Try to get the layers.t working also for dosish platforms.

p4raw-id: //depot/perl@19239

2 files changed, 32 insertions, 8 deletions

diff --git a/lib/PerlIO.pm b/lib/PerlIO.pm
index 61a748aa05..678a79dd2c 100644
--- a/lib/PerlIO.pm
+++ b/lib/PerlIO.pm
@@ -233,7 +233,23 @@ The following returns the B<names> of the PerlIO layers on a filehandle.
 The layers are returned in the order an open() or binmode() call would
 use them.  Note that the stack begins (normally) from C<stdio> or from
 C<perlio>.  Under C<stdio> the platform specific low-level I/O (like
-C<unix>) is not part of the stack, but under C<perlio> it is.
+C<unix>) is not part of the stack, but under C<perlio> (and the
+experimental C<mmap>) it is.
+
+In platforms of DOS progeny (Win32 being the most prominent) the
+lowest level layers are C<unix crlf>, meaning that Perl first uses the
+UNIX-style low-level fd layer, and then on top of that a layer that
+handles the CRLF translation.
+
+The following table summarizes the default layers on UNIX-like and
+DOS-like platforms and depending on the setting of the C<$ENV{PERLIO}>:
+
+ PERLIO   UNIX-like       DOS-like
+ 
+ none     stdio           unix crlf
+ stdio    stdio           stdio
+ perlio   unix perlio     unix perlio
+ mmap     unix mmap       unix mmap
 
 By default the layers from the input side of the filehandle is
 returned, to get the output side use the optional C<output> argument:
diff --git a/t/io/layers.t b/t/io/layers.t
index 6f161cd8b0..0da804c33f 100644
--- a/t/io/layers.t
+++ b/t/io/layers.t
@@ -18,6 +18,7 @@ plan tests => 43;
 
 use Config;
 
+my $DOSISH   = $^O =~ /^(?:MSWin32|cygwin|os2|dos|NetWare|mint)$/;
 my $NONSTDIO = exists $ENV{PERLIO} && $ENV{PERLIO} ne 'stdio';
 
 SKIP: {
@@ -26,14 +27,18 @@ SKIP: {
 
     sub check {
 	my ($result, $expected, $id) = @_;
-	my $n = scalar @$expected;
-	is($n, scalar @$expected, "$id - layers = $n");
 	if ($NONSTDIO) {
-	    # Get rid of "unix" and similar OS-specific low lever layer.
-	    shift(@$result);
+	    # Get rid of "unix".
+	    shift @$result if $result->[0] eq "unix";
 	    # Change expectations.
 	    $expected->[0] = $ENV{PERLIO} if $expected->[0] eq "stdio";
+	} elsif ($DOSISH) {
+	    splice(@$result, 0, 2, "stdio")
+		if $result->[0] eq "unix" &&
+		   $result->[1] eq "crlf";
 	}
+	my $n = scalar @$expected;
+	is($n, scalar @$expected, "$id - layers = $n");
 	for (my $i = 0; $i < $n; $i++) {
 	    my $j = $expected->[$i];
 	    if (ref $j eq 'CODE') {
@@ -74,6 +79,7 @@ SKIP: {
 	  [ "stdio" ],
 	  ":raw");
 
+    binmode(F, ":pop") if $DOSISH; # Drop one extra :crlf.
     binmode(F, ":utf8");
 
     check([ PerlIO::get_layers(F) ],
@@ -100,11 +106,13 @@ SKIP: {
 
     binmode(F, ":raw :encoding(latin1)"); # "latin1" will be canonized
 
-    {
+    SKIP: {
+	skip("too complex layer coreography", 7) if $DOSISH;
+
 	my @results = PerlIO::get_layers(F, details => 1);
 
-	# Get rid of "unix" and undef.
-	splice(@results, 0, 2) if $NONSTDIO;
+	# Get rid of the args and the flags.
+	splice(@results, 1, 2) if $NONSTDIO;
 
 	check([ @results ],
 	      [ "stdio",    undef,        sub { $_[0] > 0 },