BUG REPORT: Add buggy test case (files created by pbzip2)

ChangeLog.md

@@ -1,3 +1,6 @@
+## 0.3.0.2
+* Fix handling of concatenated bzip2 files
+
 ## 0.3.0.1
 
 * Reduce dep to `data-default-class` [#6](https://github.com/snoyberg/bzlib-conduit/pull/6)

src/Data/Conduit/BZlib.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE RecordWildCards #-}
 module Data.Conduit.BZlib (
   compress,
+  decompress1,
   decompress,
 
   bzip2,
@@ -131,6 +132,7 @@ compress CompressParams {..} = do
             yields ptr c'BZ_FINISH
   loop
   where
+    yields :: MonadIO m => Ptr C'bz_stream -> CInt -> ConduitT S.ByteString S.ByteString m ()
     yields ptr action = do
       cont <- liftIO $ throwIfMinus "bzCompress" $ c'BZ2_bzCompress ptr action
       mbout <- liftIO $ getAvailOut ptr
@@ -140,12 +142,14 @@ compress CompressParams {..} = do
       when (availIn > 0 || action == c'BZ_FINISH && cont /= c'BZ_STREAM_END) $
         yields ptr action
 
--- | Decompress a stream of ByteStrings.
-decompress
+-- | Decompress a stream of ByteStrings. Note that this will only decompress
+-- the first compressed stream in the input and leave the rest for further
+-- processing. See 'decompress'.
+decompress1
   :: MonadResource m
      => DecompressParams -- ^ Decompress parameter
      -> ConduitT S.ByteString S.ByteString m ()
-decompress DecompressParams {..} = do
+decompress1 DecompressParams {..} = do
   (ptr, inbuf) <- lift $ allocateStream
   _ <- lift $ allocate
     (throwIfMinus_ "bzDecompressInit" $
@@ -172,13 +176,41 @@ decompress DecompressParams {..} = do
         yield $ fromJust mbout
       availIn <- liftIO $ peek $ p'bz_stream'avail_in ptr
       if availIn > 0
-        then yields ptr
+        then
+            -- bzip2 files can contain multiple concatenated streams, but the
+            -- API requires that we close the stream and start a new
+            -- decompression session.
+            if ret == c'BZ_STREAM_END
+                then do
+                    dataIn <- liftIO $ peek $ p'bz_stream'next_in ptr
+                    unread <- liftIO $ S.packCStringLen (dataIn, fromIntegral availIn)
+                    leftover unread
+                    return False
+                else yields ptr
         else return $ ret == c'BZ_OK
 
+-- Decompress all the compressed bzip2 streams in the input, as the bzip2
+-- command line tool.
+decompress
+  :: MonadResource m
+     => DecompressParams -- ^ Decompress parameter
+     -> ConduitT S.ByteString S.ByteString m ()
+decompress params = do
+    next <- await
+    case next of
+        Nothing -> return ()
+        Just bs
+            | S.null bs -> decompress params
+            | otherwise -> do
+                leftover bs
+                decompress1 params
+                decompress params
 -- | bzip2 compression with default parameters.
 bzip2 :: MonadResource m => ConduitT S.ByteString S.ByteString m ()
 bzip2 = compress def
 
--- | bzip2 decompression with default parameters.
+-- | bzip2 decompression with default parameters. This will decompress all the
+-- streams in the input
 bunzip2 :: MonadResource m => ConduitT S.ByteString S.ByteString m ()
 bunzip2 = decompress def
+

test/test.hs

@@ -15,7 +15,8 @@ import Prelude as P
 main :: IO ()
 main = hspec $ do
   describe "decompress" $ do
-    forM_ ["sample1", "sample2", "sample3"] $ \file -> do
+    forM_ [1..5] $ \n -> do
+      let file = "sample"++show n
       it ("correctly " ++ file ++ ".bz2") $ do
         dec <- runConduitRes
              $ sourceFile ("test/" ++ file ++ ".bz2")