问题
I am trying to use libjpeg in my jni program on Ubuntu. I built my c++ code with g++, with libjpeg added as a library. I tried both linking the shared version and the static version, but both of them cause "undefined symbol: jpeg_std_error" error in Java (while my c++ codes worked fine). I did use "extern "C"" for the libjpeg header.
Here is my build script with static libjpeg.a (libjpeg built as part of libjpeg-turbo and renamed libjpeg151.a):
outputName=$libDir/libMyLib.so
g++ -DNDEBUG -O3 -march=native -mfpmath=sse -Ofast -flto -funroll-loops -fPIC -w -shared -o $outputName \
-I$jdkDir/include -I$jdkDir/include/linux -std=c++11 -pthread \
-L$libDir/SEngineLibraries/libjpegTurbo151Linux -ljpeg151 \
myCode.cpp
and the one with shared version (with libjpeg-turbo deb installed)
outputName=$libDir/libMyLib.so
g++ -DNDEBUG -O3 -march=native -mfpmath=sse -Ofast -flto -funroll-loops -fPIC -w -shared -o $outputName \
-I$jdkDir/include -I$jdkDir/include/linux -std=c++11 -pthread \
-ljpeg \
myCode.cpp
In my Java code, when running to codes using libjpeg, this error pops out:
symbol lookup error: /myDir/lib/libMyLib.so: undefined symbol: jpeg_std_error
Here is something might be suspicious: no matter I include the line referencing libjpeg in the build script or not, the .so library has a constant size.
回答1:
It is strange that it doesn't work with the static version of the library, because then there should not be an extra linked jpeg lib. Few options which you can try:
- specify
-Wl,--no-undefinedto print error for undefined references in the .so (by default the linker doesn't fail when shared library has unresolved symbols) - try
ldd <sharedlib>to see unresolved dependencies - for shared library linking, try adding RPATH:
-Wl,-rpath,/path/to/jpeglib_so_dir- this inserts the path to the libjpeg.so inside the shared library so that it can be resolved without being in the ldd path
来源：https://stackoverflow.com/questions/40737937/linking-libjpeg-library-to-a-shared-library-and-libjpeg-is-undefined-at-runtime