lib/io/splice.rb in io_splice-1.0.0 vs lib/io/splice.rb in io_splice-2.0.0

@@ -3,17 +3,20 @@
 
 class IO
 
   module Splice
 
-    # the version of IO::Splice, currently 0.1.0
-    VERSION = '1.0.0'
+    # the version of IO::Splice, currently 2.0.0
+    VERSION = '2.0.0'
 
-    # The maximum capacity of the pipe in bytes.
+    # The maximum default capacity of the pipe in bytes.
     # Under stock Linux, this is 65536 bytes as of 2.6.11, and 4096 before
     # We detect this at runtime as it is easy to recompile the kernel
     # and set a new value.
+    # Starting with Linux 2.6.35, pipe capacity will be tunable
+    # and this will only represent the default capacity of a
+    # newly-created pipe.
     PIPE_CAPA = begin
       rd, wr = IO.pipe
       buf = ' ' * PIPE_BUF
       n = 0
       begin
@@ -22,9 +25,73 @@
         break
       end while true
       wr.close
       rd.close
       n
+    end
+
+    # copies the contents of the IO object given by +src+ to +dst+
+    # If len is specified, then only len bytes are copied.  Otherwise
+    # the copy will be until EOF is reached on the +src+.
+    # +src+ and +dst+ must be IO objects or respond to +to_io+
+    def self.copy_stream(src, dst, len = nil, src_offset = nil)
+      src.kind_of?(String) and src = File.open(src, 'rb')
+      dst.kind_of?(String) and dst = File.open(dst, 'wb')
+      src, dst = src.to_io, dst.to_io
+      rv = len
+      src.sysseek(src_offset) if src_offset
+      if src.stat.pipe? || dst.stat.pipe?
+        if len
+          while len > 0
+            nr = len > PIPE_CAPA ? PIPE_CAPA : len
+            nr = IO.splice(src, nil, dst, nil, nr, F_MOVE)
+            if nr == 0
+              raise EOFError, "unexpected EOF with #{len} bytes left"
+            end
+            len -= nr
+          end
+        else
+          rv = 0
+          begin
+            nr = IO.splice(src, nil, dst, nil, PIPE_CAPA, F_MOVE)
+            rv += nr
+          rescue EOFError
+            break
+          end while true
+        end
+      else
+        begin
+          r, w = IO.pipe
+          if len
+            while len > 0
+              nr = len > PIPE_CAPA ? PIPE_CAPA : len
+              nr_src = copy_stream(src, w, nr)
+              nr_src == nr or
+                raise RuntimeError, "short splice from: #{nr_src} != #{nr}"
+              nr_dst = copy_stream(r, dst, nr)
+              nr_dst == nr or
+                raise RuntimeError, "short splice to: #{nr_dst} != #{nr}"
+              len -= nr
+            end
+          else
+            rv = 0
+            begin
+              nr = IO.splice(src, nil, w, nil, PIPE_CAPA, F_MOVE)
+              rv += nr
+              begin
+                nr -= IO.splice(r, nil, dst, nil, nr, F_MOVE)
+              end while nr > 0
+            rescue EOFError
+              break
+            end while true
+          end
+        ensure
+          r.close
+          w.close
+        end
+      end
+
+      rv
     end
 
   end
 end