Respect XDG directory settings on macOS

site/en/remote/output-directories.md

@@ -30,13 +30,14 @@ The solution that's currently implemented:
   subdirectory thereof. In other words, Bazel must be invoked from inside a
   [repository](../external/overview#repository). Otherwise, an error is
   reported.
-* The _outputRoot_ directory defaults to `${XDG_CACHE_HOME}/bazel` (or
-  `~/.cache/bazel`, if the `XDG_CACHE_HOME` environment variable is not set) on
-  Linux, `/private/var/tmp` on macOS, and on Windows it defaults to `%HOME%` if
+* The _outputRoot_ directory defaults to `~/.cache/bazel` on Linux,
+  `/private/var/tmp` on macOS, and on Windows it defaults to `%HOME%` if
   set, else `%USERPROFILE%` if set, else the result of calling
   `SHGetKnownFolderPath()` with the `FOLDERID_Profile` flag set. If the
-  environment variable `$TEST_TMPDIR` is set, as in a test of Bazel itself,
-  then that value overrides the default.
+  environment variable `$XDG_CACHE_HOME` is set on either Linux or
+  macOS, the value `${XDG_CACHE_HOME}/bazel` will override the default.
+  If the environment variable `$TEST_TMPDIR` is set, as in a test of Bazel
+  itself, then that value overrides any defaults.
 * The Bazel user's build state is located beneath `outputRoot/_bazel_$USER`.
   This is called the _outputUserRoot_ directory.
 * Beneath the `outputUserRoot` directory there is an `install` directory, and in

src/main/cpp/blaze_util_darwin.cc

@@ -96,7 +96,13 @@ static string DescriptionFromCFError(CFErrorRef cf_err) {
   return UTF8StringFromCFStringRef(cf_err_string);
 }
 
-string GetCacheDir() { return "/var/tmp"; }
+string GetCacheDir() {
+  string xdg_cache_home = GetPathEnv("XDG_CACHE_HOME");
+  if (!xdg_cache_home.empty()) {
+    return blaze_util::JoinPath(xdg_cache_home, "bazel");
+  }
+  return "/var/tmp";
+}
 
 void WarnFilesystemType(const blaze_util::Path &output_base) {
   // Check to see if we are on a non-local drive.

src/test/cpp/bazel_startup_options_test.cc

@@ -187,6 +187,69 @@ TEST_F(BazelStartupOptionsTest, UpdateConfigurationOnDarwin) {
                              "1629dee48cc4e53161f9b2be8614e062"),
             startup_options_->output_base);
 }
+
+TEST_F(BazelStartupOptionsTest, UpdateConfigurationOnDarwinWithTestTmpdir) {
+  SetEnv("USER", "gandalf");
+  SetEnv("HOME", "/nonexistent/home");
+  SetEnv("XDG_CACHE_HOME", "/nonexistent/cache");
+  SetEnv("TEST_TMPDIR", "/nonexistent/tmpdir");
+  ReinitStartupOptions();
+  UpdateConfiguration();
+
+  ASSERT_EQ(blaze_util::Path("/nonexistent/tmpdir/_bazel_gandalf"),
+            startup_options_->output_user_root);
+  ASSERT_EQ(blaze_util::Path("/nonexistent/tmpdir/_bazel_gandalf/install/deadbeef"),
+            startup_options_->install_base);
+  ASSERT_EQ(blaze_util::Path("/nonexistent/tmpdir/_bazel_gandalf/"
+                             "1629dee48cc4e53161f9b2be8614e062"),
+            startup_options_->output_base);
+}
+
+TEST_F(BazelStartupOptionsTest, UpdateConfigurationOnDarwinWithXdgCacheHome) {
+  SetEnv("USER", "gandalf");
+  SetEnv("HOME", "/nonexistent/home");
+  SetEnv("XDG_CACHE_HOME", "/nonexistent/cache");
+  UnsetEnv("TEST_TMPDIR");
+  ReinitStartupOptions();
+  UpdateConfiguration();
+
+  ASSERT_EQ(blaze_util::Path("/nonexistent/cache/bazel/_bazel_gandalf"),
+            startup_options_->output_user_root);
+  ASSERT_EQ(blaze_util::Path("/nonexistent/cache/bazel/_bazel_gandalf/install/deadbeef"),
+            startup_options_->install_base);
+  ASSERT_EQ(blaze_util::Path("/nonexistent/cache/bazel/_bazel_gandalf/"
+                             "1629dee48cc4e53161f9b2be8614e062"),
+            startup_options_->output_base);
+}
+
+TEST_F(BazelStartupOptionsTest, UpdateConfigurationOnDarwinNoShellExpansion) {
+  SetEnv("USER", "gandalf");
+  SetEnv("TEST_TMPDIR", "~/\"$foo/test\"");
+  SetEnv("XDG_CACHE_HOME", "~/cache${bar}");
+  SetEnv("HOME", "~/home$(echo baz)");
+
+  ReinitStartupOptions();
+  UpdateConfiguration();
+
+  ASSERT_EQ(blaze_util::Path(blaze_util::GetCwd() + "/~/\"$foo/test\"" +
+                             "/_bazel_gandalf"),
+            startup_options_->output_user_root);
+
+  UnsetEnv("TEST_TMPDIR");
+  ReinitStartupOptions();
+  UpdateConfiguration();
+
+  ASSERT_EQ(blaze_util::Path(blaze_util::GetCwd() +
+                             "/~/cache${bar}/bazel/_bazel_gandalf"),
+            startup_options_->output_user_root);
+
+  UnsetEnv("XDG_CACHE_HOME");
+  ReinitStartupOptions();
+  UpdateConfiguration();
+
+  ASSERT_EQ(blaze_util::Path("/var/tmp/_bazel_gandalf"),
+            startup_options_->output_user_root);
+}
 #endif  // __APPLE__
 
 #if defined(__WIN32__) || defined(__CYGWIN__)