perl6 NativeCall doesn't find library on Darwin

Question

I'm playing a bit with NativeCall to get familiar with that side of Perl6. Of course, I'm trying to load libstatgrab first (what else?).

So I start with easiest part - the host information. Since no cluster support yet, it's just one result - no worries for complication.

The code:

#!/usr/bin/env perl6 

use v6;
use NativeCall;

enum sg_error (
        SG_ERROR_NONE                   => 0,
        SG_ERROR_INVALID_ARGUMENT       => 1,
        ...
);

class sg_error_details is repr('CStruct') {
        has int32 $.error;
        has int32 $.errno_value;
        has Str $.error_arg;
};

sub sg_init(int32 $ignore_errors) returns int32 is native('statgrab') { * };

enum sg_host_state (
        sg_unknown_configuration        => 0,
        sg_physical_host                => 1,
        sg_virtual_machine              => 2,
        sg_paravirtual_machine          => 3,
        sg_hardware_virtualized         => 4
);

class sg_host_info is repr('CStruct') {
        has Str $.os_name;
        has Str $.os_release;
        has Str $.os_version;
        has Str $.platform;
        has Str $.hostname;
        has uint32 $.bitwidth;
        has int32 $.host_state;
        has uint32 $.ncpus;
        has uint32 $.maxcpus;
        has uint64 $.uptime;
        has uint64 $.systime;
};

sub sg_get_host_info(size_t is rw) returns Pointer is native('statgrab') is symbol('sg_get_host_info_r') { * };
sub sg_free_host_info(Pointer) is native('statgrab') is symbol('sg_free_stats_buf') { * };

sub MAIN() {
    my int32 $ignore_errors = 0;
    my $error = sg_init($ignore_errors);
    if $error != SG_ERROR_NONE {
        say "Maeh: $error";
        exit 1;
    }

    my size_t $num_host_infos = 0;
    my $res = sg_get_host_info($num_host_infos);
    if $num_host_infos > 0 {
        my $host_info = nativecast(sg_host_info, $res);
        with $host_info {
            say "You're using ", $_.os_name, " on ", $_.hostname;
        }
    }
    sg_free_host_info($res);
}

Starting it (dumb) results in loading library error:

$ perl6 statgrab.p6
Cannot locate native library 'libstatgrab.dylib': dlopen(libstatgrab.dylib, 1): image not found
  in method setup at /Users/sno/rakudo/share/perl6/sources/24DD121B5B4774C04A7084827BFAD92199756E03 (NativeCall) line 283
  in method CALL-ME at /Users/sno/rakudo/share/perl6/sources/24DD121B5B4774C04A7084827BFAD92199756E03 (NativeCall) line 570
  in sub MAIN at statgrab.p6 line 95
  in block <unit> at statgrab.p6 line 93

Okay - giving it some search path:

$ LD_LIBRARY_PATH=/opt/pkg/lib:$LD_LIBRARY_PATH perl6 statgrab.p6
Cannot locate native library 'libstatgrab.dylib': dlopen(libstatgrab.dylib, 1): image not found

Same picture when using DYLD_LIBRARY_PATH - which is supported by dlopen(3) on Darwin, too.

But changing in the directory works:

$ (cd /opt/pkg/lib && perl6 /data/Projects/OSS/p6-Unix-Statgrab/statgrab.p6 )
You're using Darwin on ernie.[...]

Is there a lack of search path passthrough in the way how moarvm is called?

Answer 1

doug$ perl6 -v
This is Rakudo Star version 2018.10 built on MoarVM version 2018.10
implementing Perl 6.c.

On a fairly recent Rakudo Star on MacOS High Sierra, the script worked "out of the box" for me:

1. edited script to remove '...'.
2. Script failed to load the library (really missing!)
3. brew install libstatgrab
4. Script ran successfully:

vader:learning doug$ perl6 nativecall_mac_Sno.pl6 
You're using Darwin on Vader.local

Homebrew installed the library as follows:

$ v /usr/local/lib
total 11904
-rw-r--r--  1 doug  admin  6080828 Sep 23 12:40 libmoar.dylib
lrwxr-xr-x  1 doug  admin       51 Mar 23 11:02 libstatgrab.10.dylib@ -> ../Cellar/libstatgrab/0.91/lib/libstatgrab.10.dylib
lrwxr-xr-x  1 doug  admin       44 Mar 23 11:02 libstatgrab.a@ -> ../Cellar/libstatgrab/0.91/lib/libstatgrab.a
lrwxr-xr-x  1 doug  admin       48 Mar 23 11:02 libstatgrab.dylib@ -> ../Cellar/libstatgrab/0.91/lib/libstatgrab.dylib
drwxr-xr-x  3 doug  admin      102 Mar 23 11:02 pkgconfig/

For me, the perl6 executable is indeed a shell script, but it worked (there was no need to pass any extra LD_LIBRARY_PATH=...).

doug$ file `which perl6`
/Applications/Rakudo/bin/perl6: POSIX shell script text executable, ASCII text, with very long lines
doug$ set | grep LIBRARY
doug$

I have also had issues with my nativecall scripts finding the library, but have always solved them by fixing the library install and/or supplying 'LD_LIBRARY_PATH'.

Sorry this experience was Less Than Awesome for you