From cdc84e9a8169c7049c59e3754667adcf3edeed80 Mon Sep 17 00:00:00 2001
From: Stevan Andjelkovic <stevan.andjelkovic@symbiont.io>
Date: Fri, 9 Apr 2021 14:03:16 +0200
Subject: [PATCH] nix(ldfi2, checker, scheduler): move stamping version out of
 buildPhase

---
 default.nix               | 21 +++++++++++++++++++--
 src/checker/default.nix   |  4 +++-
 src/ldfi2/default.nix     |  4 +++-
 src/scheduler/default.nix |  4 +++-
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/default.nix b/default.nix
index 78eced92..8b567f96 100644
--- a/default.nix
+++ b/default.nix
@@ -39,9 +39,9 @@ stdenv.mkDerivation {
         then []
         else [ ./bazel-bin/src ./bazel-out/k8-fastbuild-ST-578d10beb4b5/bin ];
 
-  phases = [ "installPhase" "installCheckPhase" ];
+  phases = [ "installPhase" "installCheckPhase" "postInstall" ];
 
-  nativeBuildInputs = if stdenv.isLinux then [ patchelf ] else [];
+  nativeBuildInputs = (if stdenv.isLinux then [ patchelf ] else []) ++ [ hexdump xxd ];
 
   propagatedBuildInputs = [ z3 ]
                           ++ lib.optional (nix-build-all || nix-build-checker)   [ checker ]
@@ -131,4 +131,21 @@ stdenv.mkDerivation {
     #   echo "version mismatch"
     #fi
   '';
+
+  # Patch the binaries replacing dummy git commits with the real current git
+  # commit hash.
+  postInstall = ''
+    export DUMMY_VERSION="$(echo -n 0000000000000000000000000000000000000000-nix \
+                                 | hexdump -ve '1/1 "%.2X"')"
+    export REAL_VERSION="$(echo -n ${pkgs.lib.commitIdFromGitRepo ./.git + "-nix"} \
+                                | hexdump -ve '1/1 "%.2X"')"
+    for component in ldfi checker scheduler; do
+        # TODO(stevan): only do the next steps if --version returns the dummy version?
+        hexdump -ve '1/1 "%.2X"' $out/bin/detsys-$component \
+                | sed "s/$DUMMY_VERSION/$REAL_VERSION/" \
+                | xxd -r -p > $out/bin/detsys-$component-patched
+        mv $out/bin/detsys-$component-patched $out/bin/detsys-$component
+        chmod 755 $out/bin/detsys-$component
+    done
+  '';
 }
diff --git a/src/checker/default.nix b/src/checker/default.nix
index 6fa5b04b..8e41ce49 100644
--- a/src/checker/default.nix
+++ b/src/checker/default.nix
@@ -18,7 +18,9 @@ in stdenv.mkDerivation rec {
                 ++ lib.optional stdenv.isLinux [ freetype.dev ];
 
   buildPhase = ''
-    export DETSYS_CHECKER_VERSION="${lib.commitIdFromGitRepo ./../../.git}-nix"
+    # This is a dummy git hash to avoid breaking the nix cache, it will be
+    # patched in the `postInstall` phase of the top-level `default.nix`.
+    export DETSYS_CHECKER_VERSION="0000000000000000000000000000000000000000-nix"
     export CLASSPATH=$(find ${mavenRepository} -name "*.jar" -printf ':%h/%f')
     export builddir=$TMP/classes
     mkdir -p $builddir
diff --git a/src/ldfi2/default.nix b/src/ldfi2/default.nix
index 3d22fba9..b079f1f2 100644
--- a/src/ldfi2/default.nix
+++ b/src/ldfi2/default.nix
@@ -32,7 +32,9 @@ pkg.overrideAttrs (attrs: {
   pname = "detsys-ldfi2";
   src = gitignoreSource ./.;
   configureFlags =
-    [ "--ghc-option=-D__GIT_HASH__=\"${nixpkgs.lib.commitIdFromGitRepo ./../../.git}-nix\"" ];
+    # This is a dummy git hash to avoid breaking the nix cache, it will be
+    # patched in the `postInstall` phase of the top-level `default.nix`.
+    [ "--ghc-option=-D__GIT_HASH__=\"0000000000000000000000000000000000000000-nix\"" ];
   # this should probably check that attrs.checkInputs doesn't exist
   checkInputs = [ nixpkgs.pkgs.haskell.packages.${compiler}.tasty-discover ];
 })
diff --git a/src/scheduler/default.nix b/src/scheduler/default.nix
index 78c968a4..c0041bc7 100644
--- a/src/scheduler/default.nix
+++ b/src/scheduler/default.nix
@@ -17,7 +17,9 @@ in stdenv.mkDerivation rec {
   buildInputs = [ clojure jdk11_headless graalvm11-ce ];
 
   buildPhase = ''
-    export DETSYS_SCHEDULER_VERSION="${lib.commitIdFromGitRepo ./../../.git}-nix"
+    # This is a dummy git hash to avoid breaking the nix cache, it will be
+    # patched in the `postInstall` phase of the top-level `default.nix`.
+    export DETSYS_SCHEDULER_VERSION="0000000000000000000000000000000000000000-nix"
     export CLASSPATH=$(find ${mavenRepository} -name "*.jar" -printf ':%h/%f')
     export builddir=$TMP/classes
     mkdir -p $builddir