From 25ce61d6f2196d33170f96bf7d3e54e31ce0337b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Forsman?= <bjorn.forsman@gmail.com>
Date: Mon, 29 Apr 2024 20:58:09 +0200
Subject: [PATCH] quartus-prime-lite: implement the SOURCE_DATE_EPOCH
 specification

For reproducible builds: https://reproducible-builds.org/specs/source-date-epoch

Some programs break with fixed/static clock (or just by the fact that
$LD_PRELOAD is set), so

* make this feature opt-in; activate by setting
  NIXPKGS_QUARTUS_REPRODUCIBLE_BUILD=1
* add a blocklist of programs that are known to misbehave, and
  completely exclude them from the SOURCE_DATE_EPOCH handling

In the future NIXPKGS_QUARTUS_REPRODUCIBLE_BUILD=1 might be the default,
but let's start gently, in case the blocklist is incomplete.
---
 .../editors/quartus-prime/default.nix         | 26 ++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/pkgs/applications/editors/quartus-prime/default.nix b/pkgs/applications/editors/quartus-prime/default.nix
index b50d505e2dbb..8358bb7f160c 100644
--- a/pkgs/applications/editors/quartus-prime/default.nix
+++ b/pkgs/applications/editors/quartus-prime/default.nix
@@ -1,5 +1,5 @@
 { lib, buildFHSEnv, callPackage, makeDesktopItem, runtimeShell
-, runCommand, unstick, quartus-prime-lite
+, runCommand, unstick, quartus-prime-lite, libfaketime, pkgsi686Linux
 , withQuesta ? true
 , supportedDevices ? [ "Arria II" "Cyclone V" "Cyclone IV" "Cyclone 10 LP" "MAX II/V" "MAX 10 FPGA" ]
 , unwrapped ? callPackage ./quartus.nix { inherit unstick supportedDevices withQuesta; }
@@ -85,15 +85,28 @@ in buildFHSEnv rec {
     progs_wrapped=()
     for prog in ''${progs_to_wrap[@]}; do
         relname="''${prog#"${unwrapped}/"}"
+        bname="$(basename "$relname")"
         wrapped="$out/$relname"
         progs_wrapped+=("$wrapped")
         mkdir -p "$(dirname "$wrapped")"
         echo "#!${runtimeShell}" >> "$wrapped"
+        NIXPKGS_QUARTUS_THIS_PROG_SUPPORTS_FIXED_CLOCK=1
         case "$relname" in
             questa_fse/*)
                 echo "export NIXPKGS_IS_QUESTA_WRAPPER=1" >> "$wrapped"
+                # Any use of LD_PRELOAD breaks Questa, so disable the
+                # SOURCE_DATE_EPOCH code path.
+                NIXPKGS_QUARTUS_THIS_PROG_SUPPORTS_FIXED_CLOCK=0
                 ;;
         esac
+        # SOURCE_DATE_EPOCH blocklist for programs that are known to hang/break
+        # with fixed/static clock.
+        case "$bname" in
+            jtagd|quartus_pgm|quartus)
+                NIXPKGS_QUARTUS_THIS_PROG_SUPPORTS_FIXED_CLOCK=0
+                ;;
+        esac
+        echo "export NIXPKGS_QUARTUS_THIS_PROG_SUPPORTS_FIXED_CLOCK=$NIXPKGS_QUARTUS_THIS_PROG_SUPPORTS_FIXED_CLOCK" >> "$wrapped"
         echo "exec $wrapper $prog \"\$@\"" >> "$wrapped"
     done
 
@@ -116,6 +129,17 @@ in buildFHSEnv rec {
     if [ "$NIXPKGS_IS_QUESTA_WRAPPER" != 1 ]; then
         export LD_PRELOAD=''${LD_PRELOAD:+$LD_PRELOAD:}/usr/lib/libudev.so.0
     fi
+
+    # Implement the SOURCE_DATE_EPOCH specification for reproducible builds
+    # (https://reproducible-builds.org/specs/source-date-epoch).
+    # Require opt-in with NIXPKGS_QUARTUS_REPRODUCIBLE_BUILD=1 for now, in case
+    # the blocklist is incomplete.
+    if [ -n "$SOURCE_DATE_EPOCH" ] && [ "$NIXPKGS_QUARTUS_REPRODUCIBLE_BUILD" = 1 ] && [ "$NIXPKGS_QUARTUS_THIS_PROG_SUPPORTS_FIXED_CLOCK" = 1 ]; then
+        export LD_LIBRARY_PATH="${lib.makeLibraryPath [ libfaketime pkgsi686Linux.libfaketime ]}''${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
+        export LD_PRELOAD=libfaketime.so.1''${LD_PRELOAD:+:$LD_PRELOAD}
+        export FAKETIME_FMT="%s"
+        export FAKETIME="$SOURCE_DATE_EPOCH"
+    fi
   '' + extraProfile;
 
   # Run the wrappers directly, instead of going via bash.