Make rename retry more frequently for longer, then try making a hardl…

…ink (#1497)

We already had a single retry after a 250ms wait for our `rename` of the installer to make it shell actionable with the correct extension.  This change makes it try every 100ms for 500ms, then use `copy_file` with a hard link option as a fall back.

The hard link is better than a true copy, as it won't take up more space.  But it won't get cleaned up on a successful install either.

Long term we should put in some background cleanup to remove old installers that were abandoned due to failures.

src/AppInstallerCLICore/Workflows/ShellExecuteInstallerHandler.cpp

@@ -181,6 +181,68 @@ namespace AppInstaller::CLI::Workflow
 
             return args;
         }
+
+        // Complicated rename algorithm due to somewhat arbitrary failures.
+        // 1. First, try to rename.
+        // 2. Then, create an empty file for the target, and attempt to rename.
+        // 3. Then, try repeatedly for 500ms in case it is a timing thing.
+        // 4. Attempt to use a hard link if available.
+        // 5. Copy the file if nothing else has worked so far.
+        void RenameFile(const std::filesystem::path& from, const std::filesystem::path& to)
+        {
+            // 1. First, try to rename.
+            try
+            {
+                // std::filesystem::rename() handles motw correctly if applicable.
+                std::filesystem::rename(from, to);
+                return;
+            }
+            CATCH_LOG();
+
+            // 2. Then, create an empty file for the target, and attempt to rename.
+            //    This seems to fix things in certain cases, so we do it.
+            try
+            {
+                {
+                    std::ofstream targetFile{ to };
+                }
+                std::filesystem::rename(from, to);
+                return;
+            }
+            CATCH_LOG();
+
+            // 3. Then, try repeatedly for 500ms in case it is a timing thing.
+            for (int i = 0; i < 5; ++i)
+            {
+                try
+                {
+                    std::this_thread::sleep_for(100ms);
+                    std::filesystem::rename(from, to);
+                    return;
+                }
+                CATCH_LOG();
+            }
+
+            // 4. Attempt to use a hard link if available.
+            if (Runtime::SupportsHardLinks(from))
+            {
+                try
+                {
+                    // Create a hard link to the file; the installer will be left in the temp directory afterward
+                    // but it is better to succeed the operation and leave a file around than to fail.
+                    // First we have to remove the target file as the function will not overwrite.
+                    std::filesystem::remove(to);
+                    std::filesystem::create_hard_link(from, to);
+                    return;
+                }
+                CATCH_LOG();
+            }
+
+            // 5. Copy the file if nothing else has worked so far.
+            // Create a copy of the file; the installer will be left in the temp directory afterward
+            // but it is better to succeed the operation and leave a file around than to fail.
+            std::filesystem::copy_file(from, to, std::filesystem::copy_options::overwrite_existing);
+        }
     }
 
     void ShellExecuteInstallImpl(Execution::Context& context)
@@ -242,23 +304,7 @@ namespace AppInstaller::CLI::Workflow
             break;
         }
 
-        // If rename fails, don't give up quite yet.
-        bool retry = true;
-
-        try
-        {
-            // std::filesystem::rename() handles motw correctly if applicable.
-            std::filesystem::rename(installerPath, renamedDownloadedInstaller);
-            retry = false;
-        }
-        CATCH_LOG();
-
-        if (retry)
-        {
-            std::this_thread::sleep_for(250ms);
-            // If it fails again, let that one throw
-            std::filesystem::rename(installerPath, renamedDownloadedInstaller);
-        }
+        RenameFile(installerPath, renamedDownloadedInstaller);
 
         installerPath.assign(renamedDownloadedInstaller);
         AICLI_LOG(CLI, Info, << "Successfully renamed downloaded installer. Path: " << installerPath);

src/AppInstallerCommonCore/Public/AppInstallerRuntime.h

@@ -60,4 +60,7 @@ namespace AppInstaller::Runtime
 
     // Checks if the file system is NTFS
     bool IsNTFS(const std::filesystem::path& filePath);
+
+    // Checks if the file system at path supports hard links
+    bool SupportsHardLinks(const std::filesystem::path& path);
 }

src/AppInstallerCommonCore/Runtime.cpp

@@ -409,6 +409,9 @@ namespace AppInstaller::Runtime
         return wil::test_token_membership(nullptr, SECURITY_NT_AUTHORITY, SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS);
     }
 
+    // TODO: Replace this function with proper checks for supported functionality rather
+    //       than simply relying on "is it NTFS?", even if those functions delegate to
+    //       this one for the answer.
     bool IsNTFS(const std::filesystem::path& filePath)
     {
         wil::unique_hfile fileHandle{ CreateFileW(
@@ -436,6 +439,11 @@ namespace AppInstaller::Runtime
         return _wcsicmp(fileSystemName, L"NTFS") == 0;
     }
 
+    bool SupportsHardLinks(const std::filesystem::path& path)
+    {
+        return IsNTFS(path);
+    }
+
 #ifndef AICLI_DISABLE_TEST_HOOKS
     void TestHook_SetPathOverride(PathName target, const std::filesystem::path& path)
     {