RFR: JDK-8319516 - Native library suffix impact on the library loading in AIX- Java Class Loader [v4]

[Maurizio Cimadamore]

On Fri, 22 Mar 2024 16:53:58 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> In case of jextract (jdk22 branch), we would then need something like the following if we want AIX to behave like the other platforms?
> 
> ```
> diff --git a/src/main/java/org/openjdk/jextract/clang/libclang/Index_h.java b/src/main/java/org/openjdk/jextract/clang/libclang/Index_h.java
> index 14eba30..c069c3b 100644
> --- a/src/main/java/org/openjdk/jextract/clang/libclang/Index_h.java
> +++ b/src/main/java/org/openjdk/jextract/clang/libclang/Index_h.java
> @@ -27,11 +27,13 @@
>  
>  package org.openjdk.jextract.clang.libclang;
>  
> +import java.io.File;
>  import java.lang.invoke.*;
>  import java.lang.foreign.*;
>  import java.nio.ByteOrder;
>  import java.util.*;
>  import java.util.function.*;
> +import java.util.StringTokenizer;
>  import java.util.stream.*;
>  
>  import static java.lang.foreign.ValueLayout.*;
> @@ -101,8 +103,21 @@ public class Index_h {
>      }
>  
>      static {
> -        String libName = System.getProperty("os.name").startsWith("Windows") ? "libclang" : "clang";
> -        System.loadLibrary(libName);
> +        String osName = System.getProperty("os.name");
> +        String libName = "";
> +        if (osName.startsWith("AIX")) {
> +            String libPath = System.getProperty("java.library.path");
> +            StringTokenizer parser = new StringTokenizer(libPath, ":");
> +            while (parser.hasMoreTokens()) {
> +                libName = parser.nextToken() + "/libclang.a";
> +                File f = new File(libName);
> +                if (f.exists() && !f.isDirectory()) break;
> +            }
> +            SymbolLookup.libraryLookup(libName + "(libclang.so.16)", Arena.global());
> +        } else {
> +            libName = osName.startsWith("Windows") ? "libclang" : "clang";
> +            System.loadLibrary(libName);
> +        }
>      }
>  
>      static final SymbolLookup SYMBOL_LOOKUP = SymbolLookup.loaderLookup()
> ```
> 
> If I try this, I get "UnsatisfiedLinkError: unresolved symbol: clang_createIndex". So, seems like the lib gets found, but symbols not loaded. Seems like there are more changes needed.

Something like that seems good. When you call "find" on that lookup, it should just forward to dlsym... I suggest you try first to simply use the lookup in a standalone file (w/o jextract) and try to lookup a symbol in clang (e.g. `clang_getClangVersion`), and see what happens.

If that doesn't work (likely), I'd suggest to write the equivalent C program with dlopen/dlsym, and make sure that works, and also note which DLOPEN/DLSYM parameters are used (maybe those are different from the ones used by the JDK?).

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PR Comment: https://git.openjdk.org/jdk/pull/17945#issuecomment-2015773691