Merge pull request #45 from nmattia/nm-fix-nixpkgs-fetch

Fix infinite recursion and empty nixpkgs

app/Niv.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -11,6 +12,7 @@ import Control.Monad
 import Control.Monad.State
 import Data.Aeson (FromJSON, FromJSONKey, ToJSON, ToJSONKey)
 import Data.Char (isSpace, toUpper)
+import Data.FileEmbed (embedFile)
 import Data.Functor ((<&>))
 import Data.Hashable (Hashable)
 import Data.Maybe (mapMaybe, fromMaybe)
@@ -23,6 +25,7 @@ import UnliftIO
 import qualified Data.Aeson as Aeson
 import qualified Data.Aeson.Encode.Pretty as AesonPretty
 import qualified Data.ByteString as B
+import qualified Data.ByteString.Char8 as B8
 import qualified Data.ByteString.Lazy as L
 import qualified Data.HashMap.Strict as HMap
 import qualified Data.Text as T
@@ -319,7 +322,7 @@ cmdInit = do
             if shouldUpdateNixSourcesNix content
             then do
               putStrLn "Updating sources.nix"
-              writeFile path initNixSourcesNixContent
+              B.writeFile path initNixSourcesNixContent
             else putStrLn "Not updating sources.nix"
         )
       , ( pathNixSourcesJson
@@ -336,14 +339,14 @@ cmdInit = do
         , \path _content -> dontCreateFile path)
       ] $ \(path, onCreate, onUpdate) -> do
           exists <- Dir.doesFileExist path
-          if exists then readFile path >>= onUpdate path else onCreate path
+          if exists then B.readFile path >>= onUpdate path else onCreate path
   where
-    createFile :: FilePath -> String -> IO ()
+    createFile :: FilePath -> B.ByteString -> IO ()
     createFile path content = do
       let dir = takeDirectory path
       Dir.createDirectoryIfMissing True dir
       putStrLn $ "Creating " <> path
-      writeFile path content
+      B.writeFile path content
     dontCreateFile :: FilePath -> IO ()
     dontCreateFile path = putStrLn $ "Not creating " <> path
 
@@ -611,24 +614,24 @@ nixPrefetchURL unpack url =
 
 -- | Checks if content is different than default and if it does /not/ contain
 -- a comment line with @niv: no_update@
-shouldUpdateNixSourcesNix :: String -> Bool
+shouldUpdateNixSourcesNix :: B.ByteString -> Bool
 shouldUpdateNixSourcesNix content =
     content /= initNixSourcesNixContent &&
-      not (any lineForbids (lines content))
+      not (any lineForbids (B8.lines content))
   where
-    lineForbids :: String -> Bool
+    lineForbids :: B8.ByteString -> Bool
     lineForbids str =
-      case dropWhile isSpace str of
+      case B8.uncons (B8.dropWhile isSpace str) of
-        '#':rest -> case dropWhile isSpace rest of
+        Just ('#',rest) -> case B8.stripPrefix "niv:" (B8.dropWhile isSpace rest) of
-          'n':'i':'v':':':rest' -> case dropWhile isSpace rest' of
+          Just rest' -> case B8.stripPrefix "no_update" (B8.dropWhile isSpace rest') of
-            'n':'o':'_':'u':'p':'d':'a':'t':'e':_ -> True
+            Just{} -> True
             _ -> False
           _ -> False
         _ -> False
 
 warnIfOutdated :: IO ()
 warnIfOutdated = do
-    tryAny (readFile pathNixSourcesNix) >>= \case
+    tryAny (B.readFile pathNixSourcesNix) >>= \case
       Left e -> putStrLn $ unlines
         [ "Could not read " <> pathNixSourcesNix
         , "Error: " <> show e
@@ -650,51 +653,15 @@ pathNixSourcesNix :: FilePath
 pathNixSourcesNix = "nix" </> "sources.nix"
 
 -- | Glue code between nix and sources.json
-initNixSourcesNixContent :: String
+initNixSourcesNixContent :: B.ByteString
-initNixSourcesNixContent = [s|
+initNixSourcesNixContent = $(embedFile "nix/sources.nix")
-# This file has been generated by Niv.
-
-# A record, from name to path, of the third-party packages
-with rec
-{
-  pkgs = import <nixpkgs> {};
-
-  sources = builtins.fromJSON (builtins.readFile ./sources.json);
-
-  mapAttrs = builtins.mapAttrs or
-    (f: set: with builtins;
-      listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
-
-  getFetcher = spec:
-    let fetcherName =
-      if builtins.hasAttr "type" spec
-      then builtins.getAttr "type" spec
-      else "tarball";
-    in builtins.getAttr fetcherName {
-      "tarball" = pkgs.fetchzip;
-      "file" = pkgs.fetchurl;
-    };
-};
-# NOTE: spec must _not_ have an "outPath" attribute
-mapAttrs (_: spec:
-  if builtins.hasAttr "outPath" spec
-  then abort
-    "The values in sources.json should not have an 'outPath' attribute"
-  else
-    if builtins.hasAttr "url" spec && builtins.hasAttr "sha256" spec
-    then
-      spec //
-      { outPath = getFetcher spec { inherit (spec) url sha256; } ; }
-    else spec
-  ) sources
-|]
 
 -- | @nix/sources.json"
 pathNixSourcesJson :: FilePath
 pathNixSourcesJson = "nix" </> "sources.json"
 
 -- | Empty JSON map
-initNixSourcesJsonContent :: String
+initNixSourcesJsonContent :: B.ByteString
 initNixSourcesJsonContent = "{}"
 
 -------------------------------------------------------------------------------

default.nix

@@ -4,6 +4,8 @@ with rec
     [ "^package.yaml$"
       "^app.*$"
       "^README.md$"
+      "^nix$"
+      "^nix.sources.nix$"
     ];
   haskellPackages = pkgs.haskellPackages.override
     { overrides = _: haskellPackages:

nix/sources.nix

@@ -1,20 +1,58 @@
+# This file has been generated by Niv.
+
 # A record, from name to path, of the third-party packages
-with
+with rec
 {
+  pkgs =
+    if hasNixpkgsPath
+    then
+        if hasThisAsNixpkgsPath
+        then import (builtins_fetchTarball { inherit (sources_nixpkgs) url sha256; }) {}
+        else import <nixpkgs> {}
+    else
+        import (builtins_fetchTarball { inherit (sources_nixpkgs) url sha256; }) {};
+
+  sources_nixpkgs =
+    if builtins.hasAttr "nixpkgs" sources
+    then sources.nixpkgs
+    else abort
+    ''
+        Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
+        add a package called "nixpkgs" to your sources.json.
+    '';
+
+  builtins_fetchTarball =
+      # fetchTarball version that is compatible between all the versions of
+      # Nix
+      { url, sha256 }@attrs:
+      let
+        inherit (builtins) lessThan nixVersion fetchTarball;
+      in
+        if lessThan nixVersion "1.12" then
+          fetchTarball { inherit url; }
+        else
+          fetchTarball attrs;
+
+  hasNixpkgsPath = (builtins.tryEval <nixpkgs>).success;
+  hasThisAsNixpkgsPath =
+    (builtins.tryEval <nixpkgs>).success && <nixpkgs> == ./.;
+
   sources = builtins.fromJSON (builtins.readFile ./sources.json);
 
-  # fetchTarball version that is compatible between all the sources of Nix
-  fetchTarball =
-    { url, sha256 }:
-      if builtins.lessThan builtins.nixVersion "1.12" then
-        builtins.fetchTarball { inherit url; }
-      else
-        builtins.fetchTarball { inherit url sha256; };
   mapAttrs = builtins.mapAttrs or
     (f: set: with builtins;
       listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
-};
 
+  getFetcher = spec:
+    let fetcherName =
+      if builtins.hasAttr "type" spec
+      then builtins.getAttr "type" spec
+      else "tarball";
+    in builtins.getAttr fetcherName {
+      "tarball" = pkgs.fetchzip;
+      "file" = pkgs.fetchurl;
+    };
+};
 # NOTE: spec must _not_ have an "outPath" attribute
 mapAttrs (_: spec:
   if builtins.hasAttr "outPath" spec
@@ -24,6 +62,6 @@ mapAttrs (_: spec:
     if builtins.hasAttr "url" spec && builtins.hasAttr "sha256" spec
     then
       spec //
-    { outPath = fetchTarball { inherit (spec) url sha256; } ; }
+      { outPath = getFetcher spec { inherit (spec) url sha256; } ; }
     else spec
   ) sources

package.yaml

@@ -11,6 +11,7 @@ executable:
     dependencies:
         - base
         - hashable
+        - file-embed
         - process
         - text
         - bytestring
@@ -24,3 +25,5 @@ executable:
         - optparse-applicative
         - unliftio
         - unordered-containers
+    data-files:
+        - nix/sources.nix