Allow choosing another SHA alg

1 files changed, 8 insertions, 2 deletions

diff --git a/checkem b/checkem
index ba7c1bd..51c56df 100755
--- a/checkem
+++ b/checkem
@@ -38,6 +38,11 @@ my %STATS = (
     size => 7,
 );
 
+# Figure out the SHA algorithm to use; defaults to sha256, but can be overriden
+# by setting CHECKEM_ALG in the environment to e.g. "sha1", which is slightly
+# faster but technically broken in practice since early 2017
+my $alg = $ENV{CHECKEM_ALG} // 'sha256';
+
 # Start a hash of filesizes to file names/stats...
 my %sizes;
 
@@ -76,8 +81,9 @@ FS: for my $fs ( grep { @{$_} > 1 } values %sizes ) {
             $inos{$dev}{$ino} = $f;
         }
 
-        # Files still the same size and not hard linked, group by digest
-        $dig //= Digest::SHA->new('sha256');
+        # Files still the same size and not hard linked, group by digest;
+        # create the digest object if it isn't already defined
+        $dig //= Digest::SHA->new($alg);
         $dig->addfile( $f->{fn} );
         push @{ $sums{ $dig->digest() } }, $f;
     }