Fix getenv segfault

src/libstore-tests/derivation-parser-bench.cc

@@ -2,7 +2,7 @@
 #include "nix/store/derivations.hh"
 #include "nix/store/store-api.hh"
 #include "nix/util/experimental-features.hh"
-#include "nix/util/environment-variables.hh"
+#include "nix/util/tests/test-data.hh"
 #include "nix/store/store-open.hh"
 #include <fstream>
 #include <sstream>
@@ -50,11 +50,7 @@ static void BM_UnparseRealDerivationFile(benchmark::State & state, const std::st
 }
 
 // Register benchmarks for actual test derivation files if they exist
-BENCHMARK_CAPTURE(
-    BM_ParseRealDerivationFile, hello, getEnvNonEmpty("_NIX_TEST_UNIT_DATA").value() + "/derivation/hello.drv");
-BENCHMARK_CAPTURE(
-    BM_ParseRealDerivationFile, firefox, getEnvNonEmpty("_NIX_TEST_UNIT_DATA").value() + "/derivation/firefox.drv");
-BENCHMARK_CAPTURE(
-    BM_UnparseRealDerivationFile, hello, getEnvNonEmpty("_NIX_TEST_UNIT_DATA").value() + "/derivation/hello.drv");
-BENCHMARK_CAPTURE(
-    BM_UnparseRealDerivationFile, firefox, getEnvNonEmpty("_NIX_TEST_UNIT_DATA").value() + "/derivation/firefox.drv");
+BENCHMARK_CAPTURE(BM_ParseRealDerivationFile, hello, (getUnitTestData() / "derivation/hello.drv").string());
+BENCHMARK_CAPTURE(BM_ParseRealDerivationFile, firefox, (getUnitTestData() / "derivation/firefox.drv").string());
+BENCHMARK_CAPTURE(BM_UnparseRealDerivationFile, hello, (getUnitTestData() / "derivation/hello.drv").string());
+BENCHMARK_CAPTURE(BM_UnparseRealDerivationFile, firefox, (getUnitTestData() / "derivation/firefox.drv").string());

src/libstore-tests/nix_api_store.cc

@@ -8,6 +8,7 @@
 #include "nix/store/tests/nix_api_store.hh"
 #include "nix/store/globals.hh"
 #include "nix/util/tests/string_callback.hh"
+#include "nix/util/tests/test-data.hh"
 #include "nix/util/url.hh"
 
 #include "store-tests-config.hh"
@@ -302,7 +303,7 @@ class NixApiStoreTestWithRealisedPath : public nix_api_store_test_base
 
         store = open_local_store();
 
-        std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+        std::filesystem::path unitTestData = nix::getUnitTestData();
         std::ifstream t{unitTestData / "derivation/ca/self-contained.json"};
         std::stringstream buffer;
         buffer << t.rdbuf();
@@ -357,7 +358,7 @@ TEST_F(nix_api_store_test_base, build_from_json)
 
     auto * store = open_local_store();
 
-    std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+    std::filesystem::path unitTestData = nix::getUnitTestData();
 
     std::ifstream t{unitTestData / "derivation/ca/self-contained.json"};
     std::stringstream buffer;
@@ -404,7 +405,7 @@ TEST_F(nix_api_store_test_base, nix_store_realise_invalid_system)
 
     auto * store = open_local_store();
 
-    std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+    std::filesystem::path unitTestData = nix::getUnitTestData();
     std::ifstream t{unitTestData / "derivation/ca/self-contained.json"};
     std::stringstream buffer;
     buffer << t.rdbuf();
@@ -449,7 +450,7 @@ TEST_F(nix_api_store_test_base, nix_store_realise_builder_fails)
 
     auto * store = open_local_store();
 
-    std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+    std::filesystem::path unitTestData = nix::getUnitTestData();
     std::ifstream t{unitTestData / "derivation/ca/self-contained.json"};
     std::stringstream buffer;
     buffer << t.rdbuf();
@@ -494,7 +495,7 @@ TEST_F(nix_api_store_test_base, nix_store_realise_builder_no_output)
 
     auto * store = open_local_store();
 
-    std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+    std::filesystem::path unitTestData = nix::getUnitTestData();
     std::ifstream t{unitTestData / "derivation/ca/self-contained.json"};
     std::stringstream buffer;
     buffer << t.rdbuf();
@@ -870,7 +871,7 @@ TEST_F(NixApiStoreTestWithRealisedPath, nix_store_get_fs_closure_error_propagati
  */
 static std::string load_json_from_test_data(const char * filename)
 {
-    std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+    std::filesystem::path unitTestData = nix::getUnitTestData();
     std::ifstream t{unitTestData / filename};
     std::stringstream buffer;
     buffer << t.rdbuf();

src/libutil-test-support/include/nix/util/tests/characterization.hh

@@ -4,20 +4,11 @@
 #include <gtest/gtest.h>
 
 #include "nix/util/types.hh"
-#include "nix/util/environment-variables.hh"
 #include "nix/util/file-system.hh"
+#include "nix/util/tests/test-data.hh"
 
 namespace nix {
 
-/**
- * The path to the unit test data directory. See the contributing guide
- * in the manual for further details.
- */
-static inline std::filesystem::path getUnitTestData()
-{
-    return getEnv("_NIX_TEST_UNIT_DATA").value();
-}
-
 /**
  * Whether we should update "golden masters" instead of running tests
  * against them. See the contributing guide in the manual for further

src/libutil-test-support/include/nix/util/tests/meson.build

@@ -10,4 +10,5 @@ headers = files(
   'json-characterization.hh',
   'nix_api_util.hh',
   'string_callback.hh',
+  'test-data.hh',
 )

src/libutil-test-support/include/nix/util/tests/test-data.hh

@@ -0,0 +1,24 @@
+#pragma once
+///@file
+
+#include <filesystem>
+#include "nix/util/environment-variables.hh"
+#include "nix/util/error.hh"
+
+namespace nix {
+
+/**
+ * The path to the unit test data directory. See the contributing guide
+ * in the manual for further details.
+ */
+static inline std::filesystem::path getUnitTestData()
+{
+    auto data = getEnv("_NIX_TEST_UNIT_DATA");
+    if (!data)
+        throw Error(
+            "_NIX_TEST_UNIT_DATA environment variable is not set. "
+            "Recommendation: use meson, example: 'meson test -C build --gdb'");
+    return std::filesystem::path(*data);
+}
+
+} // namespace nix

src/nix/nix-build/nix-build.cc

@@ -613,6 +613,8 @@ static void main_nix_build(int argc, char ** argv)
            environment variables and shell functions.  Also don't
            lose the current $PATH directories. */
         auto rcfile = (tmpDir.path() / "rc").string();
+        auto tz = getEnv("TZ");
+        auto tzExport = tz ? "export TZ=" + escapeShellArgAlways(*tz) + "; " : "";
         std::string rc = fmt(
                 (R"(_nix_shell_clean_tmpdir() { command rm -rf %1%; };)"s
                   "trap _nix_shell_clean_tmpdir EXIT; "
@@ -646,7 +648,7 @@ static void main_nix_build(int argc, char ** argv)
                 (pure ? "" : "PATH=$PATH:$p; unset p; "),
                 escapeShellArgAlways(dirOf(*shell)),
                 escapeShellArgAlways(*shell),
-                (getenv("TZ") ? (std::string("export TZ=") + escapeShellArgAlways(getenv("TZ")) + "; ") : ""),
+                tzExport,
                 envCommand);
         vomit("Sourcing nix-shell with file %s and contents:\n%s", rcfile, rc);
         writeFile(rcfile, rc);