From 3fd3482559dfd925ec8df54b8cc6b3b11f469078 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Steffen=20Sch=C3=BCmann?= <s.schuemann@pobox.com>
Date: Sun, 8 Nov 2020 11:11:35 +0100
Subject: [PATCH] refs #75, fix for windows path filtering on namespaces

---
 include/ghc/filesystem.hpp | 21 +++++++++------------
 test/filesystem_test.cpp   |  7 ++++++-
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/include/ghc/filesystem.hpp b/include/ghc/filesystem.hpp
index f1f05f1..82f6d84 100644
--- a/include/ghc/filesystem.hpp
+++ b/include/ghc/filesystem.hpp
@@ -1257,7 +1257,6 @@ class GHC_FS_API_CLASS u8arguments
 //-------------------------------------------------------------------------------------------------
 
 namespace detail {
-// GHC_FS_API void postprocess_path_with_format(path::impl_string_type& p, path::format fmt);
 enum utf8_states_t { S_STRT = 0, S_RJCT = 8 };
 GHC_FS_API void appendUTF8(std::string& str, uint32_t unicode);
 GHC_FS_API bool is_surrogate(uint32_t c);
@@ -1654,17 +1653,15 @@ GHC_INLINE void path::postprocess_path_with_format(path::impl_string_type& p, pa
 #ifdef GHC_OS_WINDOWS
         case path::auto_format:
         case path::native_format:
-            if (p.length() > 4 && p[2] == '?') {
-                if (detail::startsWith(p, std::string("\\\\?\\"))) {
-                    // remove Windows long filename marker
-                    p.erase(0, 4);
-                    if (detail::startsWith(p, std::string("UNC\\"))) {
-                        p.erase(0, 2);
-                        p[0] = '\\';
+            if (p.length() >= 4 && p[2] == '?') {
+                if (p.length() == 4 || (p.length() >= 6 && p[5] == ':')) {
+                    if (detail::startsWith(p, std::string("\\\\?\\"))) {
+                        // remove Windows long filename marker for simple paths
+                        p.erase(0, 4);
+                    }
+                    else if (detail::startsWith(p, std::string("\\??\\"))) {
+                        p.erase(0, 4);
                     }
-                }
-                else if (detail::startsWith(p, std::string("\\??\\"))) {
-                    p.erase(0, 4);
                 }
             }
             for (auto& c : p) {
@@ -2554,7 +2551,7 @@ GHC_INLINE path::impl_string_type path::native_impl() const
     if (is_absolute() && _path.length() > MAX_PATH - 10) {
         // expand long Windows filenames with marker
         if (has_root_name() && _path[0] == '/') {
-            result = "\\\\?\\UNC" + _path.substr(1);
+            result = "\\\\?\\" + _path.substr(1);
         }
         else {
             result = "\\\\?\\" + _path;
diff --git a/test/filesystem_test.cpp b/test/filesystem_test.cpp
index cb451d9..985a0c9 100644
--- a/test/filesystem_test.cpp
+++ b/test/filesystem_test.cpp
@@ -1941,6 +1941,11 @@ TEST_CASE("30.10.15.13 exists", "[filesystem][operations][fs.op.exists]")
     ec = std::error_code(42, std::system_category());
     CHECK(fs::exists(t.path(), ec));
     CHECK(!ec);
+#if defined(GHC_OS_WINDOWS) && !defined(GHC_FILESYSTEM_FWD)
+    if (::GetFileAttributesW(L"C:\\fs-test") != INVALID_FILE_ATTRIBUTES) {
+        CHECK(fs::exists("C:\\fs-test"));    
+    }
+#endif
 }
 
 TEST_CASE("30.10.15.14 file_size", "[filesystem][operations][fs.op.file_size]")
@@ -2729,7 +2734,7 @@ TEST_CASE("Windows: Long filename support", "[filesystem][path][fs.path.win.long
 #endif
 }
 
-TEST_CASE("Windows: UNC path support", "[filesystem][path][fs.path.win.unc]")
+TEST_CASE("Windows: path namespace support", "[filesystem][path][fs.path.win.namespaces]")
 {
 #ifdef GHC_OS_WINDOWS
     std::error_code ec;