Can't find libdl

[death_jester]

Hi Developers,
I have a very strange problem. I'm using a library which uses the
libdl to call the function dladdr. Now everytime I try to build my
application using this library it complains about

undefined reference to `dladdr'
collect2: ld returned 1 exit status

In my Android.mk file I added the line

LOCAL_LDLIBS :=-ldl

But it still can't find this function. I even tried to give the path
to the library with '-L'. And I checked the library file with "arm-
linux-androideabi-readelf -s -D -W libdl.so" to check if the library
really contains this functions. It does!

In my Application.mk I have only one line:

APP_STL:=gnustl_static

Can somebody help me or explain to me what I can do to find the
problem?

Cheers,
Jester

[Thomas Martitz]

dladdr() is a non-POSIX GNU extension found in glibc (see [1]). You
probably don't find it in android because it's not using glibc but the
bionic C library.

[1]: http://linux.die.net/man/3/dladdr

[Chris Stratton]

On Jul 12, 7:19 am, Thomas Martitz <thomas.mart...@student.htw-

berlin.de> wrote:
> dladdr() is a non-POSIX GNU extension found in glibc (see [1]). You
> probably don't find it in android because it's not using glibc but the
> bionic C library.

It is in the bionic sources, and apparently .so (though that is fake
as the actual runtime implementations are in /system/bin/linker)

[Chris Stratton]

On Jul 12, 7:15 am, death_jester <d3ath.jes...@googlemail.com> wrote:
> undefined reference to `dladdr'

>
> In my Android.mk file I added the line
>
> LOCAL_LDLIBS :=-ldl
>
> But it still can't find this function. I even tried to give the path
> to the library with '-L'. And I checked the library file with "arm-
> linux-androideabi-readelf -s -D -W libdl.so" to check if the library
> really contains this functions. It does!

Did you check the library from the same platform version you compiled
against? Just experimenting with this, I don't see it in android-3
or android-4, but do see it from android-8.

Pass the V=1 flag to ndk-build to see what platform's lib directory it
is actually linking against.
Try it with target=android-8 in default.properties of the main app
directory.

[death_jester]

Ok, thanks for the reply, but I'm not quiet sure how this helps me. So you say that Androids libc does contain the dladdr function, and it should work?

[death_jester]

Thank you I think this is really the problem. Because 'ndk-build' uses the libld.so from android-3 and there is no dladdr() function in it. But I though when I give it the full path to the library (with -L) it would work.

How can I define a newer Android version for ndk-build?

Thank you for your help Chris!

[Mārtiņš Možeiko]

You can do that with by putting "APP_PLATFORM := android-8" in
Application.mk file.

--
Mārtiņš Možeiko

> --
> You received this message because you are subscribed to the Google Groups
> "android-ndk" group.
> To view this discussion on the web visit
> https://groups.google.com/d/msg/android-ndk/-/QraCzU2l9ukJ.
>
> To post to this group, send email to andro...@googlegroups.com.
> To unsubscribe from this group, send email to
> android-ndk...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/android-ndk?hl=en.