From 85a24530524e5a7410fd00714a4a8f4633b4f758 Mon Sep 17 00:00:00 2001
From: cidkidnix <cidkidnix@protonmail.com>
Date: Wed, 17 May 2023 13:48:59 -0500
Subject: [PATCH] Add tests for read-only local store

Make sure we don't go down the path of making temproots when doing
operations on a read-only store
---
 src/libstore/gc.cc       |  4 ++++
 tests/local.mk           |  3 ++-
 tests/read-only-store.sh | 29 +++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 tests/read-only-store.sh

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 0038ec802..09f6ddb9e 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -110,6 +110,10 @@ void LocalStore::createTempRootsFile()
 
 void LocalStore::addTempRoot(const StorePath & path)
 {
+    if (readOnly) {
+      debug("Read-only store doesn't support creating lock files for temp roots, but nothing can be deleted anyways.");
+      return;
+    }
     createTempRootsFile();
 
     /* Open/create the global GC lock file. */
diff --git a/tests/local.mk b/tests/local.mk
index 9e340e2e2..576529567 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -134,7 +134,8 @@ nix_tests = \
   flakes/show.sh \
   impure-derivations.sh \
   path-from-hash-part.sh \
-  toString-path.sh
+  toString-path.sh \
+  read-only-store.sh
 
 ifeq ($(HAVE_LIBCPUID), 1)
 	nix_tests += compute-levels.sh
diff --git a/tests/read-only-store.sh b/tests/read-only-store.sh
new file mode 100644
index 000000000..20ded9634
--- /dev/null
+++ b/tests/read-only-store.sh
@@ -0,0 +1,29 @@
+source common.sh
+
+clearStore
+
+## Testing read-only mode without forcing the underlying store to actually be read-only
+
+# Make sure the command fails when the store doesn't already have a database
+expectStderr 1 nix-store --store local?read-only=true --add dummy | grepQuiet "unable to create database while in read-only mode"
+
+# Make sure the store actually has a current-database
+nix-store --add dummy
+
+# Try again and make sure we fail when adding a item not already in the store
+expectStderr 1 nix-store --store local?read-only=true --add eval.nix | grepQuiet "attempt to write a readonly database"
+
+# Make sure we can get an already-present store-path in the database
+nix-store --store local?read-only=true --add dummy
+
+## Ensure store is actually read-only
+chmod -R -w $TEST_ROOT/store
+chmod -R -w $TEST_ROOT/var
+
+# Make sure we fail on add operations on the read-only store
+# This is only for adding files that are not *already* in the store
+expectStderr 1 nix-store --add eval.nix | grepQuiet "error: opening lock file '$(readlink -e $TEST_ROOT)/var/nix/db/big-lock'"
+expectStderr 1 nix-store --store local?read-only=true --add eval.nix | grepQuiet "Permission denied"
+
+# Should succeed
+nix-store --store local?read-only=true --add dummy