folder of the CI user who build the Qt Conan package.
Only dependencies of Qt itself have the problem. Dependencies of the application (also installed via Conan) are found at the correct place.
The Qt package has been build in the CI using the following Conan invocation:
conan create --profile .conan/profiles/linux -s compiler=gcc -s compiler.version=9 . fah/stable
Compiler and version are explicitly set because I'm also build for another GCC version. The linux profile file also doesn't do anything interesting (as far as I can see):
include(default)
[settings]
build_type=Release
compiler.libcxx=libstdc++11
[options]
OpenSSL:shared=False
OpenSSL:no_asm=True
OpenSSL:no_asm=True
OpenSSL:no_weak_ssl_ciphers=True
OpenSSL:no_ssl2=True
OpenSSL:no_ssl3=True
OpenSSL:no_engine=True
libcurl:shared=False
libxml2:shared=False
libxml2:fPIC=True
libsodium:shared=False
pcre2:shared=False
libpng:shared=False
freetype:shared=False
bzip2:shared=False
libjpeg:shared=False
harfbuzz:shared=False
xkbcommon:shared=False
qt:shared=False
qt:with_glib=False
qt:with_sqlite3=False
qt:with_mysql=False
qt:with_pq=False
qt:with_odbc=False
qt:with_sdl2=False
qt:with_openal=False
qt:with_libalsa=False
qt:openssl=True
qt:commercial=False
qt:qtsvg=True
qt:qtdeclarative=True
qt:qtactiveqt=False
qt:qtscript=False
qt:qtmultimedia=False
qt:qttools=True
qt:qtxmlpatterns=False
qt:qttranslations=True
qt:qtdoc=False
qt:qtrepotools=False
qt:qtqa=False
qt:qtlocation=True
qt:qtsensors=True
qt:qtwayland=True
qt:qt3d=False
qt:qtimageformats=False
qt:qtgraphicaleffects=True
qt:qtquickcontrols=True
qt:qtserialbus=False
qt:qtserialport=False
qt:qtx11extras=True
qt:qtmacextras=False
qt:qtwinextras=False
qt:qtandroidextras=False
qt:qtwebsockets=True
qt:qtwebchannel=False
qt:qtwebengine=False
qt:qtwebview=False
qt:qtquickcontrols2=True
qt:qtpurchasing=False
qt:qtcharts=True
qt:qtdatavis3d=False
qt:qtvirtualkeyboard=True
qt:qtgamepad=False
qt:qtscxml=False
qt:qtspeech=False
qt:qtnetworkauth=False
qt:qtremoteobjects=False
qt:qtwebglplugin=False
qt:qtlottie=False
qt:qtconnectivity=True
Is there something I'm doing wrong during the Conan package creation or installation or is this caused by something different?
Indeed, when building qt, all paths to dependencies are hardcoded in configurations files (mkspecs\modules\qt_lib_*.pri).
I assume you are building your application with qmake, because you use static qt, and static qt is incompatible with cmake. One thing you could try is to pass the full path to harfbuzz lib to qmake by adding argument QMAKE_LIBS_HARFBUZZ=/home/kaupes/.conan/data/harfbuzz/2.4.0/bje/stable/package/c68551ae35bf5d62e66263379d58a38416eb84a9/lib/libharfbuzz.a to your qmake invocation.
Edit: it seems to be a knwonw behaviour of qt >= 5.12.1 : https://bugreports.qt.io/browse/QTBUG-72903. This feature has been reverted in 5.14.x and 5.15.x with https://github.com/qt/qtbase/commit/9864d2c6f3b628ca9f07a56b197e77bd43931cca

How to set up poppler library in Qt for embedded device?

The goal is to show pdf's on my target => imx6 board + display. My host's OS is Linux.
So far i'm having a program written in Qt 5.
It compiles fine and i'm able to see it on the display.
To show some pdfs i would like to use the poppler library.
The problem is that i'm not able to get this done. Properly ...
My steps so far:
I did the basic installation of poppler like it is described in the INSTALL file.
mkdir build
cd build
cmake ..
make
make install
then added
INCLUDEPATH += /home/user/poppler/include/poppler/qt5
LIBS += -L"/home/user/poppler/lib" -lpoppler-qt5
to my .pro file
and the #include <poppler-qt5.h> to my .cpp file.
And the result when running is this:
/home/user/poppler/lib/libpoppler-qt5.so:-1: error: file not recognized: File format not recognized
:-1: error: collect2: error: ld returned 1 exit status
Now i have just two ideas. First one is to cross-compile the poppler source code. (I tried this with a toolchain file but failed :'D)
Second idea is to put the library into Qt together with my project and compile it there - maybe that could work. I just don't know how. Help.
I'm also open for something else then poppler - i just want to show pdf's.
The problem, here, is you are somehow compiling Qt projects for ARM, using the corresponding toolchain and sysroot and ABI, and you can not just link to libraries you compiled for, say, x86_64, because they're just binary incompatible.
In the very lucky case you managed to configure creator for cross compilation, just make a creator project for the poppler library, using cmake, and configure the project with the same kit you use for the imx6 applications. Once you have it built for ARM, you can proper link it in your app, providing the full path to LIBS in the .pro file.
In case you're using Yocto, instead, just make a recipe for poppler. In case you're not, maybe you should.

How To Compile QFtp Example in Qt 5?

I have application which uses QFtp class.I have made in Qt 4 version.
But now i want to complie QFtp classe in Qt5 but it's showing some error like:
'QFtp' doesn't name and type.
how to resolve this issue. I don't want to use QNetworkAccessManager. is there any way to this?
Thank you
For the sake of completeness, the steps to use the add-ons are:
Download the sources for the add-on from https://github.com/qt/qtftp
Extract the sources somewhere (e.g. Qt5.x.y/Src/qtmyaddon)
Open a console in that folder
Read readme.txt and run the appropriate commands with the latest QT version
Run qmake
Run make (or nmake or mingw32-make or whatever)
Run sudo make install (nmake install, mingw32-make install, ...)
In the .pro file of your project, add "QT += myaddon" (e.g. "QT += ftp")
Run qmake on your project
Compile your project

static linking libtiff to qt

I'm trying to create a static application in qt so that I can run it on other platforms. I made qt static and compiled an example using these commands:
make clean
qmake -config release
make
and it runs ok on my system (ubuntu 13.10) but when I move the executable file to another system (ubuntu 12.04 lts) it gives me this error:
error while loading shared libraries: libtiff.so.5: cannot open shared object file: No such file or directory
I can find the file libtiff.so.4 on that system but not libtiff.so.5 and of course I don't really want to install anything cause I wan my app to have as few dependencies as possible. How can I link libtiff to my app properly?

QtCreator (2.8.0), using shared libraries

I developing a GUI app with Qt 5.1 and QtCreator 2.8.0 and I'm using a shared library (also compiled with Qt 5.1).
This is what I'm using in the .pro file:
INCLUDEPATH += ../MyLib
QMAKE_LIBDIR += ../MyLib/build/release
LIBS += -lMyLib
Regarding the "Run Configuration" (QtCreator) and under Linux (Ubuntu 12.04) I set the LD_LIBRARY_PATH to "(...)/MyLib/build/release" and it works well. However, on Windows, appending the library path (.dll) to PATH doesn't work. I don't get any compiling nor linking errors but when I run the app it immediately exits. If I put the .dll on the same folder as the executable it runs without any problem. Am I missing something?
Hard to say from the information you gave. Surely Windows does find the dll if you put its path into PATH. But maybe your dll uses another dll, which is not in the normal search path?
You might want to try the dependency walker: http://www.dependencywalker.com/
If your dll is based on Qt it might be that it does not find necessary qt plugins.
Check this out: http://qt-project.org/doc/qt-4.8/deployment-windows.html#application-dependencies
Qt 4, but Qt 5 is the same in this regard.

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