std.fs.rename: fix Windows implementation

The semantics of this function are that it moves both files and
directories. Previously we had this `is_dir` boolean field of
`std.os.windows.OpenFile` which required the API user to choose: are we
opening a file or directory? And the other kind would either cause
error.IsDir or error.NotDir. But that is not a limitation of the Windows
file system API; it was self-imposed.

On Windows, rename is implemented internally with `NtCreateFile` so we
need to allow it to open either files or directories. This is now done
by `std.os.windows.OpenFile` accepting enum{file_only,dir_only,any}
instead of a boolean.

lib/std/fs.zig

@@ -1361,7 +1361,7 @@ pub const Dir = struct {
                     .share_access = share_access,
                     .creation = creation,
                     .io_mode = .blocking,
-                    .open_dir = true,
+                    .filter = .dir_only,
                 }) catch |er| switch (er) {
                     error.WouldBlock => unreachable,
                     else => |e2| return e2,

lib/std/fs/watch.zig

@@ -401,7 +401,7 @@ pub fn Watch(comptime V: type) type {
                     .access_mask = windows.FILE_LIST_DIRECTORY,
                     .creation = windows.FILE_OPEN,
                     .io_mode = .evented,
-                    .open_dir = true,
+                    .filter = .dir_only,
                 });
                 errdefer windows.CloseHandle(dir_handle);
 

lib/std/os.zig

@@ -1353,7 +1353,7 @@ fn openOptionsFromFlags(flags: u32) windows.OpenFileOptions {
         access_mask |= w.GENERIC_READ | w.GENERIC_WRITE;
     }
 
-    const open_dir: bool = flags & O.DIRECTORY != 0;
+    const filter: windows.OpenFileOptions.Filter = if (flags & O.DIRECTORY != 0) .dir_only else .file_only;
     const follow_symlinks: bool = flags & O.NOFOLLOW == 0;
 
     const creation: w.ULONG = blk: {
@@ -1369,7 +1369,7 @@ fn openOptionsFromFlags(flags: u32) windows.OpenFileOptions {
         .access_mask = access_mask,
         .io_mode = .blocking,
         .creation = creation,
-        .open_dir = open_dir,
+        .filter = filter,
         .follow_symlinks = follow_symlinks,
     };
 }
@@ -2324,6 +2324,7 @@ pub fn renameatW(
         .access_mask = windows.SYNCHRONIZE | windows.GENERIC_WRITE | windows.DELETE,
         .creation = windows.FILE_OPEN,
         .io_mode = .blocking,
+        .filter = .any, // This function is supposed to rename both files and directories.
     }) catch |err| switch (err) {
         error.WouldBlock => unreachable, // Not possible without `.share_access_nonblocking = true`.
         else => |e| return e,
@@ -2435,7 +2436,7 @@ pub fn mkdiratW(dir_fd: fd_t, sub_path_w: []const u16, mode: u32) MakeDirError!v
         .access_mask = windows.GENERIC_READ | windows.SYNCHRONIZE,
         .creation = windows.FILE_CREATE,
         .io_mode = .blocking,
-        .open_dir = true,
+        .filter = .dir_only,
     }) catch |err| switch (err) {
         error.IsDir => unreachable,
         error.PipeBusy => unreachable,
@@ -2511,7 +2512,7 @@ pub fn mkdirW(dir_path_w: []const u16, mode: u32) MakeDirError!void {
         .access_mask = windows.GENERIC_READ | windows.SYNCHRONIZE,
         .creation = windows.FILE_CREATE,
         .io_mode = .blocking,
-        .open_dir = true,
+        .filter = .dir_only,
     }) catch |err| switch (err) {
         error.IsDir => unreachable,
         error.PipeBusy => unreachable,
@@ -4693,7 +4694,7 @@ pub fn realpathW(pathname: []const u16, out_buffer: *[MAX_PATH_BYTES]u8) RealPat
                 .share_access = share_access,
                 .creation = creation,
                 .io_mode = .blocking,
-                .open_dir = true,
+                .filter = .dir_only,
             }) catch |er| switch (er) {
                 error.WouldBlock => unreachable,
                 else => |e2| return e2,

lib/std/os/windows.zig

@@ -53,17 +53,26 @@ pub const OpenFileOptions = struct {
     io_mode: std.io.ModeOverride,
     /// If true, tries to open path as a directory.
     /// Defaults to false.
-    open_dir: bool = false,
+    filter: Filter = .file_only,
     /// If false, tries to open path as a reparse point without dereferencing it.
     /// Defaults to true.
     follow_symlinks: bool = true,
+
+    pub const Filter = enum {
+        /// Causes `OpenFile` to return `error.IsDir` if the opened handle would be a directory.
+        file_only,
+        /// Causes `OpenFile` to return `error.NotDir` if the opened handle would be a file.
+        dir_only,
+        /// `OpenFile` does not discriminate between opening files and directories.
+        any,
+    };
 };
 
 pub fn OpenFile(sub_path_w: []const u16, options: OpenFileOptions) OpenError!HANDLE {
-    if (mem.eql(u16, sub_path_w, &[_]u16{'.'}) and !options.open_dir) {
+    if (mem.eql(u16, sub_path_w, &[_]u16{'.'}) and options.filter == .file_only) {
         return error.IsDir;
     }
-    if (mem.eql(u16, sub_path_w, &[_]u16{ '.', '.' }) and !options.open_dir) {
+    if (mem.eql(u16, sub_path_w, &[_]u16{ '.', '.' }) and options.filter == .file_only) {
         return error.IsDir;
     }
 
@@ -87,7 +96,11 @@ pub fn OpenFile(sub_path_w: []const u16, options: OpenFileOptions) OpenError!HAN
     };
     var io: IO_STATUS_BLOCK = undefined;
     const blocking_flag: ULONG = if (options.io_mode == .blocking) FILE_SYNCHRONOUS_IO_NONALERT else 0;
-    const file_or_dir_flag: ULONG = if (options.open_dir) FILE_DIRECTORY_FILE else FILE_NON_DIRECTORY_FILE;
+    const file_or_dir_flag: ULONG = switch (options.filter) {
+        .file_only => FILE_NON_DIRECTORY_FILE,
+        .dir_only => FILE_DIRECTORY_FILE,
+        .any => 0,
+    };
     // If we're not following symlinks, we need to ensure we don't pass in any synchronization flags such as FILE_SYNCHRONOUS_IO_NONALERT.
     const flags: ULONG = if (options.follow_symlinks) file_or_dir_flag | blocking_flag else file_or_dir_flag | FILE_OPEN_REPARSE_POINT;
 
@@ -695,7 +708,7 @@ pub fn CreateSymbolicLink(
         .dir = dir,
         .creation = FILE_CREATE,
         .io_mode = .blocking,
-        .open_dir = is_directory,
+        .filter = if (is_directory) .dir_only else .file_only,
     }) catch |err| switch (err) {
         error.IsDir => return error.PathAlreadyExists,
         error.NotDir => unreachable,