libinterimap: use directories relative to $HOME for the XDG defaults.

Previously getpwuid() was called to determine the user's home directory,
while the XDG specification explicitely mentions $HOME.

Conveniently our docs always mentioned ~/, which on POSIX-compliant
systems expands to the value of the variable HOME (and the result is
unspecified when the variable is unset).  Cf. Shell and Utilities volume
of POSIX.1-2017, sec. 2.6.1:

    https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_01

2 files changed, 9 insertions, 4 deletions

diff --git a/Changelog b/Changelog
index 84a62b6..d429932 100644
--- a/Changelog
+++ b/Changelog
@@ -69,6 +69,13 @@ interimap (0.5) upstream;
    the 'foreign_keys' PRAGMA during a transaction is a documented no-op).
  - interimap: fix handling of mod-sequence values greater or equal than
    2 << 63.
+ - libinterimap: use directories relative to $HOME for the XDG
+   environment variables default values.  Previously getpwuid() was
+   called to determine the user's home directory, while the XDG
+   specification explicitely mentions $HOME.  Conveniently our docs
+   always mentioned ~/, which on POSIX-compliant systems expands to the
+   value of the variable HOME.  (Cf. Shell and Utilities volume of
+   POSIX.1-2017, sec. 2.6.1.)
 
  -- Guilhem Moulin <guilhem@fripost.org>  Fri, 10 May 2019 00:58:14 +0200
 
diff --git a/lib/Net/IMAP/InterIMAP.pm b/lib/Net/IMAP/InterIMAP.pm
index 19895c4..aacc8e7 100644
--- a/lib/Net/IMAP/InterIMAP.pm
+++ b/lib/Net/IMAP/InterIMAP.pm
@@ -92,11 +92,9 @@ sub xdg_basedir($$$$) {
     return $path if $path =~ /\A\//;
 
     my $basedir = $ENV{$xdg_variable};
-    unless (defined $basedir) {
-        my @getent = getpwuid($>);
-        $basedir = $getent[7] ."/". $default;
-    }
+    $basedir = ($ENV{HOME} // "") ."/". $default unless defined $basedir;
     die "No such directory: ", $basedir unless -d $basedir;
+
     $basedir .= "/".$subdir;
     $basedir =~ /\A(\/\p{Print}+)\z/ or die "Insecure $basedir";
     $basedir = $1;