Error with const variables

[Maurizio Cimadamore]

Hi,
what OS/platform are you on?

I tried a small example on my Linux/x64:

|// foo.c const int x = 4; |

Then compiled to a shared library:

|gcc -shared -o foo.so |

Then, from jshell:

|jshell> import java.lang.foreign.*; jshell> SymbolLookup lookup = 
SymbolLookup.libraryLookup("./foo.so", Arena.global()); lookup ==> 
java.lang.foreign.SymbolLookup$$Lambda/0x00007f8d6705ac18 at 4459eb14 
jshell> lookup.findOrThrow("x"); $3 ==> MemorySegment{ address: 
0x7f8dc403c000, byteSize: 0 } |

So, the symbol seems to be there, which is also confirmed by |objdump|:

|foo.so: file format elf64-x86-64 DYNAMIC SYMBOL TABLE: 0000000000000000 
w D *UND* 0000000000000000 __cxa_finalize 0000000000000000 w D *UND* 
0000000000000000 _ITM_registerTMCloneTable 0000000000000000 w D *UND* 
0000000000000000 _ITM_deregisterTMCloneTable 0000000000000000 w D *UND* 
0000000000000000 __gmon_start__ 0000000000002000 g DO .rodata 
0000000000000004 x |

(see last line)

I’d suggest to maybe check that (a) the shared library you are using 
(.so or .dll) does contain the constant variable symbols we’re trying to 
lookup and (b) that jextract is using a correct symbol lookup (e.g. one 
that points to your library). For (b) you might want to refer this for 
further guidance:

https://github.com/openjdk/jextract/blob/master/doc/GUIDE.md#library-loading

Cheers
Maurizio

On 08/12/2024 15:38, Adrian Trapletti wrote:

> Hi,
>
> I run jextract on 
> https://github.com/ERGO-Code/HiGHS/blob/master/src/interfaces/highs_c_api.h. 
>
>
> If I use the Java bindings to access the const variables I get 
> "java.lang.UnsatisfiedLinkError: unresolved symbol".
>
> For example
> ...
> long sense = kHighsObjSenseMinimize();
> ...
>
> results in
>
> java.lang.UnsatisfiedLinkError: unresolved symbol: kHighsObjSenseMinimize
> at 
> com.ustermetrics.highs4j/com.ustermetrics.highs4j.bindings.highs_c_api_h.lambda$findOrThrow$0(highs_c_api_h.java:44)
> at java.base/java.util.Optional.orElseThrow(Optional.java:403)
> at 
> com.ustermetrics.highs4j/com.ustermetrics.highs4j.bindings.highs_c_api_h.findOrThrow(highs_c_api_h.java:44)
> at 
> com.ustermetrics.highs4j/com.ustermetrics.highs4j.bindings.highs_c_api_h$kHighsObjSenseMinimize$constants.<clinit>(highs_c_api_h.java:804)
> at 
> com.ustermetrics.highs4j/com.ustermetrics.highs4j.bindings.highs_c_api_h.kHighsObjSenseMinimize(highs_c_api_h.java:834)
> at 
> com.ustermetrics.highs4j/com.ustermetrics.highs4j.bindings.BindingsTest.solveLinearProgramReturnsExpectedSolution(BindingsTest.java:32)
> at java.base/java.lang.reflect.Method.invoke(Method.java:580)
> at java.base/java.util.ArrayList.forEach(ArrayList.java:1597)
> at java.base/java.util.ArrayList.forEach(ArrayList.java:1597)
>
> (https://github.com/atraplet/highs4j and run the unit tests)
>
> What do I miss here?
>
> Thx and best regards,
> Adrian
>
> *Dr. Adrian Trapletti*
> CEO
>
> *Uster Metrics GmbH *|  Steinstrasse 9b, 8610 Uster, Switzerland
> P +41 32 512 83 63  | M +41 79 103 71 31
> a.trapletti at ustermetrics.com | www.ustermetrics.com 
> <http://www.ustermetrics.com>
>
>
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