1//===---- URI.h - File URIs with schemes -------------------------*- C++-*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "URI.h"
10#include "support/Logger.h"
11#include "llvm/ADT/StringExtras.h"
12#include "llvm/ADT/Twine.h"
13#include "llvm/Support/Error.h"
14#include "llvm/Support/Path.h"
15#include <algorithm>
16
17LLVM_INSTANTIATE_REGISTRY(clang::clangd::URISchemeRegistry)
18
19namespace clang {
20namespace clangd {
21namespace {
22
23bool isWindowsPath(llvm::StringRef Path) {
24 return Path.size() > 1 && llvm::isAlpha(Path[0]) && Path[1] == ':';
25}
26
27bool isNetworkPath(llvm::StringRef Path) {
28 return Path.size() > 2 && Path[0] == Path[1] &&
29 llvm::sys::path::is_separator(Path[0]);
30}
31
32/// This manages file paths in the file system. All paths in the scheme
33/// are absolute (with leading '/').
34/// Note that this scheme is hardcoded into the library and not registered in
35/// registry.
36class FileSystemScheme : public URIScheme {
37public:
38 llvm::Expected<std::string>
39 getAbsolutePath(llvm::StringRef Authority, llvm::StringRef Body,
40 llvm::StringRef /*HintPath*/) const override {
41 if (!Body.startswith("/"))
42 return error("File scheme: expect body to be an absolute path starting "
43 "with '/': {0}",
44 Body);
45 llvm::SmallString<128> Path;
46 if (!Authority.empty()) {
47 // Windows UNC paths e.g. file://server/share => \\server\share
48 ("//" + Authority).toVector(Path);
49 } else if (isWindowsPath(Body.substr(1))) {
50 // Windows paths e.g. file:///X:/path => X:\path
51 Body.consume_front("/");
52 }
53 Path.append(Body);
54 llvm::sys::path::native(Path);
55 return std::string(Path);
56 }
57
58 llvm::Expected<URI>
59 uriFromAbsolutePath(llvm::StringRef AbsolutePath) const override {
60 std::string Body;
61 llvm::StringRef Authority;
62 llvm::StringRef Root = llvm::sys::path::root_name(AbsolutePath);
63 if (isNetworkPath(Root)) {
64 // Windows UNC paths e.g. \\server\share => file://server/share
65 Authority = Root.drop_front(2);
66 AbsolutePath.consume_front(Root);
67 } else if (isWindowsPath(Root)) {
68 // Windows paths e.g. X:\path => file:///X:/path
69 Body = "/";
70 }
71 Body += llvm::sys::path::convert_to_slash(AbsolutePath);
72 return URI("file", Authority, Body);
73 }
74};
75
76llvm::Expected<std::unique_ptr<URIScheme>>
77findSchemeByName(llvm::StringRef Scheme) {
78 if (Scheme == "file")
79 return std::make_unique<FileSystemScheme>();
80
81 for (const auto &URIScheme : URISchemeRegistry::entries()) {
82 if (URIScheme.getName() != Scheme)
83 continue;
84 return URIScheme.instantiate();
85 }
86 return error("Can't find scheme: {0}", Scheme);
87}
88
89bool shouldEscape(unsigned char C) {
90 // Unreserved characters.
91 if ((C >= 'a' && C <= 'z') || (C >= 'A' && C <= 'Z') ||
92 (C >= '0' && C <= '9'))
93 return false;
94 switch (C) {
95 case '-':
96 case '_':
97 case '.':
98 case '~':
99 case '/': // '/' is only reserved when parsing.
100 // ':' is only reserved for relative URI paths, which clangd doesn't produce.
101 case ':':
102 return false;
103 }
104 return true;
105}
106
107/// Encodes a string according to percent-encoding.
108/// - Unreserved characters are not escaped.
109/// - Reserved characters always escaped with exceptions like '/'.
110/// - All other characters are escaped.
111void percentEncode(llvm::StringRef Content, std::string &Out) {
112 for (unsigned char C : Content)
113 if (shouldEscape(C)) {
114 Out.push_back('%');
115 Out.push_back(llvm::hexdigit(C / 16));
116 Out.push_back(llvm::hexdigit(C % 16));
117 } else {
118 Out.push_back(C);
119 }
120}
121
122/// Decodes a string according to percent-encoding.
123std::string percentDecode(llvm::StringRef Content) {
124 std::string Result;
125 for (auto I = Content.begin(), E = Content.end(); I != E; ++I) {
126 if (*I != '%') {
127 Result += *I;
128 continue;
129 }
130 if (*I == '%' && I + 2 < Content.end() && llvm::isHexDigit(*(I + 1)) &&
131 llvm::isHexDigit(*(I + 2))) {
132 Result.push_back(llvm::hexFromNibbles(*(I + 1), *(I + 2)));
133 I += 2;
134 } else
135 Result.push_back(*I);
136 }
137 return Result;
138}
139
140bool isValidScheme(llvm::StringRef Scheme) {
141 if (Scheme.empty())
142 return false;
143 if (!llvm::isAlpha(Scheme[0]))
144 return false;
145 return llvm::all_of(llvm::drop_begin(Scheme), [](char C) {
146 return llvm::isAlnum(C) || C == '+' || C == '.' || C == '-';
147 });
148}
149
150} // namespace
151
152URI::URI(llvm::StringRef Scheme, llvm::StringRef Authority,
153 llvm::StringRef Body)
154 : Scheme(Scheme), Authority(Authority), Body(Body) {
155 assert(!Scheme.empty());
156 assert((Authority.empty() || Body.startswith("/")) &&
157 "URI body must start with '/' when authority is present.");
158}
159
160std::string URI::toString() const {
161 std::string Result;
162 percentEncode(Scheme, Result);
163 Result.push_back(':');
164 if (Authority.empty() && Body.empty())
165 return Result;
166 // If authority if empty, we only print body if it starts with "/"; otherwise,
167 // the URI is invalid.
168 if (!Authority.empty() || llvm::StringRef(Body).startswith("/"))
169 {
170 Result.append("//");
171 percentEncode(Authority, Result);
172 }
173 percentEncode(Body, Result);
174 return Result;
175}
176
177llvm::Expected<URI> URI::parse(llvm::StringRef OrigUri) {
178 URI U;
179 llvm::StringRef Uri = OrigUri;
180
181 auto Pos = Uri.find(':');
182 if (Pos == llvm::StringRef::npos)
183 return error("Scheme must be provided in URI: {0}", OrigUri);
184 auto SchemeStr = Uri.substr(0, Pos);
185 U.Scheme = percentDecode(SchemeStr);
186 if (!isValidScheme(U.Scheme))
187 return error("Invalid scheme: {0} (decoded: {1})", SchemeStr, U.Scheme);
188 Uri = Uri.substr(Pos + 1);
189 if (Uri.consume_front("//")) {
190 Pos = Uri.find('/');
191 U.Authority = percentDecode(Uri.substr(0, Pos));
192 Uri = Uri.substr(Pos);
193 }
194 U.Body = percentDecode(Uri);
195 return U;
196}
197
198llvm::Expected<std::string> URI::resolve(llvm::StringRef FileURI,
199 llvm::StringRef HintPath) {
200 auto Uri = URI::parse(FileURI);
201 if (!Uri)
202 return Uri.takeError();
203 auto Path = URI::resolve(*Uri, HintPath);
204 if (!Path)
205 return Path.takeError();
206 return *Path;
207}
208
209llvm::Expected<URI> URI::create(llvm::StringRef AbsolutePath,
210 llvm::StringRef Scheme) {
211 if (!llvm::sys::path::is_absolute(AbsolutePath))
212 return error("Not a valid absolute path: {0}", AbsolutePath);
213 auto S = findSchemeByName(Scheme);
214 if (!S)
215 return S.takeError();
216 return S->get()->uriFromAbsolutePath(AbsolutePath);
217}
218
219URI URI::create(llvm::StringRef AbsolutePath) {
220 if (!llvm::sys::path::is_absolute(AbsolutePath))
221 llvm_unreachable(
222 ("Not a valid absolute path: " + AbsolutePath).str().c_str());
223 for (auto &Entry : URISchemeRegistry::entries()) {
224 auto URI = Entry.instantiate()->uriFromAbsolutePath(AbsolutePath);
225 // For some paths, conversion to different URI schemes is impossible. These
226 // should be just skipped.
227 if (!URI) {
228 // Ignore the error.
229 llvm::consumeError(URI.takeError());
230 continue;
231 }
232 return std::move(*URI);
233 }
234 // Fallback to file: scheme which should work for any paths.
235 return URI::createFile(AbsolutePath);
236}
237
238URI URI::createFile(llvm::StringRef AbsolutePath) {
239 auto U = FileSystemScheme().uriFromAbsolutePath(AbsolutePath);
240 if (!U)
241 llvm_unreachable(llvm::toString(U.takeError()).c_str());
242 return std::move(*U);
243}
244
245llvm::Expected<std::string> URI::resolve(const URI &Uri,
246 llvm::StringRef HintPath) {
247 auto S = findSchemeByName(Uri.Scheme);
248 if (!S)
249 return S.takeError();
250 return S->get()->getAbsolutePath(Uri.Authority, Uri.Body, HintPath);
251}
252
253llvm::Expected<std::string> URI::resolvePath(llvm::StringRef AbsPath,
254 llvm::StringRef HintPath) {
255 if (!llvm::sys::path::is_absolute(AbsPath))
256 llvm_unreachable(("Not a valid absolute path: " + AbsPath).str().c_str());
257 for (auto &Entry : URISchemeRegistry::entries()) {
258 auto S = Entry.instantiate();
259 auto U = S->uriFromAbsolutePath(AbsPath);
260 // For some paths, conversion to different URI schemes is impossible. These
261 // should be just skipped.
262 if (!U) {
263 // Ignore the error.
264 llvm::consumeError(U.takeError());
265 continue;
266 }
267 return S->getAbsolutePath(U->Authority, U->Body, HintPath);
268 }
269 // Fallback to file: scheme which doesn't do any canonicalization.
270 return std::string(AbsPath);
271}
272
273llvm::Expected<std::string> URI::includeSpelling(const URI &Uri) {
274 auto S = findSchemeByName(Uri.Scheme);
275 if (!S)
276 return S.takeError();
277 return S->get()->getIncludeSpelling(Uri);
278}
279
280} // namespace clangd
281} // namespace clang
282