content: {-# LANGUAGE CPP, TypeSynonymInstances, FlexibleInstances, RecordWildCards,
               GeneralizedNewtypeDeriving, StandaloneDeriving #-}
  {-# OPTIONS_GHC -fno-warn-orphans #-}
  -----------------------------------------------------------------------------
  --
  -- (c) The University of Glasgow 2004-2009.
  --
  -- Package management tool
  --
  -----------------------------------------------------------------------------
  
  module HastePkg710 (main) where
  
  import qualified GHC.PackageDb as GhcPkg
  import qualified Distribution.Simple.PackageIndex as PackageIndex
  import qualified Data.Graph as Graph
  import qualified Distribution.ModuleName as ModuleName
  import Distribution.ModuleName (ModuleName)
  import Distribution.InstalledPackageInfo as Cabal
  import Distribution.Compat.ReadP hiding (get)
  import Distribution.ParseUtils
  import Distribution.Package hiding (depends, installedPackageId)
  import Distribution.Text
  import Distribution.Version
  import Distribution.Simple.Utils (fromUTF8, toUTF8)
  import System.FilePath as FilePath
  import qualified System.FilePath.Posix as FilePath.Posix
  import System.Process
  import System.Directory ( getAppUserDataDirectory, createDirectoryIfMissing,
                            getModificationTime )
  import Text.Printf
  
  import Prelude
  
  import System.Console.GetOpt
  import qualified Control.Exception as Exception
  import Data.Maybe
  
  import Data.Char ( isSpace, toLower )
  import Data.Ord (comparing)
  import Control.Monad
  import System.Directory ( doesDirectoryExist, getDirectoryContents,
                            doesFileExist, renameFile, removeFile,
                            getCurrentDirectory )
  import System.Exit ( exitWith, ExitCode(..) )
  import System.Environment ( getArgs, getProgName, getEnv )
  import System.IO
  import System.IO.Error
  import GHC.IO.Exception (IOErrorType(InappropriateType))
  import Data.List
  import Control.Concurrent
  
  import qualified Data.ByteString.Char8 as BS
  
  -- Haste-specific
  import Haste.Environment
  import Haste.Version
  import System.Info (os)
  import qualified Control.Shell as Sh
  
  #if defined(mingw32_HOST_OS)
  -- mingw32 needs these for getExecDir
  import Foreign
  import Foreign.C
  #endif
  
  #ifdef mingw32_HOST_OS
  import GHC.ConsoleHandler
  #else
  import System.Posix hiding (fdToHandle)
  #endif
  
  #if defined(GLOB)
  import qualified System.Info(os)
  #endif
  
  #if !defined(mingw32_HOST_OS) && !defined(BOOTSTRAPPING)
  import System.Console.Terminfo as Terminfo
  #endif
  
  #ifdef mingw32_HOST_OS
  # if defined(i386_HOST_ARCH)
  #  define WINDOWS_CCONV stdcall
  # elif defined(x86_64_HOST_ARCH)
  #  define WINDOWS_CCONV ccall
  # else
  #  error Unknown mingw32 arch
  # endif
  #endif
  
  -- -----------------------------------------------------------------------------
  -- Entry point
  
  main :: IO ()
  main = do
    args <- getArgs
  
    case args of
      ["relocate", pkg] -> do
        Sh.shell (relocate packages pkg) >> exitWith ExitSuccess
      _ ->
        return ()
  
    case getOpt Permute (flags ++ deprecFlags) args of
          (cli,_,[]) | FlagHelp `elem` cli -> do
             prog <- getProgramName
             bye (usageInfo (usageHeader prog) flags)
          (cli,_,[]) | FlagVersion `elem` cli ->
             bye ourCopyright
          (cli,_,[]) | FlagNumericVersion `elem` cli ->
             bye $ showVersion hasteVersion ++ "\n"
          (cli,_,[]) | FlagNumericGhcVersion `elem` cli ->
             bye $ showVersion ghcVersion ++ "\n"
          (cli,nonopts,[]) ->
             case getVerbosity Normal cli of
             Right v -> runit v cli nonopts
             Left err -> die err
          (_,_,errors) -> do
             prog <- getProgramName
             die (concat errors ++ shortUsage prog)
    where
      -- for relocate
      packages = ["--global-package-db=" ++ pkgSysDir,
                  "--package-db=" ++ pkgSysDir,
                  "--package-db=" ++ pkgUserDir]
  
  -- -----------------------------------------------------------------------------
  -- Command-line syntax
  
  data Flag
    = FlagUser
    | FlagGlobal
    | FlagHelp
    | FlagVersion
    | FlagNumericVersion
    | FlagNumericGhcVersion
    | FlagConfig FilePath
    | FlagGlobalConfig FilePath
    | FlagUserConfig FilePath
    | FlagForce
    | FlagForceFiles
    | FlagAutoGHCiLibs
    | FlagMultiInstance
    | FlagExpandEnvVars
    | FlagExpandPkgroot
    | FlagNoExpandPkgroot
    | FlagSimpleOutput
    | FlagNamesOnly
    | FlagIgnoreCase
    | FlagNoUserDb
    | FlagVerbosity (Maybe String)
    | FlagIPId
    | FlagPackageKey
    deriving Eq
  
  flags :: [OptDescr Flag]
  flags = [
    Option [] ["user"] (NoArg FlagUser)
          "use the current user's package database",
    Option [] ["global"] (NoArg FlagGlobal)
          "use the global package database",
    Option ['f'] ["package-db"] (ReqArg FlagConfig "FILE/DIR")
          "use the specified package database",
    Option [] ["package-conf"] (ReqArg FlagConfig "FILE/DIR")
          "use the specified package database (DEPRECATED)",
    Option [] ["global-package-db"] (ReqArg FlagGlobalConfig "DIR")
          "location of the global package database",
    Option [] ["no-user-package-db"] (NoArg FlagNoUserDb)
          "never read the user package database",
    Option [] ["user-package-db"] (ReqArg FlagUserConfig "DIR")
          "location of the user package database (use instead of default)",
    Option [] ["no-user-package-conf"] (NoArg FlagNoUserDb)
          "never read the user package database (DEPRECATED)",
    Option [] ["force"] (NoArg FlagForce)
           "ignore missing dependencies, directories, and libraries",
    Option [] ["force-files"] (NoArg FlagForceFiles)
           "ignore missing directories and libraries only",
    Option ['g'] ["auto-ghci-libs"] (NoArg FlagAutoGHCiLibs)
          "automatically build libs for GHCi (with register)",
    Option [] ["enable-multi-instance"] (NoArg FlagMultiInstance)
          "allow registering multiple instances of the same package version",
    Option [] ["expand-env-vars"] (NoArg FlagExpandEnvVars)
          "expand environment variables (${name}-style) in input package descriptions",
    Option [] ["expand-pkgroot"] (NoArg FlagExpandPkgroot)
          "expand ${pkgroot}-relative paths to absolute in output package descriptions",
    Option [] ["no-expand-pkgroot"] (NoArg FlagNoExpandPkgroot)
          "preserve ${pkgroot}-relative paths in output package descriptions",
    Option ['?'] ["help"] (NoArg FlagHelp)
          "display this help and exit",
    Option ['V'] ["version"] (NoArg FlagVersion)
          "output version information and exit",
    Option [] ["numeric-version"] (NoArg FlagNumericVersion)
          "output version number and exit",
    Option [] ["numeric-ghc-version"] (NoArg FlagNumericGhcVersion)
          "output GHC version number and exit",
    Option [] ["simple-output"] (NoArg FlagSimpleOutput)
          "print output in easy-to-parse format for some commands",
    Option [] ["names-only"] (NoArg FlagNamesOnly)
          "only print package names, not versions; can only be used with list --simple-output",
    Option [] ["ignore-case"] (NoArg FlagIgnoreCase)
          "ignore case for substring matching",
    Option [] ["ipid"] (NoArg FlagIPId)
          "interpret package arguments as installed package IDs",
    Option [] ["package-key"] (NoArg FlagPackageKey)
          "interpret package arguments as installed package keys",
    Option ['v'] ["verbose"] (OptArg FlagVerbosity "Verbosity")
          "verbosity level (0-2, default 1)"
    ]
  
  data Verbosity = Silent | Normal | Verbose
      deriving (Show, Eq, Ord)
  
  getVerbosity :: Verbosity -> [Flag] -> Either String Verbosity
  getVerbosity v [] = Right v
  getVerbosity _ (FlagVerbosity Nothing    : fs) = getVerbosity Verbose fs
  getVerbosity _ (FlagVerbosity (Just "0") : fs) = getVerbosity Silent  fs
  getVerbosity _ (FlagVerbosity (Just "1") : fs) = getVerbosity Normal  fs
  getVerbosity _ (FlagVerbosity (Just "2") : fs) = getVerbosity Verbose fs
  getVerbosity _ (FlagVerbosity v : _) = Left ("Bad verbosity: " ++ show v)
  getVerbosity v (_ : fs) = getVerbosity v fs
  
  deprecFlags :: [OptDescr Flag]
  deprecFlags = [
          -- put deprecated flags here
    ]
  
  ourCopyright :: String
  ourCopyright = "Haste package manager version " ++ showVersion hasteVersion ++ "\n"
  
  shortUsage :: String -> String
  shortUsage prog = "For usage information see '" ++ prog ++ " --help'."
  
  usageHeader :: String -> String
  usageHeader prog = substProg prog $
    "Usage:\n" ++
    "  $p init {path}\n" ++
    "    Create and initialise a package database at the location {path}.\n" ++
    "    Packages can be registered in the new database using the register\n" ++
    "    command with --package-db={path}.  To use the new database with GHC,\n" ++
    "    use GHC's -package-db flag.\n" ++
    "\n" ++
    "  $p register {filename | -}\n" ++
    "    Register the package using the specified installed package\n" ++
    "    description. The syntax for the latter is given in the $p\n" ++
    "    documentation.  The input file should be encoded in UTF-8.\n" ++
    "\n" ++
    "  $p update {filename | -}\n" ++
    "    Register the package, overwriting any other package with the\n" ++
    "    same name. The input file should be encoded in UTF-8.\n" ++
    "\n" ++
    "  $p unregister {pkg-id}\n" ++
    "    Unregister the specified package.\n" ++
    "\n" ++
    "  $p expose {pkg-id}\n" ++
    "    Expose the specified package.\n" ++
    "\n" ++
    "  $p hide {pkg-id}\n" ++
    "    Hide the specified package.\n" ++
    "\n" ++
    "  $p trust {pkg-id}\n" ++
    "    Trust the specified package.\n" ++
    "\n" ++
    "  $p distrust {pkg-id}\n" ++
    "    Distrust the specified package.\n" ++
    "\n" ++
    "  $p list [pkg]\n" ++
    "    List registered packages in the global database, and also the\n" ++
    "    user database if --user is given. If a package name is given\n" ++
    "    all the registered versions will be listed in ascending order.\n" ++
    "    Accepts the --simple-output flag.\n" ++
    "\n" ++
    "  $p dot\n" ++
    "    Generate a graph of the package dependencies in a form suitable\n" ++
    "    for input for the graphviz tools.  For example, to generate a PDF" ++
    "    of the dependency graph: ghc-pkg dot | tred | dot -Tpdf >pkgs.pdf" ++
    "\n" ++
    "  $p find-module {module}\n" ++
    "    List registered packages exposing module {module} in the global\n" ++
    "    database, and also the user database if --user is given.\n" ++
    "    All the registered versions will be listed in ascending order.\n" ++
    "    Accepts the --simple-output flag.\n" ++
    "\n" ++
    "  $p latest {pkg-id}\n" ++
    "    Prints the highest registered version of a package.\n" ++
    "\n" ++
    "  $p check\n" ++
    "    Check the consistency of package dependencies and list broken packages.\n" ++
    "    Accepts the --simple-output flag.\n" ++
    "\n" ++
    "  $p describe {pkg}\n" ++
    "    Give the registered description for the specified package. The\n" ++
    "    description is returned in precisely the syntax required by $p\n" ++
    "    register.\n" ++
    "\n" ++
    "  $p field {pkg} {field}\n" ++
    "    Extract the specified field of the package description for the\n" ++
    "    specified package. Accepts comma-separated multiple fields.\n" ++
    "\n" ++
    "  $p dump\n" ++
    "    Dump the registered description for every package.  This is like\n" ++
    "    \"ghc-pkg describe '*'\", except that it is intended to be used\n" ++
    "    by tools that parse the results, rather than humans.  The output is\n" ++
    "    always encoded in UTF-8, regardless of the current locale.\n" ++
    "\n" ++
    "  $p recache\n" ++
    "    Regenerate the package database cache.  This command should only be\n" ++
    "    necessary if you added a package to the database by dropping a file\n" ++
    "    into the database directory manually.  By default, the global DB\n" ++
    "    is recached; to recache a different DB use --user or --package-db\n" ++
    "    as appropriate.\n" ++
    "\n" ++
    " Substring matching is supported for {module} in find-module and\n" ++
    " for {pkg} in list, describe, and field, where a '*' indicates\n" ++
    " open substring ends (prefix*, *suffix, *infix*).  Use --ipid to\n" ++
    " match against the installed package ID instead.\n" ++
    "\n" ++
    "  When asked to modify a database (register, unregister, update,\n"++
    "  hide, expose, and also check), ghc-pkg modifies the global database by\n"++
    "  default.  Specifying --user causes it to act on the user database,\n"++
    "  or --package-db can be used to act on another database\n"++
    "  entirely. When multiple of these options are given, the rightmost\n"++
    "  one is used as the database to act upon.\n"++
    "\n"++
    "  Commands that query the package database (list, tree, latest, describe,\n"++
    "  field) operate on the list of databases specified by the flags\n"++
    "  --user, --global, and --package-db.  If none of these flags are\n"++
    "  given, the default is --global --user.\n"++
    "\n" ++
    " The following optional flags are also accepted:\n"
  
  substProg :: String -> String -> String
  substProg _ [] = []
  substProg prog ('$':'p':xs) = prog ++ substProg prog xs
  substProg prog (c:xs) = c : substProg prog xs
  
  -- -----------------------------------------------------------------------------
  -- Do the business
  
  data Force = NoForce | ForceFiles | ForceAll | CannotForce
    deriving (Eq,Ord)
  
  -- | Enum flag representing argument type
  data AsPackageArg
      = AsIpid
      | AsPackageKey
      | AsDefault
  
  -- | Represents how a package may be specified by a user on the command line.
  data PackageArg
      -- | A package identifier foo-0.1; the version might be a glob.
      = Id PackageIdentifier
      -- | An installed package ID foo-0.1-HASH.  This is guaranteed to uniquely
      -- match a single entry in the package database.
      | IPId InstalledPackageId
      -- | A package key foo_HASH.  This is also guaranteed to uniquely match
      -- a single entry in the package database
      | PkgKey PackageKey
      -- | A glob against the package name.  The first string is the literal
      -- glob, the second is a function which returns @True@ if the the argument
      -- matches.
      | Substring String (String->Bool)
  
  runit :: Verbosity -> [Flag] -> [String] -> IO ()
  runit verbosity cli nonopts = do
    installSignalHandlers -- catch ^C and clean up
    prog <- getProgramName
    let
          force
            | FlagForce `elem` cli        = ForceAll
            | FlagForceFiles `elem` cli   = ForceFiles
            | otherwise                   = NoForce
          as_arg | FlagIPId        `elem` cli = AsIpid
                 | FlagPackageKey  `elem` cli = AsPackageKey
                 | otherwise                  = AsDefault
          auto_ghci_libs = FlagAutoGHCiLibs `elem` cli
          multi_instance = FlagMultiInstance `elem` cli
          expand_env_vars= FlagExpandEnvVars `elem` cli
          mexpand_pkgroot= foldl' accumExpandPkgroot Nothing cli
            where accumExpandPkgroot _ FlagExpandPkgroot   = Just True
                  accumExpandPkgroot _ FlagNoExpandPkgroot = Just False
                  accumExpandPkgroot x _                   = x
                  
          splitFields fields = unfoldr splitComma (',':fields)
            where splitComma "" = Nothing
                  splitComma fs = Just $ break (==',') (tail fs)
  
          -- | Parses a glob into a predicate which tests if a string matches
          -- the glob.  Returns Nothing if the string in question is not a glob.
          -- At the moment, we only support globs at the beginning and/or end of
          -- strings.  This function respects case sensitivity.
          --
          -- >>> fromJust (substringCheck "*") "anything"
          -- True
          --
          -- >>> fromJust (substringCheck "string") "string"
          -- True
          --
          -- >>> fromJust (substringCheck "*bar") "foobar"
          -- True
          --
          -- >>> fromJust (substringCheck "foo*") "foobar"
          -- True
          --
          -- >>> fromJust (substringCheck "*ooba*") "foobar"
          -- True
          --
          -- >>> fromJust (substringCheck "f*bar") "foobar"
          -- False
          substringCheck :: String -> Maybe (String -> Bool)
          substringCheck ""    = Nothing
          substringCheck "*"   = Just (const True)
          substringCheck [_]   = Nothing
          substringCheck (h:t) =
            case (h, init t, last t) of
              ('*',s,'*') -> Just (isInfixOf (f s) . f)
              ('*',_, _ ) -> Just (isSuffixOf (f t) . f)
              ( _ ,s,'*') -> Just (isPrefixOf (f (h:s)) . f)
              _           -> Nothing
            where f | FlagIgnoreCase `elem` cli = map toLower
                    | otherwise                 = id
  #if defined(GLOB)
          glob x | System.Info.os=="mingw32" = do
            -- glob echoes its argument, after win32 filename globbing
            (_,o,_,_) <- runInteractiveCommand ("glob "++x)
            txt <- hGetContents o
            return (read txt)
          glob x | otherwise = return [x]
  #endif
    --
    -- first, parse the command
    case nonopts of
  #if defined(GLOB)
      -- dummy command to demonstrate usage and permit testing
      -- without messing things up; use glob to selectively enable
      -- windows filename globbing for file parameters
      -- register, update, FlagGlobalConfig, FlagConfig; others?
      ["glob", filename] -> do
          print filename
          glob filename >>= print
  #endif
      ["init", filename] ->
          initPackageDB filename verbosity cli
      ["register", filename] ->
          registerPackage filename verbosity cli
                          auto_ghci_libs multi_instance
                          expand_env_vars False force
      ["update", filename] ->
          registerPackage filename verbosity cli
                          auto_ghci_libs multi_instance
                          expand_env_vars True force
      ["unregister", pkgarg_str] -> do
          pkgarg <- readPackageArg as_arg pkgarg_str
          unregisterPackage pkgarg verbosity cli force
      ["expose", pkgarg_str] -> do
          pkgarg <- readPackageArg as_arg pkgarg_str
          exposePackage pkgarg verbosity cli force
      ["hide",   pkgarg_str] -> do
          pkgarg <- readPackageArg as_arg pkgarg_str
          hidePackage pkgarg verbosity cli force
      ["trust",    pkgarg_str] -> do
          pkgarg <- readPackageArg as_arg pkgarg_str
          trustPackage pkgarg verbosity cli force
      ["distrust", pkgarg_str] -> do
          pkgarg <- readPackageArg as_arg pkgarg_str
          distrustPackage pkgarg verbosity cli force
      ["list"] -> do
          listPackages verbosity cli Nothing Nothing
      ["list", pkgarg_str] ->
          case substringCheck pkgarg_str of
            Nothing -> do pkgarg <- readPackageArg as_arg pkgarg_str
                          listPackages verbosity cli (Just pkgarg) Nothing
            Just m -> listPackages verbosity cli
                                   (Just (Substring pkgarg_str m)) Nothing
      ["dot"] -> do
          showPackageDot verbosity cli
      ["find-module", moduleName] -> do
          let match = maybe (==moduleName) id (substringCheck moduleName)
          listPackages verbosity cli Nothing (Just match)
      ["latest", pkgid_str] -> do
          pkgid <- readGlobPkgId pkgid_str
          latestPackage verbosity cli pkgid
      ["describe", pkgid_str] -> do
          pkgarg <- case substringCheck pkgid_str of
            Nothing -> readPackageArg as_arg pkgid_str
            Just m  -> return (Substring pkgid_str m)
          describePackage verbosity cli pkgarg (fromMaybe False mexpand_pkgroot)
          
      ["field", pkgid_str, fields] -> do
          pkgarg <- case substringCheck pkgid_str of
            Nothing -> readPackageArg as_arg pkgid_str
            Just m  -> return (Substring pkgid_str m)
          describeField verbosity cli pkgarg
                        (splitFields fields) (fromMaybe True mexpand_pkgroot)
  
      ["check"] -> do
          checkConsistency verbosity cli
  
      ["dump"] -> do
          dumpPackages verbosity cli (fromMaybe False mexpand_pkgroot)
  
      ["recache"] -> do
          recache verbosity cli
  
      [] -> do
          die ("missing command\n" ++ shortUsage prog)
      (_cmd:_) -> do
          die ("command-line syntax error\n" ++ shortUsage prog)
  
  parseCheck :: ReadP a a -> String -> String -> IO a
  parseCheck parser str what =
    case [ x | (x,ys) <- readP_to_S parser str, all isSpace ys ] of
      [x] -> return x
      _ -> die ("cannot parse \'" ++ str ++ "\' as a " ++ what)
  
  readGlobPkgId :: String -> IO PackageIdentifier
  readGlobPkgId str = parseCheck parseGlobPackageId str "package identifier"
  
  parseGlobPackageId :: ReadP r PackageIdentifier
  parseGlobPackageId =
    parse
       +++
    (do n <- parse
        _ <- string "-*"
        return (PackageIdentifier{ pkgName = n, pkgVersion = globVersion }))
  
  readPackageArg :: AsPackageArg -> String -> IO PackageArg
  readPackageArg AsIpid str =
      parseCheck (IPId `fmap` parse) str "installed package id"
  readPackageArg AsPackageKey str =
      parseCheck (PkgKey `fmap` parse) str "package key"
  readPackageArg AsDefault str = Id `fmap` readGlobPkgId str
  
  -- globVersion means "all versions"
  globVersion :: Version
  globVersion = Version [] ["*"]
  
  -- -----------------------------------------------------------------------------
  -- Package databases
  
  -- Some commands operate on a single database:
  --      register, unregister, expose, hide, trust, distrust
  -- however these commands also check the union of the available databases
  -- in order to check consistency.  For example, register will check that
  -- dependencies exist before registering a package.
  --
  -- Some commands operate  on multiple databases, with overlapping semantics:
  --      list, describe, field
  
  data PackageDB 
    = PackageDB {
        location, locationAbsolute :: !FilePath,
        -- We need both possibly-relative and definately-absolute package
        -- db locations. This is because the relative location is used as
        -- an identifier for the db, so it is important we do not modify it.
        -- On the other hand we need the absolute path in a few places
        -- particularly in relation to the ${pkgroot} stuff.
        
        packages :: [InstalledPackageInfo]
      }
  
  type PackageDBStack = [PackageDB]
          -- A stack of package databases.  Convention: head is the topmost
          -- in the stack.
  
  allPackagesInStack :: PackageDBStack -> [InstalledPackageInfo]
  allPackagesInStack = concatMap packages
  
  getPkgDatabases :: Verbosity
                  -> Bool    -- we are modifying, not reading
                  -> Bool    -- use the user db
                  -> Bool    -- read caches, if available
                  -> Bool    -- expand vars, like ${pkgroot} and $topdir
                  -> [Flag]
                  -> IO (PackageDBStack, 
                            -- the real package DB stack: [global,user] ++ 
                            -- DBs specified on the command line with -f.
                         Maybe FilePath,
                            -- which one to modify, if any
                         PackageDBStack)
                            -- the package DBs specified on the command
                            -- line, or [global,user] otherwise.  This
                            -- is used as the list of package DBs for
                            -- commands that just read the DB, such as 'list'.
  
  getPkgDatabases verbosity modify use_user use_cache expand_vars my_flags = do
    -- first we determine the location of the global package config.  On Windows,
    -- this is found relative to the ghc-pkg.exe binary, whereas on Unix the
    -- location is passed to the binary using the --global-package-db flag by the
    -- wrapper script.
    let err_msg = "missing --global-package-db option, location of global package database unknown\n"
    global_conf <-
       case [ f | FlagGlobalConfig f <- my_flags ] of
          [] -> do mb_dir <- getLibDir
                   case mb_dir of
                     Nothing  -> die err_msg
                     Just dir -> do
                       r <- lookForPackageDBIn dir
                       case r of
                         Nothing -> die ("Can't find package database in " ++ dir)
                         Just path -> return path
          fs -> return (last fs)
  
    -- The value of the $topdir variable used in some package descriptions
    -- Note that the way we calculate this is slightly different to how it
    -- is done in ghc itself. We rely on the convention that the global
    -- package db lives in ghc's libdir.
    top_dir <- absolutePath (takeDirectory global_conf)
  
    let no_user_db = FlagNoUserDb `elem` my_flags
  
    mb_user_conf <-
      case [ f | FlagUserConfig f <- my_flags ] of
        _ | no_user_db -> return Nothing
        [] -> do
            r <- lookForPackageDBIn hasteUserDir
            case r of
              Nothing -> return (Just (pkgUserDir, False))
              Just f  -> return (Just (f, True))
        fs -> return (Just (last fs, True))
  
    -- If the user database exists, and for "use_user" commands (which includes
    -- "ghc-pkg check" and all commands that modify the db) we will attempt to
    -- use the user db.
    let sys_databases
          | Just (user_conf,user_exists) <- mb_user_conf,
            use_user || user_exists = [user_conf, global_conf]
          | otherwise               = [global_conf]
  
    e_pkg_path <- tryIO (System.Environment.getEnv "HASTE_PACKAGE_PATH")
    let env_stack =
          nub $ case e_pkg_path of
                  Left  _ -> sys_databases
                  Right path
                    | not (null path) && isSearchPathSeparator (last path)
                    -> splitSearchPath (init path) ++ sys_databases
                    | otherwise
                    -> splitSearchPath path
  
          -- The "global" database is always the one at the bottom of the stack.
          -- This is the database we modify by default.
        virt_global_conf = last env_stack
  
    let db_flags = [ f | Just f <- map is_db_flag my_flags ]
           where is_db_flag FlagUser
                        | Just (user_conf, _user_exists) <- mb_user_conf 
                        = Just user_conf
                 is_db_flag FlagGlobal     = Just virt_global_conf
                 is_db_flag (FlagConfig f) = Just f
                 is_db_flag _              = Nothing
  
    let flag_db_names | null db_flags = env_stack
                      | otherwise     = reverse (nub db_flags)
  
    -- For a "modify" command, treat all the databases as
    -- a stack, where we are modifying the top one, but it
    -- can refer to packages in databases further down the
    -- stack.
  
    -- -f flags on the command line add to the database
    -- stack, unless any of them are present in the stack
    -- already.
    let final_stack = filter (`notElem` env_stack)
                       [ f | FlagConfig f <- reverse my_flags ]
                       ++ env_stack
  
    -- the database we actually modify is the one mentioned
    -- rightmost on the command-line.
    let to_modify
          | not modify    = Nothing
          | null db_flags = Just virt_global_conf
          | otherwise     = Just (last db_flags)
  
    db_stack  <- sequence
      [ do db <- readParseDatabase verbosity mb_user_conf modify use_cache db_path
           if expand_vars then return (mungePackageDBPaths top_dir db)
                          else return db
      | db_path <- final_stack ]
  
    let flag_db_stack = [ db | db_name <- flag_db_names,
                          db <- db_stack, location db == db_name ]
  
    when (verbosity > Normal) $ do
      infoLn ("db stack: " ++ show (map location db_stack))
      infoLn ("modifying: " ++ show to_modify)
      infoLn ("flag db stack: " ++ show (map location flag_db_stack))
  
    return (db_stack, to_modify, flag_db_stack)
  
  
  lookForPackageDBIn :: FilePath -> IO (Maybe FilePath)
  lookForPackageDBIn dir = do
    let path_dir = dir </> "package.conf.d"
    exists_dir <- doesDirectoryExist path_dir
    if exists_dir then return (Just path_dir) else do
      let path_file = dir </> "package.conf"
      exists_file <- doesFileExist path_file
      if exists_file then return (Just path_file) else return Nothing
  
  readParseDatabase :: Verbosity
                    -> Maybe (FilePath,Bool)
                    -> Bool -- we will be modifying, not just reading
                    -> Bool -- use cache
                    -> FilePath
                    -> IO PackageDB
  
  readParseDatabase verbosity mb_user_conf modify use_cache path
    -- the user database (only) is allowed to be non-existent
    | Just (user_conf,False) <- mb_user_conf, path == user_conf
    = mkPackageDB []
    | otherwise
    = do e <- tryIO $ getDirectoryContents path
         case e of
           Left err
             | ioeGetErrorType err == InappropriateType ->
                die ("ghc no longer supports single-file style package databases "
                  ++ "(" ++ path ++ ") use 'ghc-pkg init' to create the database "
                  ++ "with the correct format.")
             | otherwise -> ioError err
           Right fs
             | not use_cache -> ignore_cache (const $ return ())
             | otherwise -> do
                let cache = path </> cachefilename
                tdir     <- getModificationTime path
                e_tcache <- tryIO $ getModificationTime cache
                case e_tcache of
                  Left ex -> do
                    whenReportCacheErrors $
                      if isDoesNotExistError ex
                        then do
                          warn ("WARNING: cache does not exist: " ++ cache)
                          warn ("ghc will fail to read this package db. " ++
                                "Use 'ghc-pkg recache' to fix.")
                        else do
                          warn ("WARNING: cache cannot be read: " ++ show ex)
                          warn "ghc will fail to read this package db."
                    ignore_cache (const $ return ())
                  Right tcache -> do
                    let compareTimestampToCache file =
                            when (verbosity >= Verbose) $ do
                                tFile <- getModificationTime file
                                compareTimestampToCache' file tFile
                        compareTimestampToCache' file tFile = do
                            let rel = case tcache `compare` tFile of
                                      LT -> " (NEWER than cache)"
                                      GT -> " (older than cache)"
                                      EQ -> " (same as cache)"
                            warn ("Timestamp " ++ show tFile
                               ++ " for " ++ file ++ rel)
                    when (verbosity >= Verbose) $ do
                        warn ("Timestamp " ++ show tcache ++ " for " ++ cache)
                        compareTimestampToCache' path tdir
                    if tcache >= tdir
                        then do
                            when (verbosity > Normal) $
                               infoLn ("using cache: " ++ cache)
                            pkgs <- GhcPkg.readPackageDbForGhcPkg cache
                            mkPackageDB pkgs
                        else do
                            whenReportCacheErrors $ do
                                warn ("WARNING: cache is out of date: " ++ cache)
                                warn ("ghc will see an old view of this " ++
                                      "package db. Use 'ghc-pkg recache' to fix.")
                            ignore_cache compareTimestampToCache
              where
                   ignore_cache :: (FilePath -> IO ()) -> IO PackageDB
                   ignore_cache checkTime = do
                       let confs = filter (".conf" `isSuffixOf`) fs
                           doFile f = do checkTime f
                                         parseSingletonPackageConf verbosity f
                       pkgs <- mapM doFile $ map (path </>) confs
                       mkPackageDB pkgs
  
                   -- We normally report cache errors for read-only commands,
                   -- since modify commands because will usually fix the cache.
                   whenReportCacheErrors =
                       when (   verbosity >  Normal
                             || verbosity >= Normal && not modify)
    where
      mkPackageDB pkgs = do
        path_abs <- absolutePath path
        return PackageDB {
          location = path,
          locationAbsolute = path_abs,
          packages = pkgs
        }
  
  parseSingletonPackageConf :: Verbosity -> FilePath -> IO InstalledPackageInfo
  parseSingletonPackageConf verbosity file = do
    when (verbosity > Normal) $ infoLn ("reading package config: " ++ file)
    readUTF8File file >>= fmap fst . parsePackageInfo
  
  cachefilename :: FilePath
  cachefilename = "package.cache"
  
  mungePackageDBPaths :: FilePath -> PackageDB -> PackageDB
  mungePackageDBPaths top_dir db@PackageDB { packages = pkgs } =
      db { packages = map (mungePackagePaths top_dir pkgroot) pkgs }
    where
      pkgroot = takeDirectory (locationAbsolute db)    
      -- It so happens that for both styles of package db ("package.conf"
      -- files and "package.conf.d" dirs) the pkgroot is the parent directory
      -- ${pkgroot}/package.conf  or  ${pkgroot}/package.conf.d/
  
  -- TODO: This code is duplicated in compiler/main/Packages.lhs
  mungePackagePaths :: FilePath -> FilePath
                    -> InstalledPackageInfo -> InstalledPackageInfo
  -- Perform path/URL variable substitution as per the Cabal ${pkgroot} spec
  -- (http://www.haskell.org/pipermail/libraries/2009-May/011772.html)
  -- Paths/URLs can be relative to ${pkgroot} or ${pkgrooturl}.
  -- The "pkgroot" is the directory containing the package database.
  --
  -- Also perform a similar substitution for the older GHC-specific
  -- "$topdir" variable. The "topdir" is the location of the ghc
  -- installation (obtained from the -B option).
  mungePackagePaths top_dir pkgroot pkg =
      pkg {
        importDirs  = munge_paths (importDirs pkg),
        includeDirs = munge_paths (includeDirs pkg),
        libraryDirs = munge_paths (libraryDirs pkg),
        frameworkDirs = munge_paths (frameworkDirs pkg),
        haddockInterfaces = munge_paths (haddockInterfaces pkg),
                       -- haddock-html is allowed to be either a URL or a file
        haddockHTMLs = munge_paths (munge_urls (haddockHTMLs pkg))
      }
    where
      munge_paths = map munge_path
      munge_urls  = map munge_url
  
      munge_path p
        | Just p' <- stripVarPrefix "${pkgroot}" p = pkgroot ++ p'
        | Just p' <- stripVarPrefix "$topdir"    p = top_dir ++ p'
        | otherwise                                = p
  
      munge_url p
        | Just p' <- stripVarPrefix "${pkgrooturl}" p = toUrlPath pkgroot p'
        | Just p' <- stripVarPrefix "$httptopdir"   p = toUrlPath top_dir p'
        | otherwise                                   = p
  
      toUrlPath r p = "file:///"
                   -- URLs always use posix style '/' separators:
                   ++ FilePath.Posix.joinPath
                          (r : -- We need to drop a leading "/" or "\\"
                               -- if there is one:
                               dropWhile (all isPathSeparator)
                                         (FilePath.splitDirectories p))
  
      -- We could drop the separator here, and then use </> above. However,
      -- by leaving it in and using ++ we keep the same path separator
      -- rather than letting FilePath change it to use \ as the separator
      stripVarPrefix var path = case stripPrefix var path of
                                Just [] -> Just []
                                Just cs@(c : _) | isPathSeparator c -> Just cs
                                _ -> Nothing
  
  
  -- -----------------------------------------------------------------------------
  -- Creating a new package DB
  
  initPackageDB :: FilePath -> Verbosity -> [Flag] -> IO ()
  initPackageDB filename verbosity _flags = do
    let eexist = die ("cannot create: " ++ filename ++ " already exists")
    b1 <- doesFileExist filename
    when b1 eexist
    b2 <- doesDirectoryExist filename
    when b2 eexist
    filename_abs <- absolutePath filename
    changeDB verbosity [] PackageDB {
                            location = filename, locationAbsolute = filename_abs,
                            packages = []
                          }
  
  -- -----------------------------------------------------------------------------
  -- Registering
  
  registerPackage :: FilePath
                  -> Verbosity
                  -> [Flag]
                  -> Bool              -- auto_ghci_libs
                  -> Bool              -- multi_instance
                  -> Bool              -- expand_env_vars
                  -> Bool              -- update
                  -> Force
                  -> IO ()
  registerPackage input verbosity my_flags auto_ghci_libs multi_instance
                  expand_env_vars update force = do
    (db_stack, Just to_modify, _flag_dbs) <- 
        getPkgDatabases verbosity True{-modify-} True{-use user-}
                                  True{-use cache-} False{-expand vars-} my_flags
  
    let
          db_to_operate_on = my_head "register" $
                             filter ((== to_modify).location) db_stack
    --
    when (auto_ghci_libs && verbosity >= Silent) $
      warn "Warning: --auto-ghci-libs is deprecated and will be removed in GHC 7.4"
    --
    s <-
      case input of
        "-" -> do
          when (verbosity >= Normal) $
              info "Reading package info from stdin ... "
          -- fix the encoding to UTF-8, since this is an interchange format
          hSetEncoding stdin utf8
          getContents
        f   -> do
          when (verbosity >= Normal) $
              info ("Reading package info from " ++ show f ++ " ... ")
          readUTF8File f
  
    expanded <- if expand_env_vars then expandEnvVars s force
                                   else return s
  
    (pkg, ws) <- parsePackageInfo expanded
    when (verbosity >= Normal) $
        infoLn "done."
  
    -- report any warnings from the parse phase
    _ <- reportValidateErrors [] ws
           (display (sourcePackageId pkg) ++ ": Warning: ") Nothing
  
    -- validate the expanded pkg, but register the unexpanded
    pkgroot <- absolutePath (takeDirectory to_modify)
    let top_dir = takeDirectory (location (last db_stack))
        pkg_expanded = mungePackagePaths top_dir pkgroot pkg
  
    let truncated_stack = dropWhile ((/= to_modify).location) db_stack
    -- truncate the stack for validation, because we don't allow
    -- packages lower in the stack to refer to those higher up.
    validatePackageConfig pkg_expanded verbosity truncated_stack
                          auto_ghci_libs multi_instance update force
  
    let 
       -- In the normal mode, we only allow one version of each package, so we
       -- remove all instances with the same source package id as the one we're
       -- adding. In the multi instance mode we don't do that, thus allowing
       -- multiple instances with the same source package id.
       removes = [ RemovePackage p
                 | not multi_instance,
                   p <- packages db_to_operate_on,
                   sourcePackageId p == sourcePackageId pkg ]
    --
    changeDB verbosity (removes ++ [AddPackage pkg]) db_to_operate_on
  
  parsePackageInfo
          :: String
          -> IO (InstalledPackageInfo, [ValidateWarning])
  parsePackageInfo str =
    case parseInstalledPackageInfo str of
      ParseOk warnings ok -> return (mungePackageInfo ok, ws)
        where
          ws = [ msg | PWarning msg <- warnings
                     , not ("Unrecognized field pkgroot" `isPrefixOf` msg) ]
      ParseFailed err -> case locatedErrorMsg err of
                             (Nothing, s) -> die s
                             (Just l, s) -> die (show l ++ ": " ++ s)
  
  mungePackageInfo :: InstalledPackageInfo -> InstalledPackageInfo
  mungePackageInfo ipi = ipi { packageKey = packageKey' }
    where
      packageKey'
        | OldPackageKey (PackageIdentifier (PackageName "") _) <- packageKey ipi
            = OldPackageKey (sourcePackageId ipi)
        | otherwise = packageKey ipi
  
  -- -----------------------------------------------------------------------------
  -- Making changes to a package database
  
  data DBOp = RemovePackage InstalledPackageInfo
            | AddPackage    InstalledPackageInfo
            | ModifyPackage InstalledPackageInfo
  
  changeDB :: Verbosity -> [DBOp] -> PackageDB -> IO ()
  changeDB verbosity cmds db = do
    let db' = updateInternalDB db cmds
    createDirectoryIfMissing True (location db)
    changeDBDir verbosity cmds db'
  
  updateInternalDB :: PackageDB -> [DBOp] -> PackageDB
  updateInternalDB db cmds = db{ packages = foldl do_cmd (packages db) cmds }
   where
    do_cmd pkgs (RemovePackage p) = 
      filter ((/= installedPackageId p) . installedPackageId) pkgs
    do_cmd pkgs (AddPackage p) = p : pkgs
    do_cmd pkgs (ModifyPackage p) = 
      do_cmd (do_cmd pkgs (RemovePackage p)) (AddPackage p)
      
  
  changeDBDir :: Verbosity -> [DBOp] -> PackageDB -> IO ()
  changeDBDir verbosity cmds db = do
    mapM_ do_cmd cmds
    updateDBCache verbosity db
   where
    do_cmd (RemovePackage p) = do
      let file = location db </> display (installedPackageId p) <.> "conf"
      when (verbosity > Normal) $ infoLn ("removing " ++ file)
      removeFileSafe file
    do_cmd (AddPackage p) = do
      let file = location db </> display (installedPackageId p) <.> "conf"
      when (verbosity > Normal) $ infoLn ("writing " ++ file)
      writeFileUtf8Atomic file (showInstalledPackageInfo p)
    do_cmd (ModifyPackage p) = 
      do_cmd (AddPackage p)
  
  updateDBCache :: Verbosity -> PackageDB -> IO ()
  updateDBCache verbosity db = do
    let filename = location db </> cachefilename
  
        pkgsCabalFormat :: [InstalledPackageInfo]
        pkgsCabalFormat = packages db
  
        pkgsGhcCacheFormat :: [PackageCacheFormat]
        pkgsGhcCacheFormat = map convertPackageInfoToCacheFormat pkgsCabalFormat
  
    when (verbosity > Normal) $
        infoLn ("writing cache " ++ filename)
    GhcPkg.writePackageDb filename pkgsGhcCacheFormat pkgsCabalFormat
      `catchIO` \e ->
        if isPermissionError e
        then die (filename ++ ": you don't have permission to modify this file")
        else ioError e
    -- See Note [writeAtomic leaky abstraction]
    -- Cross-platform "touch". This only works if filename is not empty, and not
    -- open for writing already.
    -- TODO. When the Win32 or directory packages have either a touchFile or a
    -- setModificationTime function, use one of those.
    withBinaryFile filename ReadWriteMode $ \handle -> do
        c <- hGetChar handle
        hSeek handle AbsoluteSeek 0
        hPutChar handle c
  
  type PackageCacheFormat = GhcPkg.InstalledPackageInfo
                              String     -- installed package id
                              String     -- src package id
                              String     -- package name
                              String     -- package key
                              ModuleName -- module name
  
  convertPackageInfoToCacheFormat :: InstalledPackageInfo -> PackageCacheFormat
  convertPackageInfoToCacheFormat pkg =
      GhcPkg.InstalledPackageInfo {
         GhcPkg.installedPackageId = display (installedPackageId pkg),
         GhcPkg.sourcePackageId    = display (sourcePackageId pkg),
         GhcPkg.packageName        = display (packageName pkg),
         GhcPkg.packageVersion     = packageVersion pkg,
         GhcPkg.packageKey         = display (packageKey pkg),
         GhcPkg.depends            = map display (depends pkg),
         GhcPkg.importDirs         = importDirs pkg,
         GhcPkg.hsLibraries        = hsLibraries pkg,
         GhcPkg.extraLibraries     = extraLibraries pkg,
         GhcPkg.extraGHCiLibraries = extraGHCiLibraries pkg,
         GhcPkg.libraryDirs        = libraryDirs pkg,
         GhcPkg.frameworks         = frameworks pkg,
         GhcPkg.frameworkDirs      = frameworkDirs pkg,
         GhcPkg.ldOptions          = ldOptions pkg,
         GhcPkg.ccOptions          = ccOptions pkg,
         GhcPkg.includes           = includes pkg,
         GhcPkg.includeDirs        = includeDirs pkg,
         GhcPkg.haddockInterfaces  = haddockInterfaces pkg,
         GhcPkg.haddockHTMLs       = haddockHTMLs pkg,
         GhcPkg.exposedModules     = map convertExposed (exposedModules pkg),
         GhcPkg.hiddenModules      = hiddenModules pkg,
         GhcPkg.instantiatedWith   = map convertInst (instantiatedWith pkg),
         GhcPkg.exposed            = exposed pkg,
         GhcPkg.trusted            = trusted pkg
      }
    where convertExposed (ExposedModule n reexport sig) =
              GhcPkg.ExposedModule n (fmap convertOriginal reexport)
                                     (fmap convertOriginal sig)
          convertOriginal (OriginalModule ipid m) =
              GhcPkg.OriginalModule (display ipid) m
          convertInst (m, o) = (m, convertOriginal o)
  
  instance GhcPkg.BinaryStringRep ModuleName where
    fromStringRep = ModuleName.fromString . fromUTF8 . BS.unpack
    toStringRep   = BS.pack . toUTF8 . display
  
  instance GhcPkg.BinaryStringRep String where
    fromStringRep = fromUTF8 . BS.unpack
    toStringRep   = BS.pack . toUTF8
  
  
  -- -----------------------------------------------------------------------------
  -- Exposing, Hiding, Trusting, Distrusting, Unregistering are all similar
  
  exposePackage :: PackageArg -> Verbosity -> [Flag] -> Force -> IO ()
  exposePackage = modifyPackage (\p -> ModifyPackage p{exposed=True})
  
  hidePackage :: PackageArg -> Verbosity -> [Flag] -> Force -> IO ()
  hidePackage = modifyPackage (\p -> ModifyPackage p{exposed=False})
  
  trustPackage :: PackageArg -> Verbosity -> [Flag] -> Force -> IO ()
  trustPackage = modifyPackage (\p -> ModifyPackage p{trusted=True})
  
  distrustPackage :: PackageArg -> Verbosity -> [Flag] -> Force -> IO ()
  distrustPackage = modifyPackage (\p -> ModifyPackage p{trusted=False})
  
  unregisterPackage :: PackageArg -> Verbosity -> [Flag] -> Force -> IO ()
  unregisterPackage = modifyPackage RemovePackage
  
  modifyPackage
    :: (InstalledPackageInfo -> DBOp)
    -> PackageArg
    -> Verbosity
    -> [Flag]
    -> Force
    -> IO ()
  modifyPackage fn pkgarg verbosity my_flags force = do
    (db_stack, Just _to_modify, flag_dbs) <-
        getPkgDatabases verbosity True{-modify-} True{-use user-}
                                  True{-use cache-} False{-expand vars-} my_flags
  
    -- Do the search for the package respecting flags...
    (db, ps) <- fmap head $ findPackagesByDB flag_dbs pkgarg
    let 
        db_name = location db
        pkgs    = packages db
  
        pks = map packageKey ps
  
        cmds = [ fn pkg | pkg <- pkgs, packageKey pkg `elem` pks ]
        new_db = updateInternalDB db cmds
  
        -- ...but do consistency checks with regards to the full stack
        old_broken = brokenPackages (allPackagesInStack db_stack)
        rest_of_stack = filter ((/= db_name) . location) db_stack
        new_stack = new_db : rest_of_stack
        new_broken = brokenPackages (allPackagesInStack new_stack)
        newly_broken = filter ((`notElem` map packageKey old_broken)
                              . packageKey) new_broken
    --
    let displayQualPkgId pkg
          | [_] <- filter ((== pkgid) . sourcePackageId)
                          (allPackagesInStack db_stack)
              = display pkgid
          | otherwise = display pkgid ++ "@" ++ display (packageKey pkg)
          where pkgid = sourcePackageId pkg
    when (not (null newly_broken)) $
        dieOrForceAll force ("unregistering would break the following packages: "
                ++ unwords (map displayQualPkgId newly_broken))
  
    changeDB verbosity cmds db
  
  recache :: Verbosity -> [Flag] -> IO ()
  recache verbosity my_flags = do
    (db_stack, Just to_modify, _flag_dbs) <- 
       getPkgDatabases verbosity True{-modify-} True{-use user-} False{-no cache-}
                                 False{-expand vars-} my_flags
    let
          db_to_operate_on = my_head "recache" $
                             filter ((== to_modify).location) db_stack
    --
    changeDB verbosity [] db_to_operate_on
  
  -- -----------------------------------------------------------------------------
  -- Listing packages
  
  listPackages ::  Verbosity -> [Flag] -> Maybe PackageArg
               -> Maybe (String->Bool)
               -> IO ()
  listPackages verbosity my_flags mPackageName mModuleName = do
    let simple_output = FlagSimpleOutput `elem` my_flags
    (db_stack, _, flag_db_stack) <- 
       getPkgDatabases verbosity False{-modify-} False{-use user-}
                                 True{-use cache-} False{-expand vars-} my_flags
  
    let db_stack_filtered -- if a package is given, filter out all other packages
          | Just this <- mPackageName =
              [ db{ packages = filter (this `matchesPkg`) (packages db) }
              | db <- flag_db_stack ]
          | Just match <- mModuleName = -- packages which expose mModuleName
              [ db{ packages = filter (match `exposedInPkg`) (packages db) }
              | db <- flag_db_stack ]
          | otherwise = flag_db_stack
  
        db_stack_sorted
            = [ db{ packages = sort_pkgs (packages db) }
              | db <- db_stack_filtered ]
            where sort_pkgs = sortBy cmpPkgIds
                  cmpPkgIds pkg1 pkg2 =
                     case pkgName p1 `compare` pkgName p2 of
                          LT -> LT
                          GT -> GT
                          EQ -> case pkgVersion p1 `compare` pkgVersion p2 of
                                  LT -> LT
                                  GT -> GT
                                  EQ -> packageKey pkg1 `compare` packageKey pkg2
                     where (p1,p2) = (sourcePackageId pkg1, sourcePackageId pkg2)
  
        stack = reverse db_stack_sorted
  
        match `exposedInPkg` pkg = any match (map display $ exposedModules pkg)
  
        pkg_map = allPackagesInStack db_stack
        broken = map packageKey (brokenPackages pkg_map)
  
        show_normal PackageDB{ location = db_name, packages = pkg_confs } =
            do hPutStrLn stdout (db_name ++ ":")
               if null pp_pkgs
                   then hPutStrLn stdout "    (no packages)"
                   else hPutStrLn stdout $ unlines (map ("    " ++) pp_pkgs)
             where
                   -- Sort using instance Ord PackageId
                   pp_pkgs = map pp_pkg . sortBy (comparing installedPackageId) $ pkg_confs
                   pp_pkg p
                     | packageKey p `elem` broken = printf "{%s}" doc
                     | exposed p = doc
                     | otherwise = printf "(%s)" doc
                     where doc | verbosity >= Verbose = printf "%s (%s)" pkg ipid
                               | otherwise            = pkg
                            where
                            InstalledPackageId ipid = installedPackageId p
                            pkg = display (sourcePackageId p)
  
        show_simple = simplePackageList my_flags . allPackagesInStack
  
    when (not (null broken) && not simple_output && verbosity /= Silent) $ do
       prog <- getProgramName
       warn ("WARNING: there are broken packages.  Run '" ++ prog ++ " check' for more details.")
  
    if simple_output then show_simple stack else do
  
  #if defined(mingw32_HOST_OS) || defined(BOOTSTRAPPING)
      mapM_ show_normal stack
  #else
      let
         show_colour withF db =
             mconcat $ map (<#> termText "\n") $
                 (termText (location db) :
                    map (termText "   " <#>) (map pp_pkg (packages db)))
            where
                     pp_pkg p
                       | packageKey p `elem` broken = withF Red  doc
                       | exposed p                       = doc
                       | otherwise                       = withF Blue doc
                       where doc | verbosity >= Verbose
                                 = termText (printf "%s (%s)" pkg ipid)
                                 | otherwise
                                 = termText pkg
                              where
                              InstalledPackageId ipid = installedPackageId p
                              pkg = display (sourcePackageId p)
  
      is_tty <- hIsTerminalDevice stdout
      if not is_tty
         then mapM_ show_normal stack
         else do tty <- Terminfo.setupTermFromEnv
                 case Terminfo.getCapability tty withForegroundColor of
                     Nothing -> mapM_ show_normal stack
                     Just w  -> runTermOutput tty $ mconcat $
                                                    map (show_colour w) stack
  #endif
  
  simplePackageList :: [Flag] -> [InstalledPackageInfo] -> IO ()
  simplePackageList my_flags pkgs = do
     let showPkg = if FlagNamesOnly `elem` my_flags then display . pkgName
                                                    else display
         -- Sort using instance Ord PackageId
         strs = map showPkg $ sort $ map sourcePackageId pkgs
     when (not (null pkgs)) $
        hPutStrLn stdout $ concat $ intersperse " " strs
  
  showPackageDot :: Verbosity -> [Flag] -> IO ()
  showPackageDot verbosity myflags = do
    (_, _, flag_db_stack) <- 
        getPkgDatabases verbosity False{-modify-} False{-use user-}
                                  True{-use cache-} False{-expand vars-} myflags
  
    let all_pkgs = allPackagesInStack flag_db_stack
        ipix  = PackageIndex.fromList all_pkgs
  
    putStrLn "digraph {"
    let quote s = '"':s ++ "\""
    mapM_ putStrLn [ quote from ++ " -> " ++ quote to
                   | p <- all_pkgs,
                     let from = display (sourcePackageId p),
                     depid <- depends p,
                     Just dep <- [PackageIndex.lookupInstalledPackageId ipix depid],
                     let to = display (sourcePackageId dep)
                   ]
    putStrLn "}"
  
  -- -----------------------------------------------------------------------------
  -- Prints the highest (hidden or exposed) version of a package
  
  -- ToDo: This is no longer well-defined with package keys, because the
  -- dependencies may be varying versions
  latestPackage ::  Verbosity -> [Flag] -> PackageIdentifier -> IO ()
  latestPackage verbosity my_flags pkgid = do
    (_, _, flag_db_stack) <- 
       getPkgDatabases verbosity False{-modify-} False{-use user-}
                                 True{-use cache-} False{-expand vars-} my_flags
  
    ps <- findPackages flag_db_stack (Id pkgid)
    case ps of
      [] -> die "no matches"
      _  -> show_pkg . maximum . map sourcePackageId $ ps
    where
      show_pkg pid = hPutStrLn stdout (display pid)
  
  -- -----------------------------------------------------------------------------
  -- Describe
  
  describePackage :: Verbosity -> [Flag] -> PackageArg -> Bool -> IO ()
  describePackage verbosity my_flags pkgarg expand_pkgroot = do
    (_, _, flag_db_stack) <- 
        getPkgDatabases verbosity False{-modify-} False{-use user-}
                                  True{-use cache-} expand_pkgroot my_flags
    dbs <- findPackagesByDB flag_db_stack pkgarg
    doDump expand_pkgroot [ (pkg, locationAbsolute db)
                          | (db, pkgs) <- dbs, pkg <- pkgs ]
  
  dumpPackages :: Verbosity -> [Flag] -> Bool -> IO ()
  dumpPackages verbosity my_flags expand_pkgroot = do
    (_, _, flag_db_stack) <- 
       getPkgDatabases verbosity False{-modify-} False{-use user-}
                                 True{-use cache-} expand_pkgroot my_flags
    doDump expand_pkgroot [ (pkg, locationAbsolute db)
                          | db <- flag_db_stack, pkg <- packages db ]
  
  doDump :: Bool -> [(InstalledPackageInfo, FilePath)] -> IO ()
  doDump expand_pkgroot pkgs = do
    -- fix the encoding to UTF-8, since this is an interchange format
    hSetEncoding stdout utf8
    putStrLn $
      intercalate "---\n"
      [ if expand_pkgroot
          then showInstalledPackageInfo pkg
          else showInstalledPackageInfo pkg ++ pkgrootField
      | (pkg, pkgloc) <- pkgs
      , let pkgroot      = takeDirectory pkgloc
            pkgrootField = "pkgroot: " ++ show pkgroot ++ "\n" ]
  
  -- PackageId is can have globVersion for the version
  findPackages :: PackageDBStack -> PackageArg -> IO [InstalledPackageInfo]
  findPackages db_stack pkgarg
    = fmap (concatMap snd) $ findPackagesByDB db_stack pkgarg
  
  findPackagesByDB :: PackageDBStack -> PackageArg
                   -> IO [(PackageDB, [InstalledPackageInfo])]
  findPackagesByDB db_stack pkgarg
    = case [ (db, matched)
           | db <- db_stack,
             let matched = filter (pkgarg `matchesPkg`) (packages db),
             not (null matched) ] of
          [] -> die ("cannot find package " ++ pkg_msg pkgarg)
          ps -> return ps
    where
          pkg_msg (Id pkgid)           = display pkgid
          pkg_msg (PkgKey pk)          = display pk
          pkg_msg (IPId ipid)          = display ipid
          pkg_msg (Substring pkgpat _) = "matching " ++ pkgpat
  
  matches :: PackageIdentifier -> PackageIdentifier -> Bool
  pid `matches` pid'
    = (pkgName pid == pkgName pid')
      && (pkgVersion pid == pkgVersion pid' || not (realVersion pid))
  
  realVersion :: PackageIdentifier -> Bool
  realVersion pkgid = versionBranch (pkgVersion pkgid) /= []
    -- when versionBranch == [], this is a glob
  
  matchesPkg :: PackageArg -> InstalledPackageInfo -> Bool
  (Id pid)        `matchesPkg` pkg = pid `matches` sourcePackageId pkg
  (PkgKey pk)     `matchesPkg` pkg = pk == packageKey pkg
  (IPId ipid)     `matchesPkg` pkg = ipid == installedPackageId pkg
  (Substring _ m) `matchesPkg` pkg = m (display (sourcePackageId pkg))
  
  -- -----------------------------------------------------------------------------
  -- Field
  
  describeField :: Verbosity -> [Flag] -> PackageArg -> [String] -> Bool -> IO ()
  describeField verbosity my_flags pkgarg fields expand_pkgroot = do
    (_, _, flag_db_stack) <- 
        getPkgDatabases verbosity False{-modify-} False{-use user-}
                                  True{-use cache-} expand_pkgroot my_flags
    fns <- mapM toField fields
    ps <- findPackages flag_db_stack pkgarg
    mapM_ (selectFields fns) ps
    where showFun = if FlagSimpleOutput `elem` my_flags
                    then showSimpleInstalledPackageInfoField
                    else showInstalledPackageInfoField
          toField f = case showFun f of
                      Nothing -> die ("unknown field: " ++ f)
                      Just fn -> return fn
          selectFields fns pinfo = mapM_ (\fn->putStrLn (fn pinfo)) fns
  
  
  -- -----------------------------------------------------------------------------
  -- Check: Check consistency of installed packages
  
  checkConsistency :: Verbosity -> [Flag] -> IO ()
  checkConsistency verbosity my_flags = do
    (db_stack, _, _) <- 
           getPkgDatabases verbosity False{-modify-} True{-use user-}
                                     True{-use cache-} True{-expand vars-}
                                     my_flags
           -- although check is not a modify command, we do need to use the user
           -- db, because we may need it to verify package deps.
  
    let simple_output = FlagSimpleOutput `elem` my_flags
  
    let pkgs = allPackagesInStack db_stack
  
        checkPackage p = do
           (_,es,ws) <- runValidate $ checkPackageConfig p verbosity db_stack
                                                         False True True
           if null es
              then do when (not simple_output) $ do
                        _ <- reportValidateErrors [] ws "" Nothing
                        return ()
                      return []
              else do
                when (not simple_output) $ do
                    reportError ("There are problems in package " ++ display (sourcePackageId p) ++ ":")
                    _ <- reportValidateErrors es ws "  " Nothing
                    return ()
                return [p]
  
    broken_pkgs <- concat `fmap` mapM checkPackage pkgs
  
    let filterOut pkgs1 pkgs2 = filter not_in pkgs2
          where not_in p = sourcePackageId p `notElem` all_ps
                all_ps = map sourcePackageId pkgs1
  
    let not_broken_pkgs = filterOut broken_pkgs pkgs
        (_, trans_broken_pkgs) = closure [] not_broken_pkgs
        all_broken_pkgs = broken_pkgs ++ trans_broken_pkgs
  
    when (not (null all_broken_pkgs)) $ do
      if simple_output
        then simplePackageList my_flags all_broken_pkgs
        else do
         reportError ("\nThe following packages are broken, either because they have a problem\n"++
                  "listed above, or because they depend on a broken package.")
         mapM_ (hPutStrLn stderr . display . sourcePackageId) all_broken_pkgs
  
    when (not (null all_broken_pkgs)) $ exitWith (ExitFailure 1)
  
  
  closure :: [InstalledPackageInfo] -> [InstalledPackageInfo]
          -> ([InstalledPackageInfo], [InstalledPackageInfo])
  closure pkgs db_stack = go pkgs db_stack
   where
     go avail not_avail =
       case partition (depsAvailable avail) not_avail of
          ([],        not_avail') -> (avail, not_avail')
          (new_avail, not_avail') -> go (new_avail ++ avail) not_avail'
  
     depsAvailable :: [InstalledPackageInfo] -> InstalledPackageInfo
                   -> Bool
     depsAvailable pkgs_ok pkg = null dangling
          where dangling = filter (`notElem` pids) (depends pkg)
                pids = map installedPackageId pkgs_ok
  
          -- we want mutually recursive groups of package to show up
          -- as broken. (#1750)
  
  brokenPackages :: [InstalledPackageInfo] -> [InstalledPackageInfo]
  brokenPackages pkgs = snd (closure [] pkgs)
  
  -----------------------------------------------------------------------------
  -- Sanity-check a new package config, and automatically build GHCi libs
  -- if requested.
  
  type ValidateError   = (Force,String)
  type ValidateWarning = String
  
  newtype Validate a = V { runValidate :: IO (a, [ValidateError],[ValidateWarning]) }
  
  instance Functor Validate where
      fmap = liftM
  
  instance Applicative Validate where
      pure = return
      (<*>) = ap
  
  instance Monad Validate where
     return a = V $ return (a, [], [])
     m >>= k = V $ do
        (a, es, ws) <- runValidate m
        (b, es', ws') <- runValidate (k a)
        return (b,es++es',ws++ws')
  
  verror :: Force -> String -> Validate ()
  verror f s = V (return ((),[(f,s)],[]))
  
  vwarn :: String -> Validate ()
  vwarn s = V (return ((),[],["Warning: " ++ s]))
  
  liftIO :: IO a -> Validate a
  liftIO k = V (k >>= \a -> return (a,[],[]))
  
  -- returns False if we should die
  reportValidateErrors :: [ValidateError] -> [ValidateWarning]
                       -> String -> Maybe Force -> IO Bool
  reportValidateErrors es ws prefix mb_force = do
    mapM_ (warn . (prefix++)) ws
    oks <- mapM report es
    return (and oks)
    where
      report (f,s)
        | Just force <- mb_force
        = if (force >= f)
             then do reportError (prefix ++ s ++ " (ignoring)")
                     return True
             else if f < CannotForce
                     then do reportError (prefix ++ s ++ " (use --force to override)")
                             return False
                     else do reportError err
                             return False
        | otherwise = do reportError err
                         return False
        where
               err = prefix ++ s
  
  validatePackageConfig :: InstalledPackageInfo
                        -> Verbosity
                        -> PackageDBStack
                        -> Bool   -- auto-ghc-libs
                        -> Bool   -- multi_instance
                        -> Bool   -- update, or check
                        -> Force
                        -> IO ()
  validatePackageConfig pkg verbosity db_stack auto_ghci_libs
                        multi_instance update force = do
    (_,es,ws) <- runValidate $
                   checkPackageConfig pkg verbosity db_stack
                                      auto_ghci_libs multi_instance update
    ok <- reportValidateErrors es ws (display (sourcePackageId pkg) ++ ": ") (Just force)
    when (not ok) $ exitWith (ExitFailure 1)
  
  checkPackageConfig :: InstalledPackageInfo
                        -> Verbosity
                        -> PackageDBStack
                        -> Bool   -- auto-ghc-libs
                        -> Bool   -- multi_instance
                        -> Bool   -- update, or check
                        -> Validate ()
  checkPackageConfig pkg verbosity db_stack auto_ghci_libs
                     multi_instance update = do
    checkInstalledPackageId pkg db_stack update
    checkPackageId pkg
    checkPackageKey pkg
    checkDuplicates db_stack pkg multi_instance update
    mapM_ (checkDep db_stack) (depends pkg)
    checkDuplicateDepends (depends pkg)
    mapM_ (checkDir False "import-dirs")  (importDirs pkg)
    mapM_ (checkDir True  "library-dirs") (libraryDirs pkg)
    mapM_ (checkDir True  "include-dirs") (includeDirs pkg)
    mapM_ (checkDir True  "framework-dirs") (frameworkDirs pkg)
    mapM_ (checkFile   True "haddock-interfaces") (haddockInterfaces pkg)
    mapM_ (checkDirURL True "haddock-html")       (haddockHTMLs pkg)
    checkDuplicateModules pkg
    checkExposedModules db_stack pkg
    checkOtherModules pkg
    mapM_ (checkHSLib verbosity (libraryDirs pkg) auto_ghci_libs) (hsLibraries pkg)
    -- ToDo: check these somehow?
    --    extra_libraries :: [String],
    --    c_includes      :: [String],
  
  checkInstalledPackageId :: InstalledPackageInfo -> PackageDBStack -> Bool 
                          -> Validate ()
  checkInstalledPackageId ipi db_stack update = do
    let ipid@(InstalledPackageId str) = installedPackageId ipi
    when (null str) $ verror CannotForce "missing id field"
    let dups = [ p | p <- allPackagesInStack db_stack, 
                     installedPackageId p == ipid ]
    when (not update && not (null dups)) $
      verror CannotForce $
          "package(s) with this id already exist: " ++ 
           unwords (map (display.packageId) dups)
  
  -- When the package name and version are put together, sometimes we can
  -- end up with a package id that cannot be parsed.  This will lead to
  -- difficulties when the user wants to refer to the package later, so
  -- we check that the package id can be parsed properly here.
  checkPackageId :: InstalledPackageInfo -> Validate ()
  checkPackageId ipi =
    let str = display (sourcePackageId ipi) in
    case [ x :: PackageIdentifier | (x,ys) <- readP_to_S parse str, all isSpace ys ] of
      [_] -> return ()
      []  -> verror CannotForce ("invalid package identifier: " ++ str)
      _   -> verror CannotForce ("ambiguous package identifier: " ++ str)
  
  checkPackageKey :: InstalledPackageInfo -> Validate ()
  checkPackageKey ipi =
    let str = display (packageKey ipi) in
    case [ x :: PackageKey | (x,ys) <- readP_to_S parse str, all isSpace ys ] of
      [_] -> return ()
      []  -> verror CannotForce ("invalid package key: " ++ str)
      _   -> verror CannotForce ("ambiguous package key: " ++ str)
  
  checkDuplicates :: PackageDBStack -> InstalledPackageInfo
                  -> Bool -> Bool-> Validate ()
  checkDuplicates db_stack pkg multi_instance update = do
    let
          pkgid = sourcePackageId pkg
          pkgs  = packages (head db_stack)
    --
    -- Check whether this package id already exists in this DB
    --
    when (not update && not multi_instance
                     && (pkgid `elem` map sourcePackageId pkgs)) $
         verror CannotForce $
            "package " ++ display pkgid ++ " is already installed"
  
    let
          uncasep = map toLower . display
          dups = filter ((== uncasep pkgid) . uncasep) (map sourcePackageId pkgs)
  
    when (not update && not (null dups)) $ verror ForceAll $
          "Package names may be treated case-insensitively in the future.\n"++
          "Package " ++ display pkgid ++
          " overlaps with: " ++ unwords (map display dups)
  
  checkDir, checkFile, checkDirURL :: Bool -> String -> FilePath -> Validate ()
  checkDir  = checkPath False True
  checkFile = checkPath False False
  checkDirURL = checkPath True True
  
  checkPath :: Bool -> Bool -> Bool -> String -> FilePath -> Validate ()
  checkPath url_ok is_dir warn_only thisfield d
   | url_ok && ("http://"  `isPrefixOf` d
             || "https://" `isPrefixOf` d) = return ()
  
   | url_ok
   , Just d' <- stripPrefix "file://" d
   = checkPath False is_dir warn_only thisfield d'
  
     -- Note: we don't check for $topdir/${pkgroot} here. We rely on these
     -- variables having been expanded already, see mungePackagePaths.
  
   | isRelative d = verror ForceFiles $
                       thisfield ++ ": " ++ d ++ " is a relative path which "
                    ++ "makes no sense (as there is nothing for it to be "
                    ++ "relative to). You can make paths relative to the "
                    ++ "package database itself by using ${pkgroot}."
          -- relative paths don't make any sense; #4134
   | otherwise = do
     there <- liftIO $ if is_dir then doesDirectoryExist d else doesFileExist d
     when (not there) $
         let msg = thisfield ++ ": " ++ d ++ " doesn't exist or isn't a "
                                          ++ if is_dir then "directory" else "file"
         in
         if warn_only 
            then vwarn msg
            else verror ForceFiles msg
  
  checkDep :: PackageDBStack -> InstalledPackageId -> Validate ()
  checkDep db_stack pkgid
    | pkgid `elem` pkgids = return ()
    | otherwise = verror ForceAll ("dependency \"" ++ display pkgid
                                   ++ "\" doesn't exist")
    where
          all_pkgs = allPackagesInStack db_stack
          pkgids = map installedPackageId all_pkgs
  
  checkDuplicateDepends :: [InstalledPackageId] -> Validate ()
  checkDuplicateDepends deps
    | null dups = return ()
    | otherwise = verror ForceAll ("package has duplicate dependencies: " ++
                                       unwords (map display dups))
    where
         dups = [ p | (p:_:_) <- group (sort deps) ]
  
  checkHSLib :: Verbosity -> [String] -> Bool -> String -> Validate ()
  checkHSLib verbosity dirs auto_ghci_libs lib = do
    let batch_lib_file = "lib" ++ lib ++ ".jslib"
        filenames = ["lib" ++ lib ++ ".jslib",
                     "lib" ++ lib ++ ".jslib",
                     "lib" ++ lib ++ "-ghc" ++ showVersion ghcVersion ++ ".jslib",
                     "lib" ++ lib ++ "-ghc" ++ showVersion ghcVersion ++ ".jslib",
                              lib ++ "-ghc" ++ showVersion ghcVersion ++ ".jslib"]
    m <- liftIO $ doesFileExistOnPath filenames dirs
    case m of
      Nothing -> verror ForceFiles ("cannot find any of " ++ show filenames ++
                                    " on library path")
      Just dir -> liftIO $ checkGHCiLib verbosity dir batch_lib_file lib auto_ghci_libs
  
  doesFileExistOnPath :: [FilePath] -> [FilePath] -> IO (Maybe FilePath)
  doesFileExistOnPath filenames paths = go fullFilenames
    where fullFilenames = [ (path, path </> filename)
                          | filename <- filenames
                          , path <- paths ]
          go []             = return Nothing
          go ((p, fp) : xs) = do b <- doesFileExist fp
                                 if b then return (Just p) else go xs
  
  -- | Perform validation checks (module file existence checks) on the
  -- @hidden-modules@ field.
  checkOtherModules :: InstalledPackageInfo -> Validate ()
  checkOtherModules pkg = mapM_ (checkModuleFile pkg) (hiddenModules pkg)
  
  -- | Perform validation checks (module file existence checks and module
  -- reexport checks) on the @exposed-modules@ field.
  checkExposedModules :: PackageDBStack -> InstalledPackageInfo -> Validate ()
  checkExposedModules db_stack pkg =
    mapM_ checkExposedModule (exposedModules pkg)
    where
      checkExposedModule (ExposedModule modl reexport _sig) = do
        let checkOriginal = checkModuleFile pkg modl
            checkReexport = checkOriginalModule "module reexport" db_stack pkg
        maybe checkOriginal checkReexport reexport
  
  -- | Validates the existence of an appropriate @hi@ file associated with
  -- a module.  Used for both @hidden-modules@ and @exposed-modules@ which
  -- are not reexports.
  checkModuleFile :: InstalledPackageInfo -> ModuleName -> Validate ()
  checkModuleFile pkg modl =
        -- there's no interface file for GHC.Prim
        unless (modl == ModuleName.fromString "GHC.Prim") $ do
        let files = [ ModuleName.toFilePath modl <.> extension
                    | extension <- ["hi", "p_hi", "dyn_hi" ] ]
        m <- liftIO $ doesFileExistOnPath files (importDirs pkg)
        when (isNothing m) $
           verror ForceFiles ("cannot find any of " ++ show files)
  
  -- | Validates that @exposed-modules@ and @hidden-modules@ do not have duplicate
  -- entries.
  -- ToDo: this needs updating for signatures: signatures can validly show up
  -- multiple times in the @exposed-modules@ list as long as their backing
  -- implementations agree.
  checkDuplicateModules :: InstalledPackageInfo -> Validate ()
  checkDuplicateModules pkg
    | null dups = return ()
    | otherwise = verror ForceAll ("package has duplicate modules: " ++
                                       unwords (map display dups))
    where
      dups = [ m | (m:_:_) <- group (sort mods) ]
      mods = map exposedName (exposedModules pkg) ++ hiddenModules pkg
  
  -- | Validates an original module entry, either the origin of a module reexport
  -- or the backing implementation of a signature, by checking that it exists,
  -- really is an original definition, and is accessible from the dependencies of
  -- the package.
  -- ToDo: If the original module in question is a backing signature
  -- implementation, then we should also check that the original module in
  -- question is NOT a signature (however, if it is a reexport, then it's fine
  -- for the original module to be a signature.)
  checkOriginalModule :: String
                      -> PackageDBStack
                      -> InstalledPackageInfo
                      -> OriginalModule
                      -> Validate ()
  checkOriginalModule fieldName db_stack pkg
      (OriginalModule definingPkgId definingModule) =
    let mpkg = if definingPkgId == installedPackageId pkg
                then Just pkg
                else PackageIndex.lookupInstalledPackageId ipix definingPkgId
    in case mpkg of
        Nothing
             -> verror ForceAll (fieldName ++ " refers to a non-existent " ++
                                 "defining package: " ++
                                         display definingPkgId)
  
        Just definingPkg
          | not (isIndirectDependency definingPkgId)
             -> verror ForceAll (fieldName ++ " refers to a defining  " ++
                                 "package that is not a direct (or indirect) " ++
                                 "dependency of this package: " ++
                                         display definingPkgId)
  
          | otherwise
          -> case find ((==definingModule).exposedName)
                       (exposedModules definingPkg) of
              Nothing ->
                verror ForceAll (fieldName ++ " refers to a module " ++
                                 display definingModule ++ " " ++
                                 "that is not exposed in the " ++
                                 "defining package " ++ display definingPkgId)
              Just (ExposedModule {exposedReexport = Just _} ) ->
                verror ForceAll (fieldName ++ " refers to a module " ++
                                 display definingModule ++ " " ++
                                 "that is reexported but not defined in the " ++
                                 "defining package " ++ display definingPkgId)
              _ -> return ()
  
    where
      all_pkgs = allPackagesInStack db_stack
      ipix     = PackageIndex.fromList all_pkgs
  
      isIndirectDependency pkgid = fromMaybe False $ do
        thispkg  <- graphVertex (installedPackageId pkg)
        otherpkg <- graphVertex pkgid
        return (Graph.path depgraph thispkg otherpkg)
      (depgraph, _, graphVertex) =
        PackageIndex.dependencyGraph (PackageIndex.insert pkg ipix)
  
  
  checkGHCiLib :: Verbosity -> String -> String -> String -> Bool -> IO ()
  checkGHCiLib verbosity batch_lib_dir batch_lib_file lib auto_build
    | auto_build = autoBuildGHCiLib verbosity batch_lib_dir batch_lib_file ghci_lib_file
    | otherwise  = return ()
   where
      ghci_lib_file = lib <.> "o"
  
  -- automatically build the GHCi version of a batch lib,
  -- using ld --whole-archive.
  
  autoBuildGHCiLib :: Verbosity -> String -> String -> String -> IO ()
  autoBuildGHCiLib verbosity dir batch_file ghci_file = do
    let ghci_lib_file  = dir ++ '/':ghci_file
        batch_lib_file = dir ++ '/':batch_file
    when (verbosity >= Normal) $
      info ("building GHCi library " ++ ghci_lib_file ++ "...")
  #if defined(darwin_HOST_OS)
    r <- rawSystem "ld" ["-r","-x","-o",ghci_lib_file,"-all_load",batch_lib_file]
  #elif defined(mingw32_HOST_OS)
    execDir <- getLibDir
    r <- rawSystem (maybe "" (++"/gcc-lib/") execDir++"ld") ["-r","-x","-o",ghci_lib_file,"--whole-archive",batch_lib_file]
  #else
    r <- rawSystem "ld" ["-r","-x","-o",ghci_lib_file,"--whole-archive",batch_lib_file]
  #endif
    when (r /= ExitSuccess) $ exitWith r
    when (verbosity >= Normal) $
      infoLn (" done.")
  
  -- -----------------------------------------------------------------------------
  -- Searching for modules
  
  #if not_yet
  
  findModules :: [FilePath] -> IO [String]
  findModules paths =
    mms <- mapM searchDir paths
    return (concat mms)
  
  searchDir path prefix = do
    fs <- getDirectoryEntries path `catchIO` \_ -> return []
    searchEntries path prefix fs
  
  searchEntries path prefix [] = return []
  searchEntries path prefix (f:fs)
    | looks_like_a_module  =  do
          ms <- searchEntries path prefix fs
          return (prefix `joinModule` f : ms)
    | looks_like_a_component  =  do
          ms <- searchDir (path </> f) (prefix `joinModule` f)
          ms' <- searchEntries path prefix fs
          return (ms ++ ms')
    | otherwise
          searchEntries path prefix fs
  
    where
          (base,suffix) = splitFileExt f
          looks_like_a_module =
                  suffix `elem` haskell_suffixes &&
                  all okInModuleName base
          looks_like_a_component =
                  null suffix && all okInModuleName base
  
  okInModuleName c
  
  #endif
  
  -- ---------------------------------------------------------------------------
  -- expanding environment variables in the package configuration
  
  expandEnvVars :: String -> Force -> IO String
  expandEnvVars str0 force = go str0 ""
   where
     go "" acc = return $! reverse acc
     go ('$':'{':str) acc | (var, '}':rest) <- break close str
          = do value <- lookupEnvVar var
               go rest (reverse value ++ acc)
          where close c = c == '}' || c == '\n' -- don't span newlines
     go (c:str) acc
          = go str (c:acc)
  
     lookupEnvVar :: String -> IO String
     lookupEnvVar "pkgroot"    = return "${pkgroot}"    -- these two are special,
     lookupEnvVar "pkgrooturl" = return "${pkgrooturl}" -- we don't expand them
     lookupEnvVar nm =
          catchIO (System.Environment.getEnv nm)
             (\ _ -> do dieOrForceAll force ("Unable to expand variable " ++
                                          show nm)
                        return "")
  
  -----------------------------------------------------------------------------
  
  getProgramName :: IO String
  getProgramName = liftM (`withoutSuffix` ".bin") getProgName
     where str `withoutSuffix` suff
              | suff `isSuffixOf` str = take (length str - length suff) str
              | otherwise             = str
  
  bye :: String -> IO a
  bye s = putStr s >> exitWith ExitSuccess
  
  die :: String -> IO a
  die = dieWith 1
  
  dieWith :: Int -> String -> IO a
  dieWith ec s = do
    prog <- getProgramName
    reportError (prog ++ ": " ++ s)
    exitWith (ExitFailure ec)
  
  dieOrForceAll :: Force -> String -> IO ()
  dieOrForceAll ForceAll s = ignoreError s
  dieOrForceAll _other s   = dieForcible s
  
  warn :: String -> IO ()
  warn = reportError
  
  -- send info messages to stdout
  infoLn :: String -> IO ()
  infoLn = putStrLn
  
  info :: String -> IO ()
  info = putStr
  
  ignoreError :: String -> IO ()
  ignoreError s = reportError (s ++ " (ignoring)")
  
  reportError :: String -> IO ()
  reportError s = do hFlush stdout; hPutStrLn stderr s
  
  dieForcible :: String -> IO ()
  dieForcible s = die (s ++ " (use --force to override)")
  
  my_head :: String -> [a] -> a
  my_head s []      = error s
  my_head _ (x : _) = x
  
  getLibDir :: IO (Maybe String)
  getLibDir = return $ Just hasteSysDir
  
  -----------------------------------------
  -- Adapted from ghc/compiler/utils/Panic
  
  installSignalHandlers :: IO ()
  installSignalHandlers = do
    threadid <- myThreadId
    let
        interrupt = Exception.throwTo threadid
                                      (Exception.ErrorCall "interrupted")
    --
  #if !defined(mingw32_HOST_OS)
    _ <- installHandler sigQUIT (Catch interrupt) Nothing
    _ <- installHandler sigINT  (Catch interrupt) Nothing
    return ()
  #else
    -- GHC 6.3+ has support for console events on Windows
    -- NOTE: running GHCi under a bash shell for some reason requires
    -- you to press Ctrl-Break rather than Ctrl-C to provoke
    -- an interrupt.  Ctrl-C is getting blocked somewhere, I don't know
    -- why --SDM 17/12/2004
    let sig_handler ControlC = interrupt
        sig_handler Break    = interrupt
        sig_handler _        = return ()
  
    _ <- installHandler (Catch sig_handler)
    return ()
  #endif
  
  #if mingw32_HOST_OS || mingw32_TARGET_OS
  throwIOIO :: Exception.IOException -> IO a
  throwIOIO = Exception.throwIO
  #endif
  
  catchIO :: IO a -> (Exception.IOException -> IO a) -> IO a
  catchIO = Exception.catch
  
  tryIO :: IO a -> IO (Either Exception.IOException a)
  tryIO = Exception.try
  
  writeFileUtf8Atomic :: FilePath -> String -> IO ()
  writeFileUtf8Atomic targetFile content =
    withFileAtomic targetFile $ \h -> do
       hSetEncoding h utf8
       hPutStr h content
  
  -- copied from Cabal's Distribution.Simple.Utils, except that we want
  -- to use text files here, rather than binary files.
  withFileAtomic :: FilePath -> (Handle -> IO ()) -> IO ()
  withFileAtomic targetFile write_content = do
    (newFile, newHandle) <- openNewFile targetDir template
    do  write_content newHandle
        hClose newHandle
  #if mingw32_HOST_OS || mingw32_TARGET_OS
        renameFile newFile targetFile
          -- If the targetFile exists then renameFile will fail
          `catchIO` \err -> do
            exists <- doesFileExist targetFile
            if exists
              then do removeFileSafe targetFile
                      -- Big fat hairy race condition
                      renameFile newFile targetFile
                      -- If the removeFile succeeds and the renameFile fails
                      -- then we've lost the atomic property.
              else throwIOIO err
  #else
        renameFile newFile targetFile
  #endif
     `Exception.onException` do hClose newHandle
                                removeFileSafe newFile
    where
      template = targetName <.> "tmp"
      targetDir | null targetDir_ = "."
                | otherwise       = targetDir_
      --TODO: remove this when takeDirectory/splitFileName is fixed
      --      to always return a valid dir
      (targetDir_,targetName) = splitFileName targetFile
  
  openNewFile :: FilePath -> String -> IO (FilePath, Handle)
  openNewFile dir template = do
    -- this was added to System.IO in 6.12.1
    -- we must use this version because the version below opens the file
    -- in binary mode.
    openTempFileWithDefaultPermissions dir template
  
  readUTF8File :: FilePath -> IO String
  readUTF8File file = do
    h <- openFile file ReadMode
    -- fix the encoding to UTF-8
    hSetEncoding h utf8
    hGetContents h
  
  -- removeFileSave doesn't throw an exceptions, if the file is already deleted
  removeFileSafe :: FilePath -> IO ()
  removeFileSafe fn =
    removeFile fn `catchIO` \ e ->
      when (not $ isDoesNotExistError e) $ ioError e
  
  absolutePath :: FilePath -> IO FilePath
  absolutePath path = return . normalise . (</> path) =<< getCurrentDirectory
  
  -- | Only global packages may be marked as relocatable!
  --   May break horribly for general use, only reliable for Haste base packages.
  relocate :: [String] -> String -> Sh.Shell ()
  relocate packages pkg = do
      pi <- Sh.capture $ Sh.run hastePkgBinary (packages ++ ["describe", pkg])
      Sh.withTempFile Sh.TextMode $ \file h -> do
        Sh.hPutStrLn h (reloc pi)
        Sh.hClose h
        Sh.run hastePkgBinary (relocArgs file)
    where
      relocArgs file = packages ++ ["update", "--force", "--global", file]
      reloc = unlines . map fixPath . lines
  
      fixPath s
        | isKey "library-dirs: " s       = prefix s "library-dirs" importDir
        | isKey "import-dirs: " s        = prefix s "import-dirs" importDir
        | isKey "haddock-interfaces: " s = prefix s "haddock-interfaces" importDir
        | isKey "haddock-html: " s       = prefix s "haddock-html" importDir
        | isKey "include-dirs: " s       = "include-dirs: " ++ includeDir
        | otherwise                      = s
  
      prefix s pfx path = pfx ++ ": " ++ path </> stripPrefix s
  
      stripPrefix = joinPath . dropWhile (not . isKey pkg) . splitPath
  
      isKey _ "" =
        False
      isKey key str =
        and $ zipWith (==) key str
  
      importDir = "${pkgroot}"
      includeDir = "${pkgroot}" </> "include"
  
  
  {- Note [writeAtomic leaky abstraction]
  GhcPkg.writePackageDb calls writeAtomic, which first writes to a temp file,
  and then moves the tempfile to its final destination. This all happens in the
  same directory (package.conf.d).
  Moving a file doesn't change its modification time, but it *does* change the
  modification time of the directory it is placed in. Since we compare the
  modification time of the cache file to that of the directory it is in to
  decide whether the cache is out-of-date, it will be instantly out-of-date
  after creation, if the renaming takes longer than the smallest time difference
  that the getModificationTime can measure.
  
  The solution we opt for is a "touch" of the cache file right after it is
  created. This resets the modification time of the cache file and the directory
  to the current time.
  
  Other possible solutions:
    * backdate the modification time of the directory to the modification time
      of the cachefile. This is what we used to do on posix platforms. An
      observer of the directory would see the modification time of the directory
      jump back in time. Not nice, although in practice probably not a problem.
      Also note that a cross-platform implementation of setModificationTime is
      currently not available.
    * set the modification time of the cache file to the modification time of
      the directory (instead of the curent time). This could also work,
      given that we are the only ones writing to this directory. It would also
      require a high-precision getModificationTime (lower precision times get
      rounded down it seems), or the cache would still be out-of-date.
    * change writeAtomic to create the tempfile outside of the target file's
      directory.
    * create the cachefile outside of the package.conf.d directory in the first
      place. But there are tests and there might be tools that currently rely on
      the package.conf.d/package.cache format.
  -}
  