Resolving UnsatisfiedLinkError for Missing Symbols in libfio.so on Android

[hschenzhimin]

On Ubuntu, I used NDK version 27 to compile fio version 3.38 and generated libfio.so. However, when using System.load("fio") in the app, it crashes with the following error:

java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "device_is_mounted" referenced by "/data/app/com.example.performance_check-HXHM-fAkeyw52mI75oDcVw==/lib/x86_64/libfio.so"...
at java.lang.Runtime.loadLibrary0(Runtime.java:1041)
at java.lang.System.loadLibrary(System.java:1675)

The build script is as follows:

NDK_PATH="/home/work/work-space/android-ndk-r27c"
CC="${NDK_PATH}/toolchains/llvm/prebuilt/linux-x86_64/bin/x86_64-linux-android24-clang"
AR="${NDK_PATH}/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-ar"

export CC
export AR

CFLAGS="-fPIC -DANDROID -fvisibility=hidden"
LDFLAGS="-shared -Wl"

make clean

make CFLAGS="$CFLAGS"

$CC $CFLAGS $LDFLAGS *.o -o libfio.so

When analyzing the exported methods of libfio.so, I found that some methods are marked as NOTYPE. The command and its output are as follows:

readelf -s libfio.so | grep NOTYPE

Output:

 0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
13: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND device_is_mounted
14: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND buf_output_init
15: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND buf_output_free
32: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND __fio_memfree
35: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND fio_getrusage
45: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND __fio_memalign
55: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND logf
61: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND blktrace_lookup_[...]
64: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND unpack754
66: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND pack754
86: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND inflateInit_
87: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND inflate
88: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND inflateEnd

[vincentkfu]

I am not familiar with building/running fio on Android but I asked my colleague Jinyoung Choi to look at this and this is his assessment:

The reason why it appears as "NOTYPE" is that, of course, the device_is_mounted function is included in the lib/mountcheck.o object.
When doing CC, it was performed on "*.o", so the objects of the sub-folders were not included together.

$CC $CFLAGS $LDFLAGS *.o -o libfio.so --> $CC $CFLAGS $LDFLAGS *.o lib/*.o -o libfio.so (This is not enough....)

(the additional amount of objects will be reduced only when you build by giving disable hints about unnecessary contents in configuration.)
(I think to make fio a library, you need to modify header exposure (extern "c"{}) and Makefile well ...)

Anyway, in the case of fio, I have not seen the case of making it into a library and using it.
I want to know what it is for.

functions called in libfio.c do not expose functions in the form of below, so they must be added manually.

[vincentkfu]

Closing due to lack of response.