We're developing a quite large Qt-based project on linux, and we reached final RC1 stage.
Now, we encountered something really strange: in order to go into production, we added another .a library in our list of static linking libs.
The library is linked and the application runs, but every .png in the resource file is corrupted, here's the output on startup:
libpng error: IHDR: CRC error
seems like libpng cant handle those invalid png (of course). The files are there and the size is right, they just turned blank after static linking that final library. The library itself is not used anywhere, it is just linked.
Has anyone encountered such a situation before? is there a known workaround? We're using Qt 4.7.4 x64 on QtCreator 2.3.0, we would like not to upgrade for now, but it is the only option that comes into our mind for now.
It could fit a problem with symbols.
The static library and libpng could be at same time linking to other library and when linking or resolving in compile/load time something weird is happening.
You can use objdump command to inspect symbols (objdump -tT /usr/bin)
Have you tried modifying the library order when compiling/linking? I mean, for example,
gcc -lmylibrary -lQt -lOtherLOLibrary
instead of
gcc -lOtherLOLibrary -lQt -lmylibrary
And I think I'm missing something, why do you link against an unused library?
Related
I need to compile the rtree extension for SQLite from source code. The readme includes these instructions:
The easiest way to compile and use the RTREE extension is to build
and use it as a dynamically loadable SQLite extension. To do this
using gcc on *nix:
gcc -shared rtree.c -o libSqliteRtree.so
You may need to add "-I" flags so that gcc can find sqlite3ext.h
and sqlite3.h. The resulting shared lib, libSqliteRtree.so, may be
loaded into sqlite in the same way as any other dynamicly loadable
extension.
Problem I'm having is that I'm on Windows, not Linux, and so need to use MSVC. I tried:
cl rtree.c -link -out:libSqliteRtree.so
This gave cannot open include file errors until I found the various .h files it was complaining about and moved them into the same directory. Now, however, it's gotten to:
/out:rtree.exe
-out:libSqliteRtree.so
rtree.obj
Creating library libSqliteRtree.lib and object libSqliteRtree.exp
LINK : fatal error LNK1561: entry point must be defined
I admit I have pretty much zero clue what I'm doing in a compiler, and I'm not sure where to go from here to resolve its problem. Am I "translating" the compiler flags correctly from GCC to MSVC? What else can I tweak to try to get the SQLite extension out of the source code? Should I beg a favor from a developer on ateam with a Linux server and ask them to do it for me?
Thanks to Shawn for commenting to look at the SQLite Run-Time Loadable Extensions documentation, which had more information in it:
To compile on Windows using MSVC, a command similar to the following will usually work:
cl YourCode.c -link -dll -out:YourCode.dll
So for my situation: cl rtree.c -link -dll -out:libSqliteRtree.dll worked.
I am trying to set up Marble to work with Qt 5.5 on OSX. I'm not very experienced with the details of linking and such and I think that is causing the problem I am having.
Question: Did I screw up the 'marble` install or is this an easily solved linking issue?
Qt 5.5 is installed in my user directory (using Qt's network installer) on a system running OSX 10.9.5. It works fine. I followed the instructions on the Marble site to clone, build and install from source with (I believe) the appropriate Qt flags. That seemed to go without issue. When I try to build the simple test app listed here, the #include <marble/MarbleWidget.h> line gives a "file not found" error.
After the install I've ended up with the following:
A "marble" directory in my root user folder
A "Marble.app" file along with various other marble related files in the bin and include directories. However the Marble.app gives the following error on launch:
Dyld Error Message: Library not loaded:
#rpath/QtCore.framework/Versions/5/QtCore Referenced from:
/usr/local/Marble.app/Contents/MacOS/marble-qt Reason: image not
found
Binary Images:
0x7fff6a1f9000 - 0x7fff6a22c817 dyld (239.4) <7AD43B9B-5CEA-3C7E-9836-A06909F9CA56> /usr/lib/dyld
So a semi-solution: I used the Qt Creator "add Library" function and ended up with the following additions to the .pro file. I had to paste in the link to the lib since the dialog doesn't allow browsing of "usr/local/". Also, although I tried to link to the lib alias ("libmarblewidget-qt5.dylib"), the actual lib name is used.
macx: LIBS += -L$$PWD/../../../../../usr/local/lib/ -lmarblewidget-qt5.0.21.80
INCLUDEPATH += $$PWD/../../../../../usr/local/include
DEPENDPATH += $$PWD/../../../../../usr/local/include
I don't understand what this $$PWD/../../../../../ business is.
But it worked and I am able to run the example code at the link in my question.
I wish this install/build stuff wasn't so damned arcane. I've spent endless hours just trying to get things set up – really sucks the joy out of exploring this stuff and I can't say I really learned much of anything from it.
Update
So I cleaned out the "$$PWD" crap and the literal lib name and it works. Not sure what difference it makes – but there you go.
macx: LIBS += -L/usr/local/lib/ -lmarblewidget-qt5
INCLUDEPATH +=/usr/local/include
DEPENDPATH +=/usr/local/include
Either the build is faulty or you need a different version of Qt installed to run it. Usually the app has the Qt libraries that it needs wrapped up in the app itself. If it's not in there it will search your mac for it. The message says that QtCore can't be found in either place. If you look inside Google's Google Earth, you can see where the libraries are stored. You can also copy a version of QtCore into your Marble to see if it will work.
I created a C++ library project in Qt creator. After building the project I have the libMylib.so, .so.1, .so.1.0, .so.1.0.0, Makefile and mylib.o files. I added the library headers to my other project and added the path to my .pro file like this:
LIBS += "/home/peter/Workspace/build-Libtester-Desktop-Release/libMyLib.so"
When building the application I don't get no such file error, but when running it I get this:
/home/peter/Workspace/build-Libtester-Desktop-Debug/Libtester: error while loading shared libraries: libMyLib.so.1: cannot open shared object file: No such file or directory
which I can't understand, because it's right there next to the .so which it seem to find, because when the path is wrong I get a no such file or directory error when trying to build the project.
Could someone explain what I'm missing here?
Thanks for your time.
Fortunately, your problem has nothing to do with both Qt and Qt Creator. The error simply boils down to how shared libraries are searched by LD for dynamic linking on Unix OS family.
Today, I've answered similar question, have a look, please. This question was asked in regard to Mac OS X. However, Linux and Mac OS X are the same in the context of your problem. I've provided additional explanation for Linux at the bottom, so pay attention to it. "it's right there next to the .so" - you seem to have Windows background if you make this assumption, but it is wrong for Unix OS family altogether (as stated in the answer too). If you have further questions, just ask.
You are adding the library incorrectly. You are doing:
LIBS += "/home/peter/Workspace/build-Libtester-Desktop-Release/libMyLib.so"
instead of:
LIBS += -L"/home/peter/Workspace/build-Libtester-Desktop-Release" -lMyLib
The first version works on windows, but not linux.
Basically, you create a library, which will be named "libMyLib.so", and then you specify the path to its folder, prepended by "-L" and then do "-lMyLib" at the end, note that it's not "-llibMyLib", but just "-lMyLib", despite the fact that the .so name is "libMyLib".
Look here: https://wiki.qt.io/How_to_create_a_library_with_Qt_and_use_it_in_an_application for more info.
I have an library (flam3) that depends on a few utility libraries from unix (xml2, jpeg, png, z) and I am trying to make an application on Lion that uses it. I am building with the latest Xcode and when I try to link with the libraries from fink, macports, and homebrew I get the same error:
ld: warning: ignoring file /opt/local/lib/libxml2.a, file was built
for archive which is not the architecture being linked (i386)
and the libraries look different from ones that work:
bash-3.2$ file /sw/lib/libxml2.a
/sw/lib/libxml2.a: current ar archive random library
by comparision
bash-3.2$ file ~/Documents/FLAM3/libflam3.a
/Users/spot/Documents/FLAM3/libflam3.a: Mach-O universal binary with 2
architectures
/Users/spot/Documents/FLAM3/libflam3.a (for architecture x86_64):
current ar archive random library
/Users/spot/Documents/FLAM3/libflam3.a (for architecture i386):
current ar archive random library
that's the library that I compiled with Xcode.
Is there any way to get Xcode to accept this library? Is there any way to get fink/macports/homebrew to generate a library that works with Xcode? Seems like I am "doing it wrong" as these projects would all be useless if everyone had this problem.... but I don't feel like I've done anything unusual. Help?
The problem is that your libxml2.a is not built as "Universal binary". I.e. it doesn't contain all necessary architectures (In your case I believe it is i386). You need to ask fink, macports, or homebrew to build/download/install library with all necessary platforms. I know that macports has such flag (I don't remember how it's called).
The "file" command list all available architectures for .a file only when the file is trully universal (contains two or more of ppc, i386, x86_64), otherwise it only shows the vanilla "ar archive..." message. That confirms your libxml2.a has only one architecture.
The problem is not in Xcode or Lion. Possibly the default link architecture on Lion changed.
So I have installed the QtSDK on my Windows 7 64 bit machine. However, it seems like when I try to run a simple program like hello world such as:
#include <iostream>
int main(....) {
std::cout << "Hello World\n";
}
My program first gets the error:
CreateProcess: No Such file or directory.
So what I did was I went to this link here:
http://wiki.codeblocks.org/index.php?title=Installing_MinGW_with_Vista
And I first tried to add the directory to the
PATH: C:\MinGW\libexec\gcc\mingw32\MinGW-Version
(my directory is slightly different but follows same idea)
where MinGW-Version is the Version of MinGW you are using
So now that got rid of that error but now I get the error:
iostream: No such file or directory
So now I add the path where the iostream library is and that fixes that error but then I get all these other errors where it can't find other standard C++ libraries such as stddef.h or stdio.h etc. So it seems as if the C++ libraries cannot be linked to. I have tried various other things such as including C:\MinGW\bin in my path and have tried uninstalling and reinstalling Qt. Also I have checked that Qt is using the right gcc compiler by going to Tools->Options->Toolchains in Qt Creator.
It seems that the linking to C++ libraries is not correct for some reason. Could anyone help me or guide me as to why this may be happening and how to fix this?
I'm not sure why it's not working, so I'll just tell you how my environment is set up. I don't think you need to add any library paths to the system path. You should only need to add C:\MinGW\bin.
So get rid of everything except for that. Also, are you setting this through cmd or control panel? If doing it in the control panel, make sure you are putting it in the "Path" variable not "PATH" -> the former is in the lower box. I've had problems before using "PATH" in the upper box - not sure what the difference is to be honest.
The QtSDK installation usually install the mingw compiler for you in ...\QtSDK\mingw. The libraries and dlls in ...\QtSDK\Desktop\Qt\4.7.3\mingw were compiled with this compiler. The mingw compiler you installed to c:\MinGW may be a different version than that. If you want to use this compiler you would have to recompile the Qt libraries.
C++ librairies in Qt.
Go to this URL http://doc.qt.digia.com/qtcreator-2.4/creator-overview.html for how to.
It seems (I did not try it, yet) that other librairies can be easily linked to a Qt Project.
This could solve the problem.
Pythagooric