error: undefined reference to 'pthread_cond_timedwait_monotonic_np' for android-14 and android-15

[ilyatal]

Description

Linker failure happens when building a c file with pthread_cond_timedwait_monotonic_np function using NDK 17:

 /opt/android-ndk/android-ndk-r17/ndk-build V=1 -B APP_ABI=armeabi-v7a APP_PLATFORM=android-
14
rm -f ./libs/arm64-v8a/* ./libs/armeabi-v7a/* ./libs/x86/* ./libs/x86_64/*
rm -f ./libs/arm64-v8a/gdbserver ./libs/armeabi-v7a/gdbserver ./libs/x86/gdbserver ./libs/x86_64/gdbserver
rm -f ./libs/arm64-v8a/gdb.setup ./libs/armeabi-v7a/gdb.setup ./libs/x86/gdb.setup ./libs/x86_64/gdb.setup
[armeabi-v7a] Compile thumb  : pthreadtest <= pthreadtest.c
/opt/android-ndk/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin/clang -MMD -MP -MF ./obj/local/armeabi-v7a/objs/pthreadtest/pthreadtest.o.d -gcc-toolchain /opt/android-ndk/android-ndk-r17/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 -fpic -ffunction-sections -funwind-tables -fstack-protector-strong -Wno-invalid-command-line-argument -Wno-unused-command-line-argument -no-canonical-prefixes -g -target armv7-none-linux-androideabi14 -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mthumb -Os -DNDEBUG  -Ijni   -DANDROID -DHAVE_PTHREADS -D__ANDROID_API__=14 -Wa,--noexecstack -Wformat -Werror=format-security  --sysroot /opt/android-ndk/android-ndk-r17/sysroot -isystem /opt/android-ndk/android-ndk-r17/sysroot/usr/include/arm-linux-androideabi -c  jni/pthreadtest.c -o ./obj/local/armeabi-v7a/objs/pthreadtest/pthreadtest.o
[armeabi-v7a] Executable     : pthreadtest
/opt/android-ndk/android-ndk-r17/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -Wl,--gc-sections -Wl,-z,nocopyreloc --sysroot=/opt/android-ndk/android-ndk-r17/platforms/android-14/arch-arm -Wl,-rpath-link=/opt/android-ndk/android-ndk-r17/platforms/android-14/arch-arm/usr/lib -Wl,-rpath-link=./obj/local/armeabi-v7a ./obj/local/armeabi-v7a/objs/pthreadtest/pthreadtest.o -lgcc -Wl,--exclude-libs,libgcc.a -latomic -Wl,--exclude-libs,libatomic.a  -gcc-toolchain /opt/android-ndk/android-ndk-r17/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 -no-canonical-prefixes -target armv7-none-linux-androideabi14 -Wl,--fix-cortex-a8  -Wl,--build-id -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--warn-shared-textrel -Wl,--fatal-warnings    -lc -lm -o ./obj/local/armeabi-v7a/pthreadtest
jni/pthreadtest.c:5: error: undefined reference to 'pthread_cond_timedwait_monotonic_np'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [obj/local/armeabi-v7a/pthreadtest] Error 1

pthreadtest.c file conents:

#include <stdio.h>
#include <pthread.h>

int main(int argc, char ** argv){
        pthread_cond_timedwait_monotonic_np(NULL, NULL, NULL);
        return 0;
}

Android.mk file contents:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_CFLAGS += -DHAVE_PTHREADS
LOCAL_MODULE    := pthreadtest
LOCAL_SRC_FILES := pthreadtest.c

include $(BUILD_EXECUTABLE)

Environment Details

NDK:
Pkg.Desc = Android NDK
Pkg.Revision = 17.0.4754217

• Build sytem: ndk-build
• Host OS: Linux 4.4.0-124-generic aarch64-linux-android-ld doesn't ignore dependencies of shared libraries #148-Ubuntu SMP Wed May 2 13:00:18 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
• Compiler: Clang
• ABI: armeabi-v7a
• NDK API level: android-14 & android-15

[enh]

seems WAI... this function wasn't added until API 16. or are you asking "why wasn't this a compile-time error rather than a link-time error"?

here's the complete truth from the map:

libc/libc.map.txt:    pthread_cond_timedwait_monotonic_np; # introduced-arm=16 introduced-x86=16 introduced-mips=16 introduced-arm64=28 introduced-x64_64=28 introduced-mips64=28

but the header file just has

int pthread_cond_timedwait_monotonic_np(pthread_cond_t* __cond, pthread_mutex_t* __mutex,
                                        const struct timespec* __timeout) __INTRODUCED_IN_64(28);

i'm not sure why there's no __INTRODUCED_IN_32(16) there... maybe https://android-review.googlesource.com/c/platform/bionic/+/695276 will tell us...

[ilyatal]

Thanks for clarification! Before, using NDK 16b, I was able to compile this function, that's why issue was raised.

/opt/android-ndk/android-ndk-r16b/ndk-build V=1 -B APP_ABI=armeabi-v7a APP_PLATFORM=android-14
rm -f ./libs/arm64-v8a/* ./libs/armeabi/* ./libs/armeabi-v7a/* ./libs/mips/* ./libs/mips64/* ./libs/x86/* ./libs/x86_64/*
rm -f ./libs/arm64-v8a/gdbserver ./libs/armeabi/gdbserver ./libs/armeabi-v7a/gdbserver ./libs/mips/gdbserver ./libs/mips64/gdbserver ./libs/x86/gdbserver ./libs/x86_64/gdbserver
rm -f ./libs/arm64-v8a/gdb.setup ./libs/armeabi/gdb.setup ./libs/armeabi-v7a/gdb.setup ./libs/mips/gdb.setup ./libs/mips64/gdb.setup ./libs/x86/gdb.setup ./libs/x86_64/gdb.setup
[armeabi-v7a] Compile thumb  : pthreadtest <= pthreadtest.c
/opt/android-ndk/android-ndk-r16b/toolchains/llvm/prebuilt/linux-x86_64/bin/clang -MMD -MP -MF ./obj/local/armeabi-v7a/objs/pthreadtest/pthreadtest.o.d -gcc-toolchain /opt/android-ndk/android-ndk-r16b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 -fpic -ffunction-sections -funwind-tables -fstack-protector-strong -Wno-invalid-command-line-argument -Wno-unused-command-line-argument -no-canonical-prefixes -fno-integrated-as -g -target armv7-none-linux-androideabi14 -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mthumb -Os -DNDEBUG  -Ijni   -DANDROID -DHAVE_PTHREADS -D__ANDROID_API__=14 -Wa,--noexecstack -Wformat -Werror=format-security  --sysroot /opt/android-ndk/android-ndk-r16b/sysroot -isystem /opt/android-ndk/android-ndk-r16b/sysroot/usr/include/arm-linux-androideabi -c  jni/pthreadtest.c -o ./obj/local/armeabi-v7a/objs/pthreadtest/pthreadtest.o
[armeabi-v7a] Executable     : pthreadtest
/opt/android-ndk/android-ndk-r16b/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ -Wl,--gc-sections -Wl,-z,nocopyreloc --sysroot=/opt/android-ndk/android-ndk-r16b/platforms/android-14/arch-arm -Wl,-rpath-link=/opt/android-ndk/android-ndk-r16b/platforms/android-14/arch-arm/usr/lib -Wl,-rpath-link=./obj/local/armeabi-v7a ./obj/local/armeabi-v7a/objs/pthreadtest/pthreadtest.o -latomic -Wl,--exclude-libs,libatomic.a  -gcc-toolchain /opt/android-ndk/android-ndk-r16b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 -no-canonical-prefixes -target armv7-none-linux-androideabi14 -Wl,--fix-cortex-a8  -Wl,--build-id -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--warn-shared-textrel -Wl,--fatal-warnings    -lc -lm -o ./obj/local/armeabi-v7a/pthreadtest
[armeabi-v7a] Install        : pthreadtest => libs/armeabi-v7a/pthreadtest
install -p ./obj/local/armeabi-v7a/pthreadtest ./libs/armeabi-v7a/pthreadtest
/opt/android-ndk/android-ndk-r16b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-strip --strip-unneeded  ./libs/armeabi-v7a/pthreadtest

[enh]

yeah, in NDK r16 this was in a __ANDROID_API__ < 21 block (because we didn't really keep good data for very old API levels, and no-one had ever noticed that this test wasn't exactly right).

in NDK r17 we added the 64-bit guard but accidentally dropped the 32-bit guard.

https://android-review.googlesource.com/c/platform/bionic/+/695276 fixes this, but given that API 16 is the lowest API level supported by NDK r17 i'm not sure i'll actually get +2 on that change :-)

[enh]

actually, we did screw up here... my earlier claim assumed that the map was correct, but it's been pointed out to me by @rprichard that the active ingredient that caused your problem is that we accidentally changed the map.

from the git history, this function wasn't in cupcake (which was our earlier claim), but was definitely in gingerbread (which pre-dates our current claim). so i'll abandon my earlier change and upload a new one to fix the map to admit that this function was available in at least gingerbread. hopefully there's still time to get this into r17b...

[enh]

okay, https://android-review.googlesource.com/c/platform/bionic/+/695566 fixes the map.

[DanAlbert]

@enh fixed the map, over to me to update the NDK's sysroot.

[DanAlbert]

Updates merged into r17.