Try to gracefully handle absence of Digest::SHA

1 files changed, 17 insertions, 7 deletions

diff --git a/checkem b/checkem
index f64044a..8b0d7f4 100755
--- a/checkem
+++ b/checkem
@@ -42,13 +42,23 @@ my %STATS = (
     size => 7,
 );
 
-# Create a digest object; defaults to SHA-256, but can be overriden by setting
-# CHECKEM_ALG in the environment
-my $dig = Digest->new(
-    exists $ENV{CHECKEM_ALG}
-    ? $ENV{CHECKEM_ALG}
-    : 'SHA-256',
-);
+# Create a digest object, trying to safely detect ancient Perl (5.6)
+# installations, or others that are bereft of Digest::SHA, in order
+# to pick the algorithm. It can be foced with the CHECKEM_ALG environment
+# variable.
+my $dig = do {
+    my $alg;
+    if ( exists $ENV{CHECKEM_ALG} ) {
+        $alg = $ENV{CHECKEM_ALG};
+    }
+    elsif ( eval { require Digest::SHA; } ) {
+        $alg = 'SHA-1';
+    }
+    else {
+        $alg = 'MD5';
+    }
+    Digest->new($alg);
+};
 
 # Start a hash of filesizes to file names/stats...
 my %sizes;