Add SymlinkFlags needed to create symlinks to dirs on Win

lib/std/fs.zig

@@ -69,7 +69,7 @@ pub const need_async_thread = std.io.is_async and switch (builtin.os.tag) {
 
 /// TODO remove the allocator requirement from this API
 pub fn atomicSymLink(allocator: *Allocator, existing_path: []const u8, new_path: []const u8) !void {
-    if (symLink(existing_path, new_path)) {
+    if (symLink(existing_path, new_path, .{})) {
         return;
     } else |err| switch (err) {
         error.PathAlreadyExists => {},
@@ -87,7 +87,7 @@ pub fn atomicSymLink(allocator: *Allocator, existing_path: []const u8, new_path:
         try crypto.randomBytes(rand_buf[0..]);
         base64_encoder.encode(tmp_path[dirname.len + 1 ..], &rand_buf);
 
-        if (symLink(existing_path, tmp_path)) {
+        if (symLink(existing_path, tmp_path, .{})) {
             return rename(tmp_path, new_path);
         } else |err| switch (err) {
             error.PathAlreadyExists => continue,

lib/std/os.zig

@@ -1520,6 +1520,14 @@ pub fn getcwd(out_buffer: []u8) GetCwdError![]u8 {
     }
 }
 
+/// Use with `symlink` to specify whether the symlink will point to a file
+/// or a directory. This value is ignored on all hosts except Windows where
+/// creating symlinks to different resource types, requires different flags.
+/// By default, symlink is assumed to point to a file.
+pub const SymlinkFlags = struct{
+    is_directory: bool = false, 
+};
+
 pub const SymLinkError = error{
     /// In WASI, this error may occur when the file descriptor does
     /// not hold the required rights to create a new symbolic link relative to it.
@@ -1541,39 +1549,34 @@ pub const SymLinkError = error{
 /// Creates a symbolic link named `sym_link_path` which contains the string `target_path`.
 /// A symbolic link (also known as a soft link) may point to an existing file or to a nonexistent
 /// one; the latter case is known as a dangling link.
-/// On Windows, it is only legal to create a symbolic link to an existing resource. Furthermore,
-/// this function will by default try creating a symbolic link to a file. If you would like to
-/// create a symbolic link to a directory instead, see `symlinkW` for more information how to
-/// do that.
 /// If `sym_link_path` exists, it will not be overwritten.
 /// See also `symlinkC` and `symlinkW`.
-pub fn symlink(target_path: []const u8, sym_link_path: []const u8) SymLinkError!void {
+pub fn symlink(target_path: []const u8, sym_link_path: []const u8, flags: SymlinkFlags) SymLinkError!void {
     if (builtin.os.tag == .wasi) {
         @compileError("symlink is not supported in WASI; use symlinkat instead");
     }
     if (builtin.os.tag == .windows) {
         const target_path_w = try windows.sliceToPrefixedFileW(target_path);
         const sym_link_path_w = try windows.sliceToPrefixedFileW(sym_link_path);
-        return symlinkW(target_path_w.span().ptr, sym_link_path_w.span().ptr);
+        return symlinkW(target_path_w.span().ptr, sym_link_path_w.span().ptr, flags);
     }
     const target_path_c = try toPosixPath(target_path);
     const sym_link_path_c = try toPosixPath(sym_link_path);
-    return symlinkZ(&target_path_c, &sym_link_path_c);
+    return symlinkZ(&target_path_c, &sym_link_path_c, flags);
 }
 
 pub const symlinkC = @compileError("deprecated: renamed to symlinkZ");
 
 /// Windows-only. Same as `symlink` except the parameters are null-terminated, WTF16 encoded.
 /// Note that this function will by default try creating a symbolic link to a file. If you would
-/// like to create a symbolic link to a directory, use `std.os.windows.CreateSymbolicLinkW` directly
+/// like to create a symbolic link to a directory, specify this with `SymlinkFlags{ .is_directory = true }`.
-/// specifying as flags `std.os.windows.CreateSymbolicLinkFlags.Directory`.
+pub fn symlinkW(target_path: [*:0]const u16, sym_link_path: [*:0]const u16, flags: SymlinkFlags) SymLinkError!void {
-pub fn symlinkW(target_path: [*:0]const u16, sym_link_path: [*:0]const u16) SymLinkError!void {
+    return windows.CreateSymbolicLinkW(sym_link_path, target_path, flags.is_directory);
-    return windows.CreateSymbolicLinkW(sym_link_path, target_path, false);
 }
 
 /// This is the same as `symlink` except the parameters are null-terminated pointers.
 /// See also `symlink`.
-pub fn symlinkZ(target_path: [*:0]const u8, sym_link_path: [*:0]const u8) SymLinkError!void {
+pub fn symlinkZ(target_path: [*:0]const u8, sym_link_path: [*:0]const u8, flags: SymlinkFlags) SymLinkError!void {
     if (builtin.os.tag == .windows) {
         const target_path_w = try windows.cStrToPrefixedFileW(target_path);
         const sym_link_path_w = try windows.cStrToPrefixedFileW(sym_link_path);

lib/std/os/test.zig

@@ -48,7 +48,7 @@ test "readlink" {
     {
         var cwd = fs.cwd();
         try cwd.writeFile("file.txt", "nonsense");
-        try os.symlink("file.txt", "symlinked");
+        try os.symlink("file.txt", "symlinked", .{});
 
         var buffer: [fs.MAX_PATH_BYTES]u8 = undefined;
         const given = try os.readlink("symlinked", buffer[0..]);
@@ -81,7 +81,7 @@ test "readlink" {
         std.debug.warn("symlink_path={}\n", .{symlink_path});
 
         // create symbolic link by path
-        try os.symlink(target_path, symlink_path);
+        try os.symlink(target_path, symlink_path, .{});
 
         // now, read the link and verify
         var buffer: [fs.MAX_PATH_BYTES]u8 = undefined;