[buoh] nix: update depenencies

[Jan Tojnar <jtojnar src gnome org>]

commit 9f4d794f0ad4474fb85d2937f81ce74bff97a4da
Author: Jan Tojnar <jtojnar gmail com>
Date:   Fri Oct 1 04:22:19 2021 +0200

    nix: update depenencies
    
    They are now pinned by default even for shell.
    We also started using Niv for easier updating –
    one can just run `nix-shell --run 'niv update'`
    instead of manually replacing the commit id.

 default.nix      |  17 +++---
 nix/sources.json |  26 +++++++++
 nix/sources.nix  | 174 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 shell.nix        |  17 ++----
 4 files changed, 214 insertions(+), 20 deletions(-)
---
diff --git a/default.nix b/default.nix
index 371055d..a6a31af 100644
--- a/default.nix
+++ b/default.nix
@@ -34,11 +34,12 @@ Or to speed up the build by not running the test suite:
 
 */
 
-{ pkgs ?
-    (import (fetchTarball {
-      url = "https://github.com/NixOS/nixpkgs/archive/5658fadedb748cb0bdbcb569a53bd6065a5704a9.tar.gz";;
-      sha256 = "1kpmhd9v5a3fbwq86spd1p5s4npfd1jrjl14kl6h1n1l1qd6cbp6";
-    }) {})
+{ sources ? import ./nix/sources.nix
+, pkgs ?
+    import sources.nixpkgs {
+      overlays = [];
+      config = {};
+    }
 , doCheck ? true
 , shell ? false
   # We do not use lib.inNixShell because that would also apply
@@ -47,7 +48,7 @@ Or to speed up the build by not running the test suite:
 
 let
   inherit (pkgs) lib;
-in pkgs.stdenv.mkDerivation rec {
+in (if shell then pkgs.mkShell else pkgs.stdenv.mkDerivation) rec {
   name = "buoh";
 
   src =
@@ -66,9 +67,11 @@ in pkgs.stdenv.mkDerivation rec {
     pkg-config
     gettext
     python3
-    xvfb_run
+    xvfb-run
     libxslt
     wrapGAppsHook
+  ] ++ lib.optionals shell [
+    niv
   ];
 
   # Dependencies for host platform
diff --git a/nix/sources.json b/nix/sources.json
new file mode 100644
index 0000000..177dcdf
--- /dev/null
+++ b/nix/sources.json
@@ -0,0 +1,26 @@
+{
+    "niv": {
+        "branch": "master",
+        "description": "Easy dependency management for Nix projects",
+        "homepage": "https://github.com/nmattia/niv";,
+        "owner": "nmattia",
+        "repo": "niv",
+        "rev": "65a61b147f307d24bfd0a5cd56ce7d7b7cc61d2e",
+        "sha256": "17mirpsx5wyw262fpsd6n6m47jcgw8k2bwcp1iwdnrlzy4dhcgqh",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/65a61b147f307d24bfd0a5cd56ce7d7b7cc61d2e.tar.gz";,
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "nixos-unstable",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "c21ba4f7bb4a3d621eb1d187e6b5e816bb85380c",
+        "sha256": "1xkycq5sxn9yxiz545lblb2zwk3b3f6adc0bzhgksv74l44i3s1i",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/c21ba4f7bb4a3d621eb1d187e6b5e816bb85380c.tar.gz";,
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}
diff --git a/nix/sources.nix b/nix/sources.nix
new file mode 100644
index 0000000..1938409
--- /dev/null
+++ b/nix/sources.nix
@@ -0,0 +1,174 @@
+# This file has been generated by Niv.
+
+let
+
+  #
+  # The fetchers. fetch_<type> fetches specs of type <type>.
+  #
+
+  fetch_file = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchurl { inherit (spec) url sha256; name = name'; }
+      else
+        pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
+
+  fetch_tarball = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
+      else
+        pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
+
+  fetch_git = name: spec:
+    let
+      ref =
+        if spec ? ref then spec.ref else
+          if spec ? branch then "refs/heads/${spec.branch}" else
+            if spec ? tag then "refs/tags/${spec.tag}" else
+              abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
+    in
+      builtins.fetchGit { url = spec.repo; inherit (spec) rev; inherit ref; };
+
+  fetch_local = spec: spec.path;
+
+  fetch_builtin-tarball = name: throw
+    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=tarball -a builtin=true'';
+
+  fetch_builtin-url = name: throw
+    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=file -a builtin=true'';
+
+  #
+  # Various helpers
+  #
+
+  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
+  sanitizeName = name:
+    (
+      concatMapStrings (s: if builtins.isList s then "-" else s)
+        (
+          builtins.split "[^[:alnum:]+._?=-]+"
+            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
+        )
+    );
+
+  # The set of packages used when specs are fetched using non-builtins.
+  mkPkgs = sources: system:
+    let
+      sourcesNixpkgs =
+        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
+      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
+      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
+    in
+      if builtins.hasAttr "nixpkgs" sources
+      then sourcesNixpkgs
+      else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
+        import <nixpkgs> {}
+      else
+        abort
+          ''
+            Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
+            add a package called "nixpkgs" to your sources.json.
+          '';
+
+  # The actual fetching function.
+  fetch = pkgs: name: spec:
+
+    if ! builtins.hasAttr "type" spec then
+      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
+    else if spec.type == "file" then fetch_file pkgs name spec
+    else if spec.type == "tarball" then fetch_tarball pkgs name spec
+    else if spec.type == "git" then fetch_git name spec
+    else if spec.type == "local" then fetch_local spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
+    else if spec.type == "builtin-url" then fetch_builtin-url name
+    else
+      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
+
+  # If the environment variable NIV_OVERRIDE_${name} is set, then use
+  # the path directly as opposed to the fetched source.
+  replace = name: drv:
+    let
+      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
+      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
+    in
+      if ersatz == "" then drv else
+        # this turns the string into an actual Nix path (for both absolute and
+        # relative paths)
+        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + 
"/${ersatz}";
+
+  # Ports of functions for older nix versions
+
+  # a Nix version of mapAttrs if the built-in doesn't exist
+  mapAttrs = builtins.mapAttrs or (
+    f: set: with builtins;
+    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
+  );
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
+  range = first: last: if first > last then [] else builtins.genList (n: first + n) (last - first + 1);
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
+  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
+  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
+  concatMapStrings = f: list: concatStrings (map f list);
+  concatStrings = builtins.concatStringsSep "";
+
+  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
+  optionalAttrs = cond: as: if cond then as else {};
+
+  # fetchTarball version that is compatible between all the versions of Nix
+  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchTarball;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchTarball ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchTarball attrs;
+
+  # fetchurl version that is compatible between all the versions of Nix
+  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchurl;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchurl ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchurl attrs;
+
+  # Create the final "sources" from the config
+  mkSources = config:
+    mapAttrs (
+      name: spec:
+        if builtins.hasAttr "outPath" spec
+        then abort
+          "The values in sources.json should not have an 'outPath' attribute"
+        else
+          spec // { outPath = replace name (fetch config.pkgs name spec); }
+    ) config.sources;
+
+  # The "config" used by the fetchers
+  mkConfig =
+    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
+    , sources ? if isNull sourcesFile then {} else builtins.fromJSON (builtins.readFile sourcesFile)
+    , system ? builtins.currentSystem
+    , pkgs ? mkPkgs sources system
+    }: rec {
+      # The sources, i.e. the attribute set of spec name to spec
+      inherit sources;
+
+      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
+      inherit pkgs;
+    };
+
+in
+mkSources (mkConfig {}) // { __functor = _: settings: mkSources (mkConfig settings); }
diff --git a/shell.nix b/shell.nix
index ae8057f..c911b84 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,16 +1,7 @@
-/*
-
-Some developers do not want a pinned package set by default.
-If you want to use the pinned nix-shell or a more sophisticated set of arguments:
-
-    $ nix-shell default.nix --arg shell true
-
-*/
-
-{ pkgs ? import <nixpkgs> {}
+{ pkgs ? null
 , doCheck ? true
 }:
-import ./default.nix {
-  inherit pkgs doCheck;
+import ./default.nix ({
+  inherit doCheck;
   shell = true;
-}
+} // (if pkgs != null then { inherit pkgs; } else {}))