I have tried dynamic linker option also but still, dlopen() fails.
arm-none-linux-gnueabi-ld --dynamic-linker /system/bin/linker -T
armelf_linux_eabi.xsc -shared -o libNativeCpp.so NativeCpp.o
Also I have looked at object file below --
arm-none-linux-gnueabi-nm NativeCpp.o
U _GLOBAL_OFFSET_TABLE_
0000028c t _GLOBAL__I__Z11ret_mul_cppii
00000000 T _Z11ret_mul_cppii
000001e0 t _Z41__static_initialization_and_destruction_0ii
U _ZNKSs4sizeEv
U _ZNKSsixEj
U _ZNSt8ios_base4InitC1Ev
U _ZNSt8ios_base4InitD1Ev
00000030 t _ZSt17__verify_groupingPKcjRKSs
00000000 W _ZSt3minIjERKT_S2_S2_
00000000 b _ZSt8__ioinit
U __aeabi_atexit
U __aeabi_unwind_cpp_pr0
U __aeabi_unwind_cpp_pr1
U __dso_handle
Object file itself has many symbols that I did not find in /system/lib.
When I try to hit ldd for this library, I get message as "not a dynamic
executable".
I have tried to find _ZNKSs4sizeEv in /usr/lib and this symbol matches many
libraries including standard c++ library.
objdump -T /usr/lib/gcc/i486-linux-gnu/4.1/libstdc++.so | grep _ZNKSs4sizeEv
000931b0 w DF .text 0000000d GLIBCXX_3.4 _ZNKSs4sizeEv
I can also see these symbols in the library in the arm toolchain arm-2008q1.
I am not able to understand why these symbols are not there in /system/lib.
Do we need separate compiler for this, as there is no standards for mangling
the names ?
Regards
Ashutosh
On Mon, Jun 2, 2008 at 10:45 AM, Diluka Moratuwage <[EMAIL PROTECTED]> wrote:
>
> Hi,
> You might have missed the linker option. Please make sure that your
> library doesn't use the default linux linker; /lib/ld-linux.so.2 , if
> it's used then you are in trouble. You have to use the custom linker and
> build your library from scratch and check regularly for the
> functionality. Most of the default C/C++ stuff are missing in the
> Android platform, so you might spend a whole lot of time and then
> finally get into trouble. I'm writing you because same thing happened to
> me. Please make sure if there is a list of available functions in the
> platform as well, if you are using some functions from the Android
> platform.
>
> I'm quite sure this problem is due to the incompatibility of the
> libraries. So, I advise you to hit ldd, and check the libraries it loads.
>
> Thanks,
> Diluka.
>
> Ashutosh wrote:
> > Hello All,
> >
> > I am trying to call an API in a C++ library libNativeCpp.so and
> > Android does not load it. The error is --
> >
> > DEBUG/dalvikvm(1185): LOADING path /system/lib/libNativeCpp.so
> > 0x4001f6e8
> > INFO/dalvikvm(1185): Unable to dlopen(/system/lib/libNativeCpp.so):
> > Cannot find library
> >
> > I have used arm-2008q1/bin/arm-none-linux-gnueabi-gcc, arm-2008q1/bin/
> > arm-none-linux-gnueabi-g++ for compilation.
> >
> > How I tried to do that is explained below --
> >
> > I have gone through the URL
> >
> http://davanum.wordpress.com/2007/12/09/android-invoke-jni-based-methods-bridging-cc-and-java/
> > and have been able to run the program successfully.
> >
> > After this I have made some changes in the source code.
> > 1) I have changed signature of function add() in class NativeAdd. It
> > is now 'public static native long add(int a, int b)'.
> > 2) I have changed function Java_org_apache_NativeAdd_add() in file
> > org_apache_NativeAdd.c. It now looks like --
> >
> > #include "org_apache_NativeAdd.h"
> >
> > JNIEXPORT jlong JNICALL Java_org_apache_NativeAdd_add
> > (JNIEnv *env, jclass c, jint a, jint b)
> > {
> > long aa;
> > aa = ret_mul(a, b);
> > // aa = ret_mul_cpp(a, b);
> > return aa;
> > }
> >
> > The function ret_mul() is written in another file called NativeC.c.
> > Content of file is --
> > #include <stdio.h>
> > int ret_mul(int a, int b)
> > {
> > return (a * b);
> > }
> >
> > Now I compile these files and create libraries --
> >
> > arm-none-linux-gnueabi-gcc -I /usr/java/jdk1.6.0_04/include -I /usr/
> > java/jdk1.6.0_04/include/linux -fpic -c org_apache_NativeAdd.c
> > arm-none-linux-gnueabi-ld -T armelf_linux_eabi.xsc -shared -o
> > libNativeAdd.so org_apache_NativeAdd.o
> >
> >
> > arm-none-linux-gnueabi-gcc -fpic -c NativeC.c
> > arm-none-linux-gnueabi-ld -T armelf_linux_eabi.xsc -shared -o
> > libNativeC.so NativeC.o
> >
> > The file armelf_linux_eabi.xsc is modified as per the suggestion on
> > the URL
> http://honeypod.blogspot.com/2007/12/shared-library-hello-world-for-android.html
> > .
> >
> > I pushed the library to android environment --
> > adb push libNativeAdd.so /system/lib
> > adb push libNativeC.so /system/lib
> >
> > I have created an android project CallNative1 and in file
> > NativeAdd.java, I am loading libraries as below --
> > System.loadLibrary("NativeC");
> > System.loadLibrary("NativeAdd");
> >
> > When I run the project CallNative1, it prints the result as
> > multiplication of two integers.
> >
> > Now I write the same ret_mul() function in NativeCpp.cpp. Content of
> > NativeCpp.cpp is --
> >
> > #include <iostream>
> > int ret_mul_cpp(int a, int b)
> > {
> > return (a * b);
> > }
> >
> > Compiled it --
> >
> > arm-none-linux-gnueabi-g++ -fpic -c NativeCpp.cpp
> > arm-none-linux-gnueabi-ld -T armelf_linux_eabi.xsc -shared -o
> > libNativeCpp.so NativeCpp.o
> >
> > Pushed the library --
> >
> > adb push libNativeCpp.so /system/lib
> >
> > Now loading libraries as below --
> >
> > System.loadLibrary("NativeCpp");
> > System.loadLibrary("NativeAdd");
> >
> >
> > When I run CallNative1 again I can see below errors in logcat.
> >
> > DEBUG/dalvikvm(1185): LOADING path /system/lib/libNativeCpp.so
> > 0x4001f6e8
> > INFO/dalvikvm(1185): Unable to dlopen(/system/lib/libNativeCpp.so):
> > Cannot find library
> >
> >
> > Below are the information about symbols in both the libraries --
> >
> >
> > arm-none-linux-gnueabi-nm libNativeC.so
> > 00000244 a _DYNAMIC
> > 0000029c a _GLOBAL_OFFSET_TABLE_
> > 000002a8 A __bss_end__
> > 000002a8 A __bss_start
> > 000002a8 A __bss_start__
> > 000002a8 D __data_start
> > 000002a8 A __end__
> > 00000244 A __exidx_end
> > 00000244 A __exidx_start
> > 000002a8 A _bss_end__
> > 000002a8 A _edata
> > 000002a8 A _end
> > 00000214 T ret_mul
> >
> >
> > arm-none-linux-gnueabi-nm libNativeCpp.so
> > =========================================
> > 000007a0 a _DYNAMIC
> > 00000840 a _GLOBAL_OFFSET_TABLE_
> > 000006ec t _GLOBAL__I__Z11ret_mul_cppii
> > 00000460 T _Z11ret_mul_cppii
> > 00000640 t _Z41__static_initialization_and_destruction_0ii
> > U _ZNKSs4sizeEv
> > U _ZNKSsixEj
> > U _ZNSt8ios_base4InitC1Ev
> > U _ZNSt8ios_base4InitD1Ev
> > 00000490 t _ZSt17__verify_groupingPKcjRKSs
> > 00000708 W _ZSt3minIjERKT_S2_S2_
> > 00000868 b _ZSt8__ioinit
> > U __aeabi_atexit
> > U __aeabi_unwind_cpp_pr0
> > U __aeabi_unwind_cpp_pr1
> > 0000086c A __bss_end__
> > 00000868 A __bss_start
> > 00000868 A __bss_start__
> > 00000868 B __data_start
> > U __dso_handle
> > 0000086c A __end__
> > 0000079c A __exidx_end
> > 00000774 A __exidx_start
> > 0000086c A _bss_end__
> > 00000868 A _edata
> > 0000086c A _end
> >
> > I have gonr through the discussion at
> >
> http://groups.google.com/group/android-internals/browse_thread/thread/780ba5316409cf5d
> > and I also feel that the problem is with unresolved symbols.
> >
> > I pulled whole /system directory from Android and treid to grep one of
> > the undefined symbols _ZNKSs4sizeEv, in /system but could not find it.
> > But if I grep them in arm-2008q1 directory I find many matches.
> >
> > grep -r _ZNKSs4sizeEv arm-2008q1/*
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/armv4t/usr/lib/
> > libstdc++.so.6 matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/armv4t/usr/lib/
> > libstdc++.a matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/armv4t/usr/lib/
> > libstdc++.so.6.0.9 matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/armv4t/usr/lib/
> > libstdc++.so matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/thumb2/usr/lib/
> > libstdc++.so.6 matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/thumb2/usr/lib/
> > libstdc++.a matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/thumb2/usr/lib/
> > libstdc++.so.6.0.9 matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/thumb2/usr/lib/
> > libstdc++.so matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/usr/lib/libstdc+
> > +.so.6 matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/usr/lib/libstdc++.a
> > matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/usr/lib/libstdc+
> > +.so.6.0.9 matches
> > Binary file arm-2008q1/arm-none-linux-gnueabi/libc/usr/lib/libstdc+
> > +.so matches
> >
> > I don't know why these symbols are not there in /system/lib at
> > android. Statically linking a C++ library is not advisable.
> >
> > Could anyone please suggest me how do I go about it ?
> >
> > Thanks
> > Ashutosh
> >
> >
> >
> > >
> >
> >
>
>
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Android Internals" group.
To post to this group, send email to android-internals@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/android-internals?hl=en
-~----------~----~----~----~------~----~------~--~---
