1 // Copyright 2010 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/win/i18n.h"
6
7 #include <windows.h>
8
9 #include <ostream>
10 #include <string_view>
11
12 #include "base/check_op.h"
13 #include "base/strings/string_split.h"
14 #include "base/strings/string_util.h"
15
16 namespace {
17
18 using GetPreferredUILanguages_Fn = decltype(::GetSystemPreferredUILanguages)*;
19
20 constexpr std::wstring_view kNullTerminator{L"\0", 1};
21
GetPreferredUILanguageList(GetPreferredUILanguages_Fn function,ULONG flags,std::vector<std::wstring> * languages)22 bool GetPreferredUILanguageList(GetPreferredUILanguages_Fn function,
23 ULONG flags,
24 std::vector<std::wstring>* languages) {
25 DCHECK_EQ((flags & (MUI_LANGUAGE_ID | MUI_LANGUAGE_NAME)), 0U);
26 const ULONG call_flags = flags | MUI_LANGUAGE_NAME;
27 ULONG language_count = 0;
28 ULONG buffer_length = 0;
29 if (!function(call_flags, &language_count, nullptr, &buffer_length) ||
30 !buffer_length) {
31 DPCHECK(!buffer_length) << "Failed getting size of preferred UI languages.";
32 return false;
33 }
34
35 std::wstring buffer(buffer_length, '\0');
36 if (!function(call_flags, &language_count, std::data(buffer),
37 &buffer_length) ||
38 !language_count) {
39 DPCHECK(!language_count) << "Failed getting preferred UI languages.";
40 return false;
41 }
42
43 // The buffer has been populated with a series of strings separated by
44 // terminators, which ends with a single empty string (two terminators in a
45 // row). Chop off the last of those two terminators so that |buffer| is a
46 // basic_string that contains the terminator ending the last string but not
47 // the terminator denoting an empty string.
48 buffer.resize(buffer_length - 1);
49
50 // Split string on NUL characters.
51 ULONG languages_added = 0;
52 for (auto token :
53 base::SplitStringPiece(buffer, kNullTerminator, base::KEEP_WHITESPACE,
54 base::SPLIT_WANT_NONEMPTY)) {
55 languages->emplace_back(token);
56 ++languages_added;
57 }
58 DCHECK_EQ(languages_added, language_count);
59 return true;
60 }
61
62 } // namespace
63
64 namespace base {
65 namespace win {
66 namespace i18n {
67
GetUserPreferredUILanguageList(std::vector<std::wstring> * languages)68 bool GetUserPreferredUILanguageList(std::vector<std::wstring>* languages) {
69 DCHECK(languages);
70 return GetPreferredUILanguageList(::GetUserPreferredUILanguages, 0,
71 languages);
72 }
73
GetThreadPreferredUILanguageList(std::vector<std::wstring> * languages)74 bool GetThreadPreferredUILanguageList(std::vector<std::wstring>* languages) {
75 DCHECK(languages);
76 return GetPreferredUILanguageList(
77 ::GetThreadPreferredUILanguages,
78 MUI_MERGE_SYSTEM_FALLBACK | MUI_MERGE_USER_FALLBACK, languages);
79 }
80
81 } // namespace i18n
82 } // namespace win
83 } // namespace base
84