don't fail if seeking input is not permitted; add test

3 files changed, 18 insertions, 4 deletions

diff --git a/lib/asciidoctor.rb b/lib/asciidoctor.rb
index ce21f5e8..2755cfb7 100644
--- a/lib/asciidoctor.rb
+++ b/lib/asciidoctor.rb
@@ -1223,7 +1223,9 @@ module Asciidoctor
       attributes['doctime'] = doctime = input_mtime.strftime('%H:%M:%S %Z')
       attributes['docdatetime'] = %(#{docdate} #{doctime})
     elsif input.respond_to? :readlines
-      input.rewind if input.respond_to? :rewind
+      # NOTE tty, pipes & sockets can't be rewound, but can't be sniffed easily either
+      # just fail the rewind operation silently to handle all cases
+      input.rewind rescue nil
       lines = input.readlines
     elsif input.is_a? ::String
       lines = input.lines.entries
diff --git a/lib/asciidoctor/cli/invoker.rb b/lib/asciidoctor/cli/invoker.rb
index 585fd408..403748c3 100644
--- a/lib/asciidoctor/cli/invoker.rb
+++ b/lib/asciidoctor/cli/invoker.rb
@@ -67,10 +67,10 @@ module Asciidoctor
           }
 
           if infiles.size == 1 && infiles[0] == '-'
-             # allows use of block to supply stdin, particularly useful for tests
-             inputs = [block_given? ? yield : STDIN]
+            # allows use of block to supply stdin, particularly useful for tests
+            inputs = [block_given? ? yield : STDIN]
           else
-             inputs = infiles.map {|infile| ::File.new infile, 'r'}
+            inputs = infiles.map {|infile| ::File.new infile, 'r'}
           end
 
           # NOTE: if infile is stdin, default to outfile as stout
diff --git a/test/invoker_test.rb b/test/invoker_test.rb
index daa8745e..78e354f7 100644
--- a/test/invoker_test.rb
+++ b/test/invoker_test.rb
@@ -61,6 +61,18 @@ context 'Invoker' do
     assert_xpath '/*[@class="paragraph"]/p[text()="content"]', output, 1
   end
 
+  test 'should not fail to rewind input if reading document from stdin' do
+    io = STDIN.dup
+    class << io
+      def readlines
+        ['paragraph']
+      end
+    end
+    invoker = invoke_cli_to_buffer(%w(-s), '-') { io }
+    assert_equal 0, invoker.code
+    assert_equal 1, invoker.document.blocks.size
+  end
+
   test 'should accept document from stdin and write to output file' do
     sample_outpath = File.expand_path(File.join(File.dirname(__FILE__), 'fixtures', 'sample-output.html'))
     begin