xap_helper: PERL_INLINE_DIRECTORY fallback for JAOT build

systemd setups may use role accounts (e.g. `news') with
XDG_CACHE_HOME unset and a non-existent HOME directory
which the user has no permission to create.

In those cases, fallback to using PERL_INLINE_DIRECTORY if
available for building the just-ahead-of-time C++ binary.

1 files changed, 14 insertions, 3 deletions

diff --git a/lib/PublicInbox/XapHelperCxx.pm b/lib/PublicInbox/XapHelperCxx.pm
index eafe61a8..74852ad1 100644
--- a/lib/PublicInbox/XapHelperCxx.pm
+++ b/lib/PublicInbox/XapHelperCxx.pm
@@ -16,8 +16,15 @@ use autodie;
 my $cxx = which($ENV{CXX} // 'c++') // which('clang') // die 'no C++ compiler';
 my $dir = substr("$cxx-$Config{archname}", 1); # drop leading '/'
 $dir =~ tr!/!-!;
-my $idir = ($ENV{XDG_CACHE_HOME} //
-        (($ENV{HOME} // die('HOME unset')).'/.cache')).'/public-inbox/jaot';
+my $idir;
+if ((defined($ENV{XDG_CACHE_HOME}) && -d $ENV{XDG_CACHE_HOME}) ||
+                        (defined($ENV{HOME}) && -d $ENV{HOME})) {
+        $idir = ($ENV{XDG_CACHE_HOME} //
+                        (($ENV{HOME} // die('HOME unset')).'/.cache')
+                ).'/public-inbox/jaot';
+}
+$idir //= $ENV{PERL_INLINE_DIRECTORY} //
+        die 'HOME and PERL_INLINE_DIRECTORY unset';
 substr($dir, 0, 0) = "$idir/";
 my $bin = "$dir/xap_helper";
 my ($srcpfx) = (__FILE__ =~ m!\A(.+/)[^/]+\z!);
@@ -58,7 +65,11 @@ sub needs_rebuild () {
 sub build () {
         if (!-d $dir) {
                 require File::Path;
-                File::Path::make_path($dir);
+                eval { File::Path::make_path($dir) };
+                if (!-d $dir && defined($ENV{PERL_INLINE_DIRECTORY})) {
+                        $dir = $ENV{PERL_INLINE_DIRECTORY};
+                        File::Path::make_path($dir);
+                }
         }
         require PublicInbox::CodeSearch;
         require PublicInbox::Lock;