1 files changed, 51 insertions, 0 deletions
diff --git a/testsuite/tests/lib/IO/hSeek003.hs b/testsuite/tests/lib/IO/hSeek003.hs
new file mode 100644
index 0000000000..03400573c4
--- /dev/null
+++ b/testsuite/tests/lib/IO/hSeek003.hs
@@ -0,0 +1,51 @@
+-- !!! file positions (hGetPosn and hSetPosn)
+
+module Main(main) where
+
+import System.IO
+import Control.Monad ( sequence )
+
+testPosns :: Handle -> BufferMode -> IO ()
+testPosns hdl bmo = do
+   hSetBuffering hdl bmo
+   putStrLn ("Testing positioning with buffer mode set to: " ++ show bmo)
+   testPositioning hdl
+
+bmo_ls = [NoBuffering, LineBuffering, BlockBuffering Nothing, 
+          BlockBuffering (Just 511),BlockBuffering (Just 3), BlockBuffering (Just 11)]
+
+main = do
+  hdl  <- openFile "hSeek003.hs" ReadMode
+  sequence (zipWith testPosns (repeat hdl) bmo_ls)
+  hClose hdl
+
+testPositioning hdl = do
+  hSeek hdl AbsoluteSeek 0  -- go to the beginning of the file again.
+  ps   <- getFilePosns 10 hdl
+  hSeek hdl AbsoluteSeek 0
+  putStr "First ten chars: "
+  ls   <- hGetChars 10 hdl
+  putStrLn ls
+    -- go to the end
+  hSeek hdl SeekFromEnd 0  
+  ls   <- sequence (map (\ p -> hSetPosn p >> hGetChar hdl) ps)
+  putStr "First ten chars: "
+  putStrLn ls
+
+    -- position ourselves in the middle.
+  sz <- hFileSize hdl
+  hSeek hdl AbsoluteSeek (sz `div` 2)
+  ls   <- sequence (map (\ p -> hSetPosn p >> hGetChar hdl) ps)
+  putStr "First ten chars: "
+  putStrLn ls
+
+hGetChars :: Int -> Handle -> IO String
+hGetChars n h = sequence (replicate n (hGetChar h))
+
+getFilePosns :: Int -> Handle -> IO [HandlePosn]
+getFilePosns 0 h = return []
+getFilePosns x h = do
+   p <- hGetPosn h
+   hGetChar h
+   ps <- getFilePosns (x-1) h
+   return (p:ps)