protect against load a dir

Author: mohawk2

lib/Plack/Util.pm

@@ -11,6 +11,7 @@ sub FALSE() { !TRUE }
 
 # there does not seem to be a relevant RT or perldelta entry for this
 use constant _SPLICE_SAME_ARRAY_SEGFAULT => $] < '5.008007';
+use constant LOAD_ERROR => "Unknown error. Did you try to load a directory?\n";
 
 sub load_class {
     my($class, $prefix) = @_;
@@ -117,11 +118,11 @@ sub _load_sandbox {
     local $0 = $_file; # so FindBin etc. works
     local @ARGV = ();  # Some frameworks might try to parse @ARGV
 
-    return eval sprintf <<'END_EVAL', $_package;
+    return eval sprintf <<'END_EVAL', $_package, LOAD_ERROR;
 package Plack::Sandbox::%s;
 {
     my $app = do $_file;
-    if ( !$app && ( my $error = $@ || $! )) { die $error; }
+    if ( !$app && ( my $error = $@ || $! || "%s" )) { die $error; }
     $app;
 }
 END_EVAL

t/Plack-Util/load.t

@@ -45,6 +45,13 @@ use Test::More;
     unlike $@, qr/Died/;
 }
 
+{
+    eval { Plack::Util::load_psgi("t/Plack-Util/") };
+    # Perl 5.20+ gives "Did you try to load a directory",
+    #   <=5.18 "No such file or directory"
+    like $@, qr/Error while loading/;
+}
+
 {
     my $app = Plack::Util::load_psgi("t/Plack-Util/bin/findbin.psgi");
     test_psgi $app, sub {