microsoft
diff --git a/‎stl/src/filesystem.cpp‎
Lines changed: 104 additions & 17 deletions b/‎stl/src/filesystem.cpp‎
Lines changed: 104 additions & 17 deletions
diff --git a/‎tests/std/tests/P0218R1_filesystem/test.cpp‎
Lines changed: 9 additions & 0 deletions b/‎tests/std/tests/P0218R1_filesystem/test.cpp‎
Lines changed: 9 additions & 0 deletions
@@ -485,16 +485,12 @@ _Success_(return == __std_win_error::_Success) __std_win_error
     return __std_win_error{GetLastError()};
 }
 
-[[nodiscard]] __std_fs_remove_result __stdcall __std_fs_remove(_In_z_ const wchar_t* const _Target) noexcept {
-    // remove _Target without caring whether _Target is a file or directory
-    __std_win_error _Last_error;
-
-    constexpr auto _Flags = __std_fs_file_flags::_Backup_semantics | __std_fs_file_flags::_Open_reparse_point;
-    const _STD _Fs_file _Handle(_Target, __std_access_rights::_Delete, _Flags, &_Last_error);
-    if (_Last_error != __std_win_error::_Success) {
-        return {false, _Translate_not_found_to_success(_Last_error)};
-    }
+struct _File_disposition_info_ex {
+    DWORD _Flags;
+};
 
+[[nodiscard]] _Success_(return == __std_win_error::_Success) __std_win_error
+    _Set_delete_flag(_In_ __std_fs_file_handle _Handle) {
     // From newer Windows SDK than currently used to build vctools:
     // #define FILE_DISPOSITION_FLAG_DELETE                     0x00000001
     // #define FILE_DISPOSITION_FLAG_POSIX_SEMANTICS            0x00000002
@@ -503,33 +499,124 @@ _Success_(return == __std_win_error::_Success) __std_win_error
     //     DWORD Flags;
     // } FILE_DISPOSITION_INFO_EX, *PFILE_DISPOSITION_INFO_EX;
 
-    struct _File_disposition_info_ex {
-        DWORD _Flags;
-    };
     _File_disposition_info_ex _Info_ex{0x3};
 
     // FileDispositionInfoEx isn't documented in MSDN at the time of this writing, but is present
     // in minwinbase.h as of at least 10.0.16299.0
     constexpr auto _FileDispositionInfoExClass = static_cast<FILE_INFO_BY_HANDLE_CLASS>(21);
-    if (SetFileInformationByHandle(_Handle._Get(), _FileDispositionInfoExClass, &_Info_ex, sizeof(_Info_ex))) {
-        return {true, __std_win_error::_Success};
+    if (SetFileInformationByHandle(
+            reinterpret_cast<HANDLE>(_Handle), _FileDispositionInfoExClass, &_Info_ex, sizeof(_Info_ex))) {
+        return __std_win_error::_Success;
     }
 
-    _Last_error = __std_win_error{GetLastError()};
+    const auto _Last_error = __std_win_error{GetLastError()};
     switch (_Last_error) {
     case __std_win_error::_Invalid_parameter: // Older Windows versions
     case __std_win_error::_Invalid_function: // Windows 10 1607
     case __std_win_error::_Not_supported: // POSIX delete not supported by the file system
         break; // try non-POSIX delete below
+    case __std_win_error::_Access_denied: // This might be due to the read-only bit, try to clear it and try again
     default:
-        return {false, _Last_error};
+        return _Last_error;
     }
 
     FILE_DISPOSITION_INFO _Info{/* .Delete= */ TRUE};
-    if (SetFileInformationByHandle(_Handle._Get(), FileDispositionInfo, &_Info, sizeof(_Info))) {
+    if (SetFileInformationByHandle(reinterpret_cast<HANDLE>(_Handle), FileDispositionInfo, &_Info, sizeof(_Info))) {
+        return __std_win_error::_Success;
+    }
+
+    return __std_win_error{GetLastError()};
+}
+
+[[nodiscard]] __std_fs_remove_result __stdcall __std_fs_remove(_In_z_ const wchar_t* const _Target) noexcept {
+    // remove _Target without caring whether _Target is a file or directory
+    __std_win_error _Last_error;
+    bool _Able_to_change_attributes = false;
+
+    constexpr auto _Flags = __std_fs_file_flags::_Backup_semantics | __std_fs_file_flags::_Open_reparse_point;
+    _STD _Fs_file _Handle(_Target,
+        __std_access_rights::_Delete | __std_access_rights::_File_read_attributes
+            | __std_access_rights::_File_write_attributes,
+        _Flags, &_Last_error);
+    if (_Last_error == __std_win_error::_Success) {
+        _Able_to_change_attributes = true;
+    } else if (_Last_error == __std_win_error::_Access_denied) {
+        // change the underlying HANDLE of _Handle
+        // this might not be a good way of doing it (comment to be removed post review)
+        _Last_error = __std_fs_open_handle(&_Handle._Raw, _Target, __std_access_rights::_Delete, _Flags);
+        if (_Last_error != __std_win_error::_Success) {
+            return {false, _Last_error};
+        }
+    } else {
+        return {false, _Translate_not_found_to_success(_Last_error)};
+    }
+
+    // For Windows 10 1809 or later we have this flag -> FILE_DISPOSITION_FLAG_IGNORE_READONLY_ATTRIBUTE 0x10
+    // This flag also deletes read-only files
+    // NOTE: This is currently undocumented in MSDN. Refer WinBase.h for declarations
+
+    // The following bits are set here
+    // FILE_DISPOSITION_FLAG_DELETE, FILE_DISPOSITION_FLAG_POSIX_SEMANTICS,
+    // FILE_DISPOSITION_FLAG_IGNORE_READONLY_ATTRIBUTE
+    _File_disposition_info_ex _Info_ex{0x3 | 0x10};
+    constexpr auto _FileDispositionInfoExClass = static_cast<FILE_INFO_BY_HANDLE_CLASS>(21);
+    if (SetFileInformationByHandle(
+            reinterpret_cast<HANDLE>(_Handle._Get()), _FileDispositionInfoExClass, &_Info_ex, sizeof(_Info_ex))) {
         return {true, __std_win_error::_Success};
     }
 
+    _Last_error = __std_win_error{GetLastError()};
+    switch (_Last_error) {
+    // Windows versions older than 1809
+    case __std_win_error::_Invalid_parameter:
+    case __std_win_error::_Invalid_function:
+    case __std_win_error::_Not_supported:
+        break;
+    default:
+        // If we fail for reasons other than those mentioned above just return to the caller
+        return {false, _Last_error};
+    }
+
+    // code path for versions older than 1809
+    _Last_error = _Set_delete_flag(_Handle._Raw);
+    if (_Last_error == __std_win_error::_Success) {
+        return {true, __std_win_error::_Success};
+    }
+
+    if (_Last_error == __std_win_error::_Access_denied && _Able_to_change_attributes) {
+
+        FILE_BASIC_INFO _Basic_info;
+        if (!GetFileInformationByHandleEx(_Handle._Get(), FileBasicInfo, &_Basic_info, sizeof(_Basic_info))) {
+            return {false, __std_win_error{GetLastError()}};
+        }
+        // check if FILE_ATTRIBUTE_READONLY is set
+        if (_Basic_info.FileAttributes & FILE_ATTRIBUTE_READONLY) {
+            // try to remove FILE_ATTRIBUTE_READONLY
+            _Basic_info.FileAttributes ^= FILE_ATTRIBUTE_READONLY;
+            if (!SetFileInformationByHandle(_Handle._Get(), FileBasicInfo, &_Basic_info, sizeof(_Basic_info))) {
+                return {false, __std_win_error{GetLastError()}};
+            }
+            // removed FILE_ATTRIBUTE_READONLY, now try to set the delete flag again
+            _Last_error = _Set_delete_flag(_Handle._Raw);
+            if (_Last_error == __std_win_error::_Success) {
+                return {true, __std_win_error::_Success};
+            } else if (_Last_error == __std_win_error::_Access_denied) {
+                // looks like we failed to set the delete flag, after clearing the FILE_ATTRIBUTE_READONLY flag
+                // perform rollback
+                _Basic_info.FileAttributes |= FILE_ATTRIBUTE_READONLY;
+                if (!SetFileInformationByHandle(_Handle._Get(), FileBasicInfo, &_Basic_info, sizeof(_Basic_info))) {
+                    return {false, __std_win_error{GetLastError()}};
+                }
+                return {false, __std_win_error{GetLastError()}};
+            }
+        } else {
+            return {false, _Last_error};
+        }
+    } else {
+        return {false, _Last_error};
+    }
+
+
     return {false, __std_win_error{GetLastError()}};
 
 #undef _SetFileInformationByHandle
 
@@ -3281,6 +3281,15 @@ void test_remove() {
     EXPECT(!exists(filename, ec));
     EXPECT(good(ec));
 
+    create_file_containing(filename, L"hello");
+    permissions(filename, perms::owner_write | perms::group_write | perms::others_write, perm_options::remove);
+
+    // remove a read-only file also
+    EXPECT(remove(filename, ec));
+    EXPECT(good(ec));
+    EXPECT(!exists(filename, ec));
+    EXPECT(good(ec));
+
     EXPECT(remove(dirname, ec));
     EXPECT(good(ec));
     EXPECT(!exists(dirname, ec));