From 199e888785bd23073e44e56f6c74b95dc7c10ffa Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Tue, 8 Oct 2019 23:12:31 -0400
Subject: [PATCH] Handle empty sandbox_shell

Previously, SANDBOX_SHELL was set to empty when unavailable. This
caused issues when actually generating the sandbox. Instead, just set
SANDBOX_SHELL when --with-sandbox-shell= is non-empty. Alternative
implementation to https://github.com/NixOS/nix/pull/3038.
---
 src/libstore/local.mk | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libstore/local.mk b/src/libstore/local.mk
index 89fc918c3..d690fea28 100644
--- a/src/libstore/local.mk
+++ b/src/libstore/local.mk
@@ -39,9 +39,12 @@ libstore_CXXFLAGS = \
  -DNIX_LIBEXEC_DIR=\"$(libexecdir)\" \
  -DNIX_BIN_DIR=\"$(bindir)\" \
  -DNIX_MAN_DIR=\"$(mandir)\" \
- -DSANDBOX_SHELL="\"$(sandbox_shell)\"" \
  -DLSOF=\"$(lsof)\"
 
+ifneq ($(sandbox_shell),)
+libstore_CXXFLAGS += -DSANDBOX_SHELL="\"$(sandbox_shell)\""
+endif
+
 $(d)/local-store.cc: $(d)/schema.sql.gen.hh
 
 $(d)/build.cc: