From bcca922de57099a275284616e63b975fb0e6dce8 Mon Sep 17 00:00:00 2001
From: Martin Weinelt <hexa@darmstadt.ccc.de>
Date: Sun, 18 Sep 2022 19:53:14 +0200
Subject: [PATCH] prusa-slicer: Fix STEP format support
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We move the OCCTWrapper dynamic library /bin to /lib and patch the
loading code to find its location dynamically.

Previously the library load would fail on STEP imports like this:

> /nix/store/4j1rm3sqjvfii68kb51ccvynzvll0jna-prusa-slicer-2.5.0/bin/OCCTWrapper.so: cannot dynamically load executable

because when wrapped it is not a library any more.

> OCCTWrapper.so: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /nix/store/bzd91shky9j9d43girrrj6vmqlw7x9m8-glibc-2.35-163/lib/ld-linux-x86-64.so.2, BuildID\[sha1\]=28396fb28c32d0ec7bb75ea5c550760186b86c20, for GNU/Linux 2.6.32, not stripped

Co-authored-by: André-Patrick Bubel <code@apb.name>
---
 .../applications/misc/prusa-slicer/default.nix | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/pkgs/applications/misc/prusa-slicer/default.nix b/pkgs/applications/misc/prusa-slicer/default.nix
index 286abfb3fdb1..1592ef546155 100644
--- a/pkgs/applications/misc/prusa-slicer/default.nix
+++ b/pkgs/applications/misc/prusa-slicer/default.nix
@@ -130,6 +130,15 @@ stdenv.mkDerivation rec {
     # likely due to commit e682dd84cff5d2420fcc0a40508557477f6cc9d3
     # See issue #185808 for details.
     sed -i 's|test_voronoi.cpp||g' tests/libslic3r/CMakeLists.txt
+
+    # prusa-slicer expects the OCCTWrapper shared library in the same folder as
+    # the executable when loading STEP files. We force the loader to find it in
+    # the usual locations (i.e. LD_LIBRARY_PATH) instead. See the manpage
+    # dlopen(3) for context.
+    if [ -f "src/libslic3r/Format/STEP.cpp" ]; then
+      substituteInPlace src/libslic3r/Format/STEP.cpp \
+        --replace 'libpath /= "OCCTWrapper.so";' 'libpath = "OCCTWrapper.so";'
+    fi
   '';
 
   src = fetchFromGitHub {
@@ -147,11 +156,20 @@ stdenv.mkDerivation rec {
   postInstall = ''
     ln -s "$out/bin/prusa-slicer" "$out/bin/prusa-gcodeviewer"
 
+    mkdir -p "$out/lib"
+    mv -v $out/bin/*.so $out/lib/
+
     mkdir -p "$out/share/pixmaps/"
     ln -s "$out/share/PrusaSlicer/icons/PrusaSlicer.png" "$out/share/pixmaps/PrusaSlicer.png"
     ln -s "$out/share/PrusaSlicer/icons/PrusaSlicer-gcodeviewer_192px.png" "$out/share/pixmaps/PrusaSlicer-gcodeviewer.png"
   '';
 
+  preFixup = ''
+    gappsWrapperArgs+=(
+      --prefix LD_LIBRARY_PATH : "$out/lib"
+    )
+  '';
+
   meta = with lib; {
     description = "G-code generator for 3D printer";
     homepage = "https://github.com/prusa3d/PrusaSlicer";