deleteTreeMinStackSizeWithKindHint

fn deleteTreeMinStackSizeWithKindHint(parent: Dir, io: Io, sub_path: []const u8, kind_hint: File.Kind) DeleteTreeError!void {
    start_over: while (true) {
        var dir = (try parent.deleteTreeOpenInitialSubpath(io, sub_path, kind_hint)) orelse return;
        var cleanup_dir_parent: ?Dir = null;
        defer if (cleanup_dir_parent) |*d| d.close(io);

        var cleanup_dir = true;
        defer if (cleanup_dir) dir.close(io);

        // Valid use of max_path_bytes because dir_name_buf will only
        // ever store a single path component that was returned from the
        // filesystem.
        var dir_name_buf: [max_path_bytes]u8 = undefined;
        var dir_name: []const u8 = sub_path;

        // Here we must avoid recursion, in order to provide O(1) memory guarantee of this function.
        // Go through each entry and if it is not a directory, delete it. If it is a directory,
        // open it, and close the original directory. Repeat. Then start the entire operation over.

        scan_dir: while (true) {
            var dir_it = dir.iterateAssumeFirstIteration();
            dir_it: while (try dir_it.next(io)) |entry| {
                var treat_as_dir = entry.kind == .directory;
                handle_entry: while (true) {
                    if (treat_as_dir) {
                        const new_dir = dir.openDir(io, entry.name, .{
                            .follow_symlinks = false,
                            .iterate = true,
                        }) catch |err| switch (err) {
                            error.NotDir => {
                                treat_as_dir = false;
                                continue :handle_entry;
                            },
                            error.FileNotFound => {
                                // That's fine, we were trying to remove this directory anyway.
                                continue :dir_it;
                            },

                            error.AccessDenied,
                            error.PermissionDenied,
                            error.SymLinkLoop,
                            error.ProcessFdQuotaExceeded,
                            error.NameTooLong,
                            error.SystemFdQuotaExceeded,
                            error.NoDevice,
                            error.SystemResources,
                            error.Unexpected,
                            error.BadPathName,
                            error.NetworkNotFound,
                            error.Canceled,
                            => |e| return e,
                        };
                        if (cleanup_dir_parent) |*d| d.close(io);
                        cleanup_dir_parent = dir;
                        dir = new_dir;
                        const result = dir_name_buf[0..entry.name.len];
                        @memcpy(result, entry.name);
                        dir_name = result;
                        continue :scan_dir;
                    } else {
                        if (dir.deleteFile(io, entry.name)) {
                            continue :dir_it;
                        } else |err| switch (err) {
                            error.FileNotFound => continue :dir_it,

                            // Impossible because we do not pass any path separators.
                            error.NotDir => unreachable,

                            error.IsDir => {
                                treat_as_dir = true;
                                continue :handle_entry;
                            },

                            error.AccessDenied,
                            error.PermissionDenied,
                            error.SymLinkLoop,
                            error.NameTooLong,
                            error.SystemResources,
                            error.ReadOnlyFileSystem,
                            error.FileSystem,
                            error.FileBusy,
                            error.BadPathName,
                            error.NetworkNotFound,
                            error.Canceled,
                            error.Unexpected,
                            => |e| return e,
                        }
                    }
                }
            }
            // Reached the end of the directory entries, which means we successfully deleted all of them.
            // Now to remove the directory itself.
            dir.close(io);
            cleanup_dir = false;

            if (cleanup_dir_parent) |d| {
                d.deleteDir(io, dir_name) catch |err| switch (err) {
                    // These two things can happen due to file system race conditions.
                    error.FileNotFound, error.DirNotEmpty => continue :start_over,
                    else => |e| return e,
                };
                continue :start_over;
            } else {
                parent.deleteDir(io, sub_path) catch |err| switch (err) {
                    error.FileNotFound => return,
                    error.DirNotEmpty => continue :start_over,
                    else => |e| return e,
                };
                return;
            }
        }
    }
}