gistfile1.txt

cpan@perlbuild2~/CPANPRC/rakudo (nom)$ gd
diff --git a/src/core/Exception.pm b/src/core/Exception.pm
index 3f7339b..7a4b22c 100644
--- a/src/core/Exception.pm
+++ b/src/core/Exception.pm
@@ -466,6 +466,12 @@ my class X::IO::Copy does X::IO {
     }
 }
 
+my class X::IO::Lock does X::IO {
+    has Str $.lock-type;
+    has Str $.os-error;
+    method message() { "Could not obtain $.lock-type lock: $.os-error" }
+}
+
 my class X::IO::Move does X::IO {
     has $.from;
     has $.to;
diff --git a/src/core/IO/Handle.pm b/src/core/IO/Handle.pm
index 4c24478..e3e0658 100644
--- a/src/core/IO/Handle.pm
+++ b/src/core/IO/Handle.pm
@@ -753,8 +753,13 @@ my class IO::Handle {
         self.opened && nqp::p6bool(nqp::isttyfh($!PIO))
     }
 
-    method lock(IO::Handle:D: Int:D $flag) {
-        nqp::lockfh($!PIO, $flag)
+    method lock(IO::Handle:D: Bool:D :$non-blocking, Bool:D :$shared --> True) {
+        nqp::lockfh($!PIO, 0x10*$non-blocking + $shared);
+        CATCH { default {
+            fail X::IO::Lock.new: :os-error(.Str),
+                :lock-type( 'non-' x $non-blocking ~ 'blocking, '
+                    ~ ($shared ?? 'shared' !! 'exclusive') );
+        }}
     }
 
     method unlock(IO::Handle:D: --> True) {
cpan@perlbuild2~/CPANPRC/rakudo (nom)$