From 4df8c588af78ce4f74ca45ab542b05dfa6d232fd Mon Sep 17 00:00:00 2001
From: simonmar <unknown>
Date: Tue, 24 Feb 2004 12:39:12 +0000
Subject: [PATCH] [project @ 2004-02-24 12:39:12 by simonmar] New version of
 translate for mingw32, which correctly (allegedly) reverses
 the command-line translation done by the standard C runtime
 on Windows.

---
 System/Cmd.hs |   21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/System/Cmd.hs b/System/Cmd.hs
index 78d3b28..41fabb2 100644
--- a/System/Cmd.hs
+++ b/System/Cmd.hs
@@ -203,9 +203,24 @@ rawSystem cmd args = do
 
 translate :: String -> String
 translate str@('"':_) = str -- already escaped.
-translate str = '"' : foldr escape "\"" str
-  where escape '"'  str = '\\' : '"'  : str
-	escape c    str = c : str
+	-- ToDo: this case is wrong.  It is only here because we
+	-- abuse the system in GHC's SysTools by putting arguments into
+	-- the command name; at some point we should fix it up and remove
+	-- the case above.
+translate str = '"' : snd (foldr escape (True,"\"") str)
+  where escape '"'  (b,     str) = (True,  '\\' : '"'  : str)
+        escape '\\' (True,  str) = (True,  '\\' : '\\' : str)
+        escape '\\' (False, str) = (False, '\\' : str)
+	escape c    (b,     str) = (False, c : str)
+	-- This function attempts to invert the Microsoft C runtime's
+	-- quoting rules, which can be found here:
+	--     http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/progs_12.asp
+	-- (if this URL stops working, you might be able to find it by
+	-- searching for "Parsing C Command-Line Arguments" on MSDN).
+	--
+	-- The Bool passed back along the string is True iff the
+	-- rest of the string is a sequence of backslashes followed by
+	-- a double quote.
 
 foreign import ccall unsafe "rawSystem"
   c_rawSystem :: CString -> IO Int
-- 
1.7.10.4