问题
I am trying to create a shared library libddv3djava.so
I compile sources for libddv3djava.so like so:
~/Programming/intellijprojects/ddv3dbindingstest/src $ g++ -c -Wall -Werror -I. -I /usr/lib/jvm/java-8-oracle/include/ -I /usr/lib/jvm/java-8-oracle/include/linux/ -fpic com_ddv3d_Ddv3dBinding.cpp
Creating libddv3djava.so:
~/Programming/intellijprojects/ddv3dbindingstest/src $ g++ -shared -o libddv3djava.so com_ddv3d_Ddv3dBinding.o
When I do ldd on libddv3djava.so:
~/Programming/intellijprojects/ddv3dbindingstest/src $ ldd libddv3djava.so statically linked
Problem:
It say's libddv3djava.so is statically linked. I created libddv3djava.so with -shared so this makes me confused.
Question:
Why does ldd output statically linked, when libddv3djava.so isn't statically linked?
Additional info:
I'm not sure if the following is of any relevance, but it could be; libddv3djava.so is dependent on another shared library I created called libddv3d.so. Basically libddv3djava.so is a JNI-wrapper around libddv3d.so. Posting sources:
com_ddv3d_Ddv3dBinding.h:
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_ddv3d_Ddv3dBinding */
#ifndef _Included_com_ddv3d_Ddv3dBinding
#define _Included_com_ddv3d_Ddv3dBinding
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: com_ddv3d_Ddv3dBinding
* Method: initialize
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_ddv3d_Ddv3dBinding_initialize
(JNIEnv *, jobject);
/*
* Class: com_ddv3d_Ddv3dBinding
* Method: sendDrawableData
* Signature: (FFFFFFFI)V
*/
JNIEXPORT void JNICALL Java_com_ddv3d_Ddv3dBinding_sendDrawableData
(JNIEnv *, jobject, jfloat, jfloat, jfloat, jfloat, jfloat, jfloat, jfloat, jint);
/*
* Class: com_ddv3d_Ddv3dBinding
* Method: finished
* Signature: ()Z
*/
JNIEXPORT jboolean JNICALL Java_com_ddv3d_Ddv3dBinding_finished
(JNIEnv *, jobject);
/*
* Class: com_ddv3d_Ddv3dBinding
* Method: cleanup
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_ddv3d_Ddv3dBinding_cleanup
(JNIEnv *, jobject);
#ifdef __cplusplus
}
#endif
#endif
com_ddv3d_Ddv3dBinding.cpp:
#include <jni.h>
#include <ddv3d.h>
#include "com_ddv3d_Ddv3dBinding.h"
JNIEXPORT void JNICALL Java_com_ddv3d_Ddv3dBinding_initialize(JNIEnv *env, jobject thisObj)
{
ddv3d::initialize();
return;
}
JNIEXPORT void JNICALL Java_com_ddv3d_Ddv3dBinding_sendDrawableData(JNIEnv *env, jobject thisObj,
jfloat positionX, jfloat positionY, jfloat positionZ,
jfloat angle,
jfloat rotationAxisX, jfloat rotationAxisY, jfloat rotationAxisZ,
jint type)
{
ddv3d::sendDrawableData(positionX, positionY, positionZ,
angle,
rotationAxisX, rotationAxisY, rotationAxisZ,
type);
return;
}
JNIEXPORT jboolean JNICALL Java_com_ddv3d_Ddv3dBinding_finished(JNIEnv *env, jobject thisObj)
{
return ddv3d::finished();
}
JNIEXPORT void JNICALL Java_com_ddv3d_Ddv3dBinding_cleanup(JNIEnv *env, jobject thisObj)
{
ddv3d::cleanup();
return;
}
回答1:
ldd shows which shared libraries a library or executable needs. In this case none, because libddv3djava.so is statically linked.
The compiler flag -fpic and linker flag -shared enables libddv3djava.so to be used as a shared object which is something else.
To make libddv3djava.so depend on the shared library file libddv3d.so it must be added on to the linker command.
g++ -shared -o libddv3djava.so -lddvd3d com_ddv3d_Ddv3dBinding.o
If libddv3d.so isn't found you can add extra path's to search using -L flag.
来源:https://stackoverflow.com/questions/24491381/ldd-outputs-statically-linked-on-a-shared-library