Make the post import distribution checks less strict (#13036)

* Make the post import distribution checks less strict

* Use /etc

* Update comment

* Explicitely create /etc/wsl.conf

Author: OneBlue

src/linux/init/main.cpp

@@ -2618,17 +2618,20 @@ void PostProcessImportedDistribution(wsl::shared::MessageWriter<LX_MINI_INIT_IMP
     THROW_LAST_ERROR_IF(chdir(ExtractedPath) < 0);
     THROW_LAST_ERROR_IF(chroot(".") < 0);
 
+    Message->ValidDistribution = false;
+
     for (auto* path : {"/etc", "/bin/sh"})
     {
-        if (access(path, F_OK) < 0)
+        if (access(path, F_OK) >= 0)
         {
-            LOG_ERROR("Failed to access {} {}", path, errno);
-            Message->ValidDistribution = false;
-            return;
+            Message->ValidDistribution = true;
         }
     }
 
-    Message->ValidDistribution = true;
+    if (!Message->ValidDistribution)
+    {
+        return;
+    }
 
     auto [flavor, version] = UtilReadFlavorAndVersion("/etc/os-release");
 

test/windows/UnitTests.cpp

@@ -5854,6 +5854,19 @@ Error code: Wsl/InstallDistro/WSL_E_INVALID_JSON\r\n",
             // TODO: Uncomment once SetVersionDebug is removed from the tests .wslconfig.
             // VERIFY_ARE_EQUAL(err, L"");
         }
+
+        // Validate that tars containing /etc, but not /bin/sh are accepted.
+        if (LxsstuVmMode())
+        {
+            auto cleanup = wil::scope_exit_log(WI_DIAGNOSTICS_INFO, []() { LxsstuLaunchWsl(L"--unregister empty-distro"); });
+
+            DistroFileChange conf(L"/etc/wsl.conf", false);
+            conf.SetContent(L"");
+
+            auto [out, err] = LxsstuLaunchWslAndCaptureOutput(
+                L"tar cf - /etc/wsl.conf | wsl.exe --install --from-file - --name empty-distro --no-launch "
+                L"--version 2");
+        }
     }
 
     TEST_METHOD(ImportExportStdout)