Fix for issue #1, Crash with non-0 offset

Mmap.xs

@@ -224,12 +224,13 @@ mmap(var, len, prot, flags, fh = 0, off_string)
 	if (!(prot & PROT_WRITE))
 	    SvREADONLY_on(var);
 
-        /* would sv_usepvn() be cleaner/better/different? would still try to realloc... */
-	SvPVX(var) = (char *) addr + slop;
-	SvCUR_set(var, len);
-	SvLEN_set(var, slop);
+	SvPVX(var) = (char *) addr;
+	SvCUR_set(var, len + slop);
+	if (slop > 0) {
+		sv_chop(var, addr + slop);
+	}
 	SvPOK_only(var);
-        ST(0) = sv_2mortal(newSVnv((IV) addr));
+		ST(0) = sv_2mortal(newSViv((IV) addr));
 
 SV *
 munmap(var)

t/mmap.t

@@ -3,7 +3,7 @@
 BEGIN {
     use strict;
     use warnings;
-    use Test::More tests => 8;
+    use Test::More tests => 9;
 
     use_ok('Sys::Mmap');
 }
@@ -38,6 +38,12 @@ substr($temp_file_contents, 3, 1) = "Z";
 is($foo, $temp_file_contents, 'Foo can be altered in RW mode');
 munmap($foo);
 
+sysopen(FOO, $temp_file, O_RDWR) or die "$temp_file: $!\n";
+mmap($foo, 0, PROT_READ|PROT_WRITE, MAP_SHARED, FOO, 5);
+close FOO;
+is(substr($foo, 5, 1), '2', 'Offset handled');
+munmap($foo);
+
 sysopen(FOO, $temp_file, O_RDONLY) or die "$temp_file: $!\n";
 my $bar = <FOO>;
 is($bar, $temp_file_contents, 'Altered foo reflects on disk');

t/on_exit.t

@@ -0,0 +1,26 @@
+#! perl
+
+BEGIN {
+    use strict;
+    use warnings;
+    use Test::More tests => 1;
+
+    use_ok('Sys::Mmap');
+}
+
+use FileHandle;
+
+my $temp_file = "mmap.tmp";
+
+my $temp_file_contents = "0" x 1000; 
+sysopen(FOO, $temp_file, O_WRONLY|O_CREAT|O_TRUNC) or die "$temp_file: $!\n";
+print FOO $temp_file_contents;
+close FOO;
+
+# Perl was segfaulting when exiting after using a non zero offset
+# The key here is that munmap was not done before exiting
+my $foo;
+sysopen(FOO, $temp_file, O_RDWR) or die "$temp_file: $!\n";
+mmap($foo, 0, PROT_READ, MAP_SHARED, FOO, 256);
+
+unlink($temp_file);