fix: ensure XDG_DATA_DIRS contains system dirs so Vulkan drivers load

libs/linglong/tests/ll-tests/CMakeLists.txt

@@ -47,6 +47,7 @@ pfl_add_executable(
   src/linglong/package/uab_file_test.cpp
   src/linglong/package/version_test.cpp
   src/linglong/package/versionv2_test.cpp
+  src/linglong/oci_cfg_generators/container_cfg_builder_test.cpp
   src/linglong/repo/client_factory_test.cpp
   src/linglong/repo/config_test.cpp
   src/linglong/repo/ostree_repo_test.cpp

libs/linglong/tests/ll-tests/src/linglong/oci_cfg_generators/container_cfg_builder_test.cpp

@@ -0,0 +1,126 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#include <gtest/gtest.h>
+
+#include "../../common/tempdir.h"
+#include "linglong/common/strings.h"
+#include "linglong/oci-cfg-generators/container_cfg_builder.h"
+
+#include <algorithm>
+#include <filesystem>
+#include <optional>
+#include <string>
+
+using namespace linglong;
+
+namespace {
+
+std::optional<std::string> getEnvValue(const ocppi::runtime::config::types::Config &config,
+                                       const std::string &key)
+{
+    if (!config.process.has_value() || !config.process->env.has_value()) {
+        return std::nullopt;
+    }
+
+    const std::string prefix = key + "=";
+    for (const auto &entry : *config.process->env) {
+        if (entry.size() >= prefix.size() && entry.compare(0, prefix.size(), prefix) == 0) {
+            return entry.substr(prefix.size());
+        }
+    }
+    return std::nullopt;
+}
+
+bool containsPart(std::string_view value, std::string_view part)
+{
+    auto parts = common::strings::split(value, ':', common::strings::splitOption::SkipEmpty);
+    return std::find(parts.begin(), parts.end(), part) != parts.end();
+}
+
+std::ptrdiff_t countPart(std::string_view value, std::string_view part)
+{
+    auto parts = common::strings::split(value, ':', common::strings::splitOption::SkipEmpty);
+    return std::count(parts.begin(), parts.end(), part);
+}
+
+} // namespace
+
+// Regression test for issue #1457: the Vulkan ICD loader discovers driver
+// manifests by scanning each XDG_DATA_DIRS entry for a "vulkan/icd.d"
+// subdirectory. When XDG_DATA_DIRS is not present in the container environment,
+// build() must still expose the conventional system data directories so that
+// system provided drivers (e.g. the Mesa Turnip/freedreno Vulkan driver under
+// /usr/share/vulkan/icd.d) remain discoverable.
+TEST(ContainerCfgBuilderEnvTest, XdgDataDirsUnsetGetsSystemDefaults)
+{
+    TempDir tmp;
+    ASSERT_TRUE(tmp.isValid());
+    std::filesystem::create_directories(tmp.path() / "bundle");
+
+    generator::ContainerCfgBuilder builder;
+    builder.setAppId("org.deepin.base")
+      .setBasePath(tmp.path() / "base")
+      .setBundlePath(tmp.path() / "bundle")
+      .disablePatch();
+
+    auto result = builder.build();
+    ASSERT_TRUE(result.has_value()) << result.error().message();
+
+    auto xdg = getEnvValue(builder.getConfig(), "XDG_DATA_DIRS");
+    ASSERT_TRUE(xdg.has_value());
+    EXPECT_TRUE(containsPart(*xdg, "/usr/share"));
+    EXPECT_TRUE(containsPart(*xdg, "/usr/local/share"));
+}
+
+// Regression test for issue #1457: a host XDG_DATA_DIRS that only points at
+// Linyaps specific paths may be forwarded into the container, overriding the
+// Vulkan loader default search path. The forwarded value must be preserved
+// while the standard system data directories are appended so that the loader
+// still finds /usr/share/vulkan/icd.d.
+TEST(ContainerCfgBuilderEnvTest, XdgDataDirsForwardedHostValueKeepsSystemDefaults)
+{
+    TempDir tmp;
+    ASSERT_TRUE(tmp.isValid());
+    std::filesystem::create_directories(tmp.path() / "bundle");
+
+    generator::ContainerCfgBuilder builder;
+    builder.setAppId("org.deepin.base")
+      .setBasePath(tmp.path() / "base")
+      .setBundlePath(tmp.path() / "bundle")
+      .disablePatch()
+      .appendEnv("XDG_DATA_DIRS", "/var/lib/linglong/entries/share");
+
+    auto result = builder.build();
+    ASSERT_TRUE(result.has_value()) << result.error().message();
+
+    auto xdg = getEnvValue(builder.getConfig(), "XDG_DATA_DIRS");
+    ASSERT_TRUE(xdg.has_value());
+    EXPECT_TRUE(containsPart(*xdg, "/var/lib/linglong/entries/share"));
+    EXPECT_TRUE(containsPart(*xdg, "/usr/share"));
+    EXPECT_TRUE(containsPart(*xdg, "/usr/local/share"));
+}
+
+TEST(ContainerCfgBuilderEnvTest, XdgDataDirsDoesNotDuplicateSystemDefaults)
+{
+    TempDir tmp;
+    ASSERT_TRUE(tmp.isValid());
+    std::filesystem::create_directories(tmp.path() / "bundle");
+
+    generator::ContainerCfgBuilder builder;
+    builder.setAppId("org.deepin.base")
+      .setBasePath(tmp.path() / "base")
+      .setBundlePath(tmp.path() / "bundle")
+      .disablePatch()
+      .appendEnv("XDG_DATA_DIRS", "/usr/share:/usr/local/share");
+
+    auto result = builder.build();
+    ASSERT_TRUE(result.has_value()) << result.error().message();
+
+    auto xdg = getEnvValue(builder.getConfig(), "XDG_DATA_DIRS");
+    ASSERT_TRUE(xdg.has_value());
+    EXPECT_EQ(*xdg, "/usr/share:/usr/local/share");
+    EXPECT_EQ(countPart(*xdg, "/usr/share"), 1);
+    EXPECT_EQ(countPart(*xdg, "/usr/local/share"), 1);
+}

libs/oci-cfg-generators/src/linglong/oci-cfg-generators/container_cfg_builder.cpp

@@ -1513,6 +1513,41 @@ utils::error::Result<void> ContainerCfgBuilder::buildEnv() noexcept
         environment.try_emplace("QT_QPA_PLATFORMTHEME", "xdgdesktopportal");
     }
 
+    // Ensure the conventional system data directories stay reachable through
+    // XDG_DATA_DIRS. The host environment (for example a host XDG_DATA_DIRS that
+    // only points at Linyaps specific paths) may be forwarded into the container,
+    // overriding the default search path relied on by XDG-data consumers. When
+    // that happens the Vulkan ICD loader no longer scans /usr/share/vulkan/icd.d
+    // and fails to discover system provided driver manifests such as the Mesa
+    // Turnip (freedreno) driver, while OpenGL keeps working because Mesa locates
+    // DRI drivers through the compiled-in library path. Always keep the standard
+    // system data directories in XDG_DATA_DIRS so those consumers keep working.
+    {
+        const std::vector<std::string> systemDataDirs{ "/usr/local/share", "/usr/share" };
+        auto xdgIt = environment.find("XDG_DATA_DIRS");
+        std::string currentValue = (xdgIt != environment.end()) ? xdgIt->second : std::string{};
+        auto entries =
+          common::strings::split(currentValue, ':', common::strings::splitOption::SkipEmpty);
+
+        std::vector<std::string> dirs;
+        dirs.reserve(entries.size() + systemDataDirs.size());
+        for (auto entry : entries) {
+            dirs.emplace_back(entry);
+        }
+
+        bool changed = (xdgIt == environment.end());
+        for (const auto &dir : systemDataDirs) {
+            if (std::find(dirs.begin(), dirs.end(), dir) == dirs.end()) {
+                dirs.push_back(dir);
+                changed = true;
+            }
+        }
+
+        if (changed) {
+            environment["XDG_DATA_DIRS"] = common::strings::join(dirs, ':');
+        }
+    }
+
     auto envShFile = bundlePath / "00env.sh";
     std::ofstream ofs(envShFile);
     if (!ofs.is_open()) {