Use DistroFileChange instead of going through wsl.localhost (#41810)

test/windows/Common.cpp

@@ -1464,22 +1464,6 @@ std::wstring LxssWriteWslConfig(const std::wstring& Content)
     return previousContent;
 }
 
-// writes distro specific settings /etc/wsl.conf
-std::string LxssWriteWslDistroConfig(const std::string& Content, LPCWSTR DistributionName)
-{
-    std::string path = std::format("\\\\wsl.localhost\\{}\\etc\\wsl.conf", DistributionName);
-
-    std::ifstream distroConfigRead(path);
-    auto previousContent = std::string{std::istreambuf_iterator<char>(distroConfigRead), {}};
-    distroConfigRead.close();
-
-    std::ofstream distroConfig(path, std::ios_base::binary);
-    VERIFY_IS_TRUE(distroConfig.good());
-    distroConfig.write(Content.c_str(), Content.size());
-
-    return previousContent;
-}
-
 // generates a sample global WSL config for the tests
 std::wstring LxssGenerateTestConfig(TestConfigDefaults Default)
 {
@@ -2702,11 +2686,12 @@ UniqueWebServer::~UniqueWebServer()
     }
 }
 
-DistroFileChange::DistroFileChange(LPCWSTR Path, bool exists) : m_path(Path)
+DistroFileChange::DistroFileChange(LPCWSTR Path, bool exists, LPCWSTR DistributionName) :
+    m_path(Path), m_distributionName(DistributionName)
 {
     if (exists)
     {
-        m_originalContent = LxsstuLaunchWslAndCaptureOutput(std::format(L"cat '{}'", m_path)).first;
+        m_originalContent = LxsstuLaunchWslAndCaptureOutput(std::format(L"-d {} -u root cat '{}'", m_distributionName, m_path)).first;
     }
 }
 
@@ -2724,7 +2709,7 @@ DistroFileChange::~DistroFileChange()
 
 void DistroFileChange::SetContent(LPCWSTR Content)
 {
-    const auto cmd = LxssGenerateWslCommandLine(std::format(L" -u root cat > '{}'", m_path).c_str());
+    const auto cmd = LxssGenerateWslCommandLine(std::format(L"-d {} -u root cat > '{}'", m_distributionName, m_path).c_str());
     wsl::windows::common::SubProcess process(nullptr, cmd.c_str());
 
     auto [read, write] = CreateSubprocessPipe(true, false);
@@ -2751,7 +2736,7 @@ void DistroFileChange::SetContent(LPCWSTR Content)
 
 void DistroFileChange::Delete()
 {
-    VERIFY_ARE_EQUAL(LxsstuLaunchWsl(std::format(L"-u root rm -f '{}'", m_path).c_str()), 0L);
+    VERIFY_ARE_EQUAL(LxsstuLaunchWsl(std::format(L"-d {} -u root rm -f '{}'", m_distributionName, m_path)), 0L);
 }
 
 std::string ReadToString(SOCKET Handle)

test/windows/Common.h

@@ -36,7 +36,6 @@ using namespace std::chrono_literals;
 #define LXSS_DISTRO_NAME_TEST "test_distro"
 #define LXSS_DISTRO_NAME_TEST_L WIDEN(LXSS_DISTRO_NAME_TEST)
 
-#define LXSST_REMOVE_DISTRO_CONF_COMMAND_LINE L"-u root -e rm /etc/wsl.conf"
 #define LXSST_TESTS_INSTALL_COMMAND_LINE L"/bin/bash -c 'cd /data/test; ./build_tests.sh'"
 
 //
@@ -374,7 +373,7 @@ private:
 class DistroFileChange
 {
 public:
-    DistroFileChange(LPCWSTR Path, bool exists = true);
+    DistroFileChange(LPCWSTR Path, bool exists = true, LPCWSTR DistributionName = LXSS_DISTRO_NAME_TEST_L);
     ~DistroFileChange();
     DistroFileChange(const DistroFileChange&) = delete;
     DistroFileChange(DistroFileChange&&) = delete;
@@ -387,6 +386,7 @@ public:
 private:
     std::optional<std::wstring> m_originalContent;
     LPCWSTR m_path{};
+    std::wstring m_distributionName;
 };
 
 class PartialHandleRead
@@ -540,8 +540,6 @@ wil::unique_handle GetNonElevatedToken(TOKEN_TYPE Type = TokenPrimary);
 
 std::wstring LxssWriteWslConfig(const std::wstring& Content);
 
-std::string LxssWriteWslDistroConfig(const std::string& Content, LPCWSTR DistributionName = LXSS_DISTRO_NAME_TEST_L);
-
 enum class DrvFsMode
 {
     WSL1,
@@ -624,14 +622,13 @@ void Trim(std::wstring& string);
 
 inline auto EnableSystemd(const std::string& extraConfig = "", LPCWSTR distroName = LXSS_DISTRO_NAME_TEST_L)
 {
-    // enable systemd on the test distro by editing /etc/wsl.conf
-    LxssWriteWslDistroConfig("[boot]\nsystemd=true\n" + extraConfig, distroName);
+    auto config = std::make_unique<DistroFileChange>(L"/etc/wsl.conf", false, distroName);
+    config->SetContent(wsl::shared::string::MultiByteToWide("[boot]\nsystemd=true\n" + extraConfig).c_str());
     TerminateDistribution(distroName);
 
-    return wil::scope_exit([distroName] {
-        // clean up wsl.conf file
-        LxsstuLaunchWsl(std::format(L"-d {} " LXSST_REMOVE_DISTRO_CONF_COMMAND_LINE, distroName));
-        TerminateDistribution(distroName);
+    return wil::scope_exit([config = std::move(config), distroName = std::wstring(distroName)]() mutable {
+        config.reset();
+        TerminateDistribution(distroName.c_str());
     });
 }
 

test/windows/Plan9Tests.cpp

@@ -377,11 +377,11 @@ class Plan9Tests
 
     static auto EnablePlan9Logging()
     {
-        LxssWriteWslDistroConfig("[fileServer]\nlogFile=/plan9-logs.txt\nlogTruncate=false\nlogLevel=5");
+        auto config = std::make_unique<DistroFileChange>(L"/etc/wsl.conf", false);
+        config->SetContent(L"[fileServer]\nlogFile=/plan9-logs.txt\nlogTruncate=false\nlogLevel=5");
 
-        return wil::scope_exit_log(WI_DIAGNOSTICS_INFO, [] {
-            // clean up wsl.conf file
-            LxsstuLaunchWsl(L"rm /etc/wsl.conf");
+        return wil::scope_exit_log(WI_DIAGNOSTICS_INFO, [config = std::move(config)]() mutable {
+            config.reset();
             TerminateDistribution();
         });
     }
@@ -453,12 +453,13 @@ class Plan9Tests
             0u);
 
         auto cleanup = wil::scope_exit_log(WI_DIAGNOSTICS_INFO, [&]() {
-            LxsstuLaunchWsl(L"-u root rm -rf /etc/wsl.conf /tmp/plan9-group-test");
+            LxsstuLaunchWsl(L"-u root rm -rf /tmp/plan9-group-test");
             TerminateDistribution();
         });
 
         // Make plan9testuser the default
-        LxssWriteWslDistroConfig("[user]\ndefault=plan9testuser\n");
+        DistroFileChange config(L"/etc/wsl.conf", false);
+        config.SetContent(L"[user]\ndefault=plan9testuser\n");
         TerminateDistribution();
 
         // Validate that folder isn't accessible

test/windows/UnitTests.cpp

@@ -205,13 +205,6 @@ class UnitTests
 
     WSL2_TEST_METHOD(SystemdSystem)
     {
-        auto cleanup = wil::scope_exit([] {
-            // clean up wsl.conf file
-            const std::wstring disableSystemdCmd(LXSST_REMOVE_DISTRO_CONF_COMMAND_LINE);
-            LxsstuLaunchWsl(disableSystemdCmd);
-            TerminateDistribution();
-        });
-
         auto revert = EnableSystemd();
         VERIFY_IS_TRUE(IsSystemdRunning(L"--system"));
 
@@ -594,13 +587,7 @@ class UnitTests
         auto cleanupPeer =
             wil::scope_exit_log(WI_DIAGNOSTICS_INFO, [&]() { LxsstuLaunchWsl(std::format(L"--unregister {}", peerDistroName)); });
 
-        // Enable systemd in the peer distro (no helper exists for non-test distros).
-        VERIFY_ARE_EQUAL(
-            LxsstuLaunchWsl(std::format(L"-d {} -- sh -c \"mkdir -p /etc && printf '[boot]\\nsystemd=true\\n' > /etc/wsl.conf\"", peerDistroName)),
-            0L);
-
-        // Terminate so the config takes effect on next start.
-        TerminateDistribution(peerDistroName);
+        auto cleanupPeerSystemd = EnableSystemd("", peerDistroName);
 
         // Verify interop works in both distros (this also starts the peer with systemd).
         {
@@ -2207,14 +2194,11 @@ Usage:
 
     TEST_METHOD(Hostname)
     {
-        auto cleanup = wil::scope_exit([] {
-            LxsstuLaunchWsl(LXSST_REMOVE_DISTRO_CONF_COMMAND_LINE);
+        auto cleanup = wil::scope_exit([] { TerminateDistribution(); });
+        DistroFileChange config(L"/etc/wsl.conf", false);
 
-            TerminateDistribution();
-        });
-
-        auto validate = [](const std::string& input, const std::wstring& expectedOutput) {
-            LxssWriteWslDistroConfig("[network]\nhostname=" + input);
+        auto validate = [&config](const std::string& input, const std::wstring& expectedOutput) {
+            config.SetContent(wsl::shared::string::MultiByteToWide("[network]\nhostname=" + input).c_str());
             TerminateDistribution();
 
             auto [output, _] = LxsstuLaunchWslAndCaptureOutput(L"hostname");
@@ -8412,6 +8396,7 @@ Distribution successfully installed. It can be launched via 'wsl.exe -d ubuntu-d
         std::optional<decltype(EnableSystemd())> systemdCleanup;
         std::optional<decltype(EnableSystemd())> systemdCleanup2;
         std::optional<DistroFileChange> cgroupConfig;
+        std::optional<DistroFileChange> cgroupConfig2;
         if (systemd)
         {
             systemdCleanup.emplace(EnableSystemd());
@@ -8422,7 +8407,8 @@ Distribution successfully installed. It can be launched via 'wsl.exe -d ubuntu-d
         {
             cgroupConfig.emplace(L"/etc/wsl.conf", false);
             cgroupConfig->SetContent(L"[automount]\ncgroups=v1\n");
-            LxssWriteWslDistroConfig("[automount]\ncgroups=v1\n", secondDistroName);
+            cgroupConfig2.emplace(L"/etc/wsl.conf", false, secondDistroName);
+            cgroupConfig2->SetContent(L"[automount]\ncgroups=v1\n");
             TerminateDistribution();
             TerminateDistribution(secondDistroName);