qt does not try to find a 3rd party lib even though its location is specified

jsulm

What do you actually mean if you say "qt does not try to find a 3rd party lib"?
Is it not passed to the linker? Can you check in the compiler output whether it is?
Does this library have the same architecture (32bit vs. 64bit)?

asanka424

@ohuohuo Yes. I didn't know that happened. Are you one Mac, I think in mac you have to include your framework. I will check and let you know. (don't have a Mac right now)

kenchan

Don't you need something like
LIBS += -Lpathtomylib
to pass library paths to the linker?

KeithS

@ohuohuo

Take a look at the Makefile that qmake creates. Is the missing shared lib in it? If not, then there is something wrong with your .pro file.

Also check the date modified of the Makefile in case for some reason it's not getting updated.

ohuohuo

@jsulm So "qt does not try to find a 3rd party lib"? means , when I use strace tool in ubuntu12.04, I checked all the open() calls the system made, I didn't find any open() call to libMPCtrl.so file. If it was not passed to the linker, how the other libs were been found? they are in the same folder path, and in the same pro file. I just don't understand

ohuohuo

@asanka424 No, i'm using ubuntu12.04, 32bit

asanka424

Can you post compile error you get?

ohuohuo

@asanka424 well, there's no compile error... I guess it's a runtime problem

ohuohuo

@KeithS Thanks. I checked out the makefile, it seems nothing wrong. Any ideas?
CC = gcc
CXX = g++
DEFINES = -DQT_WEBKIT -DQT_OPENGL_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED
CFLAGS = -pipe -g -Wall -W -D_REENTRANT $(DEFINES)
CXXFLAGS = -pipe -g -Wall -W -D_REENTRANT $(DEFINES)
INCPATH = -I/usr/share/qt4/mkspecs/linux-g++ -I../RemoteClient -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4/QtOpenGL -I/usr/include/qt4 -I../RemoteClient/include -I../RemoteClient/Configuration/Public -I../RemoteClient/lib -I../RemoteClient -I/usr/X11R6/include -I. -I. -I../RemoteClient -I.
LINK = g++
LFLAGS =
LIBS = $(SUBLIBS) -L/usr/lib/i386-linux-gnu -L/usr/X11R6/lib -L./lib/ -Wl,-rpath=./lib/,-rpath=./ -lhcnetsdk -lPlayCtrl -lMPCtrl -lQtOpenGL -lQtGui -lQtCore -lGL -lpthread
AR = ar cqs
RANLIB =
QMAKE = /usr/bin/qmake-qt4
TAR = tar -cf
COMPRESS = gzip -9f
COPY = cp -f
SED = sed
COPY_FILE = $(COPY)
COPY_DIR = $(COPY) -r
STRIP = strip
INSTALL_FILE = install -m 644 -p
INSTALL_DIR = $(COPY_DIR)
INSTALL_PROGRAM = install -m 755 -p
DEL_FILE = rm -f
SYMLINK = ln -f -s
DEL_DIR = rmdir
MOVE = mv -f
CHK_DIR_EXISTS= test -d
MKDIR = mkdir -p

ohuohuo

@kenchan I changed it to
unix{
LIBS += -L./lib/ -Wl,-rpath=./lib/,-rpath=./ -lhcnetsdk -lPlayCtrl -lMPCtrl
}
still cannot find it. any ideas?

kenchan

not really... on MAC OS X I generally put my -LIBS += -Lsomepath and my LIBS += -lsomelib on separate lines. That is just to make it easier to change though.
I do find that the link order is important for some libraries on UNIX boxes (like Mac OS X).
Are you using a Mac or something else?
I might be useful to see what you get in the compile output window.

ohuohuo

@kenchan no, it's on Ubuntu12.04 32bit. The compile output is:

23:39:32: Running build steps for project RemoteClient...
23:39:32: Configuration unchanged, skipping qmake step.
23:39:32: Starting: "/usr/bin/make" -w
make: Entering directory /home/.../QtWorkspace/RemoteClient-build-desktop-Qt_4_8_1_in_PATH__System__Debug' make: Nothing to be done for first'.
make: Leaving directory `/home/.../QtWorkspace/RemoteClient-build-desktop-Qt_4_8_1_in_PATH__System__Debug'
23:39:32: The process "/usr/bin/make" exited normally.

kenchan

hmm not very useful since you are not rebuilding...
now what does it look like when you do this...
clean
run qmake
build or rebuild just to be sure :-)

ohuohuo

@kenchan yeah, I rebuilt that , but it's large file which part you think would be most interesting?
output of just ran qmake:
00:01:05: Running build steps for project RemoteClient...
00:01:05: Starting: "/usr/bin/qmake-qt4" /home/.../QtWorkspace/RemoteClient/RemoteClient.pro -r -spec linux-g++ CONFIG+=debug CONFIG+=declarative_debug
00:01:05: The process "/usr/bin/qmake-qt4" exited normally.

ohuohuo

@kenchan I looked at the output of ldd, it seems that this program does not depend on libMPCtrl.so and libPlayCtrl.so files. And after I changed to unix{
LIBS += -L./lib/ -Wl,-rpath=./lib/,-rpath=./ -lhcnetsdk -lPlayCtrl -lMPCtrl
}, I can neither find libMPCtrl.so nor libPlayCtrl.so.

kenchan

@ohuohuo good point, i guess you mean it is a large project with many source files?
OK how about cutting a bit that shows the last couple of compiled modules and then the linker stuff up to the end, or is that still too much?

kenchan

so if you don't link to them it will not run, is that the problem?

KeithS

@ohuohuo

"it seems that this program does not depend on libMPCtrl.so and libPlayCtrl.so files"

So maybe I'm missing something, but from what you have said it seems your app does not depend on the shared libraries hence that's why it doesn't try and load them? What exactly is the error message you are getting when you try and run the app?

btw I think your LIBS line in the .pro file is not quite right:

unix{
LIBS += -L./lib/ -Wl,-rpath=./lib/,-rpath=./ -lhcnetsdk -lPlayCtrl -lMPCtrl
}

The rpath stuff does not belong here, it should be in QMAKE_LFLAGS e.g I have:

QMAKE_LFLAGS += -rdynamic
QMAKE_LFLAGS += '-Wl,-rpath,'$$ORIGIN/../lib',-z,origin'
QMAKE_LFLAGS_RPATH=

which makes the executable look in <executable_dir>../lib for the shared libs to be loaded at runtime. Then for 3rd party libs I use:

LIBS += -L<path_to_lib> -l<lib_name>

You don't need a trailing '/' after the -L path.

asanka424

If you don't get any compile errors or runtime errors and your only concern is those .so files are not being read while your program is in run, my guess is that your program is not using those library functions at all

ohuohuo

@asanka424 exactly, so the question is how can I load these libs, I must use functions in them