From f78d2c2b3f3db6bcdcaca696abd800759740812b Mon Sep 17 00:00:00 2001
From: Niko Tyni <ntyni@debian.org>
Date: Tue, 16 Oct 2012 23:07:56 +0300
Subject: [PATCH] Fix CPAN::FirstTime defaults with nonexisting site dirs if a
 parent is writable

The site directories do not exist on a typical Debian system.  The build
systems will create them when necessary, so there's no need for a prompt
suggesting local::lib if the first existing parent directory is writable.

Also, writability of the core directories is not interesting as we
explicitly tell CPAN not to touch those with INSTALLDIRS=site.

Bug-Debian: http://bugs.debian.org/688842
Patch-Name: debian/cpan-missing-site-dirs.diff

---
 cpan/CPAN/lib/CPAN/FirstTime.pm | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/cpan/CPAN/lib/CPAN/FirstTime.pm b/cpan/CPAN/lib/CPAN/FirstTime.pm
index 3ccaeec..05d8910 100644
--- a/cpan/CPAN/lib/CPAN/FirstTime.pm
+++ b/cpan/CPAN/lib/CPAN/FirstTime.pm
@@ -2067,11 +2067,34 @@ sub _print_urllist {
     };
 }
 
+# Debian modification: return true if this directory
+# or the first existing one upwards is writable
+sub _can_write_to_this_or_parent {
+    my ($dir) = @_;
+    my @parts = File::Spec->splitdir($dir);
+    while (@parts) {
+        my $cur = File::Spec->catdir(@parts);
+        return 1 if -w $cur;
+        return 0 if -e _;
+        pop @parts;
+    }
+    return 0;
+}
+
+# Debian specific modification: the site directories don't necessarily
+# exist on the system, but the build systems create them when necessary,
+# so return true if the first existing directory upwards is writable
+#
+# Furthermore, on Debian, only test the site directories
+# (installsite*, expanded to /usr/local/{share,lib}/perl),
+# not the core ones 
+# (install*lib, expanded to /usr/{share,lib}/perl).
+# We pass INSTALLDIRS=site by default to keep CPAN from touching
+# the core directories.
+
 sub _can_write_to_libdirs {
-    return -w $Config{installprivlib}
-        && -w $Config{installarchlib}
-        && -w $Config{installsitelib}
-        && -w $Config{installsitearch}
+    return _can_write_to_this_or_parent($Config{installsitelib})
+        && _can_write_to_this_or_parent($Config{installsitearch})
 }
 
 sub _using_installbase {