C++ exceptions not handled when building on ARM32 #785
Comments
This one is actually okay. The It looks like you've got all the unwind symbols properly hidden. Unless there are some other libraries in the dependency chain that aren't mentioned or libz.so is actually a library you ship in your APK rather than the system's, I think you've got that part right. If your build system is building your library correctly, the next guess is usually that one of your third-party dependencies is broken, but it looks like your dependencies are fine too.
This looks mostly right, but it's not quite correct for libc++_shared. I'm not 100% certain it'll make a difference, but could you try:
The NDK includes some linker scripts that can deal with this for you, btw. The same directory that has libc++_shared also has libc++.so.$API files that will link things properly for that API level. Rather than doing what you're doing, you should be able to just link that file (give the full path to the linker script as if it were a library rather than Another choice would be getting your build system to use a standalone toolchain. If you've got resources to maintain a custom build system that may not actually be a better choice, but it is an option. |
|
To add a bit...
If libzip is compiled with The
The libc++.so.$API files are new in r18. In r17b, there's still just a single libc++.so file. It has the correct library list for API 14 and up: It's important that |
|
ok, you guys are awesome! your comments helped me fixed my problem, :) For others who may run in a similar issue, here what I had to do to make it work:
What I also did, but I don't think it did anything to the problem:
End of the day, the unwind symbols now looks like this: and I still have the two the unwinder symbols embedded in … but now the exceptions are working. thanks again for the pointers. |
|
Good to hear.
I see some R_ARM_NONE references to __aeabi_unwind_cpp_pr{0,1,2} in various object files in libgcc.a, so maybe libzip.so links one of those in? I also see references in the NDK's libz.a, but I think libzip.so uses libz.so instead. FWIW: I think Android's crash dumper needs the unwinding tables to generate a backtrace in a crash report. |
|
ok thanks, I add back the |
Description
I am trying to build an application that relies on the NDK for several libs.
Our lib (that I will call
libmylib.so) depends onlibzip.sowhich in turns relies onlibz.soIn short,
libmylib.so->libzip.so->libz.soI am not using ndkbuild or CMake, but rather integrated the last NDK (ndk 17) directly in our build system (custom makefiles that we have total control over).
The problem I am encountering only happens on ARM32, (all works fine on the other archs,
x86,x86_64andaarch64).What happens is that exceptions are not working properly, catching an exception in the same function works, but not from a function to another, in other word:
In our build system, we use
libc++_shared, I build libzip with clang, and use libz on the device. (that mean, we shiplibzip.so, but notlibz.so, as we are using the one on the device).After digging several issues that seems similar: #289 #774 It seems I am running in the same issue with the unwinder being used from two different places:
My understanding is that the issue I have is due to these two unreferenced symbols:
Checking
libzip.so, and sure enough:full output:
as my readelf output shows, I do have a mix of gnu symbols with clang, but what bothers me is that the only C++ library is our lib, libzip is a pure C library, and should not embed any exception unwinder (unless I am wrong somewhere…).
I have tried all the solutions proposed in #289 #774 #379 but could not resolve those two symbols :/
the NDK sits in
/usr/local/toolchains/android-ndk-r17bHere is the link command for libzip (output of clang -v) :
Here is the link command of our library:
I have been fighting this one for the last week… all works on other platforms, but am32 is giving me a hard time …
Could somebody help me figure out what is my mistake here?
@DanAlbert could I ask you a quick insight since you have been answering very similar questions in the past?
Environment Details
NDK Version: r17b
Minimum API: android-21
ABI: armeabi-v7a
Actual API of the device: android-24
STL: libc++ (shared)
Toolchain: clang
The text was updated successfully, but these errors were encountered: