X-Git-Url: https://git.immae.eu/?a=blobdiff_plain;f=lib%2Fflake-compat-patched.nix;fp=lib%2Fflake-compat-patched.nix;h=217a99fad89daa712c84c3c9671136ae7f59a18c;hb=ada96f10e64d34f06853d9915a8db580420e69b4;hp=0000000000000000000000000000000000000000;hpb=3d11eafc9c516321901908338befe4c04b58f3aa;p=perso%2FImmae%2FConfig%2FNix.git

diff --git a/lib/flake-compat-patched.nix b/lib/flake-compat-patched.nix
new file mode 100644
index 0000000..217a99f
--- /dev/null
+++ b/lib/flake-compat-patched.nix
@@ -0,0 +1,190 @@
+# Compatibility function to allow flakes to be used by
+# non-flake-enabled Nix versions. Given a source tree containing a
+# 'flake.nix' and 'flake.lock' file, it fetches the flake inputs and
+# calls the flake's 'outputs' function. It then returns an attrset
+# containing 'defaultNix' (to be used in 'default.nix'), 'shellNix'
+# (to be used in 'shell.nix').
+
+{ src, system ? builtins.currentSystem or "unknown-system" }:
+
+let
+
+  lockFilePath = src + "/flake.lock";
+
+  lockFile = builtins.fromJSON (builtins.readFile lockFilePath);
+
+  fetchTree =
+    info:
+    if info.type == "github" then
+      { outPath = fetchTarball "https://api.${info.host or "github.com"}/repos/${info.owner}/${info.repo}/tarball/${info.rev}";
+        rev = info.rev;
+        shortRev = builtins.substring 0 7 info.rev;
+        lastModified = info.lastModified;
+        lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
+        narHash = info.narHash;
+      }
+    else if info.type == "git" then
+      { outPath =
+          builtins.fetchGit
+            ({ url = info.url; }
+             // (if info ? rev then { inherit (info) rev; } else {})
+             // (if info ? ref then { inherit (info) ref; } else {})
+            );
+        lastModified = info.lastModified;
+        lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
+        narHash = info.narHash;
+      } // (if info ? rev then {
+        rev = info.rev;
+        shortRev = builtins.substring 0 7 info.rev;
+      } else {
+      })
+    else if info.type == "path" then
+      { outPath = builtins.path { path =
+          if builtins.substring 0 1 info.path == "."
+          then builtins.toString src + "/" + info.path
+          else info.path;
+        };
+        narHash = info.narHash;
+      }
+    else if info.type == "tarball" then
+      { outPath = fetchTarball info.url;
+        narHash = info.narHash;
+      }
+    else if info.type == "gitlab" then
+      { inherit (info) rev narHash lastModified;
+        outPath = fetchTarball "https://${info.host or "gitlab.com"}/api/v4/projects/${info.owner}%2F${info.repo}/repository/archive.tar.gz?sha=${info.rev}";
+        shortRev = builtins.substring 0 7 info.rev;
+      }
+    else
+      # FIXME: add Mercurial, tarball inputs.
+      throw "flake input has unsupported input type '${info.type}'";
+
+  callFlake4 = flakeSrc: locks:
+    let
+      flake = import (flakeSrc + "/flake.nix");
+
+      inputs = builtins.mapAttrs (n: v:
+        if v.flake or true
+        then callFlake4 (fetchTree (v.locked // v.info)) v.inputs
+        else fetchTree (v.locked // v.info)) locks;
+
+      outputs = flakeSrc // (flake.outputs (inputs // {self = outputs;}));
+    in
+      assert flake.edition == 201909;
+      outputs;
+
+  callLocklessFlake = flakeSrc:
+    let
+      flake = import (flakeSrc + "/flake.nix");
+      outputs = flakeSrc // (flake.outputs ({ self = outputs; }));
+    in outputs;
+
+  rootSrc = let
+    # Try to clean the source tree by using fetchGit, if this source
+    # tree is a valid git repository.
+    tryFetchGit = src:
+      if isGit && !isShallow
+      then
+        let res = builtins.fetchGit src;
+        in if res.rev == "0000000000000000000000000000000000000000" then removeAttrs res ["rev" "shortRev"]  else res
+      else { outPath = src; };
+    # NB git worktrees have a file for .git, so we don't check the type of .git
+    isGit = builtins.pathExists (src + "/.git");
+    isShallow = builtins.pathExists (src + "/.git/shallow");
+
+  in
+    { lastModified = 0; lastModifiedDate = formatSecondsSinceEpoch 0; }
+      // (if src ? outPath then src else tryFetchGit src);
+
+  # Format number of seconds in the Unix epoch as %Y%m%d%H%M%S.
+  formatSecondsSinceEpoch = t:
+    let
+      rem = x: y: x - x / y * y;
+      days = t / 86400;
+      secondsInDay = rem t 86400;
+      hours = secondsInDay / 3600;
+      minutes = (rem secondsInDay 3600) / 60;
+      seconds = rem t 60;
+
+      # Courtesy of https://stackoverflow.com/a/32158604.
+      z = days + 719468;
+      era = (if z >= 0 then z else z - 146096) / 146097;
+      doe = z - era * 146097;
+      yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
+      y = yoe + era * 400;
+      doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
+      mp = (5 * doy + 2) / 153;
+      d = doy - (153 * mp + 2) / 5 + 1;
+      m = mp + (if mp < 10 then 3 else -9);
+      y' = y + (if m <= 2 then 1 else 0);
+
+      pad = s: if builtins.stringLength s < 2 then "0" + s else s;
+    in "${toString y'}${pad (toString m)}${pad (toString d)}${pad (toString hours)}${pad (toString minutes)}${pad (toString seconds)}";
+
+  allNodes =
+    builtins.mapAttrs
+      (key: node:
+        let
+          sourceInfo =
+            if key == lockFile.root
+            then rootSrc
+            else fetchTree (node.info or {} // removeAttrs node.locked ["dir"]);
+
+          subdir = if key == lockFile.root then "" else node.locked.dir or "";
+
+          flake = import (sourceInfo + (if subdir != "" then "/" else "") + subdir + "/flake.nix");
+
+          inputs = builtins.mapAttrs
+            (inputName: inputSpec: allNodes.${resolveInput inputSpec})
+            (node.inputs or {});
+
+          # Resolve a input spec into a node name. An input spec is
+          # either a node name, or a 'follows' path from the root
+          # node.
+          resolveInput = inputSpec:
+              if builtins.isList inputSpec
+              then getInputByPath lockFile.root inputSpec
+              else inputSpec;
+
+          # Follow an input path (e.g. ["dwarffs" "nixpkgs"]) from the
+          # root node, returning the final node.
+          getInputByPath = nodeName: path:
+            if path == []
+            then nodeName
+            else
+              getInputByPath
+                # Since this could be a 'follows' input, call resolveInput.
+                (resolveInput lockFile.nodes.${nodeName}.inputs.${builtins.head path})
+                (builtins.tail path);
+
+          outputs = flake.outputs (inputs // { self = result; });
+
+          result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; };
+        in
+          if node.flake or true then
+            assert builtins.isFunction flake.outputs;
+            result
+          else
+            sourceInfo
+      )
+      lockFile.nodes;
+
+  result =
+    if !(builtins.pathExists lockFilePath)
+    then callLocklessFlake rootSrc
+    else if lockFile.version == 4
+    then callFlake4 rootSrc (lockFile.inputs)
+    else if lockFile.version >= 5 && lockFile.version <= 7
+    then allNodes.${lockFile.root}
+    else throw "lock file '${lockFilePath}' has unsupported version ${toString lockFile.version}";
+
+in
+  rec {
+    defaultNix =
+      result
+      // (if result ? defaultPackage.${system} then { default = result.defaultPackage.${system}; } else {});
+
+    shellNix =
+      defaultNix
+      // (if result ? devShell.${system} then { default = result.devShell.${system}; } else {});
+  }