ghc-pkg: don't expand ${name}-style env vars by default

For shell-based build systems the feature is still available as:
  ghc-pkg register --expand-env-vars

Historically, ghc-pkg allowed environment variables to appear in the
input files for ghc-pkg register. They are not stored in the package
database but are expanded upon registration. This feature helped for
build systems based on makefiles and shell scripts. These days the
vast majority of such files are generated by Cabal and we don't want
any ${name} strings (e.g. perhaps in a package description) getting
accidentally interpreted as an environment variable.

diff --git a/utils/ghc-pkg/Main.hs b/utils/ghc-pkg/Main.hs
index 74f761b..cef6206 100644 (file)
--- a/utils/ghc-pkg/Main.hs
+++ b/utils/ghc-pkg/Main.hs
@@ -101,6 +101,7 @@ data Flag
   | FlagForce
   | FlagForceFiles
   | FlagAutoGHCiLibs
   | FlagForce
   | FlagForceFiles
   | FlagAutoGHCiLibs

+  | FlagExpandEnvVars

   | FlagSimpleOutput
   | FlagNamesOnly
   | FlagIgnoreCase
   | FlagSimpleOutput
   | FlagNamesOnly
   | FlagIgnoreCase

@@ -126,6 +127,8 @@ flags = [
          "ignore missing directories and libraries only",
   Option ['g'] ["auto-ghci-libs"] (NoArg FlagAutoGHCiLibs)
         "automatically build libs for GHCi (with register)",
          "ignore missing directories and libraries only",
   Option ['g'] ["auto-ghci-libs"] (NoArg FlagAutoGHCiLibs)
         "automatically build libs for GHCi (with register)",

+  Option [] ["expand-env-vars"] (NoArg FlagExpandEnvVars)
+        "expand environment variables (${name}-style) in input package descriptions",

   Option ['?'] ["help"] (NoArg FlagHelp)
         "display this help and exit",
   Option ['V'] ["version"] (NoArg FlagVersion)
   Option ['?'] ["help"] (NoArg FlagHelp)
         "display this help and exit",
   Option ['V'] ["version"] (NoArg FlagVersion)

@@ -274,6 +277,7 @@ runit verbosity cli nonopts = do
           | FlagForceFiles `elem` cli   = ForceFiles
           | otherwise                   = NoForce
         auto_ghci_libs = FlagAutoGHCiLibs `elem` cli
           | FlagForceFiles `elem` cli   = ForceFiles
           | otherwise                   = NoForce
         auto_ghci_libs = FlagAutoGHCiLibs `elem` cli

+        expand_env_vars= FlagExpandEnvVars `elem` cli

         splitFields fields = unfoldr splitComma (',':fields)
           where splitComma "" = Nothing
                 splitComma fs = Just $ break (==',') (tail fs)
         splitFields fields = unfoldr splitComma (',':fields)
           where splitComma "" = Nothing
                 splitComma fs = Just $ break (==',') (tail fs)

@@ -313,9 +317,11 @@ runit verbosity cli nonopts = do
     ["init", filename] ->
         initPackageDB filename verbosity cli
     ["register", filename] ->
     ["init", filename] ->
         initPackageDB filename verbosity cli
     ["register", filename] ->

-        registerPackage filename verbosity cli auto_ghci_libs False force
+        registerPackage filename verbosity cli
+                        auto_ghci_libs expand_env_vars False force

     ["update", filename] ->
     ["update", filename] ->

-        registerPackage filename verbosity cli auto_ghci_libs True force
+        registerPackage filename verbosity cli
+                        auto_ghci_libs expand_env_vars True force

     ["unregister", pkgid_str] -> do
         pkgid <- readGlobPkgId pkgid_str
         unregisterPackage pkgid verbosity cli force
     ["unregister", pkgid_str] -> do
         pkgid <- readGlobPkgId pkgid_str
         unregisterPackage pkgid verbosity cli force

@@ -624,10 +630,11 @@ registerPackage :: FilePath
                 -> Verbosity
                 -> [Flag]
                 -> Bool              -- auto_ghci_libs
                 -> Verbosity
                 -> [Flag]
                 -> Bool              -- auto_ghci_libs

+                -> Bool              -- expand_env_vars

                 -> Bool              -- update
                 -> Force
                 -> IO ()
                 -> Bool              -- update
                 -> Force
                 -> IO ()

-registerPackage input verbosity my_flags auto_ghci_libs update force = do
+registerPackage input verbosity my_flags auto_ghci_libs expand_env_vars update force = do

   (db_stack, Just to_modify, _flag_dbs) <- 
       getPkgDatabases verbosity True True my_flags
 
   (db_stack, Just to_modify, _flag_dbs) <- 
       getPkgDatabases verbosity True True my_flags
 

@@ -648,7 +655,8 @@ registerPackage input verbosity my_flags auto_ghci_libs update force = do
             putStr ("Reading package info from " ++ show f ++ " ... ")
         readUTF8File f
 
             putStr ("Reading package info from " ++ show f ++ " ... ")
         readUTF8File f
 

-  expanded <- expandEnvVars s force
+  expanded <- if expand_env_vars then expandEnvVars s force
+                                 else return s

 
   pkg <- parsePackageInfo expanded
   when (verbosity >= Normal) $
 
   pkg <- parsePackageInfo expanded
   when (verbosity >= Normal) $