manawenuz/wz-phone
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

fix: also link libc++abi for RTTI — resolve missing __class_type_info vtable

Browse Source 
Previous fix linked c++_static but not c++abi. Android NDK splits the
static C++ runtime into two archives: libc++_static.a (STL) and
libc++abi.a (RTTI/exceptions). Without c++abi, dlopen fails on
_ZTVN10__cxxabiv117__class_type_infoE.

Now using cpp_link_stdlib(None) to suppress cc crate auto-linking, then
explicitly linking both c++_static and c++abi via cargo:rustc-link-lib.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Siavash Sameni
2026-04-05 09:00:14 +04:00
parent b204213a01
commit 622fdee51f
2 changed files with 59 additions and 44 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
crates/wzp-android/build.rs
View File

@@ -13,7 +13,7 @@ fn main() {
cc::Build::new() cc::Build::new()
.cpp(true) .cpp(true)
.std("c++17") .std("c++17")
.cpp_link_stdlib(Some("c++_static")) .cpp_link_stdlib(None)
.file("cpp/oboe_bridge.cpp") .file("cpp/oboe_bridge.cpp")
.include("cpp") .include("cpp")
.include(oboe_path.join("include")) .include(oboe_path.join("include"))
@@ -25,12 +25,19 @@ fn main() {
cc::Build::new() cc::Build::new()
.cpp(true) .cpp(true)
.std("c++17") .std("c++17")
.cpp_link_stdlib(Some("c++_static")) .cpp_link_stdlib(None)
.file("cpp/oboe_stub.cpp") .file("cpp/oboe_stub.cpp")
.include("cpp") .include("cpp")
.compile("oboe_bridge"); .compile("oboe_bridge");
} }
} }
// Android NDK splits the static C++ runtime into two archives:
// libc++_static.a — STL (containers, strings, algorithms)
// libc++abi.a — ABI (RTTI, exceptions, typeinfo vtables)
// Both are required; cc crate's cpp_link_stdlib only handles the first.
println!("cargo:rustc-link-lib=static=c++_static");
println!("cargo:rustc-link-lib=static=c++abi");
} else { } else {
// Non-Android: always use stub // Non-Android: always use stub
cc::Build::new() cc::Build::new()

92
issues/001-libc++-shared-crash.md
View File

@@ -1,6 +1,6 @@
# Issue 001: App crashes on launch — missing libc++_shared.so # Issue 001: App crashes on launch — C++ runtime not linked correctly
## Status: Fix committed, needs rebuild ## Status: Fix v2 committed, needs rebuild
## Symptom ## Symptom
@@ -13,77 +13,85 @@ or on any code path that first loads the native library.
- Nothing Phone, arm64-v8a, Android 15 - Nothing Phone, arm64-v8a, Android 15
- ADB device ID: `00142151B000973` - ADB device ID: `00142151B000973`
## Logcat crash trace ## Crash history
### Attempt 1: `libc++_shared.so` not found
``` ```
E AndroidRuntime: FATAL EXCEPTION: main
E AndroidRuntime: Process: com.wzp.phone, PID: 6048
E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so" E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so"
not found: needed by /data/app/.../base.apk!/lib/arm64-v8a/libwzp_android.so not found: needed by .../libwzp_android.so
in namespace clns-9 at com.wzp.engine.WzpEngine.<clinit>(WzpEngine.kt:115)
E AndroidRuntime: at java.lang.Runtime.loadLibrary0(Runtime.java:1097)
E AndroidRuntime: at java.lang.System.loadLibrary(System.java:1765)
E AndroidRuntime: at com.wzp.engine.WzpEngine.<clinit>(WzpEngine.kt:115)
E AndroidRuntime: at com.wzp.ui.call.CallViewModel.startCall(CallViewModel.kt:52)
E AndroidRuntime: at com.wzp.ui.call.InCallScreenKt$InCallScreen$1$1$1.invoke(InCallScreen.kt:96)
``` ```
## Root cause **Cause**: `cc::Build` defaults to dynamic C++ linking. `libc++_shared.so` never
packaged into APK.
**Attempted fix**: `.cpp_link_stdlib(Some("c++_static"))` — link STL statically.
### Attempt 2: missing `__class_type_info` vtable (RTTI)
```
E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol
"_ZTVN10__cxxabiv117__class_type_infoE" referenced by .../libwzp_android.so
at com.wzp.engine.WzpEngine.<clinit>(WzpEngine.kt:115)
```
**Cause**: Android NDK splits the static C++ runtime into two archives:
- `libc++_static.a` — STL (containers, strings, algorithms)
- `libc++abi.a` — ABI layer (RTTI typeinfo vtables, exception handling)
The `cc` crate's `.cpp_link_stdlib(Some("c++_static"))` only emits
`cargo:rustc-link-lib=static=c++_static`. It does NOT pull in `libc++abi.a`,
so all RTTI symbols (`__class_type_info`, `__si_class_type_info`, etc.)
are unresolved at dlopen time.
## Root cause (full)
`crates/wzp-android/build.rs` uses the `cc` crate to compile C++17 code `crates/wzp-android/build.rs` uses the `cc` crate to compile C++17 code
(the Oboe audio bridge). On Android targets, `cc::Build` defaults to dynamically (the Oboe audio bridge). Two things go wrong:
linking the C++ standard library (`libc++_shared.so`).
This means `libwzp_android.so` has a runtime dependency on `libc++_shared.so`. 1. Dynamic linking by default → `libc++_shared.so` not in APK
However, the Gradle build (`cargoNdkBuild` task) only copies `libwzp_android.so` 2. Even with `.cpp_link_stdlib("c++_static")`, the ABI half (`libc++abi.a`)
into `jniLibs/arm64-v8a/`. The C++ runtime is never copied alongside it, so the is not linked, leaving RTTI symbols unresolved
APK ships without `libc++_shared.so`.
At runtime, `dlopen("libwzp_android.so")` fails because the linker can't find ## Fix (v2)
the missing shared library in the app's namespace.
### Why this wasn't caught earlier Suppress the `cc` crate's automatic C++ stdlib linking with `.cpp_link_stdlib(None)`,
then explicitly link both static archives:
The previous APK (pre-QUIC wiring) was 2.0MB release / 8.9MB debug. The Oboe
C++ bridge was likely being compiled but the native library may not have been
loaded on the code path that was tested, or the dependency was satisfied by a
different linking configuration at the time.
## Fix
In `crates/wzp-android/build.rs`, add `.cpp_link_stdlib(Some("c++_static"))` to
all `cc::Build` invocations targeting Android. This tells the `cc` crate to link
`libc++_static.a` instead of `libc++_shared.so`, baking the C++ runtime directly
into `libwzp_android.so`. No separate shared library needed at runtime.
```rust ```rust
cc::Build::new() cc::Build::new()
.cpp(true) .cpp(true)
.std("c++17") .std("c++17")
.cpp_link_stdlib(Some("c++_static")) // <-- this line .cpp_link_stdlib(None) // suppress cc crate's automatic linking
.file("cpp/oboe_bridge.cpp") .file("cpp/oboe_bridge.cpp")
// ... // ...
.compile("oboe_bridge");
// Manually link both halves of the Android NDK static C++ runtime
println!("cargo:rustc-link-lib=static=c++_static");
println!("cargo:rustc-link-lib=static=c++abi");
``` ```
Applied to both the Oboe build path and the stub fallback path. This is placed once after the match block (applies to both Oboe and stub paths).
### Trade-off ### Trade-off
Static linking increases `libwzp_android.so` size slightly (~200-400KB for Static linking increases `libwzp_android.so` by ~300-500KB. Acceptable for
libc++ static). This is acceptable — the alternative (bundling libc++_shared.so avoiding shared library packaging complexity.
separately) adds complexity to the Gradle build and risks version mismatches if
multiple native libraries each bundle their own shared copy.
## Rebuild steps ## Rebuild steps
```bash ```bash
cd android && ./gradlew assembleRelease cd android && ./gradlew clean assembleRelease
adb install -r app/build/outputs/apk/release/app-release.apk adb install -r app/build/outputs/apk/release/app-release.apk
``` ```
Use `clean` to ensure the native library is fully relinked.
## Verification ## Verification
After install, the app should: After install, the app should:
1. Open without crashing 1. Open without crashing
2. Load `libwzp_android.so` successfully (check logcat for absence of UnsatisfiedLinkError) 2. Load `libwzp_android.so` successfully (no UnsatisfiedLinkError in logcat)
3. Show the call UI with CALL button 3. Show the call UI with CALL button