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use v6;
=begin pod
=head1 NAME
LibraryCheck - Determine whether a shared library is available to be loaded
=head1 SYNOPSIS
=begin code :lang<raku>
use LibraryCheck;
if !library-exists('sndfile', v1) {
die "Cannot load libsndfile";
}
=end code
=head1 DESCRIPTION
This module provides a mechanism that will determine whether a named
shared library is available and can be used by NativeCall.
It exports a single function C<library-exists> that returns a boolean to
indicate whether the named shared library can be loaded and used.
The library name should be supplied without any (OS-dependent) "lib"
prefix and no extension (for example, C<'crypt'> for C<libcrypt.so>).
This can be used in a builder to determine whether a module has a chance
of working (and possibly aborting the build), or in tests to cause the
tests that may rely on a missing library to be skipped.
The second positional argument is a L<Version> object that indicates the
version of the library that is required, it defaults to C<v1>, if you don't
care which version exists then it possible to pass a new Version object
without any version parts (i.e., C<Version.new()>). Many systems require
that the version is specified, so if portability is a concern, an actual
version number should be given.
If the C<:exception> adverb is passed to C<library-exists> then an
exception (C<X::NoLibrary>) will be thrown if the library isn't available
rather than returning C<False>. So the case above can be more simply
written as:
=for code :lang<raku>
library-check('sndfile', v1, :exception);
The implementation is somewhat of a hack currently and definitely shouldn't
be taken as an example of nice Raku code.
=end pod
module LibraryCheck {
use NativeCall :TEST;
class X::NoLibrary is Exception {
has Str $.library;
method message() returns Str {
"library { $!library } was not found";
}
}
my Bool %test-result;
sub library-exists(Str $lib, Version $v = v1, :$exception --> Bool) is export {
my $test-key = "$lib-{ $v.gist }";
if not %test-result{$test-key}:exists {
%test-result{$test-key} = True;
my $f = sub {};
my $soname = guess_library_name($lib, $v);
$f does NativeCall::Native[$f, $soname];
# This is required since 2019-10-13
# will remove when there is a new release of Rakudo
if $f.^can('setup-nativecall') {
$f.setup-nativecall;
}
$f();
CATCH {
when /'Cannot locate native library'/ { %test-result{$test-key} = False }
default { %test-result{$test-key} = True }
}
}
if not %test-result{$test-key} and $exception {
X::NoLibrary.new(library => $lib).throw;
}
%test-result{$test-key};
}
}
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