I have a plugin application (.DLL) that links dynamically to multiple other QT DLLs.
When the plugin is loaded in the third party software, it fails to find the dependencies which are located exactly in the same folder as the plugin DLL.
The structure looks like this:
myplugin.dll
platforms\
qwindowsd.dll
QtQml\
qmlplugind.dll
...
The executable of the software that loads the Plugin is installed under C:/Program Files/MySoftware/Application.exe
Weirdly enough, when I copy the contents of my packaged plugin (dlls and its dependencies) directly into the software's executable directory, next to the executable, it works like a charm, and the plugin is able to find all its DLLs in that directory. So my guess is the DLL lookup isn’t appropriate?
This might relate to this: Search path for a DLL referenced by a plug-in DLL
but the solution to load every QT dll explicitly seems wrong.
Any help on that matter would be appreciated. Thanks
EDIT:
I tried to put the path to where the DLLs are explicitly in the PATH variable without success.
Related
I am developing a Qt 5.0 dekstop application using mingw47. I use QtMultimedia in this application to record and play audio. I have tested it for debug and it works. When I try to build it for release and run the executable file, I can't play the audio file that can normally be played in debug mode. I've added the following dlls before running the executable file:
D3D_Compiler_43.dll,
icudt49.dll,
icuin49.dll,
icuuc49.dll,
libEGL.dll,
libgcc_s_sjlj-1.dll,
libGLESv2.dll,
liblibmpeg2_plugin.dll,
libstdc++-6.dll,
libwinpthread-1.dll,
Qt5Core.dll,
Qt5Gui.dll,
Qt5Multimedia.dll,
Qt5Network.dll,
Qt5Widgets.dll,
Qt5Xml.dll,
plugins/platforms/(all dlls),
plugins/mediaservice/(all dlls),
plugins/playlistformats(all dlls)
What is probably wrong? Or what other dlls am I missing?
UPDATE: Use windeployqt.exe! It works really well.
http://doc.qt.io/qt-5/windows-deployment.html#the-windows-deployment-tool
The simplest way to use windeployqt is to add the bin directory of
your Qt installation (e.g. ) to the PATH variable and then
run:
windeployqt <path-to-app-binary>
While you are running your application in release mode (when it is working, ran from inside Qt Creator), execute depends.exe and point it at the application.
Make note of all the dlls that are referenced from your Qt folder.
Alternate way if you want to take more time with it:
You can figure it out by hand by trying to delete files because Windows won't let you delete a folder or a dll while it is in use. So you could go and make a back up of your Qt installation, and then run you application, make sure it has connected to all the dll's it is going to use, and then try to delete folders and files in your Qt installation. Windows won't let you delete files that are in use by your release.
Also here is how Windows resolves dll's if you wanted to know:
http://msdn.microsoft.com/en-us/library/7d83bc18(v=vs.80).aspx
EDIT: Also, you don't need to make the folder called plugins in your exe directory. It should be something like this:
Qt 4.x:
./myexe.exe
./QtCore.dll
./imageformats/qjpegd4.dll // Note: there isn't a "plugins" folder here
Qt 5.x: (take from here)
The executable ./plugandpaint.exe
The Basic Tools plugin ./plugins/pnp_basictools.dll
The ExtraFilters plugin ./plugins/pnp_extrafilters.dll
The Qt Windows platform plugin ./platforms/qwindows.dll
The Qt Core module ./Qt5Core.dll
The Qt GUI module ./Qt5Gui.dll
The Qt Widgets module ./Qt5Widgets.dll
Also run qDebug() << QApplication::libraryPaths(), and make note of paths that are searched for dlls on your computer.
Hope that helps.
All of the DLL's in your list that have their import libraries linked to the application will be automatically loaded by the OS. If any of them are missing you will get a dialog telling you which DLL it failed to load. The only ones that look like they might be loaded manually by the application are the plugins. Make sure you are telling the QT multimedia system to load the them. Also make sure you check the error codes returned by the multiamedia manager.
Given your recent comment that the audio plays in debug mode but not in release mode is a good indication you have put the plugin DLL's in the wrong place. When you launch your application from Explorer or the command line the plugins directory needs to be in the same directory as the application. Your directory structure should look something like below
c:\stackoverflow\myprogram.exe
c:\stackoverflow\plugins\platforms\(all dlls)
c:\stackoverflow\plugins\mediaservice\(all dlls)
c:\stackoverflow\plugins\playlistformats\(all dlls)
c:\stackoverflow\D3D_Compiler_43.dll
c:\stackoverflow\icudt49.dll
... other dll's here...
c:\stackoverflow\Qt5Network.dll
c:\stackoverflow\Qt5Widgets.dll
c:\stackoverflow\Qt5Xml.dll
I've found the answer. Now my application works. It can play audio file while running the executable file.
Although not listed in depends.exe, we should add the following dlls when using QMediaPlayer:
Qt5MultimediaWidgets
Qt5OpenGL
Here is the reference: https://bugreports.qt-project.org/browse/QTBUG-30172
Static linking is not an option.
Let's say that I have an executable that relies on a DLL. One solution is to ship the DLL in the same folder as the executable. Now let's say that I need to inject a DLL into a process that relies on a DLL. Because the DLL is injected, where would I put the DLLs that it relies on? In the same folder? Or in the directory of the process that is injected to?
DLLs depending on one or more other DLLs is not something special. Even a trivial DLL will have dependencies on Windows shared components which are residing in other DLLs. A good example of these "shared components" would be Kernel32.dll and the CRT DLL such as MSVCR80.DLL etc.
You can find out exactly which other DLLs your DLL or EXE requires on by invoking the Dependency Walker. To do that, just run depends.exe from a Visual Studio Command Prompt and drag-and-drop the DLL of interest into the Window that appears. In case you don't have dependency walker available, you can download it from the above link.
I'm not sure of the DLL injection stuff, but it should generally be sufficient if you place all your (other DLL) dependencies in the same folder as your DLL, which would be the folder in which the EXE loading these DLLs resides.
Eg: If C:\test\foo.exe requires bar.dll (which in turn requires baz.dll, assuming baz.dll is not a standard windows shared component), then you would place both bar.dll and baz.dll in C:\test.
There is a lot more to how the OS determines which DLL to load, since multiple versions of the same DLL may exist at various locations and MSDN has a helpful article on the search order for dynamic linked libraries.
Hi Im trying to execute my .exe file from the debug folder.
Now before you go telling me about all the other related articles Ive looked at them all and their solutions are not helping with my problem.
Ok first off Im using Qwt library and trying to create a set of gauges. I got a gauge working now I need to get it to execute from the .exe.
Ive tried adding the platforms folder in with my directory and adding the windowsd.dll and minimald.dll but still does not work.
Please advise on any course of action this had got me stumped.
Also one post says to create a qt.conf file and place it in the directory but I cant find out how to make a .conf file.
UPDATE
the error reads
debug error!
Program:
...build-Desktop_Qt_5_0_1_MSVC2010_32bit-Debug\debug\gauge.exe
Module:5.0.1
File: kernel\qguiapplication.cpp
Line:781
Failed to load platform plugin "windows". Available platforms are:
minimal
Windows
When deploying Qt on Windows, you have to copy over a number of the dlls from the bin folder of the Qt directory.
On my system it is:
C:\Qt\4.8.4\bin
After you copy over all the required dll's from there, like QtCore4.dll and QtGui4.dll, if you are using any additional plugins like phonon or jpeg support, you need to copy those dll's over from the plugins folder:
C:\Qt\4.8.4\plugins
For example I make a folder in the folder with my exe called imageformats and I put qjpeg4.dll in that folder.
As far as Qwt works, you probably need to do a similar process to expose those dll's to your exe, and put them in the same folder as your exe.
The dll's listed above are for the "release" build of your exe. If you are running the "debug" version, it will look for <dll_name>d.dll.
The reasoning for putting in those paths has to do with the library search order that windows uses.
Qt, Phonon and multimedia codecs: how to bundle them?
http://msdn.microsoft.com/en-us/library/windows/desktop/ms682586%28v=vs.85%29.aspx
http://qt-project.org/doc/qt-4.8/deployment-windows.html#creating-the-application-package
Hope that helps.
If you have several executable and\or you don't want to copy plugins by hand, you can create a qt.conf file with the path to the plugin directory
[Paths]
Plugins = PATH_TO_QT_DIR/plugins
You need to place the qt.conf file where the executable is.
More information at http://doc.qt.io/qt-5/qt-conf.html
In Visual Studio, you create a .dll project and it creates a .dll and .lib files. You link statically to the .lib, and if the .dll is in the same folder as the .exe, everything works.
I suspect that everything would also work if the .dll was in System32 or any other PATH folder (confirm or correct, please).
But here's the question: I want my exe to find the .dll in ./DLLS/ folder, that is, if my exe is in ....../MyApp/MyApp.exe then it should look for the .dll in ...../MyApp/DLLS/MyDll.dll. I DO NOT want to include the DLLS folder in path. Is there any way I can do this?
Please note that I do not wish to use LoadLibrary explicitly, so I can't specify the path there.
Thanks in advance for any help.
Here is the default sequence which Win32 applications go through when looking for a DLL:
http://msdn.microsoft.com/en-us/library/7d83bc18(VS.80).aspx
So according to this, another approach might be to call SetCurrentDirectory or SetDllDirectory. But in order for this to work you have to use the Delay Loaded Library functionality (you specify that in Project Settings in Visual Studio). Delay loaded library means that the DLL is loaded only at the moment when the program needs it, not automatically at the programs' startup.
You could use SetDllDirectory for this. The loader will use the additional directory you specify when loading libraries. There can only be one additional directory, however, so you need to make sure that there aren't other calls to this at a later point in your application, otherwise the directory you specify will be ignored.
If that API does not allow relative directories (I'm not sure), you could always call GetModuleFileName with a NULL first parameter to get the file name of the currently executing program. With a little string manipulation, you can get the absolute path to your DLLs folder.
In a Project of mine, I use a Delphi Application which dynamically loads a wrapper DLL (exporting C-Style functions) which in turn is statically link against a bunch of 3rd party DLLs.
It works fine on my test machines, but on my customers computer it failed to initialize with an error Message like "Couldn't find entrypoint _somefunction#4AKKZ in TMYlibrary.dll".
After some investigation with sysinternal's process monitor, I realized that Windows would look fror DLLs in windows/sytem32 first, so if a DLL named similar to my DLL was present in system32, windows would pick that one and try to find my function entry points in it - which would fail.
Do you know of a possiblity to change windows' DLL the searching behaviour?
Additional Information
[Update] The .exe file is located on the top level of the application's folder tree.
The Wrapper and the 3rd-party-DLLs ar e both located in the Subfolder /bin of my apps Folder
Dev platform is windows XP/7, using VS2008 for the dlll and Delphi 2010 for the application
I found another solution myself:
SetDllDirectory adds an additional search path to the list of locations to look at.
From http://msdn.microsoft.com/en-us/library/ms686203%28v=VS.85%29.aspx
After calling SetDllDirectory, the DLL search path is:
The directory from which the application loaded.
The directory specified by the lpPathName parameter.
The system directory. Use the GetSystemDirectory function to get the
path of this directory. The name of
this directory is System32.
The 16-bit system directory. There is no function that obtains the
path of this directory, but it is
searched. The name of this directory
is System.
The Windows directory. Use the GetWindowsDirectory function to get
the path of this directory.
The directories that are listed in the PATH environment variable.
(maybe i should do my googling before I post on SO ;)
Ship the DLL in your program's folder. (same as the exe file).
Then Windows should try your version first.