Cabal revisions

src/Cabal2nix.hs

@@ -164,11 +164,12 @@ pinfo = info
                      [ P2.text ""
                      , P2.text "Recognized URI schemes:"
                      , P2.text ""
-                     , P2.text "  cabal://pkgname-pkgversion     download the specified package from Hackage"
-                     , P2.text "  cabal://pkgname                download latest version of this package from Hackage"
-                     , P2.text "  file:///local/path             load the Cabal file from the local disk"
-                     , P2.text "  /local/path                    abbreviated version of file URI"
-                     , P2.text "  <git/svn/bzr/hg URL>           download the source from the specified repository"
+                     , P2.text "  cabal://pkgname-pkgversion@pkgrevision     download the specified package from Hackage, use revision N if pkgrevision is 'rev:N' or use revision with cabal file SHA256 equal to S with pkgrevision specified as 'sha256:S,SZ (SZ part is being ignored)'"
+                     , P2.text "  cabal://pkgname-pkgversion                 download the specified package from Hackage, use latest revision"
+                     , P2.text "  cabal://pkgname                            download latest version of this package from Hackage"
+                     , P2.text "  file:///local/path                         load the Cabal file from the local disk"
+                     , P2.text "  /local/path                                abbreviated version of file URI"
+                     , P2.text "  <git/svn/bzr/hg URL>                       download the source from the specified repository"
                      , P2.text ""
                      , P2.fillSep (map P2.text (words (  "If the URI refers to a cabal file, information for building the package "
                                                       ++ "will be retrieved from that file, but hackage will be used as a source "

src/Distribution/Nixpkgs/Haskell/Hackage.hs

@@ -1,9 +1,11 @@
 module Distribution.Nixpkgs.Haskell.Hackage
-  ( HackageDB, PackageData, VersionData(..)
+  ( HackageDB, PackageData, VersionData(..), NixSha256
   , hackageTarball, readTarball, parsePackageData
   )
   where
 
+import qualified Data.List.NonEmpty as NE
+import Data.List.NonEmpty (NonEmpty)
 import Data.Map as Map
 import qualified Distribution.Hackage.DB.Parsed as P
 import Distribution.Hackage.DB.Path
@@ -19,10 +21,11 @@ type HackageDB = Map PackageName PackageData
 
 type PackageData = Map Version VersionData
 
+type NixSha256 = String
+
 data VersionData = VersionData
-  { cabalFile :: !GenericPackageDescription
-  , cabalFileSha256 :: !String
-  , tarballSha256 :: !(Maybe String)
+  { cabalFilesWithHashes :: !(NonEmpty (NixSha256, GenericPackageDescription))
+  , tarballSha256 :: !(Maybe NixSha256)
   }
   deriving (Show)
 
@@ -37,9 +40,10 @@ parsePackageData dbu pn = mapWithKey (parseVersionData (dbu ! pn))
 
 parseVersionData :: U.PackageData -> Version -> P.VersionData -> VersionData
 parseVersionData pdu v vd = VersionData
-                            { cabalFile = P.cabalFile vd
-                            , cabalFileSha256 = printSHA256 (digest (digestByName "sha256") file)
+                            { cabalFilesWithHashes = cfsWithHashes
                             , tarballSha256 = Map.lookup "sha256" (P.tarballHashes vd)
                             }
   where
-    file = U.cabalFile (U.versions pdu ! v)
+    cfsWithHashes = NE.zip sha256s (P.cabalFileRevisions vd)
+    sha256s = NE.map (\file -> printSHA256 (digest (digestByName "sha256") file))
+              (NE.fromList $ U.cabalFileRevisions (U.versions pdu ! v))

src/Distribution/Nixpkgs/Haskell/PackageSourceSpec.hs

@@ -8,7 +8,8 @@ import Control.Monad.IO.Class
 import Control.Monad.Trans.Maybe
 import Data.Bifunctor
 import qualified Data.ByteString.Char8 as BS
-import Data.List ( isSuffixOf, isPrefixOf )
+import Data.List ( isSuffixOf, isPrefixOf, stripPrefix )
+import qualified Data.List.NonEmpty as NE
 import qualified Data.Map as DB
 import Data.Maybe
 import Data.Time
@@ -29,6 +30,7 @@ import System.Directory ( doesDirectoryExist, doesFileExist, createDirectoryIfMi
 import System.Exit ( exitFailure )
 import System.FilePath ( (</>), (<.>) )
 import System.IO
+import Text.Read ( readMaybe )
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
 
@@ -90,17 +92,40 @@ loadHackageDB optHackageDB optHackageSnapshot = do
   dbPath <- maybe DB.hackageTarball return optHackageDB
   DB.readTarball optHackageSnapshot dbPath
 
+data Revision = RevisionLatest | RevisionN Int | RevisionSha256 DB.NixSha256
+
 fromDB :: IO DB.HackageDB
        -> String
        -> IO (Maybe DerivationSource, Cabal.GenericPackageDescription)
-fromDB hackageDBIO pkg = do
+fromDB hackageDBIO pkgRev = do
   hackageDB <- hackageDBIO
   vd <- maybe unknownPackageError return (DB.lookup name hackageDB >>= lookupVersion)
   let ds = case DB.tarballSha256 vd of
              Nothing -> Nothing
              Just hash -> Just (urlDerivationSource url hash)
-  return (ds, setCabalFileHash (DB.cabalFileSha256 vd) (DB.cabalFile vd))
+      cabalFilesWithHashes = DB.cabalFilesWithHashes vd
+      (cabalFileSha256, cabalFile) =
+        case rev of
+          RevisionLatest -> NE.last cabalFilesWithHashes
+          RevisionN n -> case NE.drop n cabalFilesWithHashes of
+            [] -> fail $ "invalid Haskell package " ++ show pkg ++ " revision " ++ show n
+            x : _ -> x
+          RevisionSha256 sha -> case NE.filter ((== sha) . fst) cabalFilesWithHashes of
+            [] -> fail $ "invalid Haskell package " ++ show pkg ++ " revision SHA256 " ++ show sha
+            x : _ -> x
+  return (ds, setCabalFileHash cabalFileSha256 cabalFile)
  where
+  (pkg, rev) = case span (/= '@') pkgRev of
+    (p, "") -> (p, RevisionLatest)
+    (p, r) | Just nStr <- stripPrefix "@rev:" r,
+             Just n <- readMaybe nStr,
+             n >= 0 ->
+               (p, RevisionN n)
+    (p, r) | Just sha256size <- stripPrefix "@sha256:" r,
+             sha256hex <- takeWhile (/= ',') sha256size ->
+               (p, RevisionSha256 (toNixSha256 sha256hex))
+    _ -> error $ "invalid Haskell package id " ++ show pkgRev
+  toNixSha256 = printSHA256 . packHex
   pkgId :: Cabal.PackageIdentifier
   pkgId = fromMaybe (error ("invalid Haskell package id " ++ show pkg)) (simpleParse pkg)
   name = Cabal.packageName pkgId