1 // Copyright 2019 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "sandboxed_api/util/path.h"
16
17 #include <deque>
18 #include <initializer_list>
19 #include <string>
20 #include <utility>
21
22 #include "absl/strings/match.h"
23 #include "absl/strings/str_cat.h"
24 #include "absl/strings/str_join.h"
25 #include "absl/strings/str_split.h"
26 #include "absl/strings/string_view.h"
27 #include "absl/strings/strip.h"
28
29 namespace sapi::file {
30 namespace internal {
31
32 constexpr char kPathSeparator[] = "/";
33
JoinPathImpl(std::initializer_list<absl::string_view> paths)34 std::string JoinPathImpl(std::initializer_list<absl::string_view> paths) {
35 std::string result;
36 for (const auto& path : paths) {
37 if (path.empty()) {
38 continue;
39 }
40 if (result.empty()) {
41 absl::StrAppend(&result, path);
42 continue;
43 }
44 const auto comp = absl::StripPrefix(path, kPathSeparator);
45 if (absl::EndsWith(result, kPathSeparator)) {
46 absl::StrAppend(&result, comp);
47 } else {
48 absl::StrAppend(&result, kPathSeparator, comp);
49 }
50 }
51 return result;
52 }
53
54 } // namespace internal
55
IsAbsolutePath(absl::string_view path)56 bool IsAbsolutePath(absl::string_view path) {
57 return !path.empty() && path[0] == '/';
58 }
59
SplitPath(absl::string_view path)60 std::pair<absl::string_view, absl::string_view> SplitPath(
61 absl::string_view path) {
62 const auto pos = path.find_last_of('/');
63
64 // Handle the case with no '/' in 'path'.
65 if (pos == absl::string_view::npos) {
66 return {path.substr(0, 0), path};
67 }
68
69 // Handle the case with a single leading '/' in 'path'.
70 if (pos == 0) {
71 return {path.substr(0, 1), absl::ClippedSubstr(path, 1)};
72 }
73 return {path.substr(0, pos), absl::ClippedSubstr(path, pos + 1)};
74 }
75
CleanPath(const absl::string_view unclean_path)76 std::string CleanPath(const absl::string_view unclean_path) {
77 int dotdot_num = 0;
78 std::deque<absl::string_view> parts;
79 for (absl::string_view part :
80 absl::StrSplit(unclean_path, '/', absl::SkipEmpty())) {
81 if (part == "..") {
82 if (parts.empty()) {
83 ++dotdot_num;
84 } else {
85 parts.pop_back();
86 }
87 } else if (part != ".") {
88 parts.push_back(part);
89 }
90 }
91 if (absl::StartsWith(unclean_path, "/")) {
92 if (parts.empty()) {
93 return "/";
94 }
95 parts.push_front("");
96 } else {
97 for (; dotdot_num; --dotdot_num) {
98 parts.push_front("..");
99 }
100 if (parts.empty()) {
101 return ".";
102 }
103 }
104 return absl::StrJoin(parts, "/");
105 }
106
107 } // namespace sapi::file
108