add check for git

Build/NullSoftInstaller.hs

@@ -2,6 +2,18 @@
  - 
  - git-annex should already be built by cabal, and ssh and rsync,
  - as well as cygwin libraries, already installed.
+ -
+ - This uses the Haskell nsis package (cabal install nsis)
+ - to generate a .nsi file, which is then used to produce
+ - git-annex-installer.exe
+ - 
+ - The installer includes git-annex, and utilities it uses, with the
+ - exception of git. The user needs to install git separately,
+ - and the installer checks for that.
+ -
+ - Copyright 2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
  -}
 
 {-# LANGUAGE OverloadedStrings #-}
@@ -10,9 +22,13 @@ import Development.NSIS
 
 main = writeFile "git-annex.nsi" $ nsis $ do
 	name "git-annex"
-	outFile "git-annex.exe"
+	outFile "git-annex-installer.exe"
 	installDir "$DESKTOP/git-annex"
 	requestExecutionLevel User
+	iff_ (fileExists "$WINDIR/git.exe")
+		(return ()) $ do
+		messageBox [MB_ABORTRETRYIGNORE]
+			"git does not seem to be installed. git-annex can't be used without git!"
 	-- Pages to display
 	page Directory                   -- Pick where to install
 	page InstFiles                   -- Give a progress bar while installing
@@ -22,7 +38,12 @@ main = writeFile "git-annex.nsi" $ nsis $ do
 		file [] "dist/build/git-annex/git-annex.exe"
 		fromcygwin "rsync.exe"
 		fromcygwin "ssh.exe"
+		fromcygwin "sha256.exe"
+		fromcygwin "sha1.exe"
+		fromcygwin "sha512.exe"
+		fromcygwin "sha384.exe"
 	section "DLLS" [] $ mapM_ fromcygwin 
+		setOutPath "$INSTDIR"
 		[ "cygwin1.dll"
 		, "cygasn1-8.dll"
 		, "cygheimbase-1.dll"