/utils/ghc-pkg/Main.hs

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{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

-- We never want to link against terminfo while bootstrapping.
#if defined(BOOTSTRAPPING)
#if defined(WITH_TERMINFO)
#undef WITH_TERMINFO
#endif
#endif

-- Fine if this comes from make/Hadrian or the pre-built base.
#include <ghcplatform.h>

-----------------------------------------------------------------------------
--
-- (c) The University of Glasgow 2004-2009.
--
-- Package management tool
--
-----------------------------------------------------------------------------

module Main (main) where

import qualified GHC.Unit.Database as GhcPkg
import GHC.Unit.Database hiding (mkMungePathUrl)
import GHC.HandleEncoding
import GHC.BaseDir (getBaseDir)
import GHC.Settings.Utils (getTargetArchOS, maybeReadFuzzy)
import GHC.Platform.Host (hostPlatformArchOS)
import GHC.UniqueSubdir (uniqueSubdir)
import qualified GHC.Data.ShortText as ST
import GHC.Version ( cProjectVersion )
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 qualified Distribution.Parsec as Cabal
import Distribution.Package hiding (installedUnitId)
import Distribution.Text
import Distribution.Version
import Distribution.Backpack
import Distribution.Pretty (Pretty (..))
import Distribution.Types.UnqualComponentName
import Distribution.Types.LibraryName
import Distribution.Types.MungedPackageName
import Distribution.Types.MungedPackageId
import Distribution.Simple.Utils (toUTF8BS, writeUTF8File, readUTF8File)
import qualified Data.Version as Version
import System.FilePath as FilePath
import qualified System.FilePath.Posix as FilePath.Posix
import System.Directory ( getXdgDirectory, createDirectoryIfMissing,
                          getModificationTime, XdgDirectory ( XdgData ) )
import Text.Printf

import Prelude

import System.Console.GetOpt
import qualified Control.Exception as Exception
import Data.Maybe
import Data.Bifunctor

import Data.Char ( toLower )
import Control.Monad
import System.Directory ( doesDirectoryExist, getDirectoryContents,
                          doesFileExist, removeFile,
                          getCurrentDirectory )
import System.Exit ( exitWith, ExitCode(..) )
import System.Environment ( getArgs, getProgName, getEnv )
import System.IO
import System.IO.Error
import GHC.IO           ( catchException )
import GHC.IO.Exception (IOErrorType(InappropriateType))
import Data.List ( group, sort, sortBy, nub, partition, find
                 , intercalate, intersperse, foldl', unfoldr
                 , isInfixOf, isSuffixOf, isPrefixOf, stripPrefix )
import Control.Concurrent
import qualified Data.Foldable as F
import qualified Data.Traversable as F
import qualified Data.Set as Set
import qualified Data.Map as Map
import qualified Data.ByteString as BS

#if defined(mingw32_HOST_OS)
import GHC.ConsoleHandler
#else
import System.Posix hiding (fdToHandle)
#endif

#if defined(GLOB)
import qualified System.Info(os)
#endif

#if defined(WITH_TERMINFO)
import System.Console.Terminfo as Terminfo
#endif

#if defined(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

-- | Short-circuit 'any' with a \"monadic predicate\".
anyM :: (Monad m) => (a -> m Bool) -> [a] -> m Bool
anyM _ [] = return False
anyM p (x:xs) = do
  b <- p x
  if b
    then return True
    else anyM p xs

-- -----------------------------------------------------------------------------
-- Entry point

main :: IO ()
main = do
  configureHandleEncoding
  args <- getArgs

  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,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)

-- -----------------------------------------------------------------------------
-- Command-line syntax

data Flag
  = FlagUser
  | FlagGlobal
  | FlagHelp
  | FlagVersion
  | FlagConfig FilePath
  | FlagGlobalConfig FilePath
  | FlagUserConfig FilePath
  | FlagForce
  | FlagForceFiles
  | FlagMultiInstance
  | FlagExpandEnvVars
  | FlagExpandPkgroot
  | FlagNoExpandPkgroot
  | FlagSimpleOutput
  | FlagNamesOnly
  | FlagIgnoreCase
  | FlagNoUserDb
  | FlagVerbosity (Maybe String)
  | FlagUnitId
  | FlagShowUnitIds
  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 [] ["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 [] ["simple-output"] (NoArg FlagSimpleOutput)
        "print output in easy-to-parse format for some commands",
  Option [] ["show-unit-ids"] (NoArg FlagShowUnitIds)
        "print unit-ids instead of package identifiers",
  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", "unit-id"] (NoArg FlagUnitId)
        "interpret package arguments as unit IDs (e.g. installed package IDs)",
  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 = "GHC package manager version " ++ GHC.Version.cProjectVersion ++ "\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 packages in the order given.\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\n" ++
  "    of the dependency graph: ghc-pkg dot | tred | dot -Tpdf >pkgs.pdf\n" ++
  "\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
    = AsUnitId
    | AsDefault

-- | Represents how a package may be specified by a user on the command line.
data PackageArg
    -- | A package identifier foo-0.1, or a glob foo-*
    = Id GlobPackageIdentifier
    -- | An installed package ID foo-0.1-HASH.  This is guaranteed to uniquely
    -- match a single entry in the package database.
    | IUId UnitId
    -- | A glob against the package name.  The first string is the literal
    -- glob, the second is a function which returns @True@ if the argument
    -- matches.
    | Substring String (String->Bool)

runit :: Verbosity -> [Flag] -> [String] -> IO ()
runit verbosity cli nonopts = do
  installSignalHandlers -- catch ^C and clean up
  when (verbosity >= Verbose)
    (putStr ourCopyright)
  prog <- getProgramName
  let
        force
          | FlagForce `elem` cli        = ForceAll
          | FlagForceFiles `elem` cli   = ForceFiles
          | otherwise                   = NoForce
        as_arg | FlagUnitId `elem` cli = AsUnitId
               | otherwise             = AsDefault
        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
                        multi_instance
                        expand_env_vars False force
    ["update", filename] ->
        registerPackage filename verbosity cli
                        multi_instance
                        expand_env_vars True force
    "unregister" : pkgarg_strs@(_:_) -> do
        forM_ pkgarg_strs $ \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", mod_name] -> do
        let match = maybe (==mod_name) id (substringCheck mod_name)
        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
        dumpUnits 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 :: Cabal.Parsec a => String -> String -> IO a
parseCheck str what =
  case Cabal.eitherParsec str of
    Left e  -> die ("cannot parse \'" ++ str ++ "\' as a " ++ what ++ ": " ++ e)
    Right x -> pure x

-- | Either an exact 'PackageIdentifier', or a glob for all packages
-- matching 'PackageName'.
data GlobPackageIdentifier
    = ExactPackageIdentifier MungedPackageId
    | GlobPackageIdentifier  MungedPackageName

displayGlobPkgId :: GlobPackageIdentifier -> String
displayGlobPkgId (ExactPackageIdentifier pid) = display pid
displayGlobPkgId (GlobPackageIdentifier pn) = display pn ++ "-*"

readGlobPkgId :: String -> IO GlobPackageIdentifier
readGlobPkgId str
  | "-*" `isSuffixOf` str =
    GlobPackageIdentifier <$> parseCheck (init (init str)) "package identifier (glob)"
  | otherwise = ExactPackageIdentifier <$> parseCheck str "package identifier (exact)"

readPackageArg :: AsPackageArg -> String -> IO PackageArg
readPackageArg AsUnitId str = IUId <$> parseCheck str "installed package id"
readPackageArg AsDefault str = Id <$> readGlobPkgId str

-- -----------------------------------------------------------------------------
-- 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 (mode :: GhcPkg.DbMode)
  = PackageDB {
      location, locationAbsolute :: !FilePath,
      -- We need both possibly-relative and definitely-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.

      packageDbLock :: !(GhcPkg.DbOpenMode mode GhcPkg.PackageDbLock),
      -- If package db is open in read write mode, we keep its lock around for
      -- transactional updates.

      packages :: [InstalledPackageInfo]
    }

type PackageDBStack = [PackageDB 'GhcPkg.DbReadOnly]
        -- A stack of package databases.  Convention: head is the topmost
        -- in the stack.

-- | Selector for picking the right package DB to modify as 'register' and
-- 'recache' operate on the database on top of the stack, whereas 'modify'
-- changes the first database that contains a specific package.
data DbModifySelector = TopOne | ContainsPkg PackageArg

allPackagesInStack :: PackageDBStack -> [InstalledPackageInfo]
allPackagesInStack = concatMap packages

-- | Retain only the part of the stack up to and including the given package
-- DB (where the global package DB is the bottom of the stack). The resulting
-- package DB stack contains exactly the packages that packages from the
-- specified package DB can depend on, since dependencies can only extend
-- down the stack, not up (e.g. global packages cannot depend on user
-- packages).
stackUpTo :: FilePath -> PackageDBStack -> PackageDBStack
stackUpTo to_modify = dropWhile ((/= to_modify) . location)

getPkgDatabases :: Verbosity
                -> GhcPkg.DbOpenMode mode DbModifySelector
                -> 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.
                       GhcPkg.DbOpenMode mode (PackageDB mode),
                          -- 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 mode use_user use_cache expand_vars my_flags = do
  -- Second 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
        -- See Note [Base Dir] for more information on the base dir / top dir.
        [] -> do mb_dir <- getBaseDir
                 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

  -- get the location of the user package database, and create it if necessary
  -- getXdgDirectory can fail (e.g. if $HOME isn't set)
  e_appdir <- tryIO $ getXdgDirectory XdgData "ghc"

  mb_user_conf <-
    case [ f | FlagUserConfig f <- my_flags ] of
      _ | no_user_db -> return Nothing
      [] -> case e_appdir of
        Left _    -> return Nothing
        Right appdir -> do
          -- See Note [Settings File] about this file, and why we need GHC to share it with us.
          let settingsFile = top_dir </> "settings"
          exists_settings_file <- doesFileExist settingsFile
          targetArchOS <- case exists_settings_file of
            False -> do
              warn $ "WARNING: settings file doesn't exist " ++ show settingsFile
              warn "cannot know target platform so guessing target == host (native compiler)."
              pure hostPlatformArchOS
            True -> do
              settingsStr <- readFile settingsFile
              mySettings <- case maybeReadFuzzy settingsStr of
                Just s -> pure $ Map.fromList s
                -- It's excusable to not have a settings file (for now at
                -- least) but completely inexcusable to have a malformed one.
                Nothing -> die $ "Can't parse settings file " ++ show settingsFile
              case getTargetArchOS settingsFile mySettings of
                Right archOS -> pure archOS
                Left e -> die e
          let subdir = uniqueSubdir targetArchOS
              dir = appdir </> subdir
          r <- lookForPackageDBIn dir
          case r of
            Nothing -> return (Just (dir </> "package.conf.d", 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 "GHC_PACKAGE_PATH")
  let env_stack =
        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

      top_db = if null db_flags
               then virt_global_conf
               else last db_flags

  (db_stack, db_to_operate_on) <- getDatabases top_dir mb_user_conf
                                               flag_db_names final_stack top_db

  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))
    F.forM_ db_to_operate_on $ \db ->
      infoLn ("modifying: " ++ (location db))
    infoLn ("flag db stack: " ++ show (map location flag_db_stack))

  return (db_stack, db_to_operate_on, flag_db_stack)
  where
    getDatabases top_dir mb_user_conf flag_db_names
                 final_stack top_db = case mode of
      -- When we open in read only mode, we simply read all of the databases/
      GhcPkg.DbOpenReadOnly -> do
        db_stack <- mapM readDatabase final_stack
        return (db_stack, GhcPkg.DbOpenReadOnly)

      -- The only package db we open in read write mode is the one on the top of
      -- the stack.
      GhcPkg.DbOpenReadWrite TopOne -> do
        (db_stack, mto_modify) <- stateSequence Nothing
          [ \case
              to_modify@(Just _) -> (, to_modify) <$> readDatabase db_path
              Nothing -> if db_path /= top_db
                then (, Nothing) <$> readDatabase db_path
                else do
                  db <- readParseDatabase verbosity mb_user_conf
                                          mode use_cache db_path
                    `catchException` couldntOpenDbForModification db_path
                  let ro_db = db { packageDbLock = GhcPkg.DbOpenReadOnly }
                  return (ro_db, Just db)
          | db_path <- final_stack ]

        to_modify <- case mto_modify of
          Just db -> return db
          Nothing -> die "no database selected for modification"

        return (db_stack, GhcPkg.DbOpenReadWrite to_modify)

      -- The package db we open in read write mode is the first one included in
      -- flag_db_names that contains specified package. Therefore we need to
      -- open each one in read/write mode first and decide whether it's for
      -- modification based on its contents.
      GhcPkg.DbOpenReadWrite (ContainsPkg pkgarg) -> do
        (db_stack, mto_modify) <- stateSequence Nothing
          [ \case
              to_modify@(Just _) -> (, to_modify) <$> readDatabase db_path
              Nothing -> if db_path `notElem` flag_db_names
                then (, Nothing) <$> readDatabase db_path
                else do
                  let hasPkg :: PackageDB mode -> Bool
                      hasPkg = not . null . findPackage pkgarg . packages

                      openRo (e::IOError) = do
                        db <- readDatabase db_path
                        if hasPkg db
                          then couldntOpenDbForModification db_path e
                          else return (db, Nothing)

                  -- If we fail to open the database in read/write mode, we need
                  -- to check if it's for modification first before throwing an
                  -- error, so we attempt to open it in read only mode.
                  Exception.handle openRo $ do
                    db <- readParseDatabase verbosity mb_user_conf
                                            mode use_cache db_path
                    let ro_db = db { packageDbLock = GhcPkg.DbOpenReadOnly }
                    if hasPkg db
                      then return (ro_db, Just db)
                      else do
                        -- If the database is not for modification after all,
                        -- drop the write lock as we are already finished with
                        -- the database.
                        case packageDbLock db of
                          GhcPkg.DbOpenReadWrite lock ->
                            GhcPkg.unlockPackageDb lock
                        return (ro_db, Nothing)
          | db_path <- final_stack ]

        to_modify <- case mto_modify of
          Just db -> return db
          Nothing -> cannotFindPackage pkgarg Nothing

        return (db_stack, GhcPkg.DbOpenReadWrite to_modify)
      where
        couldntOpenDbForModification :: FilePath -> IOError -> IO a
        couldntOpenDbForModification db_path e = die $ "Couldn't open database "
          ++ db_path ++ " for modification: " ++ show e

        -- Parse package db in read-only mode.
        readDatabase :: FilePath -> IO (PackageDB 'GhcPkg.DbReadOnly)
        readDatabase db_path = do
          db <- readParseDatabase verbosity mb_user_conf
                                  GhcPkg.DbOpenReadOnly use_cache db_path
          if expand_vars
            then return $ mungePackageDBPaths top_dir db
            else return db

    stateSequence :: Monad m => s -> [s -> m (a, s)] -> m ([a], s)
    stateSequence s []     = return ([], s)
    stateSequence s (m:ms) = do
      (a, s')   <- m s
      (as, s'') <- stateSequence s' ms
      return (a : as, s'')

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 :: forall mode t. Verbosity
                  -> Maybe (FilePath,Bool)
                  -> GhcPkg.DbOpenMode mode t
                  -> Bool -- use cache
                  -> FilePath
                  -> IO (PackageDB mode)
readParseDatabase verbosity mb_user_conf mode use_cache path
  -- the user database (only) is allowed to be non-existent
  | Just (user_conf,False) <- mb_user_conf, path == user_conf
  = do lock <- F.forM mode $ \_ -> do
         createDirectoryIfMissing True path
         GhcPkg.lockPackageDb cache
       mkPackageDB [] lock
  | otherwise
  = do e <- tryIO $ getDirectoryContents path
       case e of
         Left err
           | ioeGetErrorType err == InappropriateType -> do
              -- We provide a limited degree of backwards compatibility for
              -- old single-file style db:
              mdb <- tryReadParseOldFileStyleDatabase verbosity
                       mb_user_conf mode use_cache path
              case mdb of
                Just db -> return db
                Nothing ->
                  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
              e_tcache <- tryIO $ getModificationTime cache
              case e_tcache of
                Left ex -> do
                  whenReportCacheErrors $
                    if isDoesNotExistError ex
                      then
                        -- It's fine if the cache is not there as long as the
                        -- database is empty.
                        when (not $ null confs) $ do
                            warn ("WARNING: cache does not exist: " ++ cache)
                            warn ("ghc will fail to read this package db. " ++
                                  recacheAdvice)
                      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
                  when (verbosity >= Verbose) $ do
                      warn ("Timestamp " ++ show tcache ++ " for " ++ cache)
                  -- If any of the .conf files is newer than package.cache, we
                  -- assume that cache is out of date.
                  cache_outdated <- (`anyM` confs) $ \conf ->
                    (tcache <) <$> getModificationTime conf
                  if not cache_outdated
                      then do
                          when (verbosity > Normal) $
                             infoLn ("using cache: " ++ cache)
                          GhcPkg.readPackageDbForGhcPkg cache mode
                            >>= uncurry mkPackageDB
                      else do
                          whenReportCacheErrors $ do
                              warn ("WARNING: cache is out of date: " ++ cache)
                              warn ("ghc will see an old view of this " ++
                                    "package db. " ++ recacheAdvice)
                          ignore_cache $ \file -> do
                            when (verbosity >= Verbose) $ do
                              tFile <- getModificationTime file
                              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)
            where
                 confs = map (path </>) $ filter (".conf" `isSuffixOf`) fs

                 ignore_cache :: (FilePath -> IO ()) -> IO (PackageDB mode)
                 ignore_cache checkTime = do
                     -- If we're opening for modification, we need to acquire a
                     -- lock even if we don't open the cache now, because we are
                     -- going to modify it later.
                     lock <- F.mapM (const $ GhcPkg.lockPackageDb cache) mode
                     let doFile f = do checkTime f
                                       parseSingletonPackageConf verbosity f
                     pkgs <- mapM doFile confs
                     mkPackageDB pkgs lock

                 -- We normally report cache errors for read-only commands,
                 -- since modify commands will usually fix the cache.
                 whenReportCacheErrors = when $ verbosity > Normal
                   || verbosity >= Normal && GhcPkg.isDbOpenReadMode mode
  where
    cache = path </> cachefilename

    recacheAdvice
      | Just (user_conf, True) <- mb_user_conf, path == user_conf
      = "Use 'ghc-pkg recache --user' to fix."
      | otherwise
      = "Use 'ghc-pkg recache' to fix."

    mkPackageDB :: [InstalledPackageInfo]
                -> GhcPkg.DbOpenMode mode GhcPkg.PackageDbLock
                -> IO (PackageDB mode)
    mkPackageDB pkgs lock = do
      path_abs <- absolutePath path
      return $ PackageDB {
          location = path,
          locationAbsolute = path_abs,
          packageDbLock = lock,
          packages = pkgs
        }

parseSingletonPackageConf :: Verbosity -> FilePath -> IO InstalledPackageInfo
parseSingletonPackageConf verbosity file = do
  when (verbosity > Normal) $ infoLn ("reading package config: " ++ file)
  BS.readFile file >>= fmap fst . parsePackageInfo

cachefilename :: FilePath
cachefilename = "package.cache"

mungePackageDBPaths :: FilePath -> PackageDB mode -> PackageDB mode
mungePackageDBPaths top_dir db@PackageDB { packages = pkgs } =
    db { packages = map (mungePackagePaths top_dir pkgroot) pkgs }
  where
    pkgroot = takeDirectory $ dropTrailingPathSeparator (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/

-- | 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 :: FilePath -> FilePath
                  -> InstalledPackageInfo -> InstalledPackageInfo
mungePackagePaths top_dir pkgroot pkg =
   -- TODO: similar code is duplicated in GHC.Unit.Database
    pkg {
      importDirs  = munge_paths (importDirs pkg),
      includeDirs = munge_paths (includeDirs pkg),
      libraryDirs = munge_paths (libraryDirs pkg),
      libraryDynDirs = munge_paths (libraryDynDirs 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,munge_url) = mkMungePathUrl top_dir pkgroot

mkMungePathUrl :: FilePath -> FilePath -> (FilePath -> FilePath, FilePath -> FilePath)
mkMungePathUrl top_dir pkgroot = (munge_path, munge_url)
   where
    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

-- -----------------------------------------------------------------------------
-- Workaround for old single-file style package dbs

-- Single-file style package dbs have been deprecated for some time, but
-- it turns out that Cabal was using them in one place. So this code is for a
-- workaround to allow older Cabal versions to use this newer ghc.

-- We check if the file db contains just "[]" and if so, we look for a new
-- dir-style db in path.d/, ie in a dir next to the given file.
-- We cannot just replace the file with a new dir style since Cabal still
-- assumes it's a file and tries to overwrite with 'writeFile'.

-- ghc itself also cooperates in this workaround

tryReadParseOldFileStyleDatabase :: Verbosity -> Maybe (FilePath, Bool)
                                 -> GhcPkg.DbOpenMode mode t -> Bool -> FilePath
                                 -> IO (Maybe (PackageDB mode))
tryReadParseOldFileStyleDatabase verbosity mb_user_conf
                                 mode use_cache path = do
  -- assumes we've already established that path exists and is not a dir
  content <- readFile path `catchIO` \_ -> return ""
  if take 2 content == "[]"
    then do
      path_abs <- absolutePath path
      let path_dir = adjustOldDatabasePath path
      warn $ "Warning: ignoring old file-style db and trying " ++ path_dir
      direxists <- doesDirectoryExist path_dir
      if direxists
        then do
          db <- readParseDatabase verbosity mb_user_conf mode use_cache path_dir
          -- but pretend it was at the original location
          return $ Just db {
              location         = path,
              locationAbsolute = path_abs
            }
         else do
           lock <- F.forM mode $ \_ -> do
             createDirectoryIfMissing True path_dir
             GhcPkg.lockPackageDb $ path_dir </> cachefilename
           return $ Just PackageDB {
               location         = path,
               locationAbsolute = path_abs,
               packageDbLock    = lock,
               packages         = []
             }

    -- if the path is not a file, or is not an empty db then we fail
    else return Nothing

adjustOldFileStylePackageDB :: PackageDB mode -> IO (PackageDB mode)
adjustOldFileStylePackageDB db = do
  -- assumes we have not yet established if it's an old style or not
  mcontent <- liftM Just (readFile (location db)) `catchIO` \_ -> return Nothing
  case fmap (take 2) mcontent of
    -- it is an old style and empty db, so look for a dir kind in location.d/
    Just "[]" -> return db {
        location         = adjustOldDatabasePath $ location db,
        locationAbsolute = adjustOldDatabasePath $ locationAbsolute db
      }
    -- it is old style but not empty, we have to bail
    Just  _   -> die $ "ghc no longer supports single-file style package "
                    ++ "databases (" ++ location db ++ ") use 'ghc-pkg init'"
                    ++ "to create the database with the correct format."
    -- probably not old style, carry on as normal
    Nothing   -> return db

adjustOldDatabasePath :: FilePath -> FilePath
adjustOldDatabasePath = (<.> "d")

-- -----------------------------------------------------------------------------
-- 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
  createDirectoryIfMissing True filename
  lock <- GhcPkg.lockPackageDb $ filename </> cachefilename
  filename_abs <- absolutePath filename
  changeDB verbosity [] PackageDB {
      location = filename,
      locationAbsolute = filename_abs,
      packageDbLock = GhcPkg.DbOpenReadWrite lock,
      packages = []
    }
    -- We can get away with passing an empty stack here, because the new DB is
    -- going to be initially empty, so no dependencies are going to be actually
    -- looked up.
    []

-- -----------------------------------------------------------------------------
-- Registering

registerPackage :: FilePath
                -> Verbosity
                -> [Flag]
                -> Bool              -- multi_instance
                -> Bool              -- expand_env_vars
                -> Bool              -- update
                -> Force
                -> IO ()
registerPackage input verbosity my_flags multi_instance
                expand_env_vars update force = do
  (db_stack, GhcPkg.DbOpenReadWrite db_to_operate_on, _flag_dbs) <-
    getPkgDatabases verbosity (GhcPkg.DbOpenReadWrite TopOne)
      True{-use user-} True{-use cache-} False{-expand vars-} my_flags

  let to_modify = location db_to_operate_on

  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 $ toUTF8BS expanded
  when (verbosity >= Normal) $
      infoLn "done."

  -- report any warnings from the parse phase
  _ <- reportValidateErrors verbosity [] ws
         (display (mungedId 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 = stackUpTo to_modify 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
                        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 sam…