Work around std::filesystem::canonical bug on UWP (#198)

* Work around std::filesystem::canonical bug on UWP
* Fix legacy win32 filesystem code path

Author: brycehutchings

changes/sdk/pr.198.gh.OpenXR-SDK-Source.md

@@ -0,0 +1 @@
+Replace usage of std::filesystem::canonical with PathCchCanonicalize on Windows platform to work around bug on UWP platforms. This also replaces PathCanonicalize with PathCchCanonicalize and adds the appropriate library for linking in.

src/common/filesystem_utils.cpp

@@ -87,6 +87,10 @@
 #include <dirent.h>
 #endif
 
+#if defined(XR_USE_PLATFORM_WIN32)
+#include <PathCch.h>
+#endif
+
 #if defined(XR_USE_PLATFORM_WIN32)
 #define PATH_SEPARATOR ';'
 #define DIRECTORY_SYMBOL '\\'
@@ -128,7 +132,18 @@ bool FileSysUtilsGetAbsolutePath(const std::string& path, std::string& absolute)
 }
 
 bool FileSysUtilsGetCanonicalPath(const std::string& path, std::string& canonical) {
+#if defined(XR_USE_PLATFORM_WIN32)
+    // std::filesystem::canonical fails on UWP and must be avoided. This alternative will not
+    // follow symbolic links but symbolic links are not needed on Windows since the loader uses
+    // the registry as a form of indirection instead.
+    wchar_t canonical_wide_path[MAX_PATH];
+    if (FAILED(PathCchCanonicalize(canonical_wide_path, MAX_PATH, utf8_to_wide(path).c_str()))) {
+        return false;
+    }
+    canonical = wide_to_utf8(canonical_wide_path);
+#else
     canonical = FS_PREFIX::canonical(path).string();
+#endif
     return true;
 }
 
@@ -216,7 +231,7 @@ bool FileSysUtilsGetAbsolutePath(const std::string& path, std::string& absolute)
 
 bool FileSysUtilsGetCanonicalPath(const std::string& path, std::string& absolute) {
     wchar_t tmp_path[MAX_PATH];
-    if (0 != PathCanonicalizeW(utf8_to_wide(path).c_str(), tmp_path)) {
+    if (SUCCEEDED(PathCchCanonicalize(tmp_path, MAX_PATH, utf8_to_wide(path).c_str()))) {
         absolute = wide_to_utf8(tmp_path);
         return true;
     }

src/loader/CMakeLists.txt

@@ -183,7 +183,7 @@ elseif(WIN32)
         target_compile_options(openxr_loader PRIVATE /wd6386)
     endif()
 
-    target_link_libraries(openxr_loader PRIVATE advapi32)
+    target_link_libraries(openxr_loader PUBLIC advapi32 pathcch)
 
     # Need to copy DLL to client directories so clients can easily load it.
     if(DYNAMIC_LOADER AND (CMAKE_GENERATOR MATCHES "^Visual Studio.*"))
@@ -281,4 +281,4 @@ install(
     FILES ${CMAKE_CURRENT_BINARY_DIR}/OpenXRConfig.cmake
           ${CMAKE_CURRENT_BINARY_DIR}/OpenXRConfigVersion.cmake
     DESTINATION ${TARGET_DESTINATION}
-)
+)