h3-android crashes on Android: unresolved symbol cos (libm.so missing from DT_NEEDED)

[JesusCabrera84]

Summary

h3-android crashes on physical Android devices when initializing H3Core because the packaged native library (libh3-java.so) appears to be missing an explicit dependency on libm.so.

This causes unresolved symbol failures for math functions like cos.

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Environment

• Library: com.uber:h3-android:4.4.0
• Also reproduced with: 4.3.2
• Device: physical Android device
• ABI: arm64-v8a
• Android version: [fill yours]

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Minimal reproduction

val h3 = H3Core.newSystemInstance()

Crash:

java.lang.UnsatisfiedLinkError:
dlopen failed: cannot locate symbol "cos" referenced by "/data/app/.../lib/arm64/libh3-java.so"

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Additional note

Using:

H3Core.newInstance()

fails differently:

java.lang.UnsatisfiedLinkError:
No native resource found at /android-arm64/libh3-java.so

This appears expected, since Android should use newSystemInstance().

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Investigation

Inspecting the packaged native library:

readelf -d libh3-java.so

Shows:

NEEDED Shared library: [liblog.so]
NEEDED Shared library: [libdl.so]
NEEDED Shared library: [libc.so]

libm.so is missing.

However, libh3-java.so references math symbols such as cos.

This suggests the native library was built in a way that does not correctly declare the runtime dependency on Android.

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Why preloading libm does not help

Tried:

System.loadLibrary("m")
val h3 = H3Core.newSystemInstance()

Same failure.

Likely due to Android linker namespace isolation: preloading a library into the app namespace does not satisfy unresolved symbols unless the dependency exists in the library’s own DT_NEEDED chain.

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Workaround

Patch libh3-java.so to explicitly add:

libm.so

to DT_NEEDED.

After patching:

NEEDED Shared library: [libm.so]
NEEDED Shared library: [liblog.so]
NEEDED Shared library: [libdl.so]
NEEDED Shared library: [libc.so]

Then:

System.loadLibrary("h3-java")
val h3 = H3Core.newSystemInstance()

works correctly.

Confirmed working:

• latLngToCellAddress(...)
• cellToBoundary(...)

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Expected fix

The Android native library should be rebuilt so libm.so is correctly included as a runtime dependency.

This seems to affect all currently published Android artifacts.

[isaacbrodsky]

Do you have a way of validating this on a simulator? If you can provide setup details for how to reproduce this without a physical device it would greatly aid debugging it and validating a fix.