fix marked buffering

Author: bicycle1885

src/buffer.jl

@@ -119,12 +119,8 @@ end
 # Make margin with ≥`minsize`.
 function makemargin!(buf::Buffer, minsize::Integer)
     @assert minsize ≥ 0
-    if buffersize(buf) == 0
-        if buf.markpos == 0
-            buf.bufferpos = buf.marginpos = 1
-        else
-            buf.bufferpos = buf.marginpos = buf.markpos
-        end
+    if buffersize(buf) == 0 && buf.markpos == 0
+        buf.bufferpos = buf.marginpos = 1
     end
     if marginsize(buf) < minsize
         # shift data to left
@@ -133,11 +129,14 @@ function makemargin!(buf::Buffer, minsize::Integer)
             datasize = buffersize(buf)
         else
             datapos = buf.markpos
-            datasize = buffersize(buf) + buf.bufferpos - buf.markpos
+            datasize = buf.marginpos - buf.markpos
         end
         copy!(buf.data, 1, buf.data, datapos, datasize)
+        if buf.markpos > 0
+            buf.markpos -= datapos - 1
+        end
         buf.bufferpos -= datapos - 1
-        buf.marginpos = buf.bufferpos + datasize
+        buf.marginpos -= datapos - 1
     end
     if marginsize(buf) < minsize
         # expand data buffer

src/stream.jl

@@ -327,14 +327,14 @@ end
 
 function process_to_write(stream::TranscodingStream)
     buffer1 = stream.state.buffer1
-    buffer2 = stream.state.buffer2
     if buffersize(buffer1) > 0 && stream.state.code == :end
         # reset
         stream.state.code = startproc(stream.codec, :write)
         if stream.state.code != :ok
             error("failed to reset codec")
         end
     end
+    buffer2 = stream.state.buffer2
     writebuffer!(stream.stream, buffer2)
     makemargin!(buffer2, 1)
     Δin, Δout, stream.state.code = process(stream.codec, buffermem(buffer1), marginmem(buffer2))

test/runtests.jl

@@ -68,6 +68,17 @@ using Base.Test
     @test_throws BoundsError s.state.buffer1[0]
     @test_throws BoundsError s.state.buffer1[3]
     @test_throws BoundsError s.state.buffer1[3:4]
+
+    data = rand(UInt8, 1999)
+    # unmarked
+    stream = TranscodingStream(Identity(), IOBuffer(data), bufsize=7)
+    @test hash(read(stream)) == hash(data)
+    @test length(stream.state.buffer1) == 7
+    # marked
+    stream = TranscodingStream(Identity(), IOBuffer(data), bufsize=7)
+    mark(stream)
+    @test hash(read(stream)) == hash(data)
+    @test hash(stream.state.buffer1.data[1:length(data)]) == hash(data)
 end
 
 Pkg.test("CodecZlib")