From 89571de0f3a23a9ada08ed4cc2b0d2c5683f23e9 Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Mon, 10 Jul 2023 18:41:39 +0200
Subject: [PATCH] Symbolic links for the universal binary also work on Windows

---
 README.md             | 23 ++++++++++++++++-------
 src/universal.cpp     | 15 ++++++++++-----
 test/dwarfs_tools.cpp | 12 +++++-------
 3 files changed, 31 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index b377cdea..ccabb3ab 100644
--- a/README.md
+++ b/README.md
@@ -128,24 +128,33 @@ FUSE driver) in a single executable. These executables are compressed
 using [upx](https://github.com/upx/upx), so they are much smaller than
 the individual tools combined.
 
-The universal binaries can be run either through symbolic links named
-after the proper tool. e.g.:
+The universal binaries can be run through symbolic links named after
+the proper tool. e.g.:
 
 ```
-$ ln -s dwarfs-universal-0.7.0-RC5-Linux-aarch64 mkdwarfs
+$ ln -s dwarfs-universal-0.7.0-Linux-aarch64 mkdwarfs
 $ ./mkdwarfs --help
 ```
 
-Or you can select the tool by passing `--tool=<name>` as the first
-argument on the command line:
+This also works on Windows ift the file system supports symbolic links:
 
 ```
-$ .\dwarfs-universal-0.7.0-RC5-Windows-AMD64.exe --tool=mkdwarfs --help
+> mklink mkdwarfs.exe dwarfs-universal-0.7.0-Windows-AMD64.exe
+> .\mkdwarfs.exe --help
+```
+
+Alternatively, you can select the tool by passing `--tool=<name>` as
+the first argument on the command line:
+
+```
+> .\dwarfs-universal-0.7.0-Windows-AMD64.exe --tool=mkdwarfs --help
 ```
 
 Note that just like the `dwarfs.exe` Windows binary, the universal
 Windows binary depends on the `winfsp-x64.dll` from the
-[WinFsp](https://github.com/winfsp/winfsp) project.
+[WinFsp](https://github.com/winfsp/winfsp) project. However, for the
+universal binary, the DLL is loaded lazily, so you can still use all
+other tools without the DLL.
 See the [Windows Support](#windows-support) section for more details.
 
 ### Dependencies
diff --git a/src/universal.cpp b/src/universal.cpp
index 9e4586f5..a937b3e5 100644
--- a/src/universal.cpp
+++ b/src/universal.cpp
@@ -87,6 +87,12 @@ int dwarfs_main_helper(int argc, sys_char** argv) {
 }
 #endif
 
+#ifdef _WIN32
+#define EXE_EXT ".exe"
+#else
+#define EXE_EXT ""
+#endif
+
 std::map<std::string_view, int (*)(int, sys_char**)> const functions{
 #ifdef _WIN32
     {"dwarfs", &dwarfs_main_helper},
@@ -120,14 +126,13 @@ int SYS_MAIN(int argc, sys_char** argv) {
     }
   }
 
-#ifndef _WIN32
   auto path = std::filesystem::path(argv[0]);
 
-  if (auto it = functions.find(path.filename().string());
-      it != functions.end()) {
-    return safe_main([&] { return it->second(argc, argv); });
+  if (path.extension().string() == EXE_EXT) {
+    if (auto it = functions.find(path.stem().string()); it != functions.end()) {
+      return safe_main([&] { return it->second(argc, argv); });
+    }
   }
-#endif
 
   using namespace folly::gen;
 
diff --git a/test/dwarfs_tools.cpp b/test/dwarfs_tools.cpp
index e87f19bf..d1487771 100644
--- a/test/dwarfs_tools.cpp
+++ b/test/dwarfs_tools.cpp
@@ -589,9 +589,7 @@ enum class binary_mode {
 std::vector<binary_mode> tools_test_modes{
     binary_mode::standalone,
     binary_mode::universal_tool,
-#ifndef _WIN32
     binary_mode::universal_symlink,
-#endif
 };
 
 class tools_test : public ::testing::TestWithParam<binary_mode> {};
@@ -608,10 +606,10 @@ TEST_P(tools_test, end_to_end) {
   auto image_hdr = td / "test_hdr.dwarfs";
   auto fsdata_dir = td / "fsdata";
   auto header_data = fsdata_dir / "format.sh";
-  auto universal_symlink_dwarfs_bin = td / "dwarfs";
-  auto universal_symlink_mkdwarfs_bin = td / "mkdwarfs";
-  auto universal_symlink_dwarfsck_bin = td / "dwarfsck";
-  auto universal_symlink_dwarfsextract_bin = td / "dwarfsextract";
+  auto universal_symlink_dwarfs_bin = td / "dwarfs" EXE_EXT;
+  auto universal_symlink_mkdwarfs_bin = td / "mkdwarfs" EXE_EXT;
+  auto universal_symlink_dwarfsck_bin = td / "dwarfsck" EXE_EXT;
+  auto universal_symlink_dwarfsextract_bin = td / "dwarfsextract" EXE_EXT;
   std::vector<std::string> mkdwarfs_tool_arg;
   std::vector<std::string> dwarfsck_tool_arg;
   std::vector<std::string> dwarfsextract_tool_arg;
@@ -897,7 +895,7 @@ TEST_P(tools_test, mutating_ops) {
   auto non_empty_dir = mountpoint / "foo";
   auto name_inside_fs = mountpoint / "some_random_name";
   auto name_outside_fs = td / "some_random_name";
-  auto universal_symlink_dwarfs_bin = td / "dwarfs";
+  auto universal_symlink_dwarfs_bin = td / "dwarfs" EXE_EXT;
 
   if (mode == binary_mode::universal_symlink) {
     fs::create_symlink(universal_bin, universal_symlink_dwarfs_bin);