tests: allow use of alternative sha1 implementations

sha1sum(1) is only common GNU systems, and it may be installed
as gsha1sum on *BSDs.  We'll also try using the openssl sha1
implementation, too.  And finally, we'll provide our own Ruby
sha1sum.rb implementation as a last resort.

We go to great lengths to avoid our own Ruby version because we
want to avoid putting too much trust in ourselves, our Ruby
skills, and even the Ruby implementations.  This is especially
with regard to our knowledge and correct usage of Ruby 1.9
encoding support.  It would actually be *easier* to only use
sha1sum.rb and call it a day.  We just choose to support
SHA1 implementations provided by third parties if possible.

Performance is not a factor since sha1sum.rb performance is very
close to the C implementations.

1 files changed, 23 insertions, 0 deletions

diff --git a/t/bin/sha1sum.rb b/t/bin/sha1sum.rb
new file mode 100755
index 0000000..b602e79
--- /dev/null
+++ b/t/bin/sha1sum.rb
@@ -0,0 +1,23 @@
+#!/usr/bin/env ruby
+# -*- encoding: binary -*-
+
+# Reads from stdin and outputs the SHA1 hex digest of the input this is
+# ONLY used as a last resort, our test code will try to use sha1sum(1),
+# openssl(1), or gsha1sum(1) before falling back to using this.  We try
+# all options first because we have a strong and healthy distrust of our
+# Ruby abilities in general, and *especially* when it comes to
+# understanding (and trusting the implementation of) Ruby 1.9 encoding.
+
+require 'digest/sha1'
+$stdout.sync = $stderr.sync = true
+$stdout.binmode
+$stdin.binmode
+bs = 16384
+digest = Digest::SHA1.new
+if buf = $stdin.read(bs)
+  begin
+    digest.update(buf)
+  end while $stdin.read(bs, buf)
+end
+
+$stdout.syswrite("#{digest.hexdigest}\n")