1 files changed, 71 insertions, 0 deletions
diff --git a/Git/CheckIgnore.hs b/Git/CheckIgnore.hs
new file mode 100644
index 000000000..2ab7cb3dc
--- /dev/null
+++ b/Git/CheckIgnore.hs
@@ -0,0 +1,71 @@
+{- git check-ignore interface
+ -
+ - Copyright 2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.CheckIgnore (
+	CheckIgnoreHandle,
+	checkIgnoreStart,
+	checkIgnoreStop,
+	checkIgnored
+) where
+
+import Common
+import Git
+import Git.Command
+import qualified Git.Version
+import qualified Utility.CoProcess as CoProcess
+
+import System.IO.Error
+
+type CheckIgnoreHandle = CoProcess.CoProcessHandle
+
+{- Starts git check-ignore running, and returns a handle.
+ -
+ - This relies on git check-ignore --non-matching -v outputting
+ - lines for both matching an non-matching files. Also relies on
+ - GIT_FLUSH behavior flushing the output buffer when git check-ignore
+ - is piping to us.
+ -
+ - The first version of git to support what we need is 1.8.4.
+ - Nothing is returned if an older git is installed.
+ -}
+checkIgnoreStart :: Repo -> IO (Maybe CheckIgnoreHandle)
+checkIgnoreStart repo = ifM supportedGitVersion
+	( Just <$> (CoProcess.rawMode =<< gitCoProcessStart True params repo)
+	, return Nothing
+	)
+  where
+	params =
+		[ Param "check-ignore" 
+		, Params "-z --stdin --verbose --non-matching"
+		]
+
+supportedGitVersion :: IO Bool
+supportedGitVersion = do
+	v <- Git.Version.installed
+	return $ v >= Git.Version.normalize "1.8.4"
+
+checkIgnoreStop :: CheckIgnoreHandle -> IO ()
+checkIgnoreStop = CoProcess.stop
+
+{- Returns True if a file is ignored. -}
+checkIgnored :: CheckIgnoreHandle -> FilePath -> IO Bool
+checkIgnored h file = CoProcess.query h send (receive "")
+  where
+	send to = do
+		hPutStr to $ file ++ "\0"
+		hFlush to
+	receive c from = do
+		s <- hGetSomeString from 1024
+		if null s
+			then eofError
+			else do
+				let v = c ++ s
+				maybe (receive v from) return (parse v)
+	parse s = case segment (== '\0') s of
+		(_source:_line:pattern:_pathname:_eol:[]) -> Just $ not $ null pattern
+		_ -> Nothing
+	eofError = ioError $ mkIOError userErrorType "git cat-file EOF" Nothing Nothing