jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/RefPtr.h>
8#include <Kernel/FileSystem/Custody.h>
9#include <Kernel/FileSystem/VirtualFileSystem.h>
10#include <Kernel/Process.h>
11
12namespace Kernel {
13
14ErrorOr<FlatPtr> Process::sys$chdir(Userspace<char const*> user_path, size_t path_length)
15{
16 VERIFY_NO_PROCESS_BIG_LOCK(this);
17 TRY(require_promise(Pledge::rpath));
18 auto path = TRY(get_syscall_path_argument(user_path, path_length));
19 auto current_directory = m_current_directory.with([](auto& current_directory) -> NonnullRefPtr<Custody> {
20 return *current_directory;
21 });
22 RefPtr<Custody> new_directory = TRY(VirtualFileSystem::the().open_directory(credentials(), path->view(), *current_directory));
23 m_current_directory.with([&](auto& current_directory) {
24 // NOTE: We use swap() here to avoid manipulating the ref counts while holding the lock.
25 swap(current_directory, new_directory);
26 });
27 return 0;
28}
29
30ErrorOr<FlatPtr> Process::sys$fchdir(int fd)
31{
32 VERIFY_NO_PROCESS_BIG_LOCK(this);
33 TRY(require_promise(Pledge::stdio));
34 auto description = TRY(open_file_description(fd));
35 if (!description->is_directory())
36 return ENOTDIR;
37 if (!description->metadata().may_execute(credentials()))
38 return EACCES;
39 m_current_directory.with([&](auto& current_directory) {
40 current_directory = description->custody();
41 });
42 return 0;
43}
44
45ErrorOr<FlatPtr> Process::sys$getcwd(Userspace<char*> buffer, size_t size)
46{
47 VERIFY_NO_PROCESS_BIG_LOCK(this);
48 TRY(require_promise(Pledge::rpath));
49
50 if (size > NumericLimits<ssize_t>::max())
51 return EINVAL;
52
53 auto path = TRY(current_directory()->try_serialize_absolute_path());
54 size_t ideal_size = path->length() + 1;
55 auto size_to_copy = min(ideal_size, size);
56 TRY(copy_to_user(buffer, path->characters(), size_to_copy));
57 // Note: we return the whole size here, not the copied size.
58 return ideal_size;
59}
60
61}